DRAFT ENV1RONMBMTAL IMPACT STATEMENT ON THE UPGRADING OF THE BOSTON METROPOLITAN AREA SEWERAGE SYSTEM VOLUME • ONE K UNITED STATES ENVIRONMENTAL PROTECTION AGENCY • REGION I JOHA F. KENNEDY FEDERAL BUILDING • GOVERNMENT CENTER BOSTON, MASSACHUSETTS 02203 W • - ------- SUMMARY OF THE RECOI4MENDED PLAN The wastewaters from the member communities of the MDC’S Metropolitan Sewerage District will be treated at a secondary wastewater treatment plant at Deer Island. The existing primary treatment plant at Deer Island will be expanded and upgraded to provide secondary treatment for an average daily wastewater flow of 2,220,000 cubic meters per day (586 mgd), which is estimated will require treatment in the design year of 20C0. The existing inter— ceptor system and related pumping stations will be expanded and mod— if ied as required to handle peak flows. The wastewater from the southern interceptor system will receive preliminary treatment at a headworks at Nut Island and be transported to Deer Island through a pipeline—tunnel system under Boston Harbor. The secondary sludge produced at the Deer Island Treatment Plant will be dewatered and disposed of by a combination of incineration, composting, and direct landfilling. The ash disposal and composting operations will take place at Squantum Point. At present, excessive infiltration/inflow conditions exist in both the local sewer systems and in the MDC’s interceptor sewers. A thorough analysis of this condition is necessary to determine how much of this excess flow can be removed cost effectively. A recently completed tide gate rehabilitation program should result in a reduction in the amount of seawater that enters the interceptor system. The effects of that program should be evaluated to determine the extent of its success. Water conservation is another source of flow reduction that should be employed. Through a conscientious area wide water conservation program significant wastewater flow reduction is possible. While it is recognized that such a program will take several years to gain momentum, it could have a substantial effect in reducing the impact of projected future flow increases. During facilities planning consideration should be given to the effects of flow and waste reduction measures. If these measures are successful in reducing the quantity of wastewater generated, the capacities of the required facilities shculd be reduced. The interceptor system presently serving the MSD is over- loaded in some sections and in need of relief. 1 ------- About 51.5 kilometers (32 miles) of interceptor relief are required in the northern service area. The southern service area requires about 90.5 kilometers (56 miles) of interceptor relief. Space constraints in the Houghs Neck area necessitate that the sewer required to relieve the High Level Sewer be placed under Quincy Bay. This relief sewer required a pumping station at its termination at Nut Island to lift its flow to the same level as the waste- water reaching Nut Island through the High Level Sewer. The wastewater from the southern service area will be transported from Nut Island to Deer Island via a submarine pipeline and tunnel system across Boston Harbor. Before enter- ing this pipeline—tunnel system, the wastewater will receive preliminary treatment, to remove large objects and grit, in a he works provided at Nut Island. The Boston Harbor crossing consists of two 2.74 meter (9.5 foot) diameter pipes installed under the bottom of the harbor between Nut Island and the northern tip of Long Island, and 3.81 meter (12.5 foot) diameter deep rock tunnel under the President Roads Channel between Long Island and Deer Island. In order to meet NPDES permit requirements for wasewater treatment plant discharges, secondary treatment is required. This level of treatment will provide monthly average concen- trations of BOD and suspended solids which are no more than 30 mg/i. This level of effluent discharge requires removal of approximately 85 percent of incoming wastewater pollutants. The air activated sludge process was selected to achieve this level of effluent quality. The method of sludge disposal selected requires that the wastewater streams from the northern and southern service areas be kept separate. Preliminary treatment of the northern service area wastewaters will continue to be provided by the Ward Street, Columbus Park and Chelsea Creek Headworks and the Winthrop Terminal Facility on Deer Island. Wastewater from the southern service area will re- ceive preliminary treatment at a new headworks at Nut Island. This new headworks will include the existing Nut Island plant’s screening and grit removal facilities, which will be renovated and modernized, with additional facilities added to accommodate the increased flows expected. A pumping station located near the southern end of Deer Island will lift the wastewater from the southern service area into pri- mary treatment facilities. The existing primary treatment facilit- ies on Deer Island will be expanded with the addition of eight pri- mary settling tanks for the northern flow, and eight primary sett- ling tanks will be provided for the southern flow. Provision is made for additional primary treatment facilities which will be re- quired for future flows. ii ------- Secondary treatment will be accomplished through the use of twenty aeration tanks for the northern wastewater flow and eleven aeration tanks for the southern wastewater flow. Although the flows will be kept separate, a common air supply will be used for both facilities. Provision is also made for future expansion for this phase of treatment. Final sedimentation tanks provide the other half of sec- ondary treatment at Deer Island. Thirty-two tanks will be provided for the northern wastewater flow, and fifteen tanks will be provided for the southern wastewater flow, with provision made for the addition of facilities for future flows. Sludge collected from the northern flow final sedimentation tanks will be either returned to the northern flow aeration tanks for process control or wasted to the sludge management facility for dewatering and incineration. Sludge collected from the southern flow final sedimentation tanks will be either returned to the southern flow aeration tanks for process control or wasted to the sludge management facility for conditioning and dewatering prior to composting or landfilling operations. Disinfection will be accomplished through the use of chlorine and a chlorine contact basin. Provision will be made for a 15 minute detention time at periods of peak flow. This is the first place in the treatment process where the wastewaters from the north- ern and southern service areas are combined. Effluent discharge is accomplished with an effluent pumping station and a modified outfall structure. Secondary sludge disposal will be accomplished using three methods; incineration, lándf ill and composting. The selection of the methods used was based on the characteristics of the sludge and the desire to provide an acceptable alternative to incineration of all the sludge. The sludge that is wasted to the sludge management facility will be thickened using air flotation thickeners, with separate thickeners used for the northern and southern sludges. After thick- ening, the southern sludge to be composted is conditioned with ferric chloride and lime and is then dewatered in a filter press. The resulting sludge cake is then loaded into containers for shipment to Squantum Point by barge. The portion of the southern sludge to be composted is approximately 23 percent of the total secondary sludge produced, or about 50 percent of the southern secondary sludge. The remaining southern sludge will be taken to anaerobic digestors after thickening, where, in the absence of oxygen, microbial activity produces a stable end product. The fuel value of the gas produced in this process will be utilized to maintain an adequate digestion temperature. After digestion, this sludge will be chemically con- ditioned with ferric chloride and lime, dewatered using pressure filtration, and barged in containers to Squantum Point. From Squantum Point this sludge will be trucked to an MDC operated sludge landfill. 11]. ------- The secondary sludge produced in the treatment of the northern service area wastewaters will be chemically conditioned with lime and ferric chloride following air flotation thickeninq. The re- sulting material will then be dewatered in pressure filters. The resulting sludge cake will be burned in multiple hearth incinerators. The ash, and particulate matter from the air pollution control equipment, will then be loaded into containers for barge shipment to the Squantum Point ash landfill. Storage space for ash and sludge will be provided at Deer Island for inclement weather periods when daily barge shipments may not be possible. Composting and ash landfill operations at Squanturn will occur within the confines of a landscaped earth embankment. The area will be lined with an impermeable liner to prevent leachate from mixing with local groundwater. A leachate collection system will be constructed to collect all rainfall in the landfill area and discharge it to the MDC interceptor in Squantum for return to the treatment plant. Sufficient area will be provided at S uantum Point for twenty years of ash storage. After several years of operation it may be necessary to compost sludge on top of completed ash land- fill areas. When the landfill reaches its design height, it will be covered with topsoil and may be converted to a recreational area. Approximately 91 cubic meters (125 cubic yards) of ash material will be landfiiied at Squantum Point each day. Compost production will vary from 52 to 74 cubic meters (70 to 98 cubic yards). per day depend- ing on the type of bulking agent used. The sludge volume which will be directly landfilled will be approximately 170 cubic meters (227 cubic yards) per day. iv ------- COST OF RECOMMENDED PLAN’ astewater Treatment 404,290,900 Facilities 2 econdary S1U(lge Management 58,784,500 rnterceptor System 3 307,620,000 Total Capital Costs 770,695,400 \mortized Capital Costs 4 59,782,800 operation and Maintenance Costs 24,765,200 Total Annual Costs 84,548,000 Applicant’s share of Cap. Cost (10%) 77,062,500 Applicant’s Share of Amortized Cap. Cost 5,978,300 Applicant’s Share of O & M Costs 24,765,200 Applicant’s Share of Total Annual Cost 30,743,500 (1) Engineering News Record Construction Index = 2654 (2) Includes work at Nut Island and Outfall (3) Includes submerged pipelines, tunnel and related pumping stations (4) Assume average life of facilities = 30 years; Interest rate = 6-5/8 percent V ------- RESOURCE REQUIREMENTS AND OPERATION AND MAINTENANCE COSTS OF THE RECOMMENDED PLAN Resource Wastewater Treatment Sludge Manage— Requirements Plant inent Facilj y Manpower 298 86 Chlorine -Tons/Year 7,135 Fuel Oil-Gallons/Year 706,000 224,214 Electric Power-Xwhr/Year 196,571,000 27,482,675 Lime -Tons/Year 14,600 Ferric Chloride-Tons/Year 3,504 Polymer-Tons/Year 113 Annual Operation & Maintenance Costs ($ Million) $17.14 $6.31 Interceptor System & Related Pumping Stations Annual Operation & Maintenance Costs ($ Million) $1.31 Total Annual Operation & Maintenance Costs ($ Million) $24.76 Note: If it is necessary to purchase wood chips to serve as a bulking agent for the composting operation, approximately 9,000 cubic meters (12,000 cubic yards) of wood chips would be required per year. At a cost of $6.00 per cubic yard for wood chips, the resulting in- crease in the annual operation and maintenance costs for the sludge management facility would be about $72,000 per year. vi ------- TABLE OF CONTENTS Page VOLUME I Summary of Recommended Plan I List of Tables Xi List of Figures xix 1. BACKGROUND 1.1 History of the Grant Application 1-1 1.2 Water Quality and Quantity Objectives and Problems 1-8 1.3 Applicant’s Proposed Action 1-15 2. ENVIRONMENTAL INVENTORY 2.1 climatology 21 2.2 Geology 2—2 2.3 Topography 2-4 2.4 Soils 2—5 2.5 Water Resources 2-6 2.6 Aquatic Biota 2—89 2.7 Terrestrial Biota 2—96 2.8 Air Quality 2—102 2.9 Noise 2—110 2.10 Demography and Land Use 2-114 2.11 Population Projections 2—118 2.12 Energy Production and Consumption 2-120 2.13 Recreational and Scenic Areas 2—121 2.14 Sites of Special Significance 2—123 2.15 Significant Environmentally Sensitive Areas 2—125 3. ALTERNATIVE WASTEWATER MANAGEMENT SYSTEMS 3.1 Introduction 3.1.1 Method of Analysis and Approach 3-1 3.1.2 Constraints and Assumptions Affection Possible Alterna- tives 33 3.1.3 Flow and Waste Reduction Measures 3-11 vii ------- TABLE OF CONTENTS (Continued) Page VOLUME I 3. ALTERNATIVE WASTEWATER M. NAGEMENT SYSTEMS (Continued) 3.2 Preliminary Screening of Subsystem Alternatives 3-19 3.2.1 Interceptor Sewer System, Pumping Stations and Headworks 3-19 3.2.2 Coastal Area Wastewater Treatment Plants 3-32 3.2.3 Inland Satellite Wastewater Treatment Plants 3-73 3.2.4 Land Application of Wastewater Treatment Plant ffluent 3-97 3.2.5 Sludge Treatment and Disposal 3-112 3.3 Intermediate Screening of Subsystem Alternatives 3-127 3.3.1 Coastal Area Wastewater Treat- ment Plants 3-127 3.3.2 Elimination of Coastal Area Treatment Plant Subsystem Alternatives 3-138 3.3.3 Inland Satellite Wastewater Treatment Plants 3-142 3.3.4 Sludge Disposal for Coastal Area Wastewater Treatment Plants 3—156 3.3.5 Sludge Disposal for Inland Satellite Wastewater Treat- ment Plants 3-171 3.3.6 Discussion of the Remaining Sludge Management Systems 3-184 3.4 Final Screening of System Alternatives 3—205 3.4.1 Non-Satellite Systems 3—205 3.4.2 Satellite Systems 3—231 3.4.3 EMMA Plan 3—232 3.4.4 No Action Alternative 3—234 3.4.5 Modified No Action Alternative 3—235 viii ------- TABLE OF CONTENTS (Continued) Page VOLUME I 3. ALTERNATIVE WASTEWATER MANAGEMENT SYSTEMS (Continued) 3.5 Comparison of System Alternatives 3-237 3.5.1 Water Quantity 3-237 3.5.2 Water Quality 3-259 3.5.3 Biota 3—261 3.5.4 Air Quality 3—271 3.5.5 Socio-Economic Effects 3-274 3.5.6 Construction Related Transpor- tation Impacts 3-276 3.5.7 Aesthetics 3—280 3.5.8 Costs 3—280 3.5.9 Conclusion 3—281 4. THE RECOMMENDED PLAN 4.1 Description 4-1 4.1.1 General Description 4-1 4.1.2 Flow and Waste Reduction Measures 4—2 4.1.3 Interceptor Sewer System 4-6 4.1.4 Wastewater Treatment Plants 4-10 4.1.5 Sludge Disposal 4—18 4.1.6 Costs of Recommended Facilities 4—23 5. ENVIRONMENTAL IMPACTS OF THE RECOMMENDED PLAN 5.1 Introduction 5-1 5.2 Water Quality Impacts 5-8 5.3 Water Quantity Impacts 5-15 5.4 Air Quality 5-17 5.5 Noise 5—34 5.6 Biota 5—39 5.7 Socio—Economic Effects 5-42 5.8 Cultural Resources 5-44 5.9 Recreational and Scenic Sites 5-46 5.10 Sites of Special Significance 5—45 5.11 Significant Environmental Sensitive Areas 5-47 6. MEASURES TO MITIGATE ADVERSE IMPACTS 6-1 7. ADVERSE EFFECTS WHICH CANNOT BE AVOIDED 7-1 8. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF RESOURCES 8—i ix ------- TABLE OF CONTENTS (Continued) Page VOLUME I Bibliography Appendices Volume II x ------- LIST OF TABLES Page 1.1-1 Expanded Metropolitan Sewerage District 1-4 1.3—i Applicant’s Proposed Action Costs And Completion Dates For Major Projects 1-17 2.5—1 Nut Island Effluent Characteristics 2—14 2.5—2 Deer Island Effluent Characteristics 2—15 2.5—3 MDC Treatment Plants Sludge Characteristics 2-16 2.5-4 Boston Harbor Major Discharges 2-18 2.5-5 MDC Treatment Plants Toxic 1etals 2-20 2.5-6 Metals In Boston Harbor Waters 2-21 2.5-7 Metals In Boston Harbor Sediments 2-22 2.5-8 Frequency of Overflows Per Year From Each Combined System 2-24 2.5-9 General Quality Comparison Of Wastewaters 2—26 2.5-10 Water Supply Needs Mystic River Watershed 2—36 2.5-11 Mystic River Watershed Discharges 2-38 2.5-12 Water Supply Needs Charles River Drainage Basin 250 2.5-13 Charles River Watershed Discharges 2-54 2.5—14 Combined Sewer Overflow Points Charles Basin 2-58 2.5—15 Water Supply Needs Neponset River Watershed 2-63 2.5—16 Neponset River Watershed Discharges 2-69 xi ------- LIST OF TABLES Page 2.5-17 Water Supply Needs Weymouth River Watershed 2-78 2.5—18 1975 Water Quality Survey Results 2-80 2.5-19 Weymouth River Watershed Discharges 2-82 2.6-1 Characteristics Of A Typical “Clean Stream” 2-90 2.6-2 Characteristics Of A Typical “Polluted Stream” Environment 2-91 2.8-1 Massachusetts And Federal Ambient Air Quality Standards 2-103 2.8-2 Class II Ambient Air Increments 2-107 2.9-1 Common Environmental Noise Levels 2-113 3.2-1 Interceptor Sewer Modifications For Northern MSD Service Area 3-22 3.2-2 Interceptor Sewer Modifications For Southern NSD service Area With Satellites 3—24 3.2-3 Interceptor Sewer Modifications For Southern MSD Service Area Without Satellites 3—25 3.2—4 MDC Pumping Stations 3-31 3.2-5 Comparison Of Primary And Secondary Effluents MDC Wastewater Treatment Plants 3—46 3.2-6 Nut Island Toxic Metals Concentrations 3-47 3.2—7 Deer Island Toxic Metals Concentrations 3-48 3.2-8 MDC Treatment Facilities - Toxic Metals Removals 3-49 xii ------- LIST OF TABLES Page 3.2-9 Summary Of Toxic Metals Removal 3-50 3.2-10 Design Year Assumed Toxic Metals Percent Removal — Coastal Area Treatment Facilities 3-51 3.2—il Residential Metals Contributions 3—54 3.2-12 Dilution Requirements - Southern MDC Service Area Treatment Facility Discharge 3—55 3.2-13 Dilution Requirements - Northern MDC Service Area Treatment Facility Discharge 3—56 3.2-14 Water Quality Criteria - Toxic Metals 3—57 3.2-15 Average Flood Current Speeds And Net Current Speed And Direction - Boston Harbor 3-62 3.2-16 Preliminary Design Specifications - MDC Treatment Plant Outfails 3-64 3.2-17 Comparison Of Diffuser Performance 3—65 3.2-18 Charles River Satellite Treatment Plant Influent — Effluent Characteristics 3—87 3.2-19 Typical Virus Removal Efficiency - Selected Wastewater Treatment Processes 393 3.2-20 Estimated Costs For The Satellite Treatment Plants 3.2—21 Spray Irrigation Sites Within The MSD Service Area 3—102 xiii ------- LIST OF TABLES Page 3.2-22 Spray Irrigation Sites Within The EMMA Study Area And Outside The MSD Service Area 3-103 3.2—23 Rapid Infiltration Sites Within The MSD Service Area 3-104 3.2-24 Rapid Infiltration Sites Within The EMMA Study Area And Outside The MSD Service Area 3-104 3.2-25 Subdivision Of Land Application Areas By Geographic Location For Study Purposes 3-105 3.2—26 Estimated Sludge Characteristics 3-113 3.2-27 Alternative Sludge Processes 3-114 3.2—28 Remaining Sludge Process Alternatives For Coastal Plants 3-123 3.2-29 Remaining Sludge Process Alternatives For Satellite Plants 3-126 3.3-1 Comparison Of Coinposting Methods 3-168 3.3—2 Costs For Non—Satellite Sludge Management Systems 3-188 3.3-3 Energy And Resources Consumed By Non-Satellite Sludge Management Systems 3—189 3.3-4 Estimated Market Potential For Sludge Products 3-195 33-5 Metal To Fixed Solids Ratio For Sludge And Ash For Incinerator Test Sites 3-200 3.3—6 Concentration Of Metals In Particulates 3-202 xiv ------- LIST OF TABLES Page 3.3-7 Fluidized Bed Incinerator - Heavy Metal Mass Balance 3-203 3.3-8 Heavy Metals In Sludge Ash 3-203 3.4-1 Comparison Of Costs 3-228 3.5—i Effects Of Proposed Satellite Plant Discharge On Charles River Flow 3-239 3.5-2 Effects Of Proposed Satellite Plant Discharge On Neponset River Flow 3-240 3.5-3 Year 2000 Waste Flows Charles River Satellite Plant 3-242 3.5-4 Summary Of Year 2000 Sources Contributing To Charles River Satellite Plant 3-243 3.5-5 Year 2000 Water Balance - Charles River Watershed 3-244 3.5-6 Definition Of Terms - Charles River Watershed Water Balance Computations 3-245 3.5—7 Summary Of Year 2000 Flows — Neponset River Satellite Plant 3-248 3.5-8 Summary Of Year 2000 Sources — Neponset River Satellite Plant 3-249 3.5-9 Year 2000 Water Balance - Neponset River Watershed 3—250 3.5—10 Footnotes Table 3.5—9 3—251 3.5—11 Historical Flows — Charles River At Charles River village 3—254 3.5-12 Comparison Of Costs 3—279 xv ------- LIST OF TABLES Page 4.1-1 Interceptor Sewer Modifications For Northern MSD Service Area 4-25 4.1-2 Interceptor Sewer Modifications For Southern MSD Service Area 4-27 4.1-3 MDC Pumping Station Construction Costs 4—29 4.1-4 Tabulation Of Costs For The Recommended Plan Wastewater Treatment Facility 4-30 4.1-5 Resource Requirements And Operation And Maintenance Costs Of The Recommended Plan 4-31 4.1—6 Cost Of Recommended Plan 4-32 5.2-1 Comparison Of Pollutant Discharge Into President Roads 5-9 5.2-2 Dilution Requirements — Year 2000 Deer Island Secondary Plant 5-10 5.3-1 Water Export To Boston Harbor - Year 2000 5—16 5.4-1 Impact Of Recommended Plan On Air Quality 5-18 5.4-2 A Comparison Of Maximum Allowable Emissions And Potential Emissions For The Recommended Plan And The 100% sludge Incineration Alternative 5-20 5,4-3 Percentage Of Prevention Of Significant Deterioration Standards Used By The Recommended Plan 5-21 5.4-4 Minimum Ambient Concentrations Considered To Be Significant Levels 5-28 ‘ cvi ------- LIST OF TABLES Page 5.4-5 Standards And Regulations Influencing Sludge Incineration 5-30 5.4-6 Transportation Related Air Pollution Emissions 5—31 5.5-1 Boston Noise Control Regulations 5-35 5.5-2 Typical Construction Site Equipment Sound Levels 5-37 xvii ------- LIST OF FIGURES Page 1.1-1 Study Area Location 1—5 2.5-1 Watersheds Within the Expanded Metro- politan Sewer District 2—7 2.5-2 Boston Harbor 2-8 2.5—3 Boston Harbor Currents Maximum Flood Tide 2-10 2.5-4 Boston Harbor Currents Maximum Ebb Tide 2—11 2.5-5 Existing and Designated Water Quality Classifications Boston Harbor 2-12 2.5—6 Boston Harbor Discharges 2—17 2.5-7 Mystic River Watershed 2-31 2.5-8 Groundwater Favorability Mystic River Watershed 2-33 2.5-9 Water Quality Classifications Mystic River Watershed 2—35 2.5-10 Mystic River Watershed Pollutant Discharge Locations 2-37 2.5-li Charles River Watershed 2—45 2.5—12 Charles Basin Watershed 2-47 2.5-13 Groundwater Favorability Upper Charles River WaterShed 2-49 2.5-14 Groundwater Favorability Lower Charles River Watershed 2-50 2.5-15 Water Quality Classifications Charles River Watershed 2-54 2.5-16 Charles River Watershed Pollutant Discharge Locations 2-55 2.5-17 Combined Sewer Overflows Charles River Basin 2—59 xix ------- LIST OF FIGURES (Continued) Page 2.5-18 Neponset River Watershed 2—63 2.5—19 Groundwater Favorability Neponset River Watershed 2—67 2.5—20 Neponset River Watershed Water Quality Classification 2—69 2.5—2]. Pollutant Discharge Locations Neponset River Watershed 2-70 2.5-22 Weymouth River Watershed 2-76 2.5—23 Groundwater Favorability Weymouth River Watershed 2-78 2.5—24 Water Quality Calssificatic hs Weymouth River Watershed 2-79 2.5—25 Pollutant Discharge Locations Weymouth River Watershed 2-83 2.5-26 Sudbury River Watershed 2-86 2.5—27 Water Quality Classifications Sudbury River Watershed 2-88 2.5-28 Groundwater Favorability Suasco River Watershed 2—89 3.2—1 Interceptor Relief, Extension Sewer, And Pumping Station Work Required For Alternatives Which Include Satellite Treatment Plants 3-27 3.2-2 Interceptor Relief, Extension Sewer, And Pumping Station Work Required For Alternatives Which i5o Not Include Satellite Treatment Plants 3—29 3.2-3 Coastal Treatment Plant Sites Considered 3-33 3.2-4 Historic Filling Trends In Boston Harbor 3-43 3.2-5 Potential Discharge Locations - Coastal Area Treatment Facilities 3—59 xx ------- LIST OF FIGURES (Continued) Page 3.2-6 Boston Harbor Current Meters 3—61 3.2-7 Discharge Point “A” Dilution Ratios 3-67 3.2-S Discharge Point “A” Dilution Ratios 3-68 3.2-9 Satellite Sites In The Mid-Charles Basin 3—76 3.2-10 Satellite Sites In The Upper Neponset Basin 3—77 3.2-li Potential Discharge Points — Neponset River AWT Facility 3-89 3.2—12 Potential Land Applications Sites Within The EMMA Study Area 3-101 3.3-1 Additional Sites Evaluated By Mid-Charles Site Evaluation Committee 3-147 3.3-2 Alternative Discharge Locations - Charles River Satellite Plant 3-152 3.3-3 Landfill Alternatives 3—157 3.3-4 Incineration Or Pyrolysis Alternatives 3-158 3.3-5 Give Away Or Market Alternatives 3-160 3.3-6 Land Application Alternatives 3-161 3.3—7 Coincineration Alternatives 3—162 3.3—8 Landfill Alternatives 3—172 3.3-9 Alternatives For Incineration Or Pyrolysis At Both Inland Plants 3-173 3.3-10 Alternatives For Incineration Or Pyrolysis At One Inland Plant 3-174 xxi ------- LIST OF FIGURES (Continued) Page 3.3—11 Give Away Or Market Alternatives 3-176 3.3—12 Resource Recovery Center Alternatives 3-177 3.3-13 Disposal At Coastal Area Plant Alternatives 3-178 3.3—14 Land Application Alternatives 3-179 3.3—15 Remaining Sludge Disposal Alternatives 3-185 3.3-16 Alternative Plant Capacities For Sludge Treatment And Disposal 3-186 3.4-1 Deer Island Wastewater Treatment Plant For North MSD Service Area 3-209 3.4—2 Broad Meadows Wastewater Treatment Plant 3-211 3.4-3 Coastal Area Facilities Required For Deer Island - Broad Meadows Alternative 3-213 3.4-4 Nut Island Facilities Required With A Broad Meadows Or Squantuin Plant 3-215 3.4-5 Squantuin Wastewater Treatment Plant 3-217 3.4-6 Coastal Area Facilities Required For Deer Island - Squantum Alternative 3-219 3.4—7 Deer Island Wastewater Treatment Plant For Total MSD Service Area 3-221 3.4—8 Coastal Area Facilities Required For The All Deer Island Alternative 3-22 3 3.4—9 Nut Island Facilities Required With Treatment For Entire MSD Service Area At Deer Island 3-225 3.5—1 Water Sources - Charles River Satellite Plant — Year 2000 3-246 3.5—2 Water Sources — Neponset River Satellite Plant - Year 2000 3-252 xxii ------- LIST OF FIGURES (Continued) Page 3.5-3 Flow Duration Curves - USGS Gaging Station At Waltham, Mass. 3-256 4.1-1 Recommended Plan Facilities Location Map 4-7 4.1-2 Nut Island Facilities Required For Recommended Plan 4-15 4.1-3 Recommended Plan Deer Island Facilities 4-17 4.1-4 Sludge Management Flow Diagram And Solids Balance 4-19 4.1-5 Squantum Point Ash Landfill And Sludge Composting Area 4-21 5.4-1 Annual Estimated Sulfur Dioxide Levels In 1980 5—23 5.4-2 Annual Estimated Sulfur Dioxide Levels In 1985 5—24 5.4-3 Annual Estimated Total Suspended Particulate Levels in 1980 5-25 5.4-4 Annual Estimated Total Suspended Particulate Levels In 1985 5-26 xxiii ------- CHAPTER 1 BACKGROUND 1.1 HISTORY OF THE GRANT APPLICATION The Metropolitan District Commission (MDC) of the Commonwealth of Massachusetts is responsible for the operation of the Metropolitan Sewerage District (MSD), Metropolitan Parks District and the Metropolitan Water District. The MSD currently consists of 43 member commun- ities with a population of more than two million people and a service area of more than 1000 square kilometers (400 square miles). As the governing agency controlling the essential services of wastewater transport, treatment and disposal, water supply, and parks systems for a large metropolitan area, the MDC requires long—range planning to maintain adequate levels of service in all of its areas of jurisdiction. The direct operation of the current wastewater manage- ment facilities is the responsibility of the Metropolitan Sewerage District (MSD). This agency has a long history of providing wastewater management services for its member communities. Originally created in 1889 by legislative action based on recommendations of the State Board of Health, the MSD was charged with the responsibility of providing the common action required to reduce the discharge of raw sewage into the Mystic, Charles and Neponset Rivers. Until that time, local sewer systems which expanded with the growth of towns and the City of Boston had been discharging their untreated wastes directly into the three major rivers tributary to Boston Harbor. The initial MSD consisted of 18 cities and towns, including portions of Boston not served by the City’s Boston Main Drainage System. The system at that time consisted of intercepting sewers, pumping facilities, tunnels and storage tanks at Moon Island. The treatment process at that time was to discharge accumulated wastes into Boston Harbor on outgoing tides. The MSD had expanded its service area by 1895 to include the communities along the Charles River of Waltham, Water- town, the Brighton section of Boston, and parts of Newton and Brookline. These areas were added to the Boston Main Drainage System. Additional facilities (interceptor sewers, pumping stations and outfalls off Deer Island) were constructed to serve the northern towns of Arlington, Belmont, Cambridge, Chelsea, Everett, Maiden, Meirose, Somerville, Stoneham, 1—1 ------- Winchester, Winthrop, Woburn, and the Charlestown and East Boston sections of Boston. By 1898, Dedham, Hyde Park, Milton, and additional parts of Newton and Brookline were also included in the MSD service area. A third system of outfalls was constructed off Nut Island in 1904, with its associated interceptors and pumping stations. The overloaded Boston Main Drainage System was relieved by diverting flows from Brookline, Dedham, Hyde Park, Milton, Newton, Quincy, Waltham and Watertown to the Nut Island outfalls. Over the years, system changes were made, changing the service provided from interception, transport and disposal to interception, transport, treatment and disposal. The introduction of the treatment phase resulted in the de— commissioning of the Moon Island facility and the construction of the Nut and Deer Island Primary Treatment Facilities. The MSD now operates the Nut and Deer Island Primary Treatment Plants, the Somerville Marginal Conduit Treatment Facility, the Cottage Farm Storm Water Detention Facility, 12 pumping stations, 4 headworks, about 8000 kilometers (5000 miles) of local sewers, approximately 360 kilometers (225 miles) of interceptor sewers and numerous major combined sewer overflows. The Moon Island facility is operated on a standby basis by the City of Boston to provide relief during wet weather emergency periods. The passage of PL92-500, the Water Pollution Control Act of 1972, makes discharge of any pollutant illegal unless it is in compliance with Effluent Limitations of the Act set forth in Section 301. Discharge of treatment plant effluent meeting this criteria is regulated by Section 402, National Pollutant Discharge Elimination System (NPDES). Under this system the discharges of all wastewaters are regulated to provide centralized coordination and restriction of discharges to improve the quality of water resources both in and around the nation. This is the primary goal of the Act. The NPDES Permit sets the limits of permissable discharges. The current permit issued to the MDC, NPDES Permit No. MA0102351 (State No. M—180), requires primary treatment at both facilities with secondary treatment to be provided by July 1, 1977. Prior to this July, 1977 deadline, both the EPA and the MDC negotiated an extension of time for compliance with the secondary treatment implementation requirement. An extension was granted in an EPA Enforcement Compliance Schedule Letter which contains a listing of requirements and a timetable for their accomplishment. The requirements include; completion of Infiltration/Inflow Analyses of the entire MDC interceptor system, facilities for primary sludge disposal, upgrading and expanding the Nut and Deer Island treatment plants to secondary treatment, 1—2 ------- secondary sludge disposal facilities, combined sewer overflow abatement and interceptor sewer system extension and relief. To provide the necessary level of treatment for the current and future volumes of wastewater production and to determine the practical and economic limits of regional wastewater treatment, the MDC contracted an engineering consultant, Metcalf and Eddy, Inc., to perform a study to determine: a) the ultimate service area for the MDC; b) the locations and sizes of the various facilities necessary to provide treatment for the sewage produced in the service area; c) the estimated costs of these facilities; and d) organization and scheduling recommend- ations for the implementation of regional treatment. As a result of resolutions passed by the committees on public works of the U.S. Senate and U.S. House of Representatives in 1972, the Corps of Engineers became a co—participant with MDC in the study. The Study, Wastewater Engineering and Management Plan for Boston Harbor - Eastern Massachusetts Metropolitan Area , usually referred to as the EMMA Study, visualized an enlarged MSD service area with the addition of eight communities to the 43 existing member communities. (See Figure 1.1-1). A list of the communities which make up this enlarged service area is shown in Table 1.1—1. This plan includes construction of two advanced wastewater treatment facilities on the Charles and Neponset Rivers, and expanding and upgrading the existing Deer Island and Nut Island primary treatment plants to provide secondary treatment to the wastewater flows anticipated to be generated in the year 2000. The estimated cost of this plan at the time of completion of the EMMA Study was $855,000,000, based on January, 1975 prices. A significant portion of this cost is eligible for Federal funding through grants pursuant to Title II of the Federal Water Pollution Control Act of 1972, as amended. These grants will be administered through Region I of the U.S. Environmental Protection Agency. All Federal agencies are required to prepare an Environmental Impact Statement (EIS) in connection with their proposals for major Federal actions having a significant impact on the quality of the human environment. The anti- cipated Federal participation associated with implementation of the Recommended Plan, as presented by the MDC, constitutes such a major Federal action. In September, 1976, EPA Region I contracted with the firms of Greeley and Hansen and the Environmental Assessment Council, Inc. to assist in the preparation of an Environmental Impact Statement (EIS). The objective of the EIS is to determine the most environmentally acceptable, cost effective method of upgrading the MDC’S wastewater management system. 1—3 ------- TABLE 1.1-1 EXPANDED METROPOLITAN SEWERAGE DISTRICT SERVICE AREA Arlington Natick Ashland Needham Bedford Newton Belmont Norwood Boston* Quincy Braintree Randolph Brookline Reading Burlington Revere Cambridge Sharon** Canton Sherborn** Chelsea Somerville Dedham Southborough** Dover** Stoneham Everett Stoughton Framingham Wakefield Hingham Walpole Holbrook Waltham Hopkinton ** Watertown Lexington Wellesley Lincoln** WestOfl*** Lynnfield ** Westwood Maiden Weymouth Medford Wilmington Meirose Winchester Milton Winthrop Woburn *Boston Boston Proper Brighton Charlestowfl Dorchester East Boston Fenway—JamaiCa Hyde Park Mattapan Roslindale Roxbury South Boston West Roxbury ** Not presently an MSD member community. Weston has voted not to join the MSD. 3--- 4 ------- \ ./ / - (/ CA*?S4( MA S SAC HUS( ITS SAY EXISTING MSD SERVICE AREA NOTE: WESTON HAS VOTED NOT TO JOIN THE MSD / NThA / -. / POTENTIAL ENLARGED MSD SERVICE AREA LEGEND COMMUNITIES WHICH WILL POSSIBLY BE ADDED TO THE MSD SERVICE AREA A PORTION OF HINGHAM IS PRESENTLY SERVED BY THE MSD FIGURE Il-I STUDY AREA LOCATION i ..—_-‘_c ------- Various wastewater management alternatives, in addition to the MDC’S Recommended Plan, are to be considered. The principal factors to be considered in the development of alternatives are: 1) The feasibility of satellite treatment plants as compared with continued centralized treatment in the vicinity of Boston Harbor. 2) The possibility of locating treatment facilities at locations in the vicinity of Boston Harbor other than at Nut Island and Deer Island. 3) The upgrading of wastewater treatment facilities to a level of secondary treatment will require the disposal of considerably more sludge than is required for the existing primary treatment facilities. Therefore, alternative techniques for the disposal of secondary sludge are to be evaluated. Several other studies will also have an affect on the wastewater management system of the study area. These include the Infiltration/Inflow (I/I) and the Combined Sewer Overflow Regulation (CSO) studies being performed by the MDC and the 208 Areawide Waste Treatment Management Plan prepared by the Metropolitan Area Planning Council (MAPC). The CSO study will examine a range of alternatives of both a structural and non—structural nature to control combined sewer overflow discharges. The study will consider the costs, environmental impacts, implementation factors, and benefit/cost ratios of the alternatives under a range of design storms. Alternatives to be evaluated include: improved system maintenance; sewer flushing; sewer cleaning; in-line storage; sewer separation; off—line storage; and detention/chlorination. The elimination of untreated combined sewer overflows should have a major positive impact on the quality of waters adjacent to the metropolitan area. An I/I analysis of the MDC interceptor system tributary to Deer Island was prepared by Camp, Dresser and McKee, Inc. For the MDC interceptor system tributary to Nut Island, an I/I analysis is being prepared by Fay, Spof ford and Thorndike , Inc. The analysis for the Deer Island service area was finalized in March of 1978, and the analysis for the Nut Island service area is expected to be finalized during the Fall of 1978. It is anticipated the Evaluation Survey (the next step in the I/I study) will be conducted during the Spring of 1979 for both service areas. 1—6 ------- Under the proposed MDC sewer use ordinance, the MDC will have the power to direct member cc’mmunities to correct their I/I problems, if they find the problems to be excessive or unacceptable. The MDC is currently develcping criteria for identifying member communities which have such problems, as well as a procedure to implement their enforcement powers. The correction of I/I problems in sewer segments where I/I is found to be excessive could reduce the capacity requirements of both sewers and treatment plants. The results of the I/I studies should be examined upon their completion and capacity requirements adjusted accordingly. The 208 Areawide Waste Treatment Management Plan did not focus on the E study area. Although it did include some wcrk in fringe areas of the EMMA study area, the information gatbered in the 208 Study and the EMMA Study were basically intended to complement each other, and to avoid duplication of effcrt. In addition, the MDC is currently in the process of preparing a Scope of Work for the Facilities Planning process. This process will be done in phases, and it is anticipated that the entire effort will take approximately two years to complete. There will be opportunities for public participation during Facilities Planning. Throughout this EIS, various items have been recommended for inclusion in the Facilities Planning process. Some of the major items for which investigations during Facilities Planning are recommended are: Quantities of wastewater flow Wastewater treatment methods Sludge treatment and disposal methods Outfall location and design Interceptor design and routing 1—7 ------- 1.2 WATER QUALITY AND QUANTITY OBJECTIVES AND PROBLEMS 1.2.1. Water Quality and Quantity Objectives The Commonwealth of Massachusetts, Division of Water Pollution Control is the State agency responsible for the administration of the goals and objectives of the Massa- chusetts Clean Waters Act of 1967 (MCWA), which has been partly repealed and amended to take into account the sub- sequent publication of the Federal Water Pollution Control Act (FWPCA) amendments of 1972 (PL92-500). In order to achieve the objectives of the NCWA & FWPCA the Division has divided the waters of Massachusetts into 8 classifications, 5 for fresh water bodies and 3 for salt water bodies, depending on whether their physical, biological and chemical constituents meet pre—set criteria. For example, “Class A or SA” is fit for public water supply or fishing and contact activities while “Class C or SC” is the least desirable classification. Along with these published “Water Quality Standards”, a set of regulations that is designed to prevent further degradation of classified waters is also in effect. The Commonwealth of Massachusetts is currently considering revisions to the standards. Under Massachusetts General Law Chapter 131 Section 40A and Chapter 130 Section 105, the development of wetlands (inland and/or coastal) is regulated. Several towns within the Charles River drainage basin (Dedham, Dover, Needhain, Newton, Walpole, Waltham, Wellesley and Westwood) have mapped and recorded areas in which they are enforcing the provisions of Chapter 131, Sec. 40A (Inland Wetlands Restriction Act) restricting development of certain inland wetlands. Furthermore, Congress has authorized the U.S. Army Corps of Engineers to proceed with wetlarxls acquisition for the “Natural Valley Storage” concept for the Charles River watershed. The objectives are not only to provide flood control but also to assure the protection of recharge areas important for groundwater supplies and to provide open spaces. The development of the Boston Harbor Islands as major conservation and water—oriented recreation resources is recommended in the Boston Harbor Islands Comprehensive Plan of the Metropolitan Area Planning Council (1972) as an important objective for the study area. This plan has been agreed upon in principal by all affected agencies as the basis of harbor facilities planning. The Massachusetts Coastal Zone Management Program also presents environmental objectives to maintain the Massachusetts Coastal Zone as an asset to the State, by providing guidelines affecting develop- ment of coastal area on a state—wide basis. 1—8 ------- 1.2.2. Water Quality and Quantity Problems The MSD’s service area coincides with a major portion of Boston Harbor’s natural drainage area, while also including portions of the Sudbury River, Ipswich River and North Coastal drainage basins. The principal drainage basins within the Boston Harbor drainage area are those of the Mystic, Charles, Neponset and Weymouth Rivers. The major water quality and water quantity problems in the study area are briefly discussed below. A more detailed discussion is given in Chapter 2 — Environmental Inventory. A. Boston Harbor . The major sources of water pollution in Boston Harbor are: 1) combined sewer overflows; 2) treated wastewater and sludge discharges; 3) raw wastes and industrial outfalls; 4) tributary streams; 5) urban runoff; and 6) debris, refuse and oil. The Inner Harbor area is classified “SC” by the Massachusetts Division of Water Pollution Control. A classification of “SC” designates waters which are suitable for recreational boating, fishing and industrial process uses, but unsuitable for swimming and shell fishing. The Outer Harbor is classified “SB” which designates waters which are suitable for water contact sports as well as boating and shell fishing with depuration. Combined sewer overflows present the greatest threat to public health and aesthetics of the Harbor and its tributaries due to the high fecal coliform content, floating debris, and solids present in the discharge. Combined sewers are sewers which collect and transport both sanitary wastewater and storm water. Overflows are the result of the hydraulic overloading of one of the oldest combined sewer systems in the nation. A densely populated area of approximately 50 sq.km. (19.2 sq.mi.) that includes Boston, Brookline, Cambridge, Chelsea and Somerville is served by this combined sewer system. The elimination of these presently untreated combined sewer overflows would be a significant step toward the development of the recreation and economic potential of the Harbor and its tributaries. An evaluation of the impacts of combined sewer overflows and possible solutions is not part of this EIS. The primary objective of this EIS is to determine the most environmentally acceptable, cost-effective wastewater management system for the municipal wastewaters generated in the MDC service area. In addition, there have been many malfunctioning tide gates and regulators which have allowed sewers to discharge to the Harbor at low tide and during dry weather (New England Division, Corps of Engineers, 1975). These faulty appurtenances have also allowed seawater intrusion into the sewer system at high tides, thereby increasing flows at the wastewater treatment facilities and decreasing treatment facility efficiencies. It has been reported that a tidegate rehabilitation program has recently been 1—9 ------- completed, and it is expected that these improvements will contribute favorably to the water quality of the Harbor. The current characteristics of the effluents discharged through the treatment plant outfalls at Nut Island and Deer Island indicate that both treatment facilities are overloaded due to storm water runoff and infiltration and inflow into the sewerage system. As a result, these flows receive less than efficient primary treatment. In addition, the digested sludge from both facilities is discharged near the President Roads Channel during periods of ebb tides. The digested sludge is a major source of coliform bacteria and trace metals. The proposed expansion and upgrading to secondary treatment of the treatment facilities serving the MSD service area will provide a comprehensive wastewater treatment and sludge management system that will have a positive impact on the water quality of the Harbor. However, the infiltration/inflow problem must be adequately defined if the proposed solutions are to be truly efficient and cost-effective. A 1976 study by the Massachusetts Division of Water Pollution Control showed that several industries discharge into the Harbor. These discharges consist mostly of cooling water and storm water. Surveys made by the USEPA in 1975 indicated that street drain discharges are contributing to bacterial contamination of Wollaston Beach. Oil from oil terminals, particularly along the Chelsea River, is a major pollutant in Boston Harbor. Debris and refuse in the Harbor cause severe deterioration of the aesthetic quality of the Harbor and hazards to navigation. Although in some instances the degradations caused by these various pollution sources are localized or even minimal if viewed individually, they are nevertheless the components of a much broader problem which must be solved by a compre- hensive approach. B. Mystic River Drainage Basin . The Mystic River drainage basin consists of approximately 179 sq. km. (60 sq.mi.) immediately north of the City of Boston. This basin consists of three distinct sections; the Aberjona River, the Mystic Lakes and the Mystic River. The Upper and Lower Mystic Lakes separate the Aberjona and Mystic River systems. Discharge from the Lower Mystic Lake forms the Mystic River which flows 12 km. (7.4 ml) in a southeastern direction to Boston Harbor. Estimates of flow for this river have been made and yield an average flow of 2.38 to 2.61 m 3 /s (84 to 92 cf s) at its mouth. Corresponding maxynum and minimum flows were estimated to be 75.05 to 82.30 m /s (2650 to 2906 cf s) and 0.020 to 0.024 m 3 /s (0.72 to 0.84 cfs) respectively (Beauregard, 1975). Major sources of pollutant input to the Mystic River 1—10 ------- basin are urban runoff, combined sewer overflows and non- point sources such as solid waste landfill leaching. The point sources that exist are diverted out of the basin and treated at the Deer Island Treatment Plant. These discharges out of the basin, via the MDC sewer system, result in abnormally low stream flow. The Upper and Lower Mystic Lakes have exper- ienced a continued degradation of water quality in recent years. Euthrophic conditions exist in parts of the lakes. At the Upper Mystic Lake, the nutrient rich Aberjona River is the primary contributor of pollutants. Saltwater trapped in the Lower Mystic Lake due to the construction of the A. Earhart Dam in 1966 continues to be a major disruption of the ecological balance of the water body (Beauregard, 1975). The alternatives being considered in this EIS will not have any effect on the Mystic River drainage basin. The elimination of untreated combined sewer overflows should have a positive effect on the river section adjacent to the metro- politan area. C. Charles River Drainage Basin . The Charles River drainage basin occupies the central portion of the Boston Harbor drainage area covering an area of 789 sq.km. (305 sq.mi.). This area coincides with all or part of 32 municipalities, including a large portion of the City of Boston. The Charles River has a total length of 129 km. (80 mi.) due to extensive meandering. Flow measurements taken just downstream of the Cochrane Dam by the United States Geological Survey in Charles River village yielded an average flow of 8.4 3 m 3 /s (296 cfs); with maximum and minimum flows of 91.2 m Is (3220 cfs) and 0.014 m 3 /s (0.5 cfs) respectively. Due to high bacterial counts, only a few lakes within the Charles River drainage basin are presently used for swimming. Presently, the majority of the Charles River’s length provides only non—contact, passive recreation opportunities because of its degraded water quality (New England Division Corps of Engineers, 1975). Major pollutant sources in the upper basin include municipal wastewater discharges, solid waste disposal site runoff, septic tank and cesspool discharges, industrial discharges and urban runoff. In the lower basin (the Charles Basin) major sources of pollution are combined sewer overflows, urban runoff and salt water intrusion. Ground- water reservoirs in the Charles River drainage basin are hydraulically interconnected to the river or its tributaries and well withdrawals from these aquifers may result in stream f low infiltration into the groundwater system. Approximately 49,150 m 3 /d (13 mgd) of water is withdrawn from groundwater resources and is discharged out of the basin by the sewer system. The depletion of groundwater supplies and subsequent recharge from surface sources compounds the problem of low flows in the Charles River during the summer months. Low flow augmentation of the Charles River can be 1—11 ------- accomplished by treating the wastewater generated within the drainage basin at an inland satellite treatment plant and discharging the effluent to the Charles River. The discharges of a Charles River satellite plant could potentially have the dual advantages of providing low flow augmentation to the Charles River and relieving the hydraulic loading on the sewage collection system and coastal wastewater treatment facilities. However, consideration must be given to the possible adverse effects the effluent from a satellite plant may have on the water quality of the Charles River. D. Neponset River Drainage Basin . The Neponset River originates 46.7 km. (29 miles) southwest of Boston at the outlet of the Neponset Reservoir in Foxborough, Massachusetts. The river flows generally in a northeastern direction for 47.5 km. (29.5 miles) before discharging into Dorchester Bay. The entire drainage basin lies within the expanded I4SD except for a portion of Foxborough at the basin’s headwaters. The drainage area consists of 318.6 sq.krn. (123 sq.mi.). The Neponset River is one of the most critically polluted rivers in the Metropolitan Boston area. Only the headwaters, which flow rapidly, are of relatively good quality. Starting at the Town of Walpole, the river is characterized by a reduction in dissolved oxygen concentration. Industrial discharges, domestic wastes, oil discharges and solids contribute to the degradation of the river throughout its length. A survey made in the summer of 1973 by the. Massachusetts Division of Water Pollution Control indicated that the Neponset Reservoir in Foxborough was eutrophic. The effluent of Foxborough State Hospital is thought to provide nutrients for the extensive algal and aquatic vascular plant growth present in the Neponset Reservoir. Below this point, Foxborough Raceway is suspected of being a source of fecal contamination of the river. Industrial discharges near Walpole in combination with urban runoff is responsible for increasing BODt and coliform bacteria in the area. Urban runoff and non— point sources from the areas of Milton and Mother Brook also contribute to the increase of BOD 5 , coliform bacteria and nutrient loading of the Neponset River. Frequent overflows occur from the Neponset River Valley Sewer and the Dorchester Interceptor into the lower reaches of the Neponset River, threatening water quality of the lower river and estuaries (New England Division, Corps of Engineers 1975). In a 1973 survey, Frimpter found that groundwater in the Neponset drainage basin to be of a chemical quality suitable for drinking and most industrial uses. However, it is apparent from available data that chloride concentration in public supply wells may be on the increase. Speculation has been made that the sources of chloride contamination are stockpiles of salt for snow removal and runoff from paved areas (New England Division, Corps of Engineers 1973). Although low flow conditions exist 1—12 ------- in the Neponset River during summer months, the precise extent of this problem is difficult to determine because flow in the river is subject to active regulation for industrial water supply. Groundwater withdrawals from wells in close proximity to the river have been found to cause low flow problems in the basin (Metcalf and Eddy 1969). One alternative to the low flow problem is the construction of an inland satellite wastewater treatment plant discharging to the Neponset River. Objectives of such a facility would be to contribute to low flow augmentation by discharging its effluent to the river and to reduce the hydraulic loading on the sewerage system and the coastal treatment facilities. As mentioned in the discussion of the Charles River drainage basin, consideration must also be given to the possible adverse effects that satellite treatment plant effluent may have on the water quality of the Neponset River. E. Sudbury River Drainage Basin . This drainage basin has a drainage area of 438 sq.km. (169 sq.mi.) of land which dis- charges in the 66 km. (41 mile) length of the Sudbury River. Towns within the drainage basin that are being considered for inclusion in the MSD are Southborough, Hopkinton, and additional parts of Ashland, and Framingham. A survey of the Sudbury River, conducted by the Massachusetts Division of Water Pollution Control in 1973, indicated high coliforni bacteria levels along the entire length of the segment of the river that is within the study area. Overloaded septic tank systems in the upper portions of the segment and urban runoff, septic leachate, and storm and sanitary sewers in the heavily populated areas of Ashland and Framingham are thought to be sources of fecal contamination. Dissolved oxygen levels were found to be below 5 milligrams per liter (mg/i). Excessive concentrations of nutrients were not present. No point sources of pollution are contributed to the Sudbury River by the four towns of the Upper Basin which lie within the study area. Implementation of the wastewater management plan for the MSD service area will provide for collection of sanitary sewage, thereby removing a portion of the pollutant load from the Sudbury River through the elimination of the use of septic systems in these areas. F. Weymouth River Drainage Basin . The Weyrnouth River drainage basin consists of approximately 230 sq.km. (89 sq.mi.) in the towns of Randolph, Braintree, Hingham, Holbrook, Weymouth and a portion of the City of Quincy that is drained by the Weymouth Fore River, Weymouth Back River and Weir River. The waters in this region are classified as “B” and “SB”. The lower reaches of both the Weymouth Fore River and Back River do not meet their classifications. Surveys of dissolved oxygen indicate that portions of the river fall below the minimum required dissolved oxygen level of 6 mg/i, but most of the river is well oxygenated with dissolved oxygen in excess of the minimum. Sampling has also indicated that fecal coliform levels are in excess of what is permissable, indicating considerable bacterial contamination. A survey of wastewater discharges 1—13 ------- in the drainage basin has indicated that both point and non- point sources are contributing pollutants to the Weymouth River drainage basin. The major contributors appear to be septic tank drainage and storm water runoff. At the present time, no water quantity problems are present in the basin, with adequate recharge of groundwater resources possible through the riverbeds. Future changes in water use and discharge in the basin should be considered to preserve this balance. For the most part, the waters of the Weymouth River drainage basin will not be affected by the implementation of any of the proposed facilities. The objective of this EIS is to determine the most environmentally acceptable and cost effective areawide wastewater management plan for the MDC service area. The formulation and implementation of such a plan will improve water quality by providing a higher level of treatment for much of the waste ater generated in the Boston Harbor drainage area• •The higher level of treatment will reduce the daily contribution of pollutants in the drainage area. 1—14 ------- 1.3 APPLICANT’S PROPOSED ACTION The Metropolitan District Commission (MDC) has presented a comprehensive plan for wastewater management in its report, Wastewater Engineering and Management Plan for Boston Harbor - Eastern Massachusetts Metropolitan Area (EMMA Study). The principal recommendations of this report to achieve clean water goals established for Boston Harbor and its tributary rivers are: 1) Upgrading the Deer Island and Nut Island treatment plants from primary to secondary treatment. 2) Sludge disposal by means of incineration as recommended in a 1973 report prepared for the MDC by Havens and Emerson, Consulting Engineers, entitled A Plan for Sludge Management . 3) Alleviating combined stormwater—sewage overflows. 4) Construction of two advanced waste treatment plants on the Charles and Neponset Rivers. 5) Extension and improvement of the MDC’S interceptor system. This section will briefly describe the MDC’s proposed wastewater management plant (Proposed Action) The Proposed Action visualizes increasing the service area of the MSD through the addition of the Towns of Lincoln, Lynnfield, and Weston to the Deer Island service area and the addition of Dover, Hopkinton, Sharon, Sherborn and Southborough to the Nut Island service area. The treatment plant at Deer Island would be expanded and upgraded to provide secondary treatment for the increased flows from its service area. Two inland satellite wastewater treatment plants would be constructed in the Nut Island service area to reduce the extent of the expansion required at Nut Island, and to retain the wastewaters in their basins of origin, providing low—flow augmentation for the Charles and Neponset Rivers. The satellite plant that would discharge to the Charles River would serve Ashland, Framingham, Hopkinton, Natick, Sherborn and Southborough as well as parts of Dover and Wellesley. The other satellite plant would discharge to the Neponset River and serve Sharon, Stoughton and Walpole, as well as parts of Norwood and Canton. The remainder of the wastewater from the Nut Island service area would receive secondary treatment at an expanded and upgraded treatment plant at Nut Island. 1—15 ------- Advanced waste treatment facilities are recommended at both satellite plant sites in an effort to provide effluent of sufficient water quality to prevent further degradation of the two rivers. In addition to providing supplementary flow to both rivers and reducing the amount of expansion required at Nut Island, the satellite plants would also reduce the load on the interceptor system downstream of their respective locations by diverting about 117,200 m 3 /day (31 rngd) to the Middle Charles River plant and about 94,500 m 3 /day (25 mgd) to the Upper Neponset River plant in the year 2000, thereby reducing the amount of interceptor sewer relief work required. The expansion and upgrading of the Nut Island and Deer Island primary treatment facilities to provide secondary treatment for 491,500 m 3 /day (130 mgd) and 1,512,000 m 3 /day (400 rngd) of wastewater respectively in the year 2000 would require substantial increases in plant facilities. Nut Island is almost completely occupied by the present treatment facility, leaving little space available for expansion. The expansion and upgrading to secondary treatment of the Nut Island plant would require some filling of Quincy Bay. Some of the facilities required for an expanded and upgraded secondary treatment plant on Deer Island would be constructed on an adjacent area of fill in Boston Harbor. Sludge generated at the Nut Island and Deer Island plants would undergo incineration at Deer Island. (The sludge from the Nut Island plant would be piped to Deer Island). Another phase of the Proposed Action to upgrade the waters in the Boston Harbor area is the abatement of uncontrolled combined sewer overflows to the Harbor and its tributaries. Three alternative combined sewer overflow treatment and di posa1 schemes in the immediate Boston Harbor area are presented to address this problem. Each of these alternatives provides for collection, treatment and disposal facilities to replace the numerous combined sewer overflows into the Harbor. Modifications to the interceptor system have been provided to relieve existing overloaded conditions and to provide adequate capacity for future flows. The extent of this work is distributed throughout the service area, in urban as well as suburban areas. Under the MDC’S Proposed Action, extension of interceptors would be required to serve new member communities. In addition, renovation or replacement of each of ten MDC pumping stations along the interceptor sewer system has been recommended in order to provide efficient and adequate pumping capacity for future flows. The scheduled completion dates and estimated costs for each of the major phases of the MDC’S Proposed Action are shown in Table 1.3—i. In the EMMA Study, it is estimated that the total 1—16 ------- TABLE 1.3-1 APPLICANT’S PROPOSED ACTION COSTS AND COMPLETION DATES FOR MAJOR PROJECTS Completion Project Date Cost, of $ millions (1) 1. Elimination of sludge discharges into the Harbor from the Deer Island and Nut Island treatment plants 1980 $ 26 2. Combined sewer overflow abate- ment in Dorchester Bay 1981 77 3. Nut Island primary expansion and addition of secondary treatment 1984 137 4. Deer Island primary expansion and addition of secondary treatment 1984 192 5. Additional facilities for secondary sludge management 1984 28 6. Satellite treatment plants discharging to the Middle Charles and Upper Neponset Rivers 1984 91 7. Combined sewer overflow abatement in the Charles River (Back Bay Fens and Muddy River) 1983 84 8. Combined sewer overflow abatement in the Neponset River 1983 23 9. Combined sewer overflow abatement in the Inner Harbor 1986 86 10. Others: Interceptors and Pumping 1975-2000 111 TOTAL $855 (1) Costs shown in millions of dollars based on January, 1975 prices (ENR 2200) and include engineering and contingencies. Updated costs appear later in this report. Source: “Wastewater Engineering and Management Plan for Boston Harbor,” By M. Weiss and J.P. Vittands, 1976 1—17 ------- construction cost for all of the related work would be approximately $855 million. It is also estimated that annual operation and maintenance costs would increase from the present $8.34 million to $29.5 million when all the proposed facilities are in operation by the year 2000. These costs are based on January 1975 prices. Further discussion of the MDC’s Proposed Action can be found in Section 3.4.3 and throughout Section 3.5. 1—18 ------- ENV I RONMENTAL INVENTORY 2.1 CLIMATOLOGY Eastern Massachusetts is a humid region that lies in the path of the prevailing westerly winds. Precipitation is plentiful and temperatures are moderate. Storms cross the state from either the west or southwest. In addition, northeasters are common in the late autumn and winter. The mean annual temperature in the area varies from slightly above 10°C (50 0 F) along the coast to just below 10°C in the higher elevations of the interior. A summary of temperature data from the National Weather Service sta- tions at Boston (Logan Airport) and Framingham, Massachu- setts is presented in Appendix 2.1—1. Precipitation is uniformly distributed throughout the year (Appendix 2.1-2). The mean annual precipitation at Boston is 105.4 cm (41.5 inches) while at Framingham the mean is 111.3 cm (43.8 inches). During the winter months, precipitation over the area can occur as rain or snow with the annual snowfall ranging from an average of 106.7 cm (42 inches) in Boston to over 129.5 cm (51 inches) in Framing— ham. The snow begins to melt in March or early April. Winds generally come out of the west with the predomi- nant direction being from the northwest in the winter switch- ing to the southwest in the summer. Wind velocities are generally under 40.2 km/hr (24 mph). Winds in excess of 51.5 kin/hr (32 mph) can be expected at least one day in every month of the year, but these strong winds are more common and more severe in the winter. 2—1 ------- 2.2 GEOLOGY 2.2.1 Surficial Geology The surficial geology of the study area is made up pre- dominantly of glacial drift although some deposits of recent alluvium are found. These glacial deposits are remnants of the last ice advance, the Wisconsin ice age, which ended some 10,000 years ago. The unconsolidated deposits left by these ice sheets can be stratified or unstratified and are of var- ious thicknesses. Glacial till is found throughout the area and is the most abundant and widespread of glacial deposits. It is composed of unsorted clayey or silty sands and gravels. The sediments are derived primarily from subglacial ground mor- aine, terminal moraines and lateral inoraines. These deposits are unstratified, usually contain portions of silt and clay and frequently contain rocks and cobbles, some of which are as large as small houses (Metcalf & Eddy 197Sf). These de- posits range in thickness from several inches to several hundred feet. Drumlins, a geomorphic phenomenon consisting of un- stratified till, are common and notable in the Boston area. Of the more than 100 drumlins in the Boston area, Bunker and Breeds Hill on the mainland and the Boston Harbor Islands (Deer, Long, Rainsford [ in part], Moon, Thompson, Spectacle, Castle, Great Brewster, Gallop, Lovell’s, George’s, Peddocks, Bumpkin and Grape [ in part]) are some of the more notable ones. Stratified drift is common and is found principally in the lower-lying flatter areas and is thickest along present and buried pre-glacial stream valleys. Thick deposits of well-sorted, medium to coarse-grained stratified drift make up the most productive aquifers in the region. 2.2.2 Geomorphic Districts The MDC service area falls within the Seaboard Lowland subprovince of the New England Physiographic Province. Sev- eral geomorphic districts are contained wholly or partially within the area. These areas are the Boston Lowland, the Fells Upland, the Needham Upland, and to a smaller extent the Sudbury Valley and the Sharon Upland. The Boston Lowland lies generally at elevations of less than 15.2 in (50 feet) (msl). Contained within it are exten- sive areas of marshes and alluvial plains, many of which today have been reclaimed or altered. Druinlins (smooth lens- shaped hills of glacial origin) are the most distinctive topo- graphic features in the Lowland. The higher portions of the Low1and are covered to a large extent with glacial drift. 2—2 ------- The Fell.s Up1 nd 1ie to the north we5t of the BO$tQn Low1 nd. On the the st of the Upland ie bold escarpment which ranges in height fror 30.5 m (100 ft) to 91.5 in (300 ft). The ‘e1ls Upland c n be divi4ed into three sections. The eastern and middle sections are generally at less than 76.2 m (250 ft) (msl), and they contain large areas of exposed bedrock, while the western section is gener- ally higher than 76.2 m (250 ft) (msl) and is partly smooth and partly covered by drift (Skehan, 1975). The Needham Upland lies southwest of the Boston Lowland and is lower than the Fells Upland and is not as well defined. Large areas in this Upland are occupied by plains of alluvium and glacial outwash. A large portion of the relief in this area is due to the numerous drumlins, some of which have summits that reach over 91.5 m (300 ft) (msl) in elevation. 2.2.3 Lithology In and around the Boston area, the bedrock consists of igneous sedimentary and metasedimentary, and metamorphic rocks mantled discontinuously by unconsolidated depoists usually of glacial origin. The ages of the bedrock range from Precambrian to late Paleozoic with some minor volcanics of Triassic age also being mapped. The predominant igneous rocks found within the study area are seynites, volcanics and grandiorites. Outcrops of sedimentary and metasedimen- tary rocks are confined chiefly to the eastern and south- eastern parts of the area. Slates and conglomerates make up the major component of the sedimentary and metasedimentary rocks. Metamorphic rocks are abundant and outcrop in all parts of the study area. Principal formations include the Dedham Grandiorites, Cambridge Slate, Quincy Granite, Newbury-Matta- pan-Lynn Volcanics, Blue Hills Granite Prophyry, Westwood Granite and Roxbury Conglomerate. 2—3 ------- 2.3 TOPOGRAPHY The terrain in the MDC study area is integrally tied to its geological history, its bedrock composition, and deformational and erosional processes that have been active in the area in the past. The most significant of the processes that has altered the terrain of the study area was the quarternary advance of the glaciers. In the process of differential erosion, different types of rock material erode at varying rates, depending on their relative hardness. This process can be seen in the study area and is illustrated by the relatively low relief of the entire Boston Lowland (composted generally of soft sedimen- tary materials) versus the raised areas of the outlying Fells, Needham and Sharon Uplands and the Blue Hills (composed of more resistant igneous and metamorphic rocks). Rock types of various hardness have also produced variations in relief within each of the two separate areas. In addition, faulting of the bedrock material in some areas has accentuated the physical relationship of two rock types and the resultant terrain. The advance of ice sheets during the quarternary period of geologic history significantly altered the preglacial terrain. In the advancing stage, bedrock outcrops were sculptured and highly eroded, and valleys were widened and carved out. Later, when the glaciers began to melt, depo- sitional land forms were introduced, including ground mor- ames, kames, eskers, and drumlins. Thus, in some areas, the terrain was softened by valleys being filled with ground moraine or by glacial lakes being filled with sediment, while in others, it was accentuated via resistive rock outcrops rising from ground moraines or from the introduction of such features as druinlins. 2—4 ------- 2.4 SOILS Detailed soils information compiled by the U.S. Soil Conservation Service (SCS) is not available for the study area except for the town of Ashland and a small portion of the town of Natick. General soils information, however, was prepared by the SCS office in amherst, Massachusetts for the SENE study of the New England River Basins Commission. Analy- sis of general soil areas is useful for broad land use plan- ning. General soil areas were grouped from segments of the landscape in which soil series occur in distrinctive propor- tions and patterns. Mapping was accomplished by reconnais- sance of the area supplemented by on-site determinations and interpretations of current topographic and surficial geology maps prepared by the U.S. Geological Survey. A general soil area normally consists of an association of two or more major soil series and at least one minor soil phase. There were 24 general soil areas ide;tified in the SENE study area and 5 sub-groupings under these general areas. Though the soil series in a general soil area are usually derived from similar parent materials, certain characteris- tics of each series may differ widely. Commonly, however, the properties of the major soils within a general soil area have about the same degree of limitation for a particular use. While the general soil areas do not indicate the kind of soil series at any specific site, they do indicate the physical nature, composition and slopes in these areas. The major soils in each general soil area determine the overall suitability of the general soil area for many uses. A general soil map is useful to people who want an overall idea of the soils in a county, or who want to compare dif- ferent parts of a county, or determine the location of large areas which are suitable for a certain kind of land use. The soils are primarily derived from glacial material, brought to the area during the last ice age. Soils derived from glacial till are generally mixtures of clayey or silty sands and gravels. Marine beaches and windblown dunes resulted in sandy soils with very little gravely or clay content. Silty and sandy soils containing minor proportions of clay and gravel were formed from alluvium and river terrace depos- its. Fine grained and/or organic soils consist of silty and clayey sands from glacial lake bottoms, fine grained marine deposits and salt and freshwater organic soils. The soil map (Figure A2.4-l) and key to this map are presented in Appendix 2.4. Interpretive data for the various soil areas can also be found in Appendix 2.4. 2—5 ------- 2.5 WATER RESOURCES The Metropolitan Sewerage District (MSD), which is oper- ated and maintained by the Sewerage Division of the Metropoli- tan District Commission (MDC), serves an area which coincides with the natural drainage area of Boston Harbor. Included in the MDC service area are the Mystic, Neponset, and Weymouth watersheds, and a portion of the Charles River watershed. In addition, segments of the Sudbury, Concord and Shawsheen watersheds, which drain to the Merrimack River, are included within the MSD. Expansion proposed by the EMMA Study would significantly increase the area within the Sudbury basin tied into the MDC sewerage system. Figure 2.5—1 presents an over- view of the watersheds found in the MSD. Extensive groundwater resources underlie the major rivers of this region. The most productive aquifers, in terms of both water quantity and quality, are buried valleys of glacial drift. This section presents information on the water resources within the MSD including physical chracteristics, existing water quality, water supply and use, the relationship between water quantity and quality, and proposed or existing water quality management plans. 2.5.1 Boston Harbor Boston Harbor (Figure 2.5-2) is traditionally defined as the area subject to the rise and fall of the tide lying inside the line drawn from Point Allerton in Hull northwest to the Boston Harbor Light and then to the southeastern point of Deer Island. It encompasses an area of approximately 130 sq km (50 sq mi), has 290 km (180 mi) of tidal shoreline, and contains 30 islands covering 485 ha (1200 acres). Boston Harbor may be divided into the Inner Harbor, which receives flows from the Charles and Mystic rivers; the Outer Harbor including Dorchester Bay, which receives flows from the Neponset River; Quincy Bay; and Bingham Bay, into which the Weymouth Fore, Back and Weir rivers drain. The total fresh wate inflow from these tributary streams ranges from 0.6 to 85 m’/sec 20 to 3000 cfs), with an average sum- mer flow of 10 to 14 nr’/sec (350 to 500 cfs). Wastewater discharges from the Nut Island and Deer Island sewage treat- ment plants are an additional major source of freshwater inflow to th Harbor. Total discharge from both plants aver- aged 1.75x10° m 3 /D (462 xngd) for the period 1971—1975. 2—6 ------- MASSACHUSETTS BAY 5 0 5 KILOMETERS 3 0 3 MILES LEGEND WATERSHED BOUNDARY MSD BOUNDARY 8 ç,c FIGURE 2.5-1 WATERSHEDS WITHIN THE EXPANDED METROPOLITAN SEWERAGE DISTRICT ------- 0 ’ /Horbor Limit -j Low.ll islorid 1, M—4o St q Hon Ligh / 7 ,Hinghom .‘ , Oy !I Grap. isiond 6 0 Boy Bumkin Island C Wsir ..- Riv•r 1 0 K 110 METE iS 0.5 0 0.5 BOSTON HARBOR Ds.r Fluts D.sr Island , / / / _7— PRESIDENT ROADS —, — Gallops Is 0 FILURE 2 5-2 ------- Water depths in the Harbor generally range from 3 to 15 in (10 to 50 ft) mean low water depth (MLWD); however, exten- sive Harbor areas have depths less than 4.5 in (14.8 ft) NLWD. An average depth fluctuation of 2.9 in (9. ft) , resulting from a tidal interchange averaging 9062 in /sec (320,000 of 5), occurs over the tidal cycle. As a result of this exchange, tidal flow controls the hydraulic and salinity characteristics of Boston Harbor (Process Research, 1976). Theoretical flushing time for the Harbor is approximately two tidal cycles, or just under 24 hours. However, the Harbor does not respond in this manner due to the intricate network of islands and inlets creatingpoor circulation patterns. Fig- ures 2.5—3 and 2.5—4 present a generalized picture of tidal flow within the Harbor. The reader is referred to the Boston Harbor Tidal Charts (National Oceanic and Atmospheric Adiiini- stration, 1974) for detailed current velocity patterns. A discussion of Harbor flushing is presented in Section 3.2.2.B. A. Water Use . Boston Harbor is the largest seaport in New England. Two major shipping channels, President Roads and Natasket Roads, provide access, respectively, to port facili- ties in the Inner Harbor and the Weymouth Fore River. Port facilities in Boston Harbor consist of 156 piers, wharves and docks, 29 of which are designed for petroleum products handling. One of the largest shipbuilding yards on the Atlantic coast is located on the Weymouth Fore River in Quincy (New England River Basins Commission, 1975). Recreation is the additional major use of the Boston Harbor’s waters. There are about 42 beaches totalling approxi- mately 30.9 km (19.2 mi) along the Harbor’s irregular shore- line. Numerous anchorages for recreational boating exist throughout the Harbor. In addition, the proposed Boston Har- bor Islands Comprehensive Plan (Metropolitan Area Planning Council, 1972) calls for the development of many Harbor islands as recreational areas. However, the continued and future use of Boston Harbor as a recreational resource, as well as its potential as a fishing and sheilfishing resource, is dependent upon the quality of its waters. Polluted water precludes shellfish harvesting in many areas and the effective development of the Harbor as a recre- ational resource. Furthermore, the Harbor suffers a concom- mitant loss of scenic and aesthetic qualities from its degraded water quality. B. Water Quality . The State of Massachusetts has established water quality classifications for Boston Harbor as part of the classification of all State waters and prescribed rules and regulations for maintaining these classifications (Commonwealth of Massachusetts, 1974: see Appendix 2.5-1). Figure 2.5-5 pre- sents designated and existing water quality classifications for the various Harbor sections. 2—9 ------- Boy Deer stand / / / / ,---- Um t - .-.__ 41 Harbor Light George $ Island __1—_ — —- -s-— 0 K ILOMETERS 0.5 0 0.5 Ir MILES FIGURE 2.5-3 BOSTON HARBOR CURRENTS MAXIMUM FLOOD TIDE ------- Deer Island Gollop lsIond / 6’ — I’ PRESIDENT ROADS / - Sp is6 ci e Quincy Bay ‘I ,---- / ,, 1 Harbor Limit -S — \ Lowell island -S. — Georges i lgnd ‘C,— Point KILOMETERS 0.5 0 0.5 MILES FIGURE 2.5-4 BOSTON HARBOR CURRENTS MAXIMUM EBB TIDE ------- LEG END WATER USE CI ASSIFICATION 1976 CONDITION CLOSED TO SHELLFISHING / #‘ -.- —,, ————--—---—— — Gallops Is I a nd Harbo ’ Limit Lowell Os tori — Harbor Light 0 0.5 0 0.5 -I FIGURE 2.5-5 EXISTING Island 6 AND DESIGNATED HARBOR 0 Deer Island ‘I / ‘I / PRESIDENT ROADS ,- WATER QUALITY CLASSIFICATIONS BOSTON ------- The majority of the Harbor is meeting its present water quality classification, with the exception of sections of Quincy Bay, Hingham Harbor and Boston Harbor north of Logan Airport. Meeting a water quality classification is not, how- ever, indicative of “good” water quality. Class SC waters are unsuitable for contact recreation and sheilfishing. Swimming is permitted in SB waters, but shellfish taken from these waters are required to undergo depuration. The State is presently reviewing water quality standards and revisions may be forthcoming. Water quality is presently a major problem in Boston Harbor with the prime influencing factors being municipal wastewater and sludge discharges and combined sewer overflows. Additional Harbor degradation results from raw waste discharges industrial discharges, urban runoff, and degraded quality of tributary mt low and the accumulation of debris, refuse, and oil discharges (Process Research, 1976). Boston Harbor receives discharges of effluent and sludge from the MDC regional wastewater treatment facilities located on Deer Island and Nut Island. Both facilities receive a mixture of domestic and industrial wastes and provide primary treatment consisting of screening, grit removal, prechiorina— tion, pre—aeration, primary sedimentation, and post chlorina- tion prior to discharge. In addition, sludge is anaerobically digested prior to disposal in the Harbor (MDC Sewerage Division, 1976). Effluent discharge characteristics summaries are pre- sented in Table 2.5-1 and 2.5-2. Sludge characteristics are given in Table 2.5—3. Figure 2.5-6 shows outfall locations. In operation since 1952, the Nut Island Sewage Treatment Plant serves 59 percent of the total MSD service area and 36 percent of its population. Plant effluent is discharged through two main outfalls extending approximately 1829 in (6000 ft) from the Island’s north shore. Two additional out- falls - running 427 m (1400 ft) northwest and 143 in (468 ft) east from the plant - discharge during high flow periods. Following anaerobic digestion sludge is disposed of through a pipeline extending 6.8 km (4.2 mi) from the treatment plant into deep tidal water on the south side of President Roads (MDC Sewerage Division, 1976). The Deer Island Sewage Treatment facility commenced operations in 1968 and serves, respectively, 64 and 41 per- cent of the population and area within the MSD. Two main outf ails discharge a mixture of chlorinated effluent and digested sludge into President Roads. Three emergency out- falls successively discharg when influent flow rates exceed 1.51, 1.89 and 2.27 x iø6 m”/day (400, 500 and 600 mgd) (MDC Sewerage Division, 1976). 2—13 ------- TABLE 2.5—i NUT ISLAND EFFLUENT CHARACTERISTICS 1971 1972 1973 1974 1975 AVG Average Daily Flow, 5 5 5 in 3 /d 4.84x10 5 5.45x10 5.26x10 5.22x10 5 4.66z10 5.09 (ingd) (128.0) (143.9) (138.9) (137.8) (123.0) (l34. Maximum Daily Flow, m 3 /d 7.l2x] 0 5 8.0x10 5 7.9x10 5 6.62x10 5 5.48x10 5 7.18x (mgd) (188.2) (211.2) (208.8) (174.8) (144.7) (189.t Suspended Solids, mg/i 106 121 114 103 113 111.4 Z Removal 46.7 44.5 54 48.5 45.9 47.9 Grease’ mg/i 22.0 22.1 24.4 22.0 22.5 22.6 Z Removal 35.7 32.8 45.5 38.9 30.8 36.7 Settleabie Solids, mg/i 0.4 0.7 0.4 0.6 1.2 0.7 % Removal 98.9 90.3 94.9 92.5 87.0 91.7 BOD 5 , mg/i 108 95 88 119 122 106.4 % Removal 23.9 24.6 29 21.2 17.0 23.1 1—Petroleum ether solubles Source; MDC Sewerage Division, 1972, 1973, 1974, 1975, 1976 2—14 ------- TABLE 2.5—2 DEER ISLAND EFFLUENT CEARACTERISTICS 1971 1972 1973 1974 1975 AVG . Aver ge Daily Flow, 6 6 6 m /d l.25x10” l.30x10 l.l3xlO l.iixiO i.25xl0’ i.21x10 6 (nigd) (330.0) (343.2) (298.3) (293.0) (330.0) (319.4) Maximum Daily Flow, 6 6 6 m 3 /d 2.31x10 2.20x10 l.79x10” l.75x10 6 l.88x10 6 l.99x10 (ingd) (609.8) (580.8) (472.6) (462.0) (496.3) (525.4) Suspended Solids, mg/i 76 69 56 68 74 68.6 Z Removal 43.2 47.3 56 59 45 501 Grease 1 mg/i 15.5 10.9 11.3 11.7 15.7 13.0 Z Removal 46.1 45.7 48 54 44 47.6 Settleable Solids, mg/i 1.15 1.28 0.86 0.88 0.9 1.01 % Removal 73.5 66.5 78 82 82 76.4 BOD 5 ,mg/l 118.5 94.5 88 107 95 100.6 % Removal 26.9 30.0 33 34 30 30.8 1—Petroleum either solubles Source: )fl C Sewerage Division, 1972, 1973, 1974, 1975, 1976 2—15 ------- TABLE 2.5—3 MDC TREATMENT PLANTS SLUDGE CHARACTERISTICS Deer Island Nut Island Raw Digested Raw Digested Heavy Metals Mm. Max. Mm. Max. Mm. Max. Mm. Max . Arsenic 0.9 1.4 0.3 3 1 1.5 0.4 5 Cadmium 20 42 18 36 2.4 4.6 6 11 Copper 430 940 580 920 180 490 720 830 Total Chromium 170 520 390 620 66 77 140 220 Lead 30 130 170 180 120 160 220 380 Mercury 1.4 62 3 6 1.1 2.4 7 8 Nickel 11 100 74 141 16 28 48 67 Silver 34 52 68 72 1.1 1.7 3 3 Zinc 210 1600 680 2000 560 1100 1400 1600 Soluble Components Chlorides 2500 3400 2100 2800 280 370 320 330 Hardness 900 1200 2200 2600 180 200 1000 1000 Sulfate 860 8800 600 900 270 500 300 Potassium 96 180 120 200 77 110 80 120 Sodium ——— ——— 1650 1800 ——— ——— 225 300 Boron 1 1 2 10 4 4 3 5 Specific Conductance 12000 17000 11000 13000 2300 5600 3100 5900 Volatile Solids COD 1.41 1.59 1.62 2.10 1.26 1.60 1.23 1.61 BOD 0.22 0.39 0.62 0.74 0.40 0.72 0.12 0.43 Reat Value 2.8 x 1O 2.9 x IO 2.4 lO 2.6 x io 2.3 x 2.7 x io6 2.2 x iO 2.95 x lO TKN 0.06 0.07 0.032 0.050 0.036 0.40 0.075 0.100 P 0.015 0.016 0.010 0.011 0.009 0.013 0.023 0.024 SOURCE: Havens and Emerson, 1973 UNITS: Heavy Metals: mg/kg dry solids Volatile Solids: kg/kg volatile total solids Soluble Components: mg/l Heat Value: BTU/kg volatile total solids Specific Conductance: micromhos/cm @ 25°C (77°F) ------- LEGEND AREAS WITH COMBINED SEWER OVERFLOW AREAS WITH STORM SEWER OUTLETS POINT SOURCE: S E TABLE 2.5-4 Rairisferd Island — — 0 X ILOMETERS 0.5 0 0.5 MILE Quincy Bay Hingham / løy I I Grap. Island 6 SOURCE LORDet al., 97O; Water Quality Section, FIGURE 2.5-6 DISCHARGES BOSTON HARBOR ENVIRONMENTAL ASSESSMENT COUNCIL. INC. ------- TABLE 2.5-4 BOSTON HARBOR MAJOR DISCHARGES Figure 2.5—6 Reference No. Discharger Descri:ption 1 *MDC Deer Island STP Primary effluent I A *MDC Deer Island STP Emergency Screened and Chlorinated Outfall sewage 2 *}fDC Deer Island STP Digested primary sludge 3 *MDC Nut Island STP Primary effluent 3A *MDC Nut Island STP Emergency Chlorinated sewage Outfall 4 *WDC Nut Island STP Digested primary sludge 5 *Cjty of Boston Moon Island Intermittant combined Holding Tanks sewer overflows on outgoing tide 6 *Gjllette Co. Cooling waters 7 *MAssachusetts Bay Transportation Cooling waters, boiler Authority blowdown 8 *Boston Edison Cooling water, boiler blowdown 9 *Pier 6 — Fish Pier Fishing wastes 10 *Great Atlantic and Pacific Cooling water Tea Company 11 *Beth lehem Steel Shipyard cooling water and storm drains 12 *New England Aquarium Recirculation water from specimen tanks 13 *Cities Service Oil Terminal Oil storage and distributcA 14 *General Dynamics Corp. Shipbuilding 15 *Boston Edison Co., Edgar Station Cooling water 16 *Proctor and Gamble Co. Detergent manufacture 17 *White Fuel Terminal Oil storage and distributol 18 *Logan Airport Stormwater runoff SOURCE: Process Research, 1976; Water Quality Section, 1976 *NPDES Permit Issued 2—18 ------- Both treatment facilities have problems handling exces- sive flows due to storm water runoff and infiltration and inf low into the sewer system. The Nut I land Treatment Plant was designed for an av rage flow 4.24x10 m 3 /d (112 mgd) and a peak flow of l.14x10° m’ 1 /d (300 mgd). As Table 2.5-1 shows, the average daily design flow is already exceeded, thereby causing a reduction in treatment efficiency. In addition, when influent rates exceeds 9.46x10 5 m 3 /d (250 mgd) low quality effluent, receiving only pre-chlorination, is discharged through the emergency outfall to Quincy Bay. Deer Island’s de igi and peak flows are l.30x10 6 m 3 /d (343 mgd) and 3.21x10° xn-’/d (848 mgd) respectively. While average daily design flow has not been exceeded in the past five years, design capacity can easily be exceeded during severe storms. In addition, it has been estimated (Hydro- science, 1971) that 25 percentof total influent flow is due to salt water intrusion. This inflow has created operation and maintenance problems, particularly in sludge digesters (Havens and Emerson, 1973). The MDC treatment facilities discharge significant quanti- ties of toxic metals* into Boston Harbor in their effluents. Table 2.5—5 summarizes this metals discharge. In addition, large quantities of metals are present in the sludge discharge. Sampling activities by the New England Aquarium (Gilbert, et al., 1972) found particularly high water column concentra- tions of toxic metals in the Inner Harbor and in President Roads. Likewise, sediment concentrations of metals in the Inner Harbor, along the nearshore area of Dorchester Bay, in Deer Island Flats, and in Quincy Bay near the Moon and Nut islands overflows were found to be excessive. (See Table 2.5-6 . In general, areas in the vicinity of treatment plant •óutfalls and combined sewer outlets exhibited metals enrich- ment. While the nearshore enrichment is due to combined sewer overflows, the report concluded that the primary treat- ment plant discharges are a major source of metals contamina- tion in the Outer Harbor Area. Tables 2.5—6 and 2.5-7 summar- ize metals found in Harbor waters and sediments. The combined sewer area within the MSD encompasses a densely population urban area within Metropolitan Boston. All or parts of five communities (Boston, Brookline, Cambridge, *pursuant to Section 307(a) (1) of the Federal Water Pollution Control Act as amended by the Clean Water Act of 1977 a list of toxic pollutants was published in the Federal Register on January 31, 1978. The following metals, and compounds containing them, are listed as toxic pollutants: antimony, arsenic, beryl- lium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, thallium, and zinc. 2—19 ------- Influent and Effluent cottcefltratiOfl8 are average of monthly values for reported by MDC and NPDES Compliance Monitoring Reports Nut Island Flow — 5.18x10 5 m 3 /d (136.9 mgd) Deer Island Flow — 12.1x10 6 m 3 /d (319.4 mgd) period 12—75 through 9—77 TABLE 2.5—5 MDC TREATMENT PLANTS TOXIC METALS NUT ISLAND DEER ISLAND Metal Influent mg/i Effluent mg/i Removal Percent Mass KG/Day Discharge (lb/day) Enfluent mg/i Effluent m i/i Removal Percent Mass KG/Day Discharge (lb/day) Cadmium 0.0176 0.0119 32.0 6.2 (13.7) 0.021 0.019 9.5 23.0 (50.7) Chromium 0.051 0.041 24.4 21.2 (46.7) 0.147 0.108 26.5 130.7 (288.2) Copper 0.618 0.324 47.6 167.6 (369.6) 0.246 0.357 —45.1 432.2 (953.0) Lead 0.104 0.074 28.8 38.3 (84.4) 0.157 0.131 16.6 158.6 (349.7) ‘ Mercury Nickel 0.00198 0.889 0.00124 0.291 37.4 562 064 150.6 (1.4) (332.1) 0.0124 0.115 0.011 0.131 11.3 —13.1 1.33 158.6 (2.9) (349.7) Zinc 0.431 0.376 87.2 194.6 (429.1) 0.777 0.488 37.2 590.7 (1302.5) ------- TABLE 2.5—6 METALS IN BOSTON HARBOR WATERS Cadmium Chromium Copper Lead Nickel Zinc Inner Harbor 0.42 1.90 5.0 5.4 7.8 40.2 ND 2.12 1.8 6.4 1.6 3.7 President Roads 0.46 0.5 5.2 2.0 8.2 11.6 ND 3.2 1.6 3.5 1.9 7.5 Dorchester Bay 0.24 0.3 2.6 2.0 4.7 11.2 ND 4.5 0.8 2.4 1.8 1.7 Thompson—Long 0.20 0.5 2.2 1.9 6.8 9.0 Island Area ND 1.3 1.5 1.7 1.3 1.8 SOURCE: Gilbert, T., et al., 1972 All values pg/1 First value soluble phase Second value particulate phase (solids greater than 1 t) ND = Not Determined 2—21 ------- SOURCE: Gilbert,T., et al., 1972 All values are averages in mg/i for surface sediment layer. METALS IN TABLE 2.5-7 BOSTON I3JtRBOR SEDIMENTS Deer Flats Dorchester Bay Thompson—Long Island Area Quincy Ringham Bay Area east of Long Island Cadmium Chromium c2pper Lead Nickel Zinc 6.7 213.8 120.5 97.0 37.8 221.2 5.3 132.9 85.1 106.0 31.4 199.4 4.3 126.0 93.6 122.3 25.3 296.0 4.0 212.0 143.0 129.0 35.4 223.4 2.2 81.6 67.0 108.3 24.5 128.0 3.7 109.3 88.6 87.8 27.6 145.6 2—22 ------- Chelsea, and Somerville), covering approximatelY 50 sq km (19.2 sq mi) are served by one of the oldest combined sewer systems in this country. During periods of runoff (rainfall and/or snowmelt) these combined sewers may become hydrauli- cally overloaded, resulting in overflows which are discharged to both the Harbor and its tributaries. Approximately 125 combined sewer outlets discharge to Boston Harbor and its tributaries. Seventy-f lye overflows are from the City of Boston sewer system, while 18 overflow points are associated with the MDC interceptor system (New England Division, Corps of Engineers, l975c). The extent of overflow is primarily a function of storm- water flows, which are, in turn, dependent upon the rainfall intensity and duration, antecedent conditions in the tribu- tary area, and the hydraulic capacity of the sewer system. Frequency of overflows has been calculated (U.S. Environmen- tal Protection Agency, Region I, 1971) and these are presented in Table 2.5—8. These calculations indicate overflows to be a common occurrence from many combined sewers. A quality comparison of combined sewer overflows, sur- face runoff and effluents discharged from the MDC treatment facilities is presented in Table 2.5-9. It is easily deduced from these data that combined sewer overflows have major impacts on the quality of its receiving water. The problem is not, however, the overall volume of pollution discharged. This is relatively small compared to the total volume of receiving water in the Harbor. Rather the intermittent dis- charge of undisinfected fecal wastes, floating debris and solids presents a threat to the health and aesthetics of the Harbor. Both the Inner Harbor and Dorchester Bay are seri- ously affected by these loadings. Sampling activities (Water Quality Section, 1973) within the Inner Harbor suggest a strong correlation between rainfall hence overflows, and coliform counts. A typical Inner Harbor station recorded coliforin counts ranging from 240-930x10 3 MPN/ 100 ml on three separate days when 1.27 cm (0.5 inches) of rain or more had occurred within the previous 36 hours. Total coliform counts ranged from 24-90x10 3 MPN/l00 ml at the same station on three other days when rainfall totals were less than .25 cm (0.1 inches) in the previous 36 hours. The im- plication from these data is an increase in total coliform county by a factor of 100 when increased rainfall resulted in increased combined sewer overflows (Metcalf and , 1975g). High coliform counts are the primary cause of the Inner Harbor water quality classification of SC. This classifica- tion is, however, sufficient for its present predominant use 2—23 ------- TABLE 2.5-8 FREQUENCY OF OVERFLOWS PER YEAR C 4 EACH COMBINED SYS 4 (1) Number of Overflow Occurrences Per Year Na of Interceptor 1970 1995 2020 Alewife Brook Sewer, Cambridge 8 8 8 Alewife Brook Sewer, Somerville 1 1 4 Cambridge Branch Sewer, Cambridge— Charles River, R.M . 6.0 to 1.7 2 10 11 Li Cambridge Branch Sewer, Cambridge— Charles River, R.M. 1.7 to 1.2 35 35 35 South Charles System, Boston 0 0 0 B.U. Chlorination and Detention Chamber 3 56 61 64 Boston Marginal Conduit Charles River, RN. 2.8 to 1.2 11 11 11 Boston Marginal Conduit Charles River, R,M. 2.8 32 35 38 Boston Marginal Conduit Charles River- Tidewater 50 65 88 Somerville—Medford Branch Sever, Somerville 72 79 80 Cambridge Branch Sewer, Somerville 46 49 50 N. Metropolitan Sewer, Chelsea 7 18 27 Chelsea Branch Sewer, Chelsea 63 66 71 Charlestown Branch Sewer, Charlestown 45 47 50 E. Boston Branch Sewer, B. Boston 26 27 27 East Boston Low Level Sewer and Moore St. interceptor 24 26 27 East Side Interceptor, Boston 69 90 2—24 ------- TABLE 2.5—8 (Continued) 1970 1995 2020 Roxbury Canal Sewer, Rcxbury 2 3 3 Dorchester Brook Sewer, Dorchester 44 47 51 S. Boston Interceptor, S. Boston 46 46 46 Neponset River Valley Sewer and 5 5 Dorchester Interceptor, Dorchester 93 0 0 1 U.S. Environmental Protection Agency, Region I, 1971. 2 Assumes completion of the North Charles Relief Sewer which is presently under construction 3 mese are the rainfall intensities and the number of times overflows to the detention chamber occur. In many cases, overflows to the river will not occur. 4 Continuous overflow of 4 cfs dry weather flow in 2020. 5 continuous overflow of 4 cfs dry weather flow in 1995 and 15 cfs dry weather flow in 2020. 2— 25 ------- TABLE 2.5—9 GENERAL QUALITY CC* PARISON OF WASTEWATERS Suspended 30D 5 Solids Total Coliforms ix g/l mg/i MPN/100 ml Combined Sewage Average 1 115 410 x io 6 First Flush 1 170—182 330—848 1.5 to 310 x io6 Extended Flush 1 26—53 113—174 1.5 to 310 x io6 Surface Runoff’ 30 630 4 x 10 Deer Island Plant Effluent 2 100 69 (3) Nut Island Plant Effluent 2 106 111 (3) 1. Metcalf and Eddy, 1974 2. See Tables 2.5—1 and 2.52 3. Negligible due to disinfection. 2—26 ------- as a major commercial waterway. Nevertheless, a water qual- ity of the Inner Harbor is degraded and these waters represent a continuing source of bacterial contamination to the entire Harbor. The relationship between rainfall and coliform counts found to exist in the Inner Harbor was also found valid for Dorchester Bay. In addition, a modelling effort (Process ResearcI 1974) to determine the major sources of Dorchester Bay bacteria contamination concluded discharges from Deer and Nut islands were not contributing to the Dorchester Bay beach problems. The primary cause of Dorchester Bay’s pol- lution was isolated as combined sewer overflows. High coliform counts following significant rainfall efents seriously effect the Bay’s use as a recreational and shelifishing resource. Recommendations have been made (Mass. Dept. of Public Health, 1970) to restrict bathing in Dorches- ter Bay during periods of low tides and after rainfalls of certain minimum intensities. Roughly 87 percent of the pro- ductive softshell clam habitat, 3.9 sq km (1.5 sq ml), are grossly contaminated and closed to all sheilfishing activi- ties. Shellfish taken from the remaining areas are required to undergo depuration prior to consumption (Testaverde and Richards, 1971). Two major raw waste discharges exist in Boston Harbor in addition to combined sewer overflows, the Moon Island flolding Facility and sewage from the Town of Hull. The City of Boston operates the Calf Pasture Pumping Station and the Moon Island detention facility. During per- iods of high runoff the pump station is activated and diverts a maximum of about 5.9x10 5 m 3 /d (155 mgd) to Moon Island’s holding tanks to prevent overflows in the immediate shoreline area. Detained overflows are held until 1 hour after high tide and then discharged on the outgoing tide for a maximum period of 3 hours. This discharge is chlorinated during the months of May through September. These discharge procedures are outlined in the City of Boston’s NPDES discharge permit for the Moon Island facility (New England Division, Corps of Engineers, 1975c). Raw discharge occurs about 25 times per year from Moon Island (Kennedy Engineers, 1976) and this has been implicated in pollution incidents in Quincy Bay. Indeed, the Quincy Health Department closes Quincy Bay beaches following these discharges (New England Division, Corps of Engineers, 1975). 2—27 ------- The Town of Hull presently discharges untreated combined sewage and urban runoff through a total of 13 outfalls into Hinghaiu and Massachusetts bays (Silva, 1977). A new second- ary treatment facility is presently under construction in the town. The l.2x10 4 m 3 /d (3.2 mgd) plant will discharge efflu- ent through a single outfall into Massachusetts Bay while incinerating sludge. In addition, storm and sanitary sewer flows are being separated. This plant was expected to begin servicing the Town in April, 1978; however, the partially com- pleted facility was damaged by a severe winter storm early in 1978 and it is not known when the plant will commence opera- tion (Mc Donald, 1978). In 1975, the Massachusetts Division of Water Pollution Control surveyed direct discharges to Boston Harbor. In addition to the discharges from Deer and Nut islands, this study (Water Quality Section, 1976) found seven other indus- tries discharging into the Harbor, and these consisted mostly of cooling waters and storm drain water. Table 2.5-4 presents discharge locations and a description of the industrial source, while Figure 2.5-6 gives the spatial distribution of these sources. A Harbor shoreline survey (Lord, et al., 1970) identified 130 street drains (32 percent of the total discharge points found) discharging into Boston Harbor. This discharge, and urban runoff in general, has traditionally been considered as non—polluting to receiving waters. However, recent studies (Enviro Control, Inc. 1974; USEPA, 1971) have shown that such flows may contribute a major portion of any water body’s pollutional load. As Table 2.5-9 indicates, these flows may contain loads of lower quality than secondary effluent repre- senting significant slug loadings to the nearshore receiving waters. The impact of urban runoff upon the Harbor’s water quali- ty is difficult, if not impossible, to determine due to the influence of combined overflows. Quincy Bay, however, receives no combined overflows (Metcalf and Eddy, 1975g) and a recent survey by the U.S. Environmental Protection Agency (1975) indicates Street drain discharge is contributing to bacterial contamination of Wollaston Beach. Urban runoff may be con- cluded, therefore, as having a negative impact (of undefined magnitude) on Harbor water quality in certain areas. Numerous sources of debris and refuse exist in Boston Harbor including dilapidated shorefront structures, derelict wrecked vessels, dumping from ships and pleasure craft, shore- line dumping, and abandoned shorefront dumps (Spectacle Island). These have two major adverse effects upon the Harbor: 1) severe deterioration of Harbor aesthetic qualities, and 2) hazards to navigation (New England Division Corps of Engineers, l975c). 2—28 ------- Oil is a major pollutant in Boston Harbor in those waters proximate to oil terminals, especially along the Chelsea River. Discharge to sewers is an additional source of Harbor oil pol- lution. Oil enters sewers from accidental tank or pipeline leakages, industrial discharges, and deliberate or accidental dumping into storm sewers. MDC treatment facilities are esti- mated to be discharging 6.1-6.8 in 3 (1600-1800 gallons) of oil per day, while the discharge from combined overflow and storm sewers is unknown (New England Division, Corps of Engineers, 1975c). C. Water Quality Management Planning for Boston Harbor . The Federal Water Pollution Control Act I inendments of 1972, Section 303(e), require each state to establish water quality management plans to cover distinct hydrologic basins within the state. The purpose of each plan is to prescribe pollution abatement requirements which will result in water quality appropriate to the anticipated or desired future uses of the basin’s water. Both point and non-point sources of pollution should be ad- dressed in these plans. The Eastern Massachusetts Metropolitan Area Study (EMMA) has been approved by the Regional Adininistra- tor for Region I of the EPA as the water quality management plan for Boston Harbor. (Approval granted in letter dated September 13, 1976 from John A.S. McGlennon, Regional Admini- strator, to Thomas C. McMahon, Director Massachusetts Division of Water Pollution Control (see Appendix 2.5-2). The recommended EMMA Plan (Metcalf and Eddy, 1975k) envi- sioned the expansion of the MSD from the current 43 to a total of 51 member communities. In addition, the plan calls for the expansion and upgrading to secondary treatment of existing sewage treatment facilities at Deer and Nut islands, construc- tion of two satellite treatment plants to service certain out- lying portions of the expanded MSD, and institution of measures to alleviate the combined sewer overflow and storm water runoff problems. Necessary additions and improvements to the inter- ceptor system, as well as construction staging and costs are also presented. In addition to the proposed treatment plan upgrading, sludge discharge to the Harbor will be terminated. The MDC is camnitted to the incineration of primary sludge, as outlined in the report A Plan for Sludge Management by Havens and Emerson, Consulting Engineers (1973). 2.5.2 Mystic River Watershed The Mystic River watershed occupies an area of approxi- mately 179 sq km (69 sq mi) immediately north of the City of Boston. Elevation within the basin ranges from sea level to 114 meters (374 feet) above sea level and the basin has been described as being composed of gentle hills (Beauregard, 1975). 2—29 ------- The Mystic River watershed (Figure 2.5-7) ma y be con- sidered as consisting of three distinct sections: the Aber— jona River, the Mystic Lakes, and the Mystic River. The Aberjona River originates on a marshy area in the northern part of Reading Township and flows in a southerly direction for 14.8km (8.7 mi) before discharging into the Upper Mystic Lake. Along its course of travel the Aberjona flows through numerous wetland areas and receives the flow of three major tributary streams: Hall’s Brook, Sweetwater Brook, and Horn Pond Brook. In addition, three river sections are cuiverted to allow passage under two industrial parks and a high school athletic field. Flow measurements of the Aberjona are recorded at the U.S.G.S. gaging station located just downstream of the conflu- ence of the Aberjona River and Horn Pond Brook in Winchester. Average daily flow at this station for the period 1939-1975 was 0.77 m 3 /s (27.3 cfs). Discharge extremes range from a maximum dischar9e of 24.2 zn 3 /s (855 Cf s) to a one day low flow of 0.007 in / (0.25 cf s) (U.S.G.S., 1976). In addition, the Aberjona has a 7 day low flow with a 10 year recurrence interval of 001 m 3 /s (0.42 cfs) (New England Division, Corps of Engineers, ].975c). Approximately 34 percent of the total Mystic River watershed area contributes to these flows. The Upper and Lower Mystic Lakes separate the Aberjona and Mystic River systems. Upper Mystic Lake occupies 0.67 sq km (0.26 sq mi) within three communities. Two small bays are located in series near the lake’s inlet and are separated from the main body by a narrow neck. Bottom contours of the main body approximate a bowl with steep gradients descending to a maximum depth of 25 in (82 feet). Flows from the Upper Lake discharge over a spiliway and drop approximately 18 in (6 feet) to the Lower Lake. Lower Mystic Lake covers an area of 0.36 sq km (0.14 sq mi). Two deep holes, with maximum depths of 21.3 m (70 feet) and 13.8 in (45 feet) dominate this lake’s bottom con- figuration. A single tributary, Mill Brook, flows into Lower Mystic Lake at its southwest shore. Discharge from the Lower Mystic Lake forms the Mystic River which flows 12 km (7.4 mi) in a southeastern direction to Boston Harbor. Alewife Brook is tributary to the river entering about 1.6 km (1 mi) downstream of Lower Mystic Lake while Maiden River joins the Mystic above the Amelia Earhart Darn. The dam, located 3.2 kin (2 mi) upstream of the River’s mouth, separates fresh and tidal waters in the River. There is little elevation change along the Mystic’s course and if not for the meiia Earhart Darn, the entire River would be subject to tidal elevation changes (Beauregard, 1975). 2—30 ------- WATERSHED LOCATION L1 I SOURCI: Boston Inn.r Harbor FIGURE 2.5-7 MYSTIC RIVER WATERSHED ------- There areno flow ga ges on the Mystic; however estimates of flow for this river have been made based upon flows recorded at the Aberjona River gage. These estimates (Beauregard, 1975), which range from 3.1 to 34 times the Aberjona gage reading, yield an average Mystic River flow of 2.38 to 2.61 xn 3 /s (84 to 92 ft 3 /s) at its mouth. Corresponding maximum and minimum f lows were estimated to be 75.0 to 82.3 m 3 /sec (2650 to 2907 cfs) and 0.022—0.024 m 3 /s (0.78—0.85 cfs) respectively. The 7 day, 10 year low flow resulting from these estimates is 0.037 to 0.040 1n 3 /s (1.3 to 1.4 cfs). Extreme flood flows have caused problems within the basin. Major flood damage has occurred throughout the Mystic River watershed on four different occasions: March, 1936; August, 1955; October, 1962; and March, 1968. Problem areas along the tributaries are due to local conditions and backwater ef- fects. Significant problem areas include (New England River Basins Commission, 1975): 1) the floodplain along Horn Pond Brook from the Woburn—Winchester line to its confluence with the Aberjona River; 2) the lower portion of Mill Brook in Arlington; 3) the area along Alewife Brook from the Mystic River to Little Pond; and 4) areas along the mainstem of the Mystic River. Within the Mystic River basin lies a preglacial valley known as the Merrimack—Mystic Valley which extends from Lowell through Woburn and Winchester and is contiguous with the Aber- jona River in many reaches (see Figure 2.5-8). Large sand and gravel deposits are contained within this valley, and these provide ground water supplies to many users in the upper water- shed. (Beauregard, 1975). Additionally, a ground water reser- voir exists in the lower Mystic basin town of Everett. This is the only aquifer, however, with development potential in the lower part of the basin. A. Water Use . Drinking water is supplied to most basin com- munities and industries by the MDC. Two conununities, however, utilize ground water sources for drinking water supplies. The wn of Woburn regulates the water level in Horn Pond to maintain recharge to its gravel packed wells located around the pond perimeter. Winchester relies both on ground water supplies and its three surface water reservoirs. Approximately 5.5 x IO m 3 (l4.5x10 6 gals) of ground water is withdrawn daily in the upper Mystic watershed for industrial, commercial and municipal use. No water is drawn directly from the Aberjona 2—32 ------- - - -. \ I N • LEGEND NJ f. CDS!I?$ i wC r g° i;.’: , •tU’— : T! & _ 1L . “ ‘: :‘‘ “ ‘ P IL!C giti - SOURCE:MAPC Wat.r Ouatity Pro •ct Mop FIGURE 2.5.-8 GROUNDWATER FAVORABILITY MYSTIC RIVER WATERSHED ( MILES 1.51.50 1 I I I 21012 KM ------- River, Mystic Lake, or the freshwater portion of the Mystic River for municipal or industrial use due to the predominantly low flow conditions found in the watershed. Table 2.5—10 presents water supply needs in the Mystic River watershed. Projected 1990 water demand (New England River Basins Commission, 1975) indicates all eleven towns within the watershed will be supplied by the MDC if present use patterns continue. An earlier water supply study (New England Division, Corps of Engineers, 1973) presented similar results, indicating that those towns within the Mystic water- shed not presently on MDC water had no alternative to meeting 1990 demand other than supply by the MDC. The Mystic River is heavily used for non-contact recrea- tion; however, swimming is prohibited due to high coliform counts. Both the Aberjona River and the Mystic Lakes are open to swimming, but their use for this type of recreation is limited. Only the lower body of the Upper Mystic Lake is of sufficient quality to afford swimming. As recently as 1970 the Massachusetts Division of Fish- eries and Game stocked the Upper Mystic Lake with trout. Stocking was discontinued, however, due to the continuing decline in water quality creating an unsuitable habitat. In general, the waters of the Mystic River watershed support general aquatic animal life and present limited recreational opportunities due to poor water quality (Beauregard, 1975). B. Water Quality . Water quality classifications for the Mystic River watershed are presented in Figure 2.5-9 along with existing stream classifications. With the exception of the headwaters of the Aberjona River, most stream segments do not meet their designated water quality classification. Major sources of pollutant input to the Mystic River Basin are urban runoff, combined sewer overflows, and non- point sources. A number of point source discharges exist; however, the entire basin lies within the present MSD and, consequently, most point source discharges are diverted out of the basin for treatment at Deer Island. Figure 2.5-10 and Table 2.5-11 present the location and description of known pollutant sources within the basin. Urban runoff is a problem throughout the basin. Communi- ties within the Mystic River watershed are predominantly urban and suburban in character, with large tracts of imper- vious area. As a result, storxnwater runoff easily washes any accumulation of street pollutants into nearby waterways. 2—34 ------- WATERSHED LOCATION Winchester L.k.s LEGEND o WATER USE CLASSIFICATION O 1976 CONDITION CHANGE IN CLASSIFICATION 1 0 1 1 KILOMETEIS 0.5 0 03 MILlS SOURCE; Wat.r Q &IIy Section.1976d lostori Innr Harbor FIGURE 2.5-9 WATER QUALITY CLASSIFICATIONS MYSTIC RIVER WATERSHED ------- TABLE 2.5—10 WATER SUPPLY NEEDS MYSTIC RIVER WATERSHED’ Township Existing System, 1970 Safe Yie1d 2 ’ Source m 3 /d (MCD ) Averag,e Demand 1 1990 m /d (MCD) Design Demand, 1990 m /d (MCD) Proposed Additional Su iv Source LNew England River Basins Commission, 1975 2 Safe Yield for MDC are estimates of water approximated its safe yield. 3 Groundwater yield reported as system pumping capacity. t ) 0 Arlington MDC 25738 (6.80) 31264 (8.26) 31264 (8.26) MDC Belmont MDC 9841 (2.60) 11695 (3.09) 11695 (3.09) MDC Chelsea MDC 13626 (3.60) 13361 (3.53) 13361 (3.53) MDC Everett MDC 30280 (8.00) 35124 (9.28) 35124 (9.28) MDC Maiden MDC 26116 (6.90) 28728 (7.59) 28728 (7.59) MDC Medford MDC 30658 (8.10) 34897 (9.22) 34897 (9.22) MDC Meirose MDC 11355 (3.00) 13209 (3.49) 13209 (349) MDC Somerville MDC 40499 (10.70) 42808 (11.31) 42808 (11.31) MDC Stoneham MDC 12869 3.40) 19947 (5.27) 19947 (5.27) MDC Winchester MDC Wells 5299 2649 (1.40) (o.io) 10333 (2.73) 10333 (2.73) MDC Woburn Wells Horn Pond 31037 (9084) (8.20) (2.39) 30204 (7.98) 51968 (13.73) MDC volume supplied in 1970 when the total demand on the MDC System 4 Einergency supplies. ------- WATERSHED LOCATION FIGURE 2.5-10 POLLUTANT MYSTIC RIVER WATERSHED DISCHARGE LOCATIONS LEGEND POLLUTANT DISCHARGE LOCATION SEE TABLE 2.5—11 Winck.st.r srvoir Lok.s 1 0 1 — 1 KILOMETERS SOURCE I.aursgard 1975 03 0 0.5 MILES Boston Inner Harbor ------- TABLE 2.5—11 MYSTIC RIVER WATERSHED DISCHARGES* Discharger Discharge * Exxon Corp. * Allied Concrete * Boston Naval Hospital *Sc aft s Candy Co. * nstar Corp. Boston Cane Sugar Refinery *Re re Sugar Refinery * U.S. Gypsi m Co. *Wobu Sanitary Landfill National Polychemical Co. Dump *To of Stoneham SOuRCE: Water Quality SectIon, 1976 Beauregard, 1975 *! DES Permits Issued Circuit board plating wastes Compressor cooling water Heating/air conditioning system water Heating/air conditioning system water Turbine cooling water Cooling water Cooling water, roof drainage Cooling water, occasional sludge from sulfuric acid tanks Cooling tower blowdown, boiler blowdown, equipment wash water Yard drainage Concrete truck rinse water Boiler blowdown Cooling water Cooling water, yard drainage Cooling water, spent soda solution from gas scrubber Sanitary wastes Leachate from municipal refuse and accumulated chemical wastes Combined overflows from muni- cipal sewer system Combined overflows 1 * Systems Printed Circuit Co. 2 * Raytheon Spencer Lab 3 *J}3 Winn 4 * Parkview Apartments 5 Grace & Company, Dewey & Almy Chemical Division 6 *Spir_it, Inc. 7 *Avco Everett Research Lab 8 * Monsanto, Co. 9 * Boston Edison 10 11 12 13 14 15 16 17 18 19 * City of Cambridge 2—38 ------- In the upper portions of the Aberjona, a 1971 survey found in excess of 53 street and parking lot drains discharg- ing to the river (Defeo, 1971 as cited by New England Division, Corps of Engineers, 1975c). In the lower watershed, portions of the Mystic River and Alewife Brook run near major parkways and receive their storinwater runoff. In many areas road salt is stored near the Mystic and its tributaries and occasional salt pollution cannot be avoided. In addition, the towns of Woburn, Winchester and Arlington often dump snow removed from highways into the Mystic and its tributaries and large amounts of oil, sand and salt are released to the water when this snow melts (New England Division, Corps of Engineers, 1975c). A measure of urban runoff’s impact may be obtained by comparing sampling data from two comprehensive water quality surveys, 1967 and 1973 (Beauregard, 1975). Rainfall occurred during the 1973 sampling, while the 1967 survey was dry. Increased concentrations of BOD 5 , coliform bacteria, ammonia- nitrogen and total phosphorus were observed in the Aberjona in 1973 and attributed to stormwater runoff. Two areas within the watershed have combined sewer over- flow problems: Sweetwater Brook, and the Mystic River, in- cluding Alewife Brook. The town of Stonehain has two combined sewer overflows into Sweetwater Brook from its municipal sewage collection system. The magnitude and frequency of discharge from these outlets is unknown. Alewife Brook is subject to direct discharge of sewage from combined overflows which grossly pollute the stream along its entire length. During the 1973 survey, high coli- form, ammonia—nitrogen, and total phosphorus levels were found in all reaches sampled. The decline in water quality in the Mystic River below its confluence with Alewife Brook has been attributed to the influx of pollutants from Alewife Brook (Beauregard, 1975). Overflows fran the Somerville-Medford Branch Sewer dis- charge into the Mystic River. The influence of these upon river water quality can be seen by again comparing 1967 to 1973 survey data. Ammonia-nitrogen, nitrate-nitrogen, and coliform counts were much higher in 1973 than 1967. Increases in 1973 are concluded to be the result of precipitation induced combined overflows (Beauregard, 1975). Major non-point pollution sources exist near Hall’s Brook in the upper watershed. National Polychemicals Company manu- factures organic chemicals used in the plastic industry. Prior to its tie into MDC sewer system, it discharged its waste to a swampy area adjacent to its plant. This accumulation of extremely acidic wastes is a continuous source of discharge containing high ammonia nitrogen, sulfides, and chlorides to Hall’s Brook (Beauregard, 1975). 2—39 ------- Industries actively discharging to streams in the basin discharge predominantly cooling waters. These are not seen as a major source of pollution. Ground water quality may be determined from the most recently published summary of drinking water quality sampling in Massachusetts (State of Massachusetts, 1975). Eight water supply wells in Woburn were sampled and had good overall water quality. Water was shown to be weakly acidic (pH 6.3-6.9) with moderate (300 iimhos/cm) specific conductance values. Two wells, however, yielded higher readings (BOO i.irnhos/cm), indicating infiltration into the aquifer of water with higher than nor- mal dissolved solids content. In addition, chloride concen- tration increases paralleled specific conductance increases. It appears as though low quality water is beginning to infil- trate into Woburn’s wells. The quality of groundwater with- drawn for industrial use in the basin is unknown. The upper Mystic Lake has experienced a continued degra- dation of water quality in recent years. Eutrophic conditions exist in part the lake and the nutrient rich Aberjona River is primarily responsible. Aquatic plants and algae prevail in the relatively shallow reaches in the summer (Beauregard, 1975). A 1975 comprehensive survey of the Upper Lake (Chese- borough and Screpetus, 1975) concluded: 1) The Upper Mystic Lake develops a serious oxygen deficit below 4.6 m (15 feet) in the summer. 2) The Lake is characterized by high nitrogen con- centrations, with the Aberjona River as a major source. 3) Urban runoff and non—point sources affect the Lake. Particularly striking is the large increase in chloride concentrations attributed to road salt runoff during winter months. 4) Transparency of the Lake water is low, and appears to be caused by suspended solids entering from the Aberjona River. 5) The Lake’s main basin does not suffer from massive algal blooms or heavy aquatic plant growth. However, the shallow northern basins do experience relatively heavy macrophyte growth. 2—40 ------- The Lower Mystic Lake suffers severe water quality prob- lems unique to any lake in Massachusetts (Beauregard, 1975). Construction of the Amelia Earhart Dam in 1966 has in effect trapped a saltwater layer in the Lower Mystic Lake, which has become anaerobic. Below 9 in (29.5 ft) dissolved oxygen concentrations are zero. Algae and aquatic plants prolifer- ate during the summer months, and the lake is considered highly eutrophic. C. Water Quantity—Quality Problems . Ground water and sur- face water systems within the upper Mystic River basin are hydraulically linked. Heavy ground water withdrawals by industries adjacent to the Aberjona River result in abnormally low stream flow because of discharge out of the basin via the MDC sewer system. Low stream flows present water quality problems due to reduced stream aeration and increased pollu- tant concentrations. These effects are most pronounced in the lower portions of the watershed. Low stream flows, and their associated low stream velo- cities, from the Aberjona River result in extremely long detention times for the Mystic Lakes. This presents ideal conditions for the algae blooms and excessive macrophyte growths which occur in these lakes during the summer months. During summer months when little flow is released from the upstream portions of the basin, the Mystic River is essen- tially a large lake. Little recreational use occurs and, because of the high nutrient concentrations, algae and aquatic plants flourish. Industrial demand for ground water is expected to remain relatively constant, and only Woburn’s water supply withdrawals are expected to increase (Frimpter, 1973a). As a result, low Uow conditions within the basin are not expected to change in the near future. D. Water Quality Management . Ongoing planning activities that could potentialI y affect the waters of the Mystic River basin are the 208 area-wide wastewater management planning and the 303(e) Basin Plan. The 208 plan deals with institutional arrangements and non—structural measures to prevent over-development in sensi- tive environmental areas and to minimize the impact of non- point sources of pollution. Being conducted by the Metro- politan Area Planning Council (MAPC) this plan is presently in its initial phase. As a large portion of this basin’s problems stein from non-point pollution, it is anticipated that this activity will help basin water quality. 2—41 ------- The EMMA Study, which included the Mystic River water- shed, has been accepted as the 303(e) basin plan for this watershed. Initial EMMA recommendations called for construc- ting a 7570 m 3 /d (2 mgd) advanced wastewater treatment facili- ty on the Aberjona River to retain water within the basin and augment streamf lows. However, the plant was found to be an uneconomical means of flow augmentation and the proposal was not carried into the final EMMA recommendations. 2.5.3 Charles River Watershed The Charles River watershed occupies the central portion of the Boston Harbor drainage area, covering an area of 788 sq k in (304 sq ml). This area coincides with all or part of 32 municipalities, including a large portion of the City of Boston. Nine of these towns in the upper watershed - Mu- ford, Bellingham, Franklin, Medway, Holliston, Millis, Nor- folk, Wrenthain, and Medfield - are not part of the existing or proposed expanded MSD. The watershed (Figure 2.5-11) has a southwest-northeast orientation with a total length of 50 kin (31 ml) along this axis while the river has a total length of approximately 129 kin (80 ml) due to its extensive meandering. Total elevation change from its headwaters to Boston Harbor is approximately 107 in (350 ft). The Charles River Watershed is generally divided into the Charles River Basin and the Charles Basin. The former covers 686 sq km (265 sq ml) and extends from the River’s headwaters to the Watertown dam while the latter is that portion of the watershed downstream of the Watertown dam and covers 102 sq km (39 sq mi). The Charles River originates 40 km (25 ml) southwest of Boston in the Town of Hopkinton. The river meanders for approximately 515 km (32 mi) through the nine upper water- shed towns before entering the MSD. Along this course the River passes over 5 dams and drops 30.5 in (100 ft). In ad- dition, five major tributaries - Hopping Brook, Mine Brook, Mill River, Stop River and Bogastow Brook - join the River in this reach. At approximately river kilometer 77 (river mile 48) the Charles River flows into the MSD. This section of the River has little natural elevation change, and lies in the back- water of the South Natick Dam. Below the South Natick Dam, the River meanders for 9.7 km (6 ml), and turns to the east as it flows to the Cochrane Dam. Flow measurements are taken just downstream of the Cochrane Dam by the U.S.G.S. at the Charles River Village gage. Aver- age flow, unadjusted for diversions, over 38 years of record 2—42 ------- WATERSHED LOCATION LII LINCOLN WAYLAND 2 0 2 K•LOMETEIS 2 0 2 MILES ASHLAND HOPKINTON SOURCE: Erdmann. Bilger. and Travis 1977 Jamaica Pond BOSTON Mother Brook Diversioii WALPOLE GEND * U.S.G.S. GAGING STATION Box Pond, BELLINGHA M FIGURE 2.5- I I CHARLES RIVER WATERSHED ------- at this location is 8.3 zn 3 /s (295 cfs). Maximum and minimum flows recorded are 91.2 m 3 /s (3220 cfs) and 0.014 m 3 /s (0.5 of s) respectively (U.S.G.S., 1976), while the 7 day low flow with a 10 year recurrence interval for this station is 0.33 xn 3 /s (11 cfs) (Walker, Wandle and Caswell, 1976). The Charles flows east from Charles River Village for roughly 8 km (5 mi) before coming to Mother Brook. Accord- ing to Massachusetts law up to one—third of the Charles River flow can be diverted through Mother Brook to the Neponset River. Historical records indicate the actual diversion aver- ages 26 percent. The original purpose of the diversion was for industrial water use. However, the use of this water in industrial plants on Mother Brook has ceased and its present primary purpose is to moderate flood flows in the lower Charles River watershed. In addition, the diversion has a major effect on low flow conditions in river reaches of both rivers below the diversion (New England Division, Corps of Engineers, 1971). From this diversion to River flows northwest towards the Town of Weston before turning east towards Boston Harbor. Two important tributaries join the River along this reach: Waban Brook and Stony Brook. Waban Brook originates in Weston and flows through Nonesuch Pond, Morses Pond and Lake Waban before entering the Charles in Wellesley. Stony Brook has its source at Sandy Pond in Lincoln Township and flows southeast to join the Charles in Waltham The City of Cam- bridge impounds a large portion of this tributary’s flow in the Stony Brook Reservoir for water supply (New England Divi- sion, Corps of Engineers, 1971). The Charles then flows approximately 8 km (5 mi) from its confluence with Stony Brook to the Watertown Dam, the Charles River Basin boundary. Along this stretch of River, flow passes the Moody Street, Bleachery, and Rolling Stone Dams. A gaging station is maintained just downstream of the Moody Street Dam in Waltham. Flow over the 44 years of record at this site have averaged 8. m 3 /s (290 cfs), while maximum and minimum flows are 75.6 m Is (2670 cfs) and 0.003 rn 3 /s (0.1 cfs) respectively. All of these flows are less than those recorded upstream at Charles River Village, re- flecting the effects of the Mother Brook diversion (U.S.G.S., 1976). The Charles Basin (Figure 2.5-12) is a 13.8 km (8.6 mi) long impoundment of the Charles River located in Metropoli- tan Boston. The basin extends from the Watertown Dam, at river kilometer 15.7 (river mile 9.8), to the Charles River Dam at kilometer 1.9 (mile 1.2). Including major parts of Boston, Cambridge, Brookline, Newton and Watertown, the basin is highly urbanized. 2—44 ------- WATERSHED LOCATION LI Watertown Dam Boston Harbor BOSTON BROOKLINE I— Stony ,/‘ Brook Conduit / / / Turtle Pond KILOMETERS 0.5 0 03 MILES SOURCE: Water Quality Section, 1976b FIGURE 2.5-12 CHARLES BASIN WATERSHED ------- The Basin more closely resembles a lake than a river. The upper three-quarters of the Basin is about 3.1 in (10 ft) deep, with widths varying from 45.7 to 121.9 in (150-400 ft). Depths in the lower portion average 6.1 in (20 ft), with a maximum depth of 11.6 in (38 ft), and a maximum width of 670.6 in (2200 ft) (Water Quality Section, 1976). Outflow from the basin is via sluice gates at the Charles River Dam discharging to tidewater. Basin elevation is normally main- tained at 0.73 m (2.38 ft) above mean sea level (MSL), while tidal stage variation is from 1.4 in (4.6 ft) below MSL to 1.49 in (4.9 ft) above MSL. As the result of this situation outflow is possible only when the tide is favorable (Water Quality Section, 1976). Two major tributaries to the Charles Basin are Stony Brook, whose source is Turtle Pond in the Stony Brook Reser- vation in Boston, and Muddy River which flows from Jamaica Pond along the Boston-Brookline boundary. The Back Bay Fens is a 2.4 km (1.6 mi) long backwater of the basin at Charles Gate and is the remains of the 3.03 sq km (1.17 sq mi) Back Bay which was filled during the mid-nineteenth cen- tury (Water Quality Section, 1975). Floods may occur in the Charles River watershed any season of the year. Early spring rains and snowmelt caused the floods of March 1936 and March 1968, while heavy summer rains generated the floods of July 1938 and August 1955. The river has extensive marshlands throughout its upper reaches which have a moderating effect upon flood flows, making rain- fall volume, not intensity, the critical factor determining flood magnitude (New England Division, Corps of Engineers, 1971b). The Charles Basin, however, has serious flood problems due to its impervious nature. High intensity, short dura- tion storms often cause flood problems. It has been esti- mated that ninety-percent of peak flood flows in the Charles Basin originate within the Charles Basin’s watershed (New England Division, Corps of Engineers, 197lb). The principal water bearing formations in the Charles River basin are sand and gravel deposits of glacial origin and the bedrock underlying the basin. Only the sand and gravel aquifers are capable of sustaining goodyieldsto wells. These deposits are scattered throughout the basin (see Figures 2.5-13 and 2.5—14), but are primarily found in low flat areas adjacent to the Charles, its tributaries, and some lakes. The aquifers are a major factor in sustain- ing streaxnf low during periods of little precipitation (Frimpter, l973b). 2—46 ------- LEGEND y1, c m c?a .s c — r-c LtC T 1 S PUv SOURCE:MAPC Wat.r Quality Pro jsct Map FIGURE 2.5-13 GROUNDWATER FAVORABILITY UPPER CHARLES RIVER WATERSHED MILES 1.51.50 L J i I F — 210 KM ‘C s VtC •EUC SOURCE: MAPC Water Quality Project Map ------- F - - - ‘ . *_- ,. .4 — 4. -- , : -- “ - -. r :- - - ‘ — - ‘ - - • ‘ —.• • - - / -= ‘ - I — —. — ( - - . - - . • - - ‘- - -. f: _ 4 . : - - - 7/ , - . •-. — - — - -- - - / A p LEGEND - — • . -: _______ L • ‘• -• — MILES ; T 1.5 1 .5 0 1 2 1 C 1 2 KM ic p • - f... SOURCE:MAPC Wa ’. , Quality ProI.c? Map FIGURE 2.5-14 GROUNDWATER FAVORABILITY LOWER CHARLES RIVER WATERSHED SOURCE: MAPC Water Quality Project Map /— ------- Saturated aquifer thickness ranges from 6.1 to 24.4 in (20 to 80 ft) at locations of town water supply wells. Wells in sand and gravel aquifers within the Charles iver basin have good specific yields which average 0.003 in /s per meter (40 gpm per foot) of drawdown (Walker, Wandle and Caswell, 1976). These wells are designed for large pumping capaci- ties, which range from 0.006 to 0.09 xn 3 /s (100 to 1500 gpm). Withdrawals from these wells average 0.03 in 3 /s (500 gpm) (Walker, Wandle and Caswell, 1976). Groundwater recharge is by surface water infiltration from the areas adjacent to the aquifers. In addition, ground- water reservoirs in the basin are hydraulically connected to the river or its tributaries and well withdrawals from these aquifers may result in induced streamfiow infiltration (Frimpter, l973b). The groundwater formation found throughout the Boston area shows an exceedingly wide permeability range resulting from the myriad of materials used to fill the area in the 1800’s. Recharge to this area results mainly from sewer line and water main leaks as the area is predominantly covered with impervious surfaces. Groundwater discharge, particularly in landfilled areas, is to sewers, storm drains, or adjacent water bodies. The only well withdrawals in the area are those associated with dewatering for construction activities (Cotton and Delaney, 1975). A. Water Use . The water demand of seven communities (Boston, Brookline, Lexington, Newton, Waltham, Watertown and Weston) with the Charles River watershed are fully supplied by the MDC. These are all located in the highly urbanized lower portion of the watershed. In addition, two communities (Cam- bridge and Needham) supplement their existing sources with MDC water (New England River Basins Commission, 1975). Aver- age daily water usage in the Charles River watershed (see Table 2.5—12) totalled 1 .51x10 5 m 3 /d (40 mgd) in 1970, with the MDC and local sources supplying 67 and 33 percent respect- ively (Walker, Wandle and Caswell, 1976). Increased water demand anticipated in 1990 for all nine towns presently served by the MDC is expected to be supplied by the MDC. In addition, it appears that Weflesley and Natick will have to turn to the MDC as increased use of local ground- water sources does not appear viable. The Dedham Water Company also appears to have insufficient supplies to meet estimated 1990 maximum daily demands and may have to go to the MDC for water (New England River Basins Commission, 1975). In the upper portion of the watershed, Bellingham, Dover, Holliston, Medfield, Millis, Norfolk and Sherborn all appear to have sufficient groundwater potential to meet 1990 demands. 2—49 ------- TABLE 2,5—12 WATER SUPPLY NEEDS 1 CHARLES RIVER DRAINAGE BASIN Town.hii Source ‘New England River Basins Co imiisslon, 1975 2 Safe yield for MDC are estimatet of water volume supplied in 1970 when the total demand of the MDC system approximated its safe yield. Proposed Additional Suvolv Source cafe Yie1d 2 3 (M CD) Average Demand—1990 Design D nand-1990 m /d (MCD) m fd (MCD) 01 0 Be llingh.a Boston Brookline Wall. MDC MDC 8,321.0 536,344.5 28,009.0 (2.20) (141.60) (7.39) 7,570.0 577,591.0 33,535.1 (2.00) (152.48) (8.85) 15,329.3 577,591.0 33,535.1 (4.05) (152 .48) (8.85) Ground water MDC ! WC Cambridge Hobbs Brook Fresh Pond 51,854.5 (13.69) 92,543.3 (24.43) 92,543.3 (24.43) MDC Dedham 4 Dover Stony Brook MDC W.11 . Well. 33,686.5 29,144.5 757.0 (8.89) (7.69) (0.20) 12,263.4 1,362.6 (3.24) (0,36) 23,429.2 3,255.1 (3.28) (0.86) Ground water Ground vatir Ground water and tDC Franklin Holliaton Lexington Lincoln Well. Well. MDC Wells Sandy Pond 9,084.0 7,191.5 11,032.5 2,649.5 1,514.0 (2,40) (1.90) (4.50) (o.io) (0.40) 12,641.9 7,532.2 24,299.7 4,050.0 (3.34) (1.99) (6.42) (1.07) 24,034.8 15,253.6 24,299.7 4,050.0 (6.35) (4.03) (6.42) (1.07) Ground water Ground water MDC None and Milford Water Co. Medfie ld Medvay Milford Wells Wells Well. Charles River 4,163.5 6,813.0 1,514.0 3,785.0 (1.10) (1.80) (0.40) (1.00) 6,548.1 6,056.0 12,074.2 (1.73) (1.60) (3.19) 13,740.0 12,490.5 12,074.2 ( 3.63) (3.30) (3.19) Ground water Ground water Milford Water and Co. Milford Water (Louisa Lake) Co. Millie Natick Needham Newton Wells Well. Wells MDC MDC 3,785.0 34,822.0 12,869.0 3,785,0 43,906.0 (1.00) (9.19) (3.40) (1.00) (11.59) 6,321.0 38,812.0 19,644.2 48,750.8 (1.67) (10.26) (5.19) (12.87) 12,944.7 64,117,9 19,644.2 48,750.8 (3.42) (16.93) (5.19) (12.87) Ground water MDC MDC MDC Norfolk Wrentha5 State School Norfolk Cor— Un iown 1,476.2 rectional Institution Sherborn Waltham Watertown WeU.esley Weston 5 Wrentham Private Supplies MDC MDC Wells Wells MDC Wells ——— 40,878.0 18,168.0 29,144.5 7,948.5 1,514.0 7,570,0 (to.ig) (4.80) 0.69) (2.10) 13.40) (2.00) 1,022.0 48,372.3 20,522.6 18,243.7 12,528.4 7,267,2 (1.92) 14,723,1 (0.66) 0.2.77) (5.42) ( 8.81) ( 3.31) (3.89) Ground water and Milford Water Co. .39) ).23) (12.77) .42) (4.82) (3.31) (0,92) Ground water 3,482.2 2,498.1 48,372.3 20,522.6 33,383,7 12,528.4 Ground water MDC MDC MDC MDC 4 Dedham Water Company services both Dedham and Westwood 5 Wegton now entirely served by the MDC. 3 Groundwater yield reported as system pumping capacity. ------- Franklin, Medway and Wrentham, however, may not be able to meet demands by means of local groundwater sources and may have to turn to the MDC or form a regional water supply agency with the Town of Milford. Milford presently uses Echo Lake as the primary source of its water supply and is expected to meet future demands by increased development of the Lake (New England River Basin Commission, 1975). Only a few lakes within the watershed are presently used for swimming. The Charles River was once lined with many heavily used swimming beaches; however, the last public beach (in Natick) was closed 20 years ago due to high bac- terial counts. Today, the majority of the river’s length provides only non—contact passive recreation opportunities because of its degraded water quality. In addition, the waters of the Charles Basin are so severely degraded that non-contact recreation is unpleasant in many areas (New England Division, Corps of Engineers, 1975c). B. Water Quality . The Charles River has been given water quality classifications (Figure 2.5-15) ranging from A to C, with most of the segments classified B. However, the general condition of the majority of the River may be described as poor. Except for a short reach at the River’s headwaters, no section of the River meets its water quality classification (Water Quality Section, 1976c). Sources of pollution are different in the Charles River basin and the Charles Basin due to the differences in the character of the contributing watershed. Major pollutant sources in the upper watershed include municipal sewage, solid waSte disposal sites, subsurface disposal, industrial dis- charges and urban runoff. In the Charles Basin major sources are combined sewer overflows, urban runoff and salt water intrusion. Locations and descriptions of known pollutant discharges are present in Figure 2.5-16 and Table 2.5-13. The headwaters of the Charles River are of high quality and meet their A classification. Below this segment, signi- ficant problems arise. From its headwaters, the Charles flows into Cedar Swamp Pond in Milford. This is a shallow, eutrophic impoundment choked with weeds and exhibiting high algal counts. Dissolved oxygen is low, while nutrient concentrations are high. Over- flows and bypasses from the Milford sewer system create these conditions (Water Qualtiy Section, 1976c). Below this point, the River receives the discharge from the Milford sewage treatmen p1ant. This secondary treatment facility discharges 10598 in /d (2.8 mgd) into the River. Treatment efficiency is poor, resulting in a discharge which 2—51 ------- FIGURE 2.5-15 WATER QUALITY CLASSIFICATIONS CHARLES RIVER WATERSHED WATERSHED LOCATION LII 2 0 2 IlIOMI 1(1% 2 0 2 MILL S Jamaica Pond Mother Brook D’vers Box LEGEND * U.S.G.S. GAGING STATION o WATER USE CLASSIFICATION o 1976 CONDITION — CHANGE IN CLASSIFICATION Parl I uw t w.t.r .it S.ctei -J ------- WATERSHED LOCATION 2 0 2 K H.OM ITt IS 2 0 2 A I I — MILES Jamaica Pond Box Pond, SOURCE: Water Quality Section. 1976c P.sr l Mother Brook Diversion j GEND * U.S.G.S. GAGING STATION ® POLLUTANT DISCHARGE LOCATIONS SEE: TABLE 2.5-13 FIGURE 2.5-16 POLLUTANT CHARLES RIVER WATERSHED DISCHARGE LOCATIONS ------- TABLE 2.5—13 CHARLES RIVER WATERSHED DISCHARGES Map No . Discharger Discharge 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 * Milford Municipal Sewage Treatment Plant * Medfield Municipal STP * Medfield State Hospital STP * Barry Division, Barry—Wright Corp. * Quincy Market Cold Storage * Haartz-Mason, Inc. * Cambridge Electric—Blackstone Station * Massachusetts Institute of Techno- logy - Magnetics Laboratory * Cambridqe Electric - 1(endall Station * Franklin Municipal STP * Garelick Farms * Wrentharn State School STP * Norfolk-Walpole MCI * Cott Corporation * Millis Municipal STP * Ty-Car Manufacturing * Community Service Stations, Inc. * St. Regis Paper Company * Massachusetts Broken Stone * Belmont Springs Water Company Secondary effluent Tertiary effluent Domestic sewage effluent Cooling water Cooling water Cooling water Chlorinated cooling water Cooling water Chlorinated cooling water Secondary effluent Dairy plant wastes Secondary effluent Domestic sewage effluent Carbonated soft drink wastes Secondary effluent Metal finishing effluent Runoff containing petroleum products Cooling water Paving mixture effluent Water supply facility SOURCE: Water Quality Section, 1976 *NPDES Permits Issued 2—54 ------- is high in organic matter, nitrogen, phosphorus, and metals. Low oxygen levels, algal blooms and an abundance of sludge worms on the River bottom are a result of the discharge (New England Division, Corps of Engineers, 1975c). Below Milford, the Charles receives pollutants from subsurface disposal systems in North Bellingham, and the Franklin sewage treatment plant. Removal efficiency at this plant is poor as its average flow exceeds its design flow. Dissolved oxygen levels are depressed, nutrient levels high and algal blooms occur in this reach of the Charles (Water Quality Section, 1976c). The Stop River has a somewhat naturally degraded quality due to the drainage from the wetland areas in its head. It also receives waste discharges from the Norfolk and Walpole Massachusetts Correctional Institution and enters the Charles River with depressed dissolved oxygen levels and high nutrient content. Below the Stop River pollution enters the Charles via flows from Sugar Brook. The Medfield secondary treatment plant, the Medfield State Hospital, the National Can Company, and the Cott Corporation all discharge to this tributary. In addition, the Millis sanitary landfill is located in this area. Anaerobic conditions, toxic ammonia levels, low pH, sludge deposits, and odors occur in Sugar Brook, which has been used for years solely to convey wastes. It is one of the most severely polluted segments in the Charles River watershed. Downstream of Sugar Brook to the Cochrane Dam there are no major industrial or municipal discharges. Water quality generally improves through this reach and is primarily influ- encedbyleachate from a solid waste disposal area in Natick and runoff from adjacent roadways. Between the Cochrane and Watertown Dams the River has high algal productivity, bacterial contamination, widespread litter and debris and is severely degraded. Landfills in Newton and Waltham are proximate to the River along this reach. Industrial discharges in this segment originate on South Meadow Brook, Stony Brook and from a number of sources just above the Watertown Dam. In addition, there are sewer overflow and bypasses in Waltham and urban runoff from the towns of Wellesley and Weston discharging to the River (Water Quality Section, 1976c). The Charles Basin has severely degraded water quality. Urban areas adjacent to this water body are served by combined sewer systems which overflow frequently. These include the MDC Charles River Valley Sewer, the MDC North and South Charles 2—55 ------- Relief Sewers, the Brookline Sewer, the MDC Boston Marginal Conduit, the Stony Brook Sewer and the MDC Cambridge Branch Sewer. Figure 2.5-17 identifies overflow points to the basin. These discharge heavy concentrations of coliforra bacteria, oxygen demanding wastes, and nutrients into the Charles Basin (New England Division, Corps of Engineers, 1975c). A salt water layer exists in the entire length of the basin. Trapped by the Charles River Dam, this layer causes the Charles Basin to stratify. The bottom layer is anaero- bic, with high sulfide and nutrient concentrations and no aquatic life. Bottom muds have been described as black ooze and any disturbance of this layer causes the release of hydro- gen sulfide gas (New England Division, Corps of Engineers, 1975c; Camp, Dresser and McKee, Inc., 1976). Groundwater in undeveloped areas contains only slightly more dissolved solids than proximate surface waters. The groundwater tends to have a low pH, averaging 6.2 in water from town supply wells tapping sand and gravel aquifers, and in places may require treatment to reduce corrosive ten- dencies. At some localities the groundwater contains slightly more iron and manganese than is recommended by the U.S. Public Health Service for public water supplies (Wandle, Walker and Caswell, 1976). At many places the quality of groundwater has changed over the years. The chloride concentration of water from town supply wells has increased generally. The increase is smallest in the less developed southern part of the basin and greatest in the more urbanized northern part. Part of the water pumped from town supply wells has been induced from nearby streams that receive sodium chloride from high- way de—icing operations. The Town of Weston was forced to abandon a major water supply well in the vicinity of the Massachusetts Turnpike and Route 128 due to its contamina— tion by chlorides from road de-icing salts (New England River Basins Conunission, 1975). At various places in the basin groundwater has been locally contaminated by seepage from landfills and discharge from septic tanks (Walker, Wandle and Caswell, 1976). Groundwater found within the Charles Basin is not suit- able for any use due to its low quality and limited avail- ability. C. Water Quantity - Quality Problems . As has been described in the preceding sections, water quality degradation exists throughout the Charles River watershed, except for a small reach at the River’s headwaters. This conditions will affect the feasibility of locating additional point sources in the basin without detrimental effects. The EMMA study reconinended a mid-Charles River treatment facility with the capacity of 2—56 ------- 25 River Valley Sewer :4 CAMBRIDGE Somerville. Charlestown North Charles Relief Sewer Cambridge MDC Storm MSR. Branch Sewer Binney St. Sewer 1 . oposed Station 13 Rutherford Ave. Ovorflow . Chlorinatiop’ Boston Marginal Conduit 0.5 0 05 Ii KILOMETERS 05 0 05 MILES - - Foul Flow Channels Boston 1 And Gate Houses 2 LEGEND SEWER OVERFLOWS RIVER BASIN SEE: TABLE 2.5T4 BOSTON SOURCE: Camp Dresi.r and McKse. Inc. 1976 I OVERFLOW POINT FIGURE 2.5-17 COMBINED CHARLES ------- TABLE 2.5—14 COMBINED SEWER OVERFLOW POINTS CHARLES BASIN 1. Lowell St. Overflow 2. Boston Marginal Conduit Discharge 3. Fruit St. Overflow 4. Pinckney St. Overflow 5. Berkley St. Overflow 6. Dartmouth St. Overflow 7. Hereford St. Overflow 8. Charlesgate & Fens Pond Overflows 9. Deerfield St. Overflow 10. St. Mary’s Street Overflow 11. Faneuil Brook Overflow 12. Parson’s St. Overflow 13. Miller’s River Overflow 14. Cambridge Marginal Conduit Discharge 15. Binney St. Overflow 16. Massachusetts Avenue Overflow 17. Talbot Street Overflow 18. B.U. Detention Facility Discb* 19. Pearl St. Overflow 20. Pleasant Avenue Overflow 21. Western Avenue Overflow 22. Plympton Street Overflow 23. Elliot Square Overflow 24. Bath-Hawthorne St. Oserfiow 25. Gibson Street Overflow 26. Lowell Street Overflow SOURCE: Camp Dresser and McKee, Inc., 1976 2—58 ------- l.17x10 5 m 3 /d (31 mgd) while acknowledging that it might not meet water quality criteria under 7 day 10 year low flow conditions. Flow augmentation benefits associated with the plant were viewed as outweighing potential water quality prob- lems. Continuing the present practice for transporting waste- water out of the watershed to Boston Harbor will result in the increasing export of groundwater out of the Basin which will qualitatively reduce the River’s basef low. This effect is very difficult to quantify and is the key to the flow augmentation issue. Simply stated - “Will the additional export of water from the basin have a significant effect on the Charles River’s low flow? Is flow augmentation necessary to assure river flow and water supply in the future?” This question is examined in a later section of this report and is linked to existing and future water quality in the Charles River. D. Water Quality Management Planning . The Massachusetts Division of Water Pollution Control has prepared a 303 (e) plan for the Charles River watershed (Water Quality Section, l.76c). It developed waste load allocations for publically owned treatment facilities in the watershed and concluded that treatment levels beyond secondary would be required to meet water quality standards. In addition, it proposes to reclassify C waters as Bi to make the water quality goal throughout the watershed “fishable/swimmable waters. The Basin Plan endorses the EMMA recommended Middle Charles Satellite Plant as it would provide wastewater treat- ment and disposal where needed, reduce flows to the Nut Island plant, and help to alleviate low flow problems in the lower reaches of the River. Further recommendations include a study of a possibility of eliminating or curtailing the Mother Brook diversion. The basin plan is presently under review and may be amended as a result of the Impact Statement process. A recent study (Camp, Dresser and McKee, 1976) of pos- sible ways to eliminate the anaerobic salt water layer in the Charles Basin has recommended the installation of seven mechanical aerators at strategic points in the basin. The investigators felt that this would keep the entire basin aerobic and help to reduce the problems associated with a stratified anaerobic condition. 2.5.4 Nèponset River Watershed The Neponset River originates 46.7 km (29 mi) northwest of Boston at the outlet of the Neponset Reservoir in Foxborough, Massachusetts. The Ikiver flows in a generally northeastern 2—59 ------- direction for 475 km (29.5 mi) before discharging into Dor- chester Bay. The Neponset River watershed (Figure 2.5—18) includes all or part of eleven municipalities, including the southwest section of the City of Boston, and has a drainage area of 318.6 sq km (123 sq mi). The entire watershed lies within the expanded MSD, except for a portion of Foxborough at the basin’s headwaters. The Neponset Reservoir in Foxborough is the headwaters of the Neponset River. It is both spring and tributary fed, has an average depth of 1.8 in (6 ft) and covers 1.09 sq km (0.42 sq mi). Discharge from the reservoir flows directly into Crack Rock Pond, and then north from this impoundment through culverts under the Bay State Raceway and into Clark Pond. From Clark Pond the River meanders 4.3 km (2.7 mi) through Cedar Meadow Swamp and enters Upper Blackburn Pond. Inf lows from two tributaries, School Meadow Brook and an unnamed stream, join the River in this stretch. Union Pond, the water supply for the Kendall Company in Walpole, is located a short distance downstream of the Blackburn Pond dam. The River is joined by the flows from Turner Pond and Diamond Brook below the Kendall Company. The River then flows through what was Stetson Pond (the dam was washed out by recent floods) and changes direc- tion to the northeast. Cobbs Pond, Plimpton Pond, and Bird Pond are all tributary to the River along this reach. Below Bird Pond the River flows into the Hollingsworth and Vose Coxnpanh impoundment in East Walpole. Hawes Brook enters the River below this point. The U.S.G.S. gaging station in Norwood is located approxi- mately 0.8 kin (0.5 mi) downstream of Hawes Brook. Average flow at the station, based on 36 years of record is 1.49 in 3 /s (52.6 cfs) (U. S .G. S., 1976). Flow extremes include a maximum flow of 42.2 m 3 /s (1490 erg) during the 1955 flood and a daily minimum of 0.04 m 3 /s (1.4 cfs) in 1963. The 7 day low flow with a 10 year recurrence interval at this station is 0.14 m 3 /s (4.9 cfs) (Brackley, Fleck, and Meyer, 1976). Below Norwood, the Neponset begins a 14.2 km (8.8 mi) meandering course through the Fowl Meadow Marsh. The marsh extends along the River’s main stem from 1.6 km (1 mi) down- stream of the Norwood gage to Paul’s Bridge in the Hyde Park section of Boston and covers an area of 15.5 sq km (6 sq mi) (Anderson-Nichols & Co., 1971). The Neponset receives inflows from four tributary streams in this reach: Union Brook, Pur- gatory Brook, Pecunit Brook, and Ponkapog Brook. 2—60 ------- Dorchester Bay LJI WATERSHED LOCATION DOVER 2 2 9 2 KILOMETERS 9 2 BOSTON -J LU U. 0 LU / Reservoir SOURCE: Water Quality Section, 976f Inkapog Pond LEGEND * U.S.G.S. GAGING STATION FIGURE 2.5-18 NEPONSET RIVER WATERSHED ------- The River’s East Branch also joins the River as it flows through Fowl Meadow. The East Branch drains an area of approxi- mately 77.7 sq km (30 sq mi). Average discharge recorded in Canton for this section of the River is 1.45 mi/sec (51.1 cf s), based on 23 years of data (U.S.G.S., 1976). Maximum and minimum recorded flows are 50.7 m 3 /sec (1790 cf s) and 0.017 m 3 /s (0.60 cfs), respectively. The 7 day low flow with a 10 year recurrence interval at this location is 0.10 m 3 /s (3.4 cf s) (Brackley, Fleck, and Meyer, 1976). 1 pproximate1y 2.4 kin (1.5 mi) downstream of Paul’s Bridge Mother Brook joins the Neponset River. This tributary carries diverted Charles River flows to the Neponset River. The average discharge through Mother B ook, measured just below the diversion in Dedhant, is 2.25 in is (79.3 cfs) over the last 44 years (U.S.G.S., 1976). Downstream of Mother Brook is the MDC dam at the Tileston and Hollingsworth Company, which regulates flows for flood control in the downstream area and for water supply for Tile- ston and Hollingsworth Co. The final impoundment on the river, Boston City Pond, is formed by the Walter Baker Dam. This darn also serves to separate the fresh water river and saline estu- ary. Pine Tree Brook is tributary to the River above this darn, while Uniquity Brook enters the estuary below the dam. Recharge to the aquifers is estimated at 15,140 m 3 /day (44mgd). This infiltration occurs naturally through both the surface deposits and along certain reaches of the River and its tributaries (Brackley, Fleck and Meyer, 1976). In addi- tion, virtually all the public supply wells in the basin cause some infiltration of surface water into the contiguous aquifers (Frimpter, 1973c). A. Water Use . Domestic water supply within the basin is pro- vided by both the MDC and local sources. Milton and Quincy receive full MDC supply, while 99 percent of Norwood’s water comes from the MDC. Canton supplies 75 percent of its needs from local wells, with the remainder supplied by the MDC. Sharon, Stoughton, Walpole and Westwood are all presently sup- plied from local groundwater sourcqs. Average groundwater with- drawal for water supplyis 79,485 &/d (21 ingd) (New England River Basins Commission, 1975). No water is drawn directly from the Neponset for drinking water supply. Table 2.5-15 summarizes present projected water supply needs within the basin. For the most part existing supplies are adequate to meet demands; however, Stoughton will have to tie into the MDC water supply system to meet its 1990 requirements while Westwood and Sharon will need partial MDC supply to meet their projected demands (New England River Basins Commission, 1975). 2—62 ------- TABLE 2.5—15 1 New England River Basins Commission, 1975 WATER SUPPLY NEEDS NEPONSET RIVER WATERSHED 1 2 Safe yields for MDC are estimates of water volume supplied in 1970 when the total demand on the MDC system approximated its safe yield. 3 Groundwater yields reported as system pumping capacity. 4 Emergency supplies Existing System Safe Yield 2 ’ 3 Average Demand, 1990 mi/d (MGD) mi/d (MCD ) Township Boston Canton Milton Norwood Quincy Sharon Stoughton Walpole Westwood and Dedham 5 Source MDC Wells MDC MDC Wells MDC MDC Wells Wells Wells Wells Design Demand, 1990 m3/d (MGDL 577591 (152.60) 18773 (4.96) Proposed Additional Supply Source 536334 11355 3785 9463 11355 11355 38607 14004 11733 13247 29144 577591 (152.60) 18773 (4.96) (141.70) (3. 00) (1.00) (2.50) (3.00) (3.00) (10.20) (3.70) (3.10) (3.50) (7.70) 13779 21915 47085 9386 14572 22520 12263 9121 (3.64) (5.79) (12.44) (2.48) (3.85) (5.95) (3.24) (2.41) 13777 21915 47085 18546 27327 40083 23429 18016 (3.64) (5. 79) (12.44) (4.90) (7.23) (10.59) (6.19) (4.76) MDC Groundwater and MDC MDC MDC MDC Groundwater MDC Gro tndwater and Willet Pond Groundwater and MDC 5 Towns form single service area served by Dedham Water Company. ------- The total elevation drop along the River’s course approxj. mates 83.8 m (275 feet). The majority of this change, 68.6 m (225 feet), occurs in the first 16.1 km (10 mi) between the Neponset Reservoir and the Norwood gaging station. A drop of 3.1 m (10 feet) is experienced between the gage and the beginning of Fowl Meadow Marsh. As the River flows through Fowl Meadow there is virtually no elevation change. A fairly rapid elevation change takesplace downstream from the Tileston and Hollingsworth dam. The groundwater reservoir (see Figure 2.5-19) underlying the Neponset River Basin includes bedrock, glacial till and stratified drift. Wells developed in bedrock and till gener- ally have yields of only a few cubic meters per second (gallons per minute) and are subject to seasonal variations in water level. Wells developed in the stratified drift, however, have excellent water bearing properties (Brackley, Fleck, and Meyer, 1976). Accumulations of stratified drift to 45.7 m (150 feet) underlie major sections of the River in the Town of Walpole below Cedar Meadow Swamp and the entire Fowl Meadow Marsh. These deposits have a transmissivity estimated to be greater than 372.6 m 3 -d/m (30,000 gpd/ft) and yields from wells developed in them are commonly in excess of 0.02 m 3 /s (300 gpm). Storage within these formations is estimated to be 4.9x10 7 m 3 (l3xl0 gal) (Brackley, Fleck, and Meyer, 1976). Most industries within the basin rely upon the MDC for water supply; however, six major industries within the basin use surface impoundments of the River for water supply. These industries are: (Metcalf and Eddy, 1969; Water Quality Sec- tion 1976f). 1) Bird Machine Company, South Wa].pole 2) Kendall Company, Walpole 3) Bird and Sons, Inc., East Walpole 4) Hollingsworth and Vose Company, East Walpole 5) Plymouth Rubber Company, Canton 6) Tileston and Hollingsworth Company, Hyde Park. Water usage by these companies is approximately 44,000 m 3 /d (11.7 mgd) (Water Quality Section, 1976 2—64 ------- L i i i i.E J, (25 Ji *EC..uU O Eiii ii?E’ ‘C SOURCE MAPC W t.r Quality Pro ject Map MILES 1.51.50 1 1 _ I I I _I j I I I I 21012 KM FIGURE 2.5-19 GROUNDWATER FAVORABILITY NEPONSET RIVER WATERSHED ,t. Ci C i U - LEGEND IIRI DUU(2ilII1I 16-li I 1. S-3 CCi ( C ICI ¶0 WESCCOCO CiS0CiD(I &IC 1 125 1 1P LY ------- Certain sections of the River are suitable for recrea- tion, such as the Fowl Meadow Marsh area which can be used for boating recreation. In addition, recreational facilities are found on several ponds in the basin and several of the brooks within the basin are presently stocked by the Division of Fisheries and Wildlife with trout. However, the majority of water based activities within the basin have ceased due to degraded water quality. B. Water Quality . The Neponset River has significant water quality problems. Present point and non-point sources, past discharge practices, and the natural sluggish nature of the river are the causative agents. The River has a Class B desgination along most of its length and only the rapidly flowing headwaters meet applicable water quality criteria. Figure 2.5—20 presents water quality classifications for the Neponset River. The Neponset basin contains a highly urbanized region with the cities of Quincy, Milton, and the Dorchester, Rox- bury, and Hyde Park sections of Boston, having a significant influence on water quality in the basin. Runoff from streets, parking lots, multiple family dwellings, and junkyards located within these communities has been hypothesized to contribute to deteriorating conditions within the River (New England Division, Corps of Engineers, l975c). In addition, nutrients introduced by residential and agricultural use of fertilizers and land stripping, in the form of industrial, residential and highway construction have been identified as having an adverse impact upon the River and its tributaries (Water Quality Section, 1973). Principal industrial discharges (Figure 2.5 —2land Table 2.5-16) to the Neponset River begin at its headwaters at the Neponset Reservoir in Foxborough. The effluent from chemical treatment of plating wastes from the Foxborough Company enter the Neponset Reservoir and are diluted through mixing. Midway along the length of the River dcgnestic waste, oil discharges, and solids are contributed respectively by the Bird Machine Company, Kendall Company, and Hot-Top Pavements, Inc. (Water Quality Section, 1973). Private discharges of domestic waste enter the Neponset from the advanced waste-water treatment plant of Foxborough State Hospital and the Foxborough Raceway. Although overt discharges by the Foxborough Raceway have been eliminated, continued poor water quality in the area indicates some form of waste input to the river remains (Water Quality Section, 1973). In addition to the above point sources, a variety of factories and paper mills formerly discharged wastes contain- ing organic materials andmetals directly into the river. 2—66 ------- LOCATION WATER SHED 2 2 0 2 L __ J KILOMETERS 9 MILES Dorchester Bay apog Pond SOURCE: Water Quality Section. 1976a * 0 0 LEGEND US.G.S. GAGING STATION WATER USE CLASSIFICATION 1976 CONDITION CHANGE IN CLASSIFICATION FIGURE 2.5 -20 WATER NEPONSET RIVER WATERSHED QUALITY CLASSIFICATION ------- Dorchester Bay WATERSHED LOCATION 9 2 -- KILOMETERS 2 2 MILES pay Pond (J 3 Reservoir SOUP’E Waist Quality Section. 19761 LEGEND * USGS. GAGING STATION POLLUTANT DISCHARGE LOCATIONS SEE: TABLE 2.5-16 FIGURE 2.5.-21 POLLUTANT DISCHARGE LOCATIONS NEPONSET RIVER WATERSHED ------- TABLE 2.5—16 NEPONSET RIVER WATERSHED DISCHARGES Map Location Discharger Discharge 1 *Foxboro Co. Plating wastewater following chemical neutralization and settling 2 *Fox yJro State Hospital Domestic wastewater following extended aeration and sand bed filtration 3 * Bird Machine Co. Domestic wastewater following extended aeration and lagooning 4 * Kendall Co. Cooling water 5 *Hollingsworth & Vose Co. Filter bed backwash, no treat- ment 6 * Bird and Sons, Inc. Cooling water 7 * Bird and Sons, Inc.-Asphalt Cooling water plant 8 * erjcan Biltrite, Inc. Cooling water 9 * Bird & Son, Inc. — Norwood Untreated wash water Granular Div. 1D * Plymouth Ru bber Co. Cooling water 11 * Magnesium Casting Cooling water Source: Water Quality Section, 1976 *NPDES Permit Issued 2—69 ------- Although many of these now discharge to the MDC sewerage sys- tem, sludge blankets on the river bottom from these practices still exist, exerting a negative effect on water quality (New England Division, Corps of Engineers, 1975c). Frequent over— f lows occur from the Neponset River Valley Sewer and the Dor- chester Interceptor into the lower reaches of the Neponset River. This contamination is a serious threat for the water quality of the lower River and estuary (New England Division, Corps of Engineers, 1975c). The suimner, 1973 Neponset River Basin Study conducted by the Massachusetts Division of Water Pollution Control pro- vides the data for an analysis of the Neponset River water quality. That survey indicated the Neponset Reservoir to contain significant blue—green algal blooms during summer months, which are responsible for super saturation of the waters — an average of 8.9 mg/i dissolved oxygen was found in the month of July. Average BOD 5 was 6.15 mg/i while nutrient concentrations varied from 0-0.27 mg/i NH 3 -N and 0.7-1.0 mg/i total phosphorus as P. A geometric mean of 300 coliform organisms per 100 ml was within the Class B designation of these waters. Evaluation of the data led to the eutrophic designation given to the Neponset Reservoir by the Divison. This eutrophic state continued downstream to the outlet of Crackrock Pond. The effluent of Foxborough State Hospital is thought to have provided nutrients for the exten- sive algal and aquatic vascular plant growth present. The marsh within Crackrock Pond provided for stabilization of the nutrients as shown by the predominance of N0 3 -N (0.35 mg/i) over NH 3 —N (0.015 mg/i). Below this point, Foxborough Raceway is suspected of being a source of fecal contamination to the River. A mean of greater than 20,000 coliform organisms per 100 ml was encountered in the area of the facility. Decreasing dis- solved oxygen levels downstream of the raceway recovered prior to entering the area of influence of the Kendall Com- pany. Turbulent mixing was responsible for this. The Kendall Company is located in the center of urban- ized Waipole. This industry, in combination with urban run- off from the city, is responsible for increasing BOD 5 concen- trations. In addition, oil films have been traced to the Kendall Company. A strong indication of non-point source contamination of the River is deduced from the increase in coiiform bacteria in the area. Below this point, until the River enters the Fowl Meadow marsh area, dissolved oxygen levels fluctuated. The marsh appearea as an area which moderates the effects of waste inputs to the River. While dissolved oxygen values generally declined and SOD 5 values generally increased, their change was minimized such that average D.O. values never fell 2—70 ------- below 5.0 mg/i. irimonia nitrogen and nitrate nitrogen trends were variable, as they exhibited a slight increase in the month of July and a slight decrease in August. Below the Fowl Meadow marsh area the state of the River deteriorated. Combined sewer overflows, urban runoff, and non—point sources from the area of Milton and Mother Brook contributed to increasing BOD 5 , NH 3 -N, N0 3 -N and coliform loads upon the River. Dissolved oxygen levels recovered only after the water had passed over the MDC Dam at the Tileston and Hollingsworth Company and physical reaeration had occurred. Below this point, benthic oxygen demand in the impoundment behind the Walker Baker Dam resulted in a slight D.O. drop in the final fresh water portion of the Rivers In the 1973 survey (Frimpter, 1973c), groundwater quality in the Neponset basin was found to be. suitable for drinking and most industrial uses. The water was generally identified as being soft and slightly acidic. Levels of sodium chloride (10 to 15 mg/i) were found to be elevated above those considered natural concentrations, but well within the 250 mg/i limit required by the U.S. Public Health Service for drinking water. Local occurrences of undesirable concentrations of iron, manga- nese, and color had been reported in Westwood and Walpole (Frirnpter, 1973c). Incidents of groundwater contamination have appeared within the basin on a local scale. At least one public sup- ply well was closed due to fecal coliforin contamination. The Massachusetts Department of Public Health has generated data which indicate 50 percent of public supply wells contained more than 12 mg/i chloride in 1962. In 1968, 50 percent of public supply wells containedmore than 26 mg/i chloride (Frimp- ter, l973c). Speculation has been made that the sources of chloride contamination are stockpiles of road salt and runoff from paved areas (New England Division, Corps of Engineers, 1975c). Specific sites identified are located in Westwood, where a salt stockpile is situated in the Purgatory Brook drainage basin, and in Dedham and Milton where both salt stockpiles and runoff from Routes 128 and 95 threaten groundwater sup- plies in the Fowl Meadow Marsh. Evidence already exists which indicates that every well pumping from the Fowl Meadow aquifer is experiencing an increase in salt content (New England Division, Corps of Engineers, l975c). C. Water Quantity—Quality Problems . Low flow conditions exist on the Neponset River during summer months; however, the precise extent of this problem is difficult to determine 2—71 ------- because the flow in the River is subject to active regulation for industrial water supply. The Neponset Reservoir Company and the Neponset Reservoir Corporation own and control the Neponset Reservoir, Crackrock Pond, and Norfolk Street wells and Willett Pond. The three impoundments are operated to impound winter and spring runoff and release it during dry- weather periods when streainflow is insufficient for industrial consumption. In addition, if there is insufficient storage in the Neponset Reservoir for the required release, the Nor- folk Street wells are activated to discharge 1135-1892 m 3 /d (0. 3-0.5 mgd) into the reservoir (Metcalf and Eddy, 1969). River flow regulation generally occurs from July through October and averages 106 days per year. Regulation is per- formed by the companies’ operating committee and is based mainly upon the committee’s experience. When flow appears insufficient for industrial consumption, water is released from thç Neponset Reservoir at a rate somewhat less than 13247 m-’/d (3.5 mgd). In addition, Willett Pond is discharged at an unknown rate to meet the demand of the Tileston and Hollingsworth Company in Hyde Park (Metcalf and Eddy, 1969). Flow measurements of the Neponset at the Norwood gage are highly affected by upstream reservoir regulations. An investigation (Metcalf and Eddy, 1969) of flows at the Nor- wood gage concluded that flows there are the result of up- stream regulation. In addition, it was concluded that the minimum daily flow and minimum seven day flow are poor indi- cators of expected future low flow conditions. Average daily flow occurring during the minimum flow month or mini- mum flow three month period were indicated to be a better measure of drought conditions (Metcalf and Eddy, 1969). Groundwater withdrawals from wells in close proximity to the River have been found to cause low flow problems in the basin. A case in point is the Mine Brook valley which runs from Medfield to Walpole, and within which wells have been pumped at rates sufficient to dry Mine Brook in Walpole during periods of low flow. D. Water Quality Management Planning . The EMMA Study is the accepted 303(e) basin plan for the Neponset River. This plan calls for construction of an advanced wastewater treatment facility, located in the Canton Norwood area of the basin. Serving five towns within the watershed, the plant would pro- cess an estimated 94625 rn 3 /d (25 mgd) and retain water within the basin augmenting stream flows (Metcalf and Eddy, 1975k). The 208 areawide wastewater management planning is pre- sently in its initial stages in this basin. It is, however, expected to help identify non-point pollution problems within the Neponset River watershed when completed. 2—72 ------- 2.5.5 Weymouth River Watershed The Weymouth River watershed (Figure 2.5—22), as defined within this section, is the land area drained by the Weymouth Fore River, Weymouth Back River and the WeIr River. Located in the southeast section of the Boston Harbor drainage area, the Weymouth River watershed occupies approximately 207 sq km (80 sq mi) in the towns of Randolph, Braintree, Hingham, Hol- brook, Weyniouth and a portion of the City of Quincy. The watershed’s terrain is rolling and hilly, with a maximum ele- vation of 79.3 in (260 ft). The Weymouth Fore River originates at Lake Holbrook, approximately 5.6 kin (3.5 mu) upstreamof the River’s estuary. The river flows north to form the Cochato River and then the Monatiquot River, which is regarded as the main stem of the Weymouth Fore River. In Braintree, the River discharges into its estuary. Total elevation drop from its headwaters to the sea level estuary is roughly 38.1 m (215 ft). In addition, the river is joined by a number of tributaries, including the Farm River, Lee Brook, Govers Brook, Tumbling Brook and Cranberry Brook (Water Quality Section, 1976f). Directly east lies the Weymouth Back River, which origi- nates at the outlet of Whitman’s Pond in Weymouth. This river flows directly north for 0.6 km (0.4 mi) prior to discharging into its estuary. Whitman’s Pond is fed by the Mill River, which flows for 2.4 km (1.5 mi) from its origin at Great Pond in Weyxnouth. The River’s total elevation change over its course is somewhat less than 22.9 in (75 ft). The Weir River has its origins in the upper portion of Weymouth Township. It flows in a general northeastern direc- tion through the Town of Hingham as the Old Swamp and Plymouth Rivers before turning north to discharge into Hingham Bay. Fulling Mill Brook is the Weir River’s major tributary along its 6.4 km (4 mi) course. A major sub-watershed is the Town River basin. Origi- nating at the outlet of the Old Quincy Reservoir in Braintree, Town River Brook flows northeast through Quincy to Town River Bay. Within this watershed, flow gaging stations are maintained at two locations: Town Brook in Quincy and on the Old Swamp River near South Weymouth. Maximum discharges of record are 13.6 m 3 /s (481 ft 3 /s) at Town Brook and 16.0 m 3 /s (566 ft 3 /s) on the Qid Swamp River, while minimi 3 m flows recorded equal 0.005 mi/s (0.19 ft 3 /s) and 0.003 in /s (0.11 ft 3 /s) respect- ively at these two locations (U.S.G.S., 1976). Insufficient data exist to develop flow-duration curves for these rivers. 2—73 ------- P ILOME’EPS 1 0 ‘ Ut F—I DAM fOunCE *D*• u&’v end R.p.o ch Sec’ion. 1976k FIGURE 2.5.-22 WEYMOUTH RIVER WATERSHED 0 WATERSHED LOCATION Quincy Bay • Iingham Bay él’ Meadow Br. 1 0 1 LEGEND * USES. GAGING STATION ------- Flooding is a problem along portions of Town Brook, Fur- nace Brook, and Hayward Brook in Quincy, with major flooding occurring in both 1955 and 1968. A flooding problem also exists on portions of theMonatiquot River in Braintree. These problems are a result of urbanization increasing flood peaks and runoff volumes beyond the existing channel capacity (New England River Basins Commission, 1975). Extensive groundwater resources (Figure 2.5—23) exist in the watershed with the best aquifers being composed of glacial till and stratified drift deposits. These formations, with up to 15.1 m (50 ft) of saturated thickness, underlie the Cochato, Monatiquot, and Swamp Rivers and the area adjacent to Great Pond in Weymouth. Additionally, the aquifer charac- teristics and well yields are identical to those of the neigh- boring Neponset River watershed: transmissivity greater than 372.6 m 3 /m..d (30,000 gpd/ft) and yield of 0.02 m 3 /s (300 gpm) or better (Brackely, Fleck and Meyer, 1976). A. Water Use . Municipalities within the Weymouth River water- shed presently receive water supplies from a combination of surface and groundwater sources. Present water use along with projected demands are presented in Table 2.5-17. The Hingham Water Company serves both the towns of Hingham and Hull and should be able to meet projected demandswithexisting sources. Braintree, Holbrook and Randolph presently use the Great Pond Reservoir and can meet projected demands by increasing diver- sions from the Richardi Reservoir. Increased demand in Weymouth could be met using existing standby wells if these sources were treated to remove high iron concentrations. The option for Weymouth is more economical than connection to MDC supplies (New England River Basins Commission, 1975). Recreational use of the Weymouth watershed’s water include boating and passive activities. Boating activity make heavy use of anchorages and channels in the Town River Bay, Weymouth Back River and the Weir River. The excess of 3000 craft have been reported in the existing recreational fleet (New England River Basins Commission, 1975). The entire shoreline and salt estuary of the Weymouth Back River in Hinghain is a designated recreational area. In addition, directly across this River in Weymouth is Great Esker Park. Together these parks form one of the most scenic recreational areas in Boston Harbor. This area is enjoyed by a large number of people for passive recreation (Metropolitan Area Planning Council, 1976. B. Water Quality . Waters within the Weymouth River watershed are classified B and SB (Figure 2.5-24). However, the lower portions of the Fore and Back Rivers are not meeting their classification. Present upstream classifications are unknown. 2—75 ------- c2c SOURCE:MAPC Water Quality Proj.ct Map LEGEND uj ic 0I L I I U1IT LF. Ji L25 !& 1 -i --t r WLL JLL 11L 2 1 0 1 2 KM MLIC W*Tfl tY I.L FIGURE 2.5-23 GROUNDWATER FAVORABILITY WEYMOUTH RIVER WATERSHED MILES 1.5 1 .5 0 L__ i I i ------- WATERSHED LOCATION Quincy Bay V I4ngham Bay ? River Bay. 1 0 ,_J MILES I ’ DAM WATER USE CLASSIFICATION 976 CONDITION SOURCE:Wo,.r Quality Section. 1976o FIGURE 2.5-24 WATER QUALITY CLASSIFICATIONS WEYMOUTH RIVER WATERSHED Upper Reservoir Meadow Br. 101 K ILOMETE I Holbrook LEGEND * USGS. GAGING STATION ------- TABLE 2.5—17 WATER SUPPLY NEEDS WEYMOUTh RIVER WATERSHED 1 Existing System Proposed Safe Yield 1 Avera e Demands 1990 Desi. Demand 1990 Additional Township Source m 3 /d (MCD) m d (MCD) MGD ) Supply Source Braintree Great Pond Rea. 23,921.2 (6.32) 23,921.2 (6.32) Further develop & Diversion8 10,498,0 (2.77) Richardi Richardi Rea 11,355.0 (3.00) Reservoir Tubular Well 1,514.0 (0.40) Eingham Fulling Mill 12,452.7 (3.29) 12,452.7 (3.29) None Dug Well 8,327 Gravel—Packed Wella 14,761.5 (2.20) Holbrook See Randolph 6,056.0 (1.60) 6,056.0 (1.60) See Randolph ‘ Hull See Hingham 9,500.4 (2.51) 9,500.4 (2.51) See Hingham Randolph Great Pond Res. 16,540.5 (4.37) 16,540.5 (4.37) Further develop & Diversions 4,920.5 (1.30) Richardi Gravel—Packed Wells 9,462.5 (2.50) Reservoir Weymouth Great Pond Res. 23,050.7 (6.09) 23,050.7 (6.09) Treated & Diversions 17,032.5 (4.50) groundwater Gravel—packed Wells 14,004.5 (3.70) ‘Mew England River Basins CommIssion, 1975. 2 Croundwater yield reported as system pumping capacity. 3 Einergency supplies. ------- During June of 1975, the Massachusetts Division of Water pollution Control conducted its first intensive water quality survey within this watershed, sampling the Weymouth Fore and Weymouth Back rivers and their tributaries. Chemical and bacteriological analyses were performed on the sampled. Table 2.5-18 summarizeS the results of this survey. In addition, a survey of wastewater discharges into watershed streams was performed in December, 1975 (Water Quality Section, l976f). Discharge locations and descriptions are presented in Figure 2.5-25 and Table 2.5—19 respectively. Parameters of particular importance in determining the River’s present conditions are dissolved oxygen and coliform bacteria. Dissolved oxygen levels ranged below the Class B water criteria of 5.0 mg/i in the Fore River, while remaining well above it in the Back River. However, only 4 of 15 Fore River samples were below 5.0 mg/i indicating good D.O. levels being maintained in this river. Coliform and fecal coliform levels exceeded the Class B standard of not more than 1000 MPN/100 ml in both rivers. In addition, only 4 of all loca- tions sampled (20) had coliform counts meeting Class B stand- ards. These rivers appear therefore, to be meeting dissolved oxygen standards while exhibiting considerable bacterial con- tamination and violating that standard. The wastewater discharge survey located nine sources of discharge into the Weymouth Fore River with the majority of these located adjacent to the River’s estuary and Town River Bay. Upstream discharges are cooling water and not indicated as degrading the stream. However, discharges into the lower portion of the River are probably contributing to its present water quality condition being below its designated classifi- cation. In addition to wastewater discharges, numerous other points for pollution input to the waters of the lower water- shed exist. During the 1968 Boston Harbor Pollution Survey (Lord, et al., 1968), points of storm drainage, septic tank and cesspool discharges, sewer overflows and small commercial establishment discharges were located in the lower reaches of the Weir, Fore and Back rivers, and in Town River Bay. The total number of discharge points into these four water bodies were, respectively, 19, 12, 42, and 11. Significant pollutant loads undoubtedly come from these sources. Overall water quality in this watershed appears good from a dissolved oxygen standpoint. However, other parameters (fecal coliforms, ammonia, phosphorus) indicate questionable quality. Fecal coliforms exceed standards along most of both the Fore and Back rivers. The lowest ammonia level reported, 0.02 mg/i, is the recommended (Committee on Water Quality Criteria, 1972) maximum allowable concentration to 2—79 ------- TABLE 2.5-18 1975 WATER QUALITY SURVEY RESULTS 1 Dissolved Oxygen, tug/i BOD 5 , tug/i Temperatures, °C F) Total Solids, mg/i Total Suspended Solids, mg/i Nitrate—Nitrogen, mg/i Ammonia—Nitrogen, mg/i pH. units Total Phosphorus as P, mg/i Total Alkalinity, mg/i Chlorides, mg/i Fecal Coliforms, MPN/100 ml Total Coliforms, NPN/l00 m1 4 Weymouth Fore River 4.2—8.3 1.6—3.6 15 • 9 2i .7 144—6800 0.5—7.5 0.1—1.0 0.02—0.24 6.9—7.8 0. 02—0. 10 26.0—56.0 24—2930 60—20000 450—36050 Weymouth Back River 3 7.2—8.3 1.4—2.5 16 ,8 —22.1 (62,2—71.8 ) 108—1900 1.5—5.5 0.4—1.1 0.02—0.06 7.0—7.5 0.01—0.04 20. 0—46 .5 32—975 50—5000 450—4900 4 Range of geometric means (60,6 -71 ,1) 1 Water 2 Range 3 Range Quality Section, 1976f of averages of 15 samples of average of 5 samples 2—80 ------- LOCATION Quincy Bay I4ngham Bay Town River Bay. 1 0 MILES 1—I DAM POLLUTANT DISCHARGE LOCATIONS SEE: TABLE 2.5—19 SOUPCF: Wot•r Ouality S.ctieni, 1976k FIGURE 2.5-25 POLLUTANT DISCHARGE WEYMOUTH RIVER WATERSHED LOCATIONS WATERSHED R. Upper Reservoir Meadow Br. 101 KILOMETEIS Holbrook LEGEND * USC S. GAGING STATION ------- TABLE 2.5-19 WEYMOUTH RIVER WATERSHED DISCHARGES Map No Discharger Discharge 1 *Chase & Sons, Inc. cooling water 2 *Armstrong Cork Co. cooling water and autoclave condensate 3 * achigan Abrasive Products cooling water 4 *BrajI tree Electric Light Co. electric power plant cooling water 5 *Qujncy Oil Co. oil terminal drainage 5 *Boston Edison Co., electric power plant Edgar Station cooling water 7 *proctor & Gamble Co. detergent manufacture wastes B *Clties Service Oil Terminal oil terminal drainage 9 *G nera1 Dynamics Corp. cooling water, boiler blowdown, shipyard drainage Source; Water Quality Section, 1976-f * DES Permit Issued 2—82 ------- prevent fish toxicity. Phosphorus levels exceed that which is recognized (0.01 mg/i) as the critical level above which exces- sive plant growth can occur. The implication is that insidious non-point sources, such as septic tank drainage and storm water runoff, are starting to create water quality problems in the Weymouth River watershed. C. Water Quantity-Quality Problems . No water quantity-quality problems are presently documented as existing in the Weymouth River watershed. However, the water supply for all towns in this watershed originates within the waters, with a portion of it being discharged outside the basin via the MDC sewer sys— tern. An increased discharge to the sewer system has the poten- tial to decrease stream flow due to the loss of septic tank recharge. The effect of any proposed sewering upon this water— shed’s hydrologic budget should be carefully considered prior to the initiation of the future action. D. Water Quality Management P1annin . The EMMA Report is the official 303(e) basin plan for the rivers of this watershed. In its present recommended form, however, it will not have any effect upon water quality within the Weymouth River watershed. The ongoing 208 planning should be helpful in defining, and developing controls for, the non-point sources within this watershed. 2.5.6 Sudbury River Watershed The Sudbury River has its source in the Town of Westborough, from which it flows east through Cedar Swamp to Framingham. In Framinghani the River turns sharply north and sequentially travels within the borders of Sudbury, Wayland, Lincoln and the Town of Concord where it joins with the Assabet River to form the Concord River. A drainage basin (Figure 2.5—26) of 438 sq km (169 sq mi) contributes to the 66 km (41 mi) long Sudbury River. Towns with- in the basin proposed for inclusion in the MSD are Southborough Hopkinton and Ashland, while Framingham presently discharges to Nut Island. The Sudbury River can be divided into distinct physical sec- tions. The first is upstream of Framingham where the river is narrow and flows rapidly. Several small impoundments restrict free flow through this section. The second section is character- ized by two major impoundments (Sudbury Reservoirs Nos. 1 and 2) in Frazningham, while the third section of the river flows through the National Wildlife Refuge Meadowlands in the towns of Sudbury, Wayland, Lincoln and Concord. River movement is sluggish through the Meadowlands as river elevation changes only 0.31 m (1 ft) Over a distance of 19.3 km (12 mi). 2—83 ------- LI WATERSHED LOCATION WE STFO RD I / LINCOLN ‘bury B ILL ERICA ‘4 .’ Concord River EDFORD River Cochituate SHE RBOR N HOLLISTON 3 3 0 3 - KILOMETERS 0 MILES SOURCE: Wat., Quality S.ction. 1976g Merrimack Assabet GRAFTON UPTON 3 FIGURE 2.5-26 SUDBURY RIVER WATERSHED ------- The towns included in this discussion are located within the first and second sections of the river. These sections of the Sudbury are covered by the anti—degradation clause of the 1974 Massachusetts Water Quality Standards. The clause prohibits any new wastewater discharge upstreamof the most upstream municipal discharge (Water Quality Section, l976f). A. Water Quality . A survey (Water Quality Section, 1976) of the Sudbury River was conducted by the Massachusetts Division of Water Pollution Control in the summer of 1973. The first river segment is contained within the expanded MSD. This segment extends from the source of the Sudbury to the outlet of Saxonville Pond. High coliform bacteria levels were encountered along the entire length of the segment, indicating fecal contamination to be occurring. The possible sources of contamination were identified as subsurface dis- posal problems in the upper portions of the segment and urban runoff, septic leachate, storm sewers, and wastewater sewers in the heavily populated areas of Ashland and Framingharn. The entire length of this segment has been designated as Class B waters. (Water quality classifications for the Sud- bury are presented in Figure 2.5—27). However, dissolved oxygen levels were found to be below the Class B criteria. Excessive concentrations of nutrients were not present. The remainder of the Sudbury River lies outside of the designated study area. However, alterations imposed upon the upstream region will undoubtedly affect the downstream environment. Problems associated with these reaches include high levels of coliform bacteria, moderate nutrient concentra- tions, heavy doses of pesticides, and dissolved oxygen deficien- cies aggravated by the introduction of organic matter from the surrounding marshlands. Sections of the upper Sudbury River are part of the Metro- politan District Commission’s water supply system. Impound- DEnts in the towns of Ashland and Framingham are presently maintained as an emergency water supply and have not actively been used as a potable water ,source since before 1930. A minimum discharge of 0.066 ma/s (2.32 cfs) must be released at the outlet to this reservoir system. However, rarely has such a minimum been reached as the 97 year average release is 3.24 1n 3 /s (114.5 cfs). During the 1973 survey, flow was moni- tored from July 5 to August 31 at Reservoir o. 1 at Framing- ham. Discharge ranged from 0.176 to 4.446 m /s (6.2 to 157 cfs) with a mean of 1.413 m 3 /s (49.9 cfs). Two additonal impoundments are present on the Upper Sud- bury River, namely the Sudbury Reservoir in the towns of Southborough and Marlborough, and the Framingham Reservoir 2—85 ------- LII WATERSHED LOCATION Merrimack River WATER USE CLASSIFICATION 1976 CONDITION CHANGE IN CLASSIFICATION Assabet River Sudbury River Lake Cochituate SOURCE: Water Quality Section: 1976a 3 3 0 3 KILOMETERS 9 MILES FIGURE 2.5-27 WATER QUALITY CLASSIFICATIONS River 3 SUDBURY RIVER WATERSHED ------- -. S _ I S \ 1 \ . / T <—’\ : ( ( x ‘-S S 5 , .5 S C! - —-I —- - =1 F - •j - . ! — r -- - -- ç—’ . . -.- - S J : — - — V. - T : - _____ LE:EI LD : - J - : : Ti ; _ - ‘r — - - - --‘ -— -. - .‘I•__S _” —• .77 • - - .,- . : -; - - ‘ _— - - - - -. - A -i c 7 I - - - .—. - -‘ i —1. - .çi 5 • K STti Y i -. .- J ‘ - - & ‘ -‘ T - -. - -‘ -. -. \ p— .. - . - ‘ & -. • ‘ ‘ :- - - S -. S : CT L 1 MILES /, 1o 1i - 2 1 0 1 2 • -! I = . . ‘i.. . ,. .L KM JS . - - .0’ - -. SOURCE: MAPC Wotr Quality Proj.ct Map FIGURE 2.5-28 GROUNDWATER FAVORABILITY SUASCO RIVER WATERSHED ------- No. 3. The combined capacity of the systems is 3. 18xl0 7 in 3 (8.4 billion gallons) which are utilized to supplement water supplies during summer high demand periods in the MDC system. Of the four communities contained within the study area, Ashland and Hopkinton are dependent upon groundwater as their potable water source while Framinghazn and Southborough are tied into the MDC system. Because of their dependence on sub- surf ace water the two former communities must be particularly protective of their groundwater resources. No point sources of pollution are contributed to the Sudbury River by the four towns of the upper basin which lie within the study area. From Westborough to Franiinghaxn no specific sites of waste discharges have been identified. Two point source waste discharges, however, do exist along the lower length of the Sudbury River. The first dis- charge is the Marlborough East Advanced Wastewater Treatment Plant which releases its effluent to Hop Brook. Hop Brook flows for 12.9 km (8 mi) before entering the Sudbury. The second discharge is the Raytheon Corporation which releases a secondary treated effluent of approximately 151.4 in 3 /d (40,000 gal/d) to the River. The discharge has little effect upon the water quality of the River because of the small amount of effluent flow and the fact that the discharge flows through a swamp before reaching the Sudbury River. B. Water Quality Management Planning . The Water Quality Management Plan (303e) for the Sudbury basin (Water Quality Section, 1976) is in basic agreement with the recommendations of the EMMA Plan. Framingham and Ashland are presently experiencing water quality related problems because the capacity of the existing MSD trunk line is insufficient. The Sudbury Basin Plan recommends expansion of the MDC intercep- tor to alleviate these problems. Hopkinton and Southborough do not have pressing needs and the 303(e) plan recommends inclusion of these towns in the MSD when, and if, central sewerage systems are required. The EMMA study proposed mid-Charles satellite plant would supply low flow augmentation for the Charles River. However, two towns in the proposed satellite plant tributary area lie within the Sudbury basin. Ashland and Hopkinton have local groundwater supplies (Figure 2.5-28 presents groundwater resources within the area). The proposed system would transfer wastewaters from their basin of origin to the adjacent Charles River basin. Prior to implementations, thought must be given to the negative impacts this inter-basin transfer may have on ground and surface water resources within the Sudbury River watershed. 2—88 ------- 2.6 AQUATIC AND MARINE BIOTA Water quality is often described in physical-chemical terms while others describe water quality by the biota it supports. Both are workable and usually concurrent criteria. In general, the fresh water quality of lakes and rivers in the MDC service area is somewhat degraded. This implies that additives, from various point and non-point sources, have altered the physical and chemical environments of the MDC’S waters such that the biotic assemblages have changed. Organ- isms that cannot tolerate “less than pristine” conditions are usually not found in such waters. Most biota need oxygen and food. The aquatic microflora and microfauna rely on oxygen that is dissolved in the water (Dissolved Oxygen or DO) and inorganic and organic food in the form of detritus and dissolved nutrients. When there is an overabundance of food, oxygen is often depleted via bio- logical processes. Clean waters are typified by ample DO and low nutrient levels. In such waters the total biomass is less than in more polluted environment. In this situation, the ecosystem functions very efficiently. That is, gases and nutrients are cycled such that, under most conditions, neither is lack- ing. Clean water environments are also characterized by specific biotic communities. The addition of pollutants to clean waters often imposes a stress on the native biota. Factors such as sludge deposits on the stream bottom and low DO levels can substantially affect the ecosystem and completely alter the composition of the biota. This effect may be manifested by algal blooms, over- abundance of “trash” fish (carp and suckers), high bacterial levels, and if conditions become particularly stressed, fish kills can occur and/or the water can become toxic. Tables 2.6-1 and 2.6-2 illustrate the relationships between physical, chemical, and biological factors in a stream environment. The two cases illustrated represent typical “clean” and “pol- luted” stream environments. In reality, these cases represent two extremes which cover an infinite range of real world cir- cumstances. In the MDC study area, an adequate characterization of aquatic organisms is lacking in many cases. Due to the cause— and-effect relationship between water quality and biota, at least a general idea as to the nature of the biotic communi- ties may be had by evaluating the available water quality data. 2—89 ------- Table 2.6—i CI ARACTERISTICS OF A TYPICAL “CLEAN STREAM” ENVIRONMENT General Features: * “Clean” bottom, no sludge deposits * Water relatively clear Chemical Features: * Dissolved oxygen is high, water smells “fresh”, no foul “rotten egg” smell * Organic content low * Nutrient levels low * No toxic materials present Biological Features: * Bacterial count low * Number of species high * Number of organisms per species low * Characteristic “clean stream” organisms found — Invertebrates: — Caddis fly, mayfly, stonefly and damseifly larvae, beetles, clams - Fish: — Darters, minnows, sunfishes, bass, yellow perch 2—90 ------- Table 2.6—2 CHARACTERISTICS OF A TYPICAL “POLLUTED STRLN” ENVIRONMENT General Features: * Bottom covered with thick black organic sediment layer * Water turbid Chemical Features: * Dissolved oxygen low, foul “rotten egg” smell sometimes present * Organic content high * Nutrient levels high Biological Features: * Bacterial count high * Number of species low * Number of organisms per species high * Characteristic “pollution tolerant” organisms found - Invertebrates: - Midge and mosquito larvae, sludge worms, air-breathing snails, rat-tailed maggots - Fish: - None in severe cases; carp, suckers, catfish in less extreme situations 2—91 ------- Much of the water in the MDC study area is “unclean”. In some areas, as a result of point source discharges, the water is polluted. The effects are evident upon examining representative chemical and biological data. However, severe pollution is most serious in localized areas. For example, in a river, water quality gradually improves downstream from a point source. Thus, chemical and biological data are sub- ject to rapid change. Based on limited data, and inferred from water quality parameters, a compilation of aquatic organisms which are likely to be found in the river basins of the MSD area was developed. Certain groups or associations of species may be characteristic of a certain ‘peof environment. It does not mean, however, the individual species are reliable indi- cators of environmental conditions in a particular area. The Charles River was examined thoroughly from 1973 through 1976 (Erdxnann, 1977). The findings concur with textbook descriptions of polluted waters (Ruttner, 1974 and Reid, 1961). The DO levels were depressed at point source discharge locations of organic waste. In addition, algal growth stimulated by point and non-point discharges caused large daily variations in DO along the length of the River. The organic content and nutrient levels of the Charles River are increased by the polluting point source organic waste discharges of the upper watershed. Downstream, biological processes (e.g., algal growth) and non-point sources further increase organic and nutrient levels. The bacterial quality is poor along the length of the Charles River. Total coliform levels were consistently violated at all the sampling stations. Because of inade- quate disinfection of some sewage effluents, a public health risk exists in some parts of the River. The Neponset River may be generally classified as a recovering river. Upstream portions of the River have rela- tively high dissolved oxygen levels to the Town of Walpole. Below this point, DO levels decrease. Organisms which occur below the Neponset Reservoir Dam include subxnergent plants such as milfoil ( Myrio hyllum sp.) and flatworms, caddisflies and isopods. As the River travels downstream, floating and and emergent aquatic vegetation becomes abundant. There is an accumulation of oil on the river bottom and along the shore as one continues downstream. Beetle larvae, tubificids and snails are evident. The Neponset basin, as an urbanized area, contributes to the degradation of the downstream water quality. In the lower reaches of the River, species diversity decreases and the individiuals in each species increase. For example, few mayf lies are present, there is an increase in snails and larvae, 2—92 ------- and the variety of fish may be expected to decrease. Imme- diately below the confluence of Mother Brook, combined sewer overflows, urban runoff, and non—point sources provide the primary degradation of water quality. Therefore, the aquatic biota will reflect a degraded environment. There is an in- crease in co].iform bacteria and BOD in the area. Organisms which may be expected to occur include sludge worms, midge larvae, carp and suckers. At the headwaters of the Mystic River Basin, the ? ber- jona River flows from marshes in Reading and the Halls Brook tributary. Numerous sources of pollutants enter these waters. The upper reaches of the Aberjona above Reading may be con- sidered a clean water area and, therefore, organisms such as minnows, sunfish, caddisfly, inayf lies and other fresh water organisms may be expected. Below the area and along Hall’s Brook pollution levels increase. Pollution levels are rela- tively high including coliform counts, BOD and nitrogen levels. However, the Aberjona can be said to show some signs of recovery. Organisms associated with “recovery” zones in a river include: snails, midges, catfish and beetles. Numbers of planktonic organisms increase with distance downstream, particularly after the confluence with Horn Pond Brook. When the Aberjona River enters the Mystic Lakes, high nutrient levels are probably responsible for excessive aquatic growth. Seasonal variations of phytoplankton in the Mystic Lakes occur due to physical, chemical and biotic factors. Highest phytoplankton levels occur in spring with a seondary peak in late summer. The diatoms, Asterionella and Fragilaria , predominate in the spring. During summer an assemblage of green and blue green algae take over lasting through autumn. In winter diatoms again prevail. The number of zooplankton present depends upon the food supply (Phytoplankton), envi- ronmental conditions and predation. Zooplankton constitute one of the chief trophic links between algae and fish. Most noticeable were Bosmina sp., Ceriodaphoria sp., and Daphnia sp. Various macrophytes are also found including pondweed ( Potamogeton richardsonii) , pickereiweed ( Potamogeton crispus ) and yellow water lily ( Nuphar sp.). The water quality is improved as water enters Lower Mystic Lake due to the long detention time in Upper Mystic Lake. However, coliform levels rise, in addition to increases in both BOD and suspended solids in the lower lake due to surrounding land uses. Below the lakes Alewife Brook, which is highly polluted, enters the Mystic River. The River experiences large algal populations which are caused by increased pollution levels. Coliform levels are high. The high pollution levels do not provide suitable environment for clean water organisms, there- fore, green and blue green algae, snails, “trash” fish (carp, suckers) and various larvae may be found. Below the Amelia Earhart Dam tidal conditions exist. Therefore, there will be marine aquatic organisms. 2—93 ------- For the Weymouth River Basin there is extremely little data from which an analysis of the aquatic community can be made. Both the WeylTtouth Fore and Weymouth Back Rivers are tidal in nature below the first dam up river from Boston Har- bor, indicating that estuarine and marine organisms will be found in the tidal area. Above the saline region, fresh water organisms will predominate. It appears that this river system may be classified as a recovering environment, which is influ- enced by heavy commercial industry along its banks. Due to the lack of information on the basin, no conclusive statements as to the organisms which will occur can be made. The marine environment is affected by pollutants similarly to fresh waters. The major difference, of course, is that marine waters are open to the “oceanic mixing bowl” which is influenced by currents, wind, and the like. The open water of Boston Harbor is polluted. This is especially significant when compared to the water of Massa— chusetts Bay which lies to the east. This fact indicates that the “mixing bowl” effect is not that significant in the Boston Harbor area. In fact, the shellfish in many areas near point sources of pollution are contaminated. Virtually all of the shellfish beds in the Boston Harbor region have been declared contaminated by the Massachusetts Department of Public Health (Appendix 2.6-9). Bacterial analyses of Boston Harbor show the greatest contamination exists in the western parts of the Harbor. For example, Dorchester Bay was considered “grossly contaminated” by the US. Public Health Service while Hingham Bay is mostly “clean”. The standards for coliform counts are: 0-70 Coliform bacteria per 100 ml of water...clean 71-700 Coliform bacteria per 100 ml of water. . .moderately contaminated Over-700 Coliform bacteria per 100 ml of water. . .grossly contaminated Dissolved oxygen concentrations are mostly good through- out Boston Harbor (9-10 ppm). This is because there is usu- ally adequate and sufficient growth of algae to prevent DO depression. However, depressed DO levels should be expected in the vicinity of point sources of pollution. Low DO levels will affect the make-up of the benthic biota by favoring the pollution tolerant organisms such as sludge worms and other polychaete worms. 2—94 ------- A tremendous variety of organisms exists in the fresh water and marine environments in the MDC study area. However, development and carelessness has upset the natural balance of various ecosystems in favor of organisms that are toler- ant of pollution. In addition, many organisms have ingested toxins, and are now concentrated sources of these toxins. It is for this reason that many shelifisheries have closed. Lists of aquatic and marine organisms are compiled in Appendix 2.6. Each group of organisms has representatives that are both tolerant and intolerant of pollution. This indicates that the waters in the MDC study area range from clean to polluted. No inferences can be drawn as to the relative cleanliness of a particular body of water without further study. 2—95 ------- 2.7 VEGETATION AND WILDLIFE 2.7.1. Major Ecosystems The MDC study area contains six major ecosystems that support different types of plants and animals. Though each supports biotic assemblages that differ, all are relatively important. The six ecosystems to be examined are: urban and residential environments, old fields, deciduous forests, coniferous forests (or plantations), freshwater wetlands, and salt marshes. Most of the plants are common to more than one ecosystem, thus an entire assemblage of plants cate- gorizes a major ecosystem rather than a few plants. The local salt marshes are the only exception to this. Species lists of the common plants and animals in the MDC study area are presented in Appendices 2.7-1 through 2.7-3. A. Urban-Residential Ecosystem . The cities are typified by plantings of various pollution resistant trees such as tree- of-heaven, London plane, ginkgo and honeylocust. In addition, oaks will often be found lining the streets. Various orna- mental plantings are found in the parks. The roadsides are lined with ruderal plants such as goldenrods, grasses, evening primrose, wormwood and the like. Despite their outward appearance, cities often harbor an array of wildlife. The Norway rat, house mouse, gray squirrel, racoons and opossums are likely inhabitants. Pigeons, sparrows, seagulls and starlings abound as well. The parks, however, often provide suitable habitat for many migrating birds. Local bird societies often keep lists of unusual Sitings. Residential areas are often typified by landscaped lawns, open fields, wood lots or large open areas adjacent to the towns. Hence, a more diversified flora can be ex- pected. All of the city plantings can be found in addition to hearty plants that have remained or reinvaded from other undeveloped areas. Wild cherries, birches, maples, beech and cottonwood trees are usually common. Again, the urban fauna is present in these areas. In addition, depending on the proximity to undeveloped areas, wildlife species such as deer, cottontail rabbits, pheasants, woodpeckers, meadowlarks, and various snakes and amphibians will be found. B. Old Fields . Old fields are second growth, herb dominated habitats that form, for example, because an abandoned farm has been left fallow and is overgrown with wild plants or a forest has been cleared and herbaceous plants invade. 2—96 ------- Old fields are comprised of annual grasses and herbs during the first year of abandonment. By the second year, perennial plants have begun to invade. Within ten years perennial grasses and herbs, shrubs and young trees are typically found. This mixture of growth forms provides unusually good wildlife habitat which contains ample food for both resident and visiting animals. If water is present, the wildlife potential is excellent. Cover is usually abun- dant because it is a function of the growth habits of the invading plants. Rugosa rose and honeysuckle, which are conmion old field plants, are especially good cover for birds and small mammals such as rabbits and woodchucks. As old field habitats mature, the amount of herbaceous growth decreases while the woody growth increase. This pro- cess, called succession, may give rise to a mature forest. This sucessional process is discussed in Appendix 2.7-4. C. Deciduous Forests . After 50-75 years, old fields usually harbor a majority of woody plants. As the deciduous trees in the field mature, the old field can now be categorized as a deciduous forest. Some of the major canopy species likely to be found are red, white, black and chestnut oaks, sugar and red maples, hickories, gray and sweet birch and white ash. Many different trees and shrubs will fill the under- story of the forest. Plants such as maple-leaf viburnum, witch hazel, dogwood, spicebush, blueberries, huckleberries and hophornbeam are frequently encountered. In addition, many of the trees thatoriginally invaded the old field are still present. These trees are vestigial because they cannot reproduce successfully due to the competition in the form of shade from other trees. The gray birch, hawthorns, apples and cherry are some of the species that are vestigial rem- nants of an old field. Deciduous forests support a unique assemblage of animals. Deer are probably the most important animal from an aesthetic and recreational viewpoint. Raccoons, opossums, red and grey squirrels, chipmunks, shrews, various bats, river otters, weasels, mink, red and gray foxes and voles are often abun— dant. Though the NDC study area is extensively developed. there still remain many woodland parcels. Appendix 2.7-5 tabulates the acreage of forest, both deciduous and conifer- ous, found in each town. This is one type of approximation of the degree of urbanization, suburbanization or rural nature of a community. 2—97 ------- D. Coniferous Forests . The study area lies south of the region which is conducive to the growth of the true boreal forest. However, large stands of white pine and various other conifers do exist. These areas support different bird populations and fewer large mammals. This is due to lack of food (herbage and woody growth) in the understory of these forests. The stands of conifers in the study area are not so large as to prevent the animal residents from making feeding forays to ad:jacent ecosystems. Thus, the animal populations in these areas should not differ greatly from those in the deciduous forests. E. Freshwater Wetlands . Whenever the water table rises above the soil’s surface for at least a short period of time during the year, the character of the vegetation is altered. These habitats support distinct aggregations of plants that are, in part, considered hydrophytes. If the habitat in question is dominated by trees and shrubs it is called a swamp. Here red maple, sourguin, blueberries and sweetpepper bush would be common. When the area is herb dominated, it is called a marsh. Many species of sedges, grasses and herba- ceous flowering plants are found in marshes. Finally, when there is an abundance of Sphagnum moss, a bog situation exists. When the bog is near the coast, Atlantic white cedar will be found. Inland bogs will contain black spruce and eastern larch. Appendix 2.7—6 contains a complete appraisal and evaluation system for ascertaining the kind and value of wetlands commonly found in the area. Freshwater wetlands usually support high proportions of rare and endangered plants and animals when compared to the other types of ecosystems. These wetland habitats, when undisturbed, also support very diverse floras and faunas. However, there are fewer acres of wetlands than dry uplands. (Appendix 2.7—7 tabulates the amount of fresh and salt marsh habitats in each town). Hence, this habitat type is not too common and is thus valuable. The diversity and variety of these habitats make the generation of their species lists ponderous. If wetlands prove to be important in the final site selection, a thor- ough on-site analysis can be conducted at that time. E. Salt Marsh . Coastal wetlands are extremely valuable habitats. The majority of all salt marshes provide recrea- tional and aesthetic value beyond calculation. Their impor- tance to the perpetuation of both sport and commercial marine fisheries is undisputed. Smith (1974) notes that temperate salt marshes are among the most productive ecosystems in the world. In addition, their production is readily assimilable 2—98 ------- to the primary consumers. These wetlands provide vital habi- tat and food for a variety of wildlife, including mammals, waterfowl and shorebirds, invertebrates and small fish. The coastal marshes’ buffering ability during storm tides is indispensible for stabilizing the highly erodable shorelines. Twenty—seven species of vascular plants have been iden- tified in and adjacent to the salt marshes of Massachusetts Bay. A mix of spike grass, sea lavender, glasswort, cord- grass and salt hay is corrunonly found. (National Commission on Water Quality, 1975). The salt marshes and the rooted plants within them serve as important sources of food and habitat to waterfowl and detritus feeders (Kladec and Wentz, 1974). Before any construction is begun, the presence and state of any coastal wetlands should be ascertained. Coastal marshes are intrinsically valuable without having the burden of the many variables that alter the character of a fresh- water marsh. Nonetheless, Massachusetts is now aware of the value of all wetlands by virtue of the State’s general laws, Chapter 131, Section 40A and Chapter 130, Section 105, regu- lating the development of any wetland (inland or coastal). Several towns within the study area have mapped and recorded areas in which they are enforcing the provisions of Chapter 131, Section 40A (Inland Wetlands Restriction Act), by restricting development on certain inland wetlands. These towns are: Dedham, Dover, Needham, Newton, Walpole, Waltham, Wellesley and Westwood. 2.7.2. Rare and Endangered Species The following animal species are considered rare or endangered by the Massachusetts Division of Fish and Game. An asterisk denotes inclusion on the Federal list of Endan- gered and Threatened Species. Rare Beach Meadow Vole M1 C2’QtU8 br9 erV Birds — None Reptiles — None Amphibians — None 2—99 ------- Endangered Eastern Cougar* Fe lie concolor Indiana Bat* Myotia aockzlia Birds Southern Bald Eagle* ffaliaeetus 1. leUCOCephalUB Northern Bald Eagle &4iaeetue 1. was1n.ngtoni enst s American Peregrine Falcon* Falco peregrvnus Eskimo Curlew* Nwneniua borealis Ipswlch Sparrow Pae8erculus princepe Reptiles Plymouth Red—Bellied Turtle Pseudemys rubriventrie bangei Bog Turtle Clenriye rnuhienbergi Leatherback Turtle Dex noche lye coriacea Atlantic Ridley* Lepidocheiy8 kempi Atlantic Loggerhead Cca’etta caretta Green Turtle Chei nia mydas Timber Rattlesnake Crotalue horridue Northern Copperhead Agkistrodon contortrix Amphibians — None Massachusetts has no official list of rare and endangered plants. The New England Botanical Club is preparing a pre- liminary list for circulation to interested groups and indi- viduals (Shaw 1978). The proposed Federal List of Threatened and Endangered Species cites two species which may occur in Massachusetts: Juncus pervetus (bog rush) and Isotria medeoloides (small whorled pogonia). Isotria , however, “is a dubious native” of the state (Shaw,1978). An unofficial list of endangered organisms was compiled by Benjamin Isgur, a Massachusetts State Conservationist, and published by the Massachusetts Audubon Society (Newsletter, October 1973). This list appears in Appendix 2.7-8. All possible precautions should be taken to avoid dis- turbance of the preferred habitats of the rare and/or endan- gered species which may inhabit the study area. Their habi- tats include mature forest vegetation, especially along water (Southern and Northern Bald Eagle, American Peregrine), caves (Indiana Bat), and fresh water wetlands (Plymouth Red- Bellied Turtle and Bog Turtle). Salt marsh vegetation is 2—100 ------- vital as a base of the estuarine food web and loss of this highly productive community could negatively affect the endangered leatherback turtle, atlantic ridley, atlantic loggerhead and green turtle. Ecological site analysis should address each habitats’ potential to support these rare or endangered species. 2—101 ------- 2.8 AIR QUALITY 2.8.1 Standards and Pollutants Being Controlled Ambient air quality is currently defined in terms of measured concentrations of air contaminants in a given local area. The six principal air pollutants involved are: total suspended particulates (TSP), carbon monoxide (CO), sulfur dioxide (SO 2 ), photochemical oxidants (Ox), nitrogen dioxide (NO 2 ) and non-methane hydrocarbons (HC). Acceptable levels of these pollutants are defined by established ambient air quality standards. Primary and secondary ambient air quality standards define permissible short—term and annual average concentra- tions of the criteria pollutants. Primary ambient air quality standards are designed to protect the public health, and they are based on air quality criteria which allow an adequate margin of safety. Secondary standards define air quality at levels which are designed to protect the public welfare including property and vegetation. By law, state air quality standards must be at least as stringent as the federal standards. The State of Massa- chusetts adopted the federal standards, which are presented in Table 2.8—1. Except for annual averages, these standards may not be exceeded more than once per year. The EMMA study area lies within the Boston Air Quality Control Region (AQCR) for the most part, and the MDC system lies entirely within this region. A number of air quality monitoring stations are scattered throughout the MDC study area. The maximum air pollutant concentrations measured for the period of January-December 1976 and the number of air quality violations at the monitoring sites are given in Appendix, Tables A2.8-2 and A2-8-3. No hydrocarbon data is available for this period. Each major pollutant will be examined in the following sections. Air quality data has been extracted from the yearly report series “Annual Report on Air Quality in New England” (EPA, 1973-1976). Total Suspended Particulates Particulate matter may be observed in a solid or liquid state. Suspended particulates remain in the air for longer periods of time in contrast to settleable particulates which readily settle out. These particulates may originate from a number of sources, with the primary two being stationary sources of fossil fuel combustion and motor vehicles. Z— 102 ------- TABLE 2.8—1 MASSACHUSETTS AND FEDERAL AZ 1BIENT AIR QUALITY STANDARDS Average Concentration Averaging Type of Primary Standard Secondary Standard Contaminant Time Average ug/m 3 ppm ug/nvS Sulfur Dioxide (SO 2 ) Year Arithmetic Mean 80 0.03 —— Day Maximum (a) 365 0.14 -- -- 3-Hour Maximum (a) None None 1,300 0.5 Total Suspended Particulates Year Geometric Mean 75 60 (b) (TSP) Day Maximum (a) 260 150 Carbon Monoxide (CO) 8 Hours Maximum (a) 10 (mg/rn 3 ) 9 10 (mg/rn 3 ) 9 1 Hour Maximum (a) 40(mg/m 3 ) 35 40 (mg/rn 3 ) 35 Photochemical Oxidants (03) 1 Hour Maximum (a) 160 0.08 160 0.08 Hydrocarbons (Non—Methane) 3 Hours Maximum (a,b) 160 0.24 160 0.24 Between 6&9 a.m. Nitrogen Dioxide (NO 2 ) Year Arithmetic Mean 100 0.05 100 0.05 a) Federal standards other than annual average may be exceeded once per year. b) A guide to be used in assessing implementation plans to achieve the 24-hour standard. ------- In the study area, violation of the particulate levels allowed in the standards has occurred on many occasions dur- ing the years 1973-1975. During 1976, six monitoring sites in the study area violated the National Ambient Air Quality Standards (NAAQS) for the 24 hour secondary standard of 150 pg/rn 3 . The highest levels registered during the January- December 1976 period were 283 and 265 pg/rn 3 . EPA has noted that the Kenmore Square data may be biased due to site loca- tion, but a final evaluatign is yet to be made. The 24 hour primary standard (260 pg/ma) was never exceeded more than once at any monitoring station during the January-December 1976 study period, therefore, it net the NAAQS primary stan- dards. The highest one day reading of 283 pg/nr’ was regis- tered at the Medford (Fellsway and Route 16) monitoring sta- tion. The annual geometric mean of 75 pg/rn was exceeded at the Kenmore Square and both Medford monitoring sites. Sulfur Dioxide Sulfur dioxide originates predominantly from human activi- ties including combustion of fuels and smelting of metals. When these activities occur in concentrated metropolitan areas, the sulfur dioxide levels will experience a definite rise over the .2 ppb (parts per billion) background levels, to levels in the range of .1 ppm (parts per million) in urban areas. The sulfur oxides are very reactive in the atmosphere, espe- cially in the presence of water. They may react synergistically in the presence of various catalysts to form substances which are corrosive, and harmful to one’s health. No violations of the SO standards, primary or secondary, were found during 1973—1976 in the study area. The levels found in 1976 ranged from a 24 hour high of 288 pg/rn 3 in Med- ford to a low of 29 pg/rn 3 at the Woburn site. Carbon Monoxide The background concentration of carbon monoxide (CO), a colorless, odorless gas, is approximately .1 ppm. At levels of several hundred ppm it can effect the human system via dizziness, loss of mental acuity and eventually death. The primary source of CO is incomplete fuel combustion by the internal combustion engine. Therefore, the highest concentra- tions are found in areas where the greatest density of operating automobiles exists. The one hour primary standard for CO has been exceeded only once in the January 1975-December 1976 sampling period. This occurred at Waltham, in 1975, where a maximum level of 42.2 pg/rn 3 was recorded once. This is not in viola ion of the NAAQS. The secondary standards for Co (10 mg/rn for 8 hr) have been exceeded at five monitoring sites a total of 97 times in 1975 and 132 times for 1976. The highest levels for secondary standards in 1975 were recorded at the Waltham 2—104 ------- monitoring site (22.9 hg/rn 3 ), while in 1976, the Kenmore Sta- tion and Visconti Street sites within Boston showed the highest levels, 19.1 and 18.6 pg/rn 3 respectively. The automobile is the major source of carbon monoxide, and hence, it tends to be highly localized. Levels may fluctuate significantly with time of day and with site location. Nitrogen Dioxide The primary sources of NO 2 are combustion processes involving coal and petroleum in which high temperatures are involved. Inert nitrogen combines with oxygen at high tem- peratures and tends to remain in that form if cooled quickly. The nitrogen compounds are important factors in the produc- tion of photochernical smog. In 1975 one violation of the annual standard was recorded. This was recorded at Kenmore Square where a level of 102 pg/rn 3 was found. For the period January-December 1976 no violations took place. The highest annual average for the 1976 time span was 86 pg/rn 3 at the Kenmore Square St tion, while the lowest level occurred at Framingham, 35 pg/m- . The 1975 NOx readings have been said to be high by EPA, thus the validity of the 1975 data are in doubt. Hydrocarbons Man made hydrocarbons (HC) constitute a relatively small proportion of the total amount of HC emitted to the atmosphere, however, their localized concentrations may be significant. The importance of these compounds is their reaction with other atn spheric pollutants in the presence of sunlight to form oxidants. The largest source of hydrocarbons have not demon- strated direct adverse effects on human health. No hydrocar- bon levels were reported in EPA’S annual air quality reports. Photochernical Oxidants Photochemical oxidants are a secondary pollutant formed by the reaction of primary pollutants (nitrogen dioxide and hydrocarbons) in sunlight. These constituents cause a problem of a regional nature. Ozone is a major constituent of oxidants (at times up to 99 percent) and, therefore, it may not be indicative of oxidant levels. Monitoring sites in the region have shown repeated viola- tions of the one hour 160 pg/rn 3 ozone standard. The highest 1975 levels were found at Framingham and Quincy, which had maximum levels of 408 and 325 pg/rn 3 respectively. Po1l tant levels in these areas continued to exceed the (160 pg/rn ) limit in 1976. The highest levels for 1976 were Waltham (466 pg/rn 3 ) 2—105 ------- and Ashland (427 ig/m 3 ). The total number of stations vio— ].ating the standard decreased front seven in 1975 to five in 1976. Study of the emissions inventory for the study area, (Appendix 2.8-4) indicates that transportation accounts for approximately 97 percent of the Co emissions and 27.7 percent of the particulate emissions. Of the particulate load, approx- imately 42 percent is accounted for by residential, commercial, and industrial fuel consumption while 13.5 percent is accounted for by solid waste disposal of all types. By definition, if any one of the monitoring stations within an AQCR records data that indicates a contravention of established standards, that AQCR is said to be in “non-attain- ment.,” As several stations within the Boston AQCR have recorded such values for particulates, carbon monoxide and photocheniical oxidants, the Boston AQCR has been given a non-attainment status for these pollutants. 2.8.2 Air Regulations Under the 1970 version of the Clean Air Act and the up- dated 1977 Clean Air Act Amendments, EPA was required to attain or maintain the National Ambient Air Quality Standards. As part of EPA’s regulatory program an Emission Offset Interpre- tive Ruling and Prevention of Significant Air Quality Deterior- ation Regulations (PSD) have been published. The emission of f— set policy (EOP) deals with air quality in non-attainment areas, while PSD regulations apply to attainment and non-attain- ment areas. Prevention of Significant Deterioration To carry out the Congressional mandate, the PSD regula- tions were initially promulgated on December 5, 1974. Subse- quently, on August 7, 1977 the Clean Air Act Amendments of 1977 became law. The 1977 amendments change the 1970 Act and EPA ’s regulations in many respects, particularly with regard to PSD. Therefore, on June 19, 1978 new PSD guidelines were published to incorporate all the new requirements. EPA’s regulatory program designates areas of the Nation into three classes. The regulations specifically apply to particulates and sulfur dioxide pollution. Specific numerical increments of each air pollutant were permitted under each class up to a level considered to be significant for that area. Class I increments permitted only minor air quality deteriora- tion; Class II increments where moderate growth and air deter- ioration is allowed; Class III increments, deterioration up to the secondary NAAQS. EPA initially designated all clean areas of the Nation as Class II . Boston retains a Class II designa- tion. Table 2.8-2 below presents the maximum allowable Class II increments. These increments are to be treated in basically 2—106 ------- the same regulatory manner as the NAAQS (F.R. Vol. 43, No. 118, June 19, 1978 p. 26—380). TABLE 2.8-2 CLASS II AMBIENT AIR INCREMENTS Particulate Matter: Maximum Allowable Increase (ug/m 3 ) Annual Geometric Mean 19 24-h maximum 37 Sulfur Dioxide: Maximum A11owa 1e Increase ( ig/m ) Annual Arithmetic Mean 20 24-h maximum 91 3-h maximum 512 It should be noted that each NAAQS acts as an overriding ceiling of maximum concentrations for any allowable increment. Sources are subject tc a PSD analysis on the basis of their armual potential emissions. A major source is defined as a source having the potential to emit (emissions without air pollution controls) 90,720 kg (100 tons) per year or more or any air pollutant regulated under the Act for any of 28 specified stationary sources. The term major source also includes any other source with the potential to emit 226,800 kg (250 tons) per year of any air pollutant. No major sta- tionary source may be constructed unless the minimum PSD requirements (where applicable) have been met. States may exempt those sources with minimal emissions from air quality review if the sources would not effect ambient air quality. Only those major sources which would have allow- able emissions equal to or greater than 45,360 kg (50 tons) per year, 453.5 kg (1,000 pounds) per day, or 45.3 kg (100 Pounds) per hour, or an area where the increment is known to be violated must receive an ambient review. Only these sources must undergo review for Best Available Control Technology (BACT) and then only for those pollutants for which the source Would be major (F.R. Vol. 43 No. 118, June 19, 1978 p. 26—381). S milar1y a PSD review provides a detailed analysis of air quality related impacts including monitoring requirements, ambient increments and new source information. 2—107 ------- Each source, prior to approval, must meet all applicable emission limitations under the state implementation plan and all applicable emissions standards and standards of performance. In addition, allowable emissions must not cause or contribute to air pollution violations of the NAAQS or PSD increment regulations. Emission Offset Ruling If a source locates in a non—attainment area, in addition to PSD requirements regarding long-range impact on an increment and BACT, the source may be subject to the emission offset interpretive ruling. The offset ruling controls the construc- tion of sources which cause or contribute to air quality con- centrations in excess of any NAAQS. The ruling applies to major new sources locating in non—attainment areas. While all sources are subject to SIP review for emission limitations, the major sources must also meet stringent requirements for lowest achievable emission rate (LAER) and more than equiva- lent emission reductions. A major source is defined under the 1976 offset ruling as having allowable emission rate of 90,720 kg (100 tons) per year (907,200 kg (1000 tons] for carbon monoxide). t(1C flU5 4 Should a source locate outside of the non-attainment do tl nD area, or in a “clean” zone, quantification of the added pol- lution incr nents that may occur some distance away in a non- attainment area must be determined. A “clean zone” is a portion of a non—attainment area designated as meeting the NAAQS. A new source would not be considered to cause or con- tribute to a violation of a NAAQS if the air quality impact is less than the specified significance levels in the regula- tions (generally based on class I PSD increment levels). Should the significance levels be exceeded, the offset policy would be triggered into effect. If the source does not affect an area presently exceeding standards or cause a new NAAQS violation, the sources may be approved after meeting all applicable regulations. The concept behind emission offsets if to provide a net improvement in air quality when a source locates in a non- attainment area. Emission offset credit is to be allowed only foremission reductions which would not otherwise be accomplished as a result of the Clean Air Act. The ruling states emission offsets must be exceeded the new sources’ emissions and the offsets must be on an intrapo].lutant basis (e.g. TSP increases may not be offset against SO 2 reductions). For sources that would contribute to concentrations that exceed a NAAQS, several conditions are required before a source 2—108 ------- may be approved. A major new source must make reasonable pro- gress towards attainment and meet the following conditions: 1. The new source must meet the lowest achievable emission rate for that type of source. 2. All existing sources owned or operated by the source owner must be in compliance with SIP requirements. 3. Emission offset reductions from existing sources in the area around the proposed new source must be obtained to compensate for the additional pollutant load from the new source (Existing sources are not required to provide offsets). 4. These offsets must provide a net benefit to the air quality It should be noted that the December 1976 emission of f- set policy interpretive ruling will be updated by EPA. The proposed changes will modify portions of the 1976 interpreta- tions; however, the 1976 ruling continues to apply until a final statement is published. 2—109 ------- 2.9 NOISE The study area consists of a wide range of noise environ- ments including a major airport, heavily traveled urban regions suburban areas and semi—rural countryside. Noise, defined as unwanted sound, will tend to be localized and non-persistent. This is because noise essentially decays instantaneously leaving no residue; however, in many situations the noise may be of a continuous nature (traffic) and therefore seem persistent. In order to help determine possible future impacts, the present noise levels in the study area should be known. Appen- dix 2.9-1 gives existing noise levels. The data were generated during a 1977 noise survey of Boston sponsored by the City of Boston Conservation Commission. The decibel is the unit of measurement used to depict sound pressure levels. The “A—weighted” (dBA) decibel scale assigns higher values to noise frequencies which the human ear perceives as most annoying. This unit may also be used to give a statistical description of noise levels by using or L 50 levels. Appendix 2.9-1 presents L and L 50 levels for peak noise hours (rush hour) and for nighttime hours. The L].o and L5 0 noise levels statistically define the noise level that is exceeded 10 percent and 50 percent of the time respectively, for the time period under consideration. Both the magnitude and frequency of occurrence of the loudest noise events are indicated by Lic (dBA) levels, while L5Ø (dBA) levels indicate average noise levels. Boston, as is typical for major urban areas, has several major sources of noise. Transportation related noise is the major source of unwanted sound in the study area. Industrial and commercial noise is another large contributor to noise levels. Logan Airport and vehicle traffic are the two predom- inant constituents of transportation noise. Noise levels will vary with the time of day measurements are taken (diurnally) due to the large daily variations in traffic flow. These var- iatons may also occur on a daily and seasonal basis. Daytime noise levels are higher than nighttime noise levels, and winter readings have been found to be lower than other seasonal readings. The 1977 Boston Noise Survey shows a wide range of noise levels in the Boston Area. Rush hour L 10 levels were seen to vary greatly with location. In the Brighton-Aliston area a low of 50 dBA (Lie) was found, in contrast to a high of 82 dEAL 10 ) in several other Boston Areas (South End, Charlestown). 2—110 ------- Nighttime L 1 noise levels range from a low of 43 dBA (L 10 ) in the Brig1 on—Allston area to a high of 77 dBA (L 1 ) in the Back Bay. The L 50 levels are also presented in Appendix 2.9-1. These levels are lower than L 10 levels since they indicate average noise levels. Rush hour noise ranges from 50 cIBA (L 50 ) to 78 dBA (L 50 ) and nighttime levels range from 40 cIBA (L 50 ) to 68 dBA (L 50 ) in the study area. Major highways interlace the study area, and urban traf- fic is prevalent through a large portion of the region. Thus, relatively high noise levels may be expected in and adjacent to the major noise sources. Noise studies have indicated there is a noise signature that corresponds to the type and spatial arrangement of industrial activities, transportation corridors, and land use patterns within a community. Therefore, noise levels for the entire area will vary from community to com- munity depending on the number of noise sources within the community and one’s proximity to the noise. Generally, for residential areas noise levels may range from 55-70 dBA; with 55 dBA indicative of suburban area, while 70 dBA may be con- sidered a noisy urban area. Noise levels attributable to aircraft takeoffs and land- ings will vary depending on several factors including the make of the plane, receptor location, and plane glidepath. Takeoff noise levels are generally higher than approachnoise levels. On takeoff, depending on jet plane type, noise levels may range between 90-105 dBA, while on approach, levels are lower, rang- ing from 84—100 dBA. Rail traffic may generate from 73—96 cIBA at 100 feet from the track depending on the speed of the train. Rail traffic, as well as air traffic, will vary with season, the day of the week, time of day and with weather conditions. The noise problem has real significance. High sound levels have been shown to have physiological and psycho- logical effects on people. In most cases the effect is ob- served only during and shortly after an exposure to noise. Noise levels have been shown to interfere with hearing and sleep. Sleep deprivation is, in fact, one of the major noise related problems. A lack of sleep, or a lack of one of the several stages of sleep, may eventually have detrimental effects on an individual’s health. High noise levels have also been proven to cause hearing loss. At present, for example, continued exposure tonoise levels over 90 dBA is prohibited indoors by the Waish-Healey Act. A proposal is presently being considered by OSHA to lower this level to 85 cIBA. A temporary threshold shift in 2—111 ------- hearing may occur upon exposure to loud noises. This causes a temporary loss of hearing in certain frequency bands. The amount of time necessary to return to normal hearing will depend upon the length and intensity of exposure to a noise by an individual. Continued exposure to high noise levels may cause permanent hearing loss. Common levels of noise found in the envirorunent are provided in Table 2.9-1. Less direct or tangible effects of noise are physio- logical stress, annoyance, and task interference. These effects are more difficult to define because they are not exclusively produced by noise, nor are they simple functions of the noise level. An individual may react differently to different noise levels and specific noise conditions. Thus, noise levels may adversely affect an individual to different degrees depending on the person’s own psychological response to the noise. Nevertheless, it is clear that art increasingly noise-filled environment interferes with human well—being. 2—112 ------- Table 2.9—1 COMMON ENVIRONMENTAL NOISE LEVELS Sound Pressure Level dBA Environmental Condition o Threshold of hearing Rustle of leaves 20 Broadcasting studio 30 Bedroom at night 40 Library 50 Quiet office 60 Conversational speech (at 1 m) 70 Average radio 74 Light traffic noise 80 Typical factory 90 Subway 100 Symphony orchestra 110 Rock band 120 Aircraft takeoff 140 Threshold of pain SOURCE: White, 1975 2—113 ------- 2 • 10 DEMOGRAPHY AND LAND USE This section swnrnarjzes current demographic and land use trends in the Metropolitan District Commission (MDC) service area. Reference is made throughout this discussion to the more extensive narrative and related tabular materials which appear in Appendix 2.10. A.. Regional Overview . Currently 43 communities including the City of Boston are served by the waste treatment facilities of the MDC on Deer and Nut islands. An additional eight com- munities are now programmed to enter the service region, in- creasing the total population served by approximately 3 percent. The service region (51 communities) had a population of 2,273,000 in 1975. During 1950—60 the region gained 4 percent additional population; during 1960—70, 2.7 percent; and during 1970-75, 0.3 percent. The gradual reduction in growth rates over this span of time occurred in the context of diminishing rates of increase in the remaining inner and outer suburbs (See Appendix 2.10, Table A2.lO-l). In 1975, approximately 90 percent of all households living in the 43 community service area were served by the MSD system. Any future change in the total volume of wastewater processed by the system will be due to three factors: incorporation of more generators of wastes (households, businesses, etc.) within existing communities, addition of new communities, and changes in rates of usage by individual user categories. While there is appreciable undeveloped land, particularly in the outer sub- urbs, and significant opportunities for redevelopment at higher intensities in the more central communities including the City of Boston, it is unlikely that merely increasing sewage treat- nient capacity will stimulate appreciable new development. Since 1950 the Boston Standard Metropolitan Statistical Area (SMSA), which includes all but three of the 51 communities, has experienced steadily declining rates of growth (1950-60, 7.5 percent; 1960-70, 6.1 percent) while the State of Massachu- setts peaked during 1960—70 (1950—60, 9.8 percent; 1960—70, 10.5 percent; 1970-75, 2.4 percent). National growth rates have steadily declined since 1950 (1950—60, 19.5 percent; 1960—70, 12.5 percent; 1970—75, 4.7 percent). Clearly, the SMSA has failed to maintain its proportionate share of state growth and the state has failed to maintain its share of national growth. Both central city and suburbs are at least momentarily converging to zero rates of population growth. (See Appendix 2.10, Table A2.10—1). 2—114 ------- B. Current Population Characteristics . This section con- side ithe major dimensions of demographic variation among the 51 communities of the expanded MDC Service Area. During 1950—60, more communities experienced population growth rates in excess of 30 percent than in 1960-70, or for the extrapolated period 1970-80. Negative growth cornmuni- ties exhibited surprising persistence once the trend of decline had begun. Communities with the lowest ratios of undeveloped to developed land tended to have the greatest population stability as measured by percentage change in population dur- ing 1950—75. among the MDC member communities there exists moderate variation in population age distribution. Within the SMSA as a whole, this distribution contains: age 0—18, 31.9 percent; age 16-65, 56.9 percent; age 65+, 11.3 percent (1970). The average age of SMSA residents is gradually increasing. Central city (Boston) age distribution is skewed to the older age groups (See Appendix 2.10, Table A2.10-2). The racial mix varies widely among MDC member communities. The following communities had non-white population proportions in excess of 4.0 percent in 1970; Boston (1960, 9.8 percent; 1970, 18.2 percent), Cambridge (1960, 6.3 percent; 1970, 8.9 percent), and Lincoln (1960, 2.6 percent; 1970, 4.3 percent). In the SMSA as a whole, there has occurred a small increase in the proportion of the non—white population in recent years (1960, 3.4 percent; 1970, 5.5 percent). This increase has been disproportionately shared among MDC communities though growth of non-white populations in outlying communities dur- ing 1960-70 is apparent. (See Appendix 2.10, Table A2.10-2. For income correlates see Appendix 2.10, Table A2.lO—3). C. Economic Analysis . This section summarizes key findings regarding the structure of the Boston regional economy, its recent performance and its outlook. In recent years, New England has led the downturn in the Northeastern economy. Now, however, the Middle Atlantic States (New York, Pennsylvania and New Jersey) are in rela- tive decline while those of New England appear, at least niomentarily, to have stabilized. The region overall, however, 1.8 currently less competitive in comparison to the South and West. Three counties contain the bulk of the expanded MDC ser- vice area (Middlesex, Norfolk and Suffolk). As a whole, this three-county economy derives its impetus from the following Sectors: manufacturing (23.3 percent of all employees), services (21.6 percent), retail trade (16.0 percent), government 2—115 ------- (15.3 percent) and finance, insurance and real estate (7.8 percent). These percentages are not wholly representative of the national economy. Over the period 1959-75, overall employment in the three— county area has increased by 31 percent (i.e. 1959-65, 10.9 percent; 1965—70, 17.9 percent; and 1970-75, 4.9 percent), having experienced a peak rate in 1965-70. Service-producing activities have shown considerable vitality while goods-pro- ducing activities have been far less active during the last three decades. (See Appendix 2.10, Tables A2.l0-4 and A2.lO—5). Similar trends prevailed in Massachusetts as a whole. (See Appendix 2.10, Table A2.10-6). D. Land Use: Patterns and Plans . In this section, land use has been tabulated in three major categories (residential, non-residential and vacant land) for each of the 51 communi- ties and grouped into geographic sub-areas identical to those utilized in the analysis of transportation corridors in the EMMA Study (See Appendix 2.10, Table A2.l0-7). The land use composition of individual communities varies considerably. The dominant determinants of regional land use structure include: access to the central city, radial and circumferen’- tiál transportation development, environmental constraints, historical patterns of peripheral development and business development in core and peripheral nodes of activity. The total supply of transitional open space and forest lands is quite large within all sub-areas of the Boston region (Appendix 2.10, Table A2l0—7). Additional crop and pasture lands provide still more opportunity for new development, yet current development pressures are moderate or less. A survey of the major planning goals among the 51 com- munities found the more central, older areas to be stressing economic revitalization, physical redevelopment and neighbor- hood stabilization. More peripheral communities are apparently more concerned about strengthening their tax bases while enhancing their residential amenities. (See Appendix 2.10 for a full discussion). E. Transportation . This section describes the present con- figuration of the regional transportation network and suinmar- izes future transportation plans. The importance of transpor- tation for the development of peripheral lands is, of course, substantial. The existing major highway system includes three inter- state routes (Route 1—95, Topsfield to Sharon; Route 1-93, North Reading to Boston; and the Massachusetts Turnpike, 2—116 ------- Ashland to Boston). The first two run north—south, the third, east-west. All feed circumferential Route 128. Additional arterials (U.S. Route 1, Mass Routes 1A, 2, 3, and 24) provide access to and from the study area. Alternative modes of travel include several radial branches of the commuter rail line, rapid transit lines in the dense Boston core and rapid transit lines in key peripheral locations. There are also four publicly owned airports in the EMMA region, four major seaports and various other transportation facilities (See pendix 2.10). Major expressway expansion through the year 2000 will not occur within the circumference of Route 128, by guberna- torial decision (1972). Nor is expansion of the commuter rail system currently under consideration within the Boston region. Expansion of the rapid transit system, however, is now envisioned (Blue, Orange and Red lines of the system). In overview, the transport system of the EMMA region provides unusually efficient connections within the urban core and between core and periphery. Circular movements are more restricted. On the whole, recent improvements have tended to produce a far more dispersed development pattern within the region, not easily served by public services or facilities. (See Appendix 2.10, Tables A2.lO—9). 2—117 ------- 2.11 POPULATION PROJECTIONS FOR THE MSL) COMMUNITIES This summary outlines and evaluates the current alter- native population projections for the expanded MDC service area, by community. Three major population projection series exist: EMMA, SENE and MAPC (See Appendix 2.11 for methodology). A. Metro olitan Area Planning Council (MAPC) Projections . These projections to the year 2000, by individual community, utilize a 1975 base. The projection procedure entailed these steps: trend extrapolation (contrained) by community to 2000, then correlation with independent sectoral employment projections (EMPIRIC) to insure consistency. B. Southeastern New England Study (SENE) Pro ections . These Office of Business and Economic Research Statistics (OBERS) were produced under provisions of the Federal Water Resources Planning Act of 1965. for a study area including the Black- stone, Charles, Mystic, Ipswich and Parker River Basins, plus areas to the east of these rivers. The OBERS Projection pro- cedure involves these three steps: projection of national economic growth, allocation to sub-national economic areas and then converting these regional economic forecasts into population forecasts. C. The EMMA Study Projections . These projections were pre- pared by Metcalf and Eddy, Inc., and released in October, 1975. A two-step method was pursued. The first step is to project aggregate regional population using both “regional share” and “cohort-component” methods. The second step is to disaggregate one or the other of these, by community, utilizing the EMPIRIC Model based on the technique of simul- taneous regressions as described in Appendix 2.11. D. The Alternate Projections . Only the EMMA and MAPC pro- jections are disaggregated by individual community. Still one can compare the aggregate regional forecasts of all three. They are not, however, entirely comparable in the aggregate since the SENE projections cover a four-county region. The results are listed below: Population Percent (in Thousands) change 1970 1990 1970—1990 Area Source: A. EMMA B. MAPC C. SENE *Thjs refers the MDC **This four-county region includes Middlesex, Norfolk, Plymouth and Suffolk. 2,266 2,444 + 7.9 2,266 2,408 + 6.3 2,192 2,440 +11.3 to the 51 communities proposed MSD Area* MSD Area* Four County Area** to be served by 2—118 ------- The SENE projections were rejected for reasons discussed in the Appendix. And while EMMA and MAPC projections are quite similar in the aggregate, the MAPC results are more sensitive due to their spatial allocation procedure. For the study area as a whole both projections can be considered equivalent. Wastewater projections were developed in the EMMA study from EMMA projections. Due to the similarity between the EMMA and MAPC projections, this study utilizes both EMMA population and wastewater projections. (Both EMMA and MAPC projections are summarized in Appendix 2.11, Table A2.ll—l). 2—119 ------- 212 ENERGY PRODUCTION AND CONSUMPTION The predominant energy form in the New England area is electrical power, for which the area has no naturally occur- ring fuel supplies for its generation. New England is thus especially susceptible to national shortages of oil and natural gas, since it is totally dependent upon imports, either domes- tic or foreign. Natural gas has been in increasingly short supply with many companies switching to liquid gas. The gas supplies are also dependent upon imports. Two suppliers provide the majority of the electricity to the study area: the Boston Edison Company and the New England Power Company. Several retail companies provide for local distribution, with Massachusetts Electric and Boston- Edison providing this service to the majority of the resi- dents in the area. Electrical energy is produced through a combination of fossil fuel, hydroelectric, internal combus- tion and nuclear sources. Virtually all of the power com- panies are linked together through a system in which one company can draw on the reserves of another to meet peak demands and supplement their own production. This cooper- ative agreement is called the New England Power Pool and services the States of Connecticut, Rhode Island, Massachu- setts, Vermont, New Hampshire and Maine. Both supplies and the distribution network appear to be adequate to meet current demands. At the present time the new England Power Pool has an installed reserve peak capacity of an estimated 40 percent. The actual operating reserve capacity is about 25-30 percent (Department of Energy, 1978). The primary reason for this excess is accounted for by the fact that load increases have not occurred at rates originally anticipated. Based on population estimates and the present generating capacity, electrical power does not appear to be a limiting factor affecting growth in the study area. 2—120 ------- 2.13 RECREATIONAL/SCENIC AREAS There are many recreational attractions within the study area which provide both passive and active recreational oppor- tunities to the public. These attractions include such things as local playgrounds, several large tracts of developed and undeveloped park land, numerous historic sites, and the harbor and ocean coastline with its associated fishing, swimming and boating. Additionally, there are numerous freshwater ponds, lakes and freshwater streams which are utilized extensively. Several planning documents have been prepared which address the open space and recreational needs of the corrimuni- ties within the project area. The MAPC, in 1969, published a four volume study entitled Qpen pace and Recreation Plan and Program for Metropolitan Boston on the specific needs of the area. Volume I of this study was updated and published in July of 1976. This report (MAPQ, 1976) concentrated on the aspects of the original plan that can realistically be used for open space and recreation today. Other such docu- ments include the Statewide Comprehensive Outdoor Recreation Plan (SCORP) published by the State of Massachusetts, Decem- ber, 1976, the Southeast New England Study (SENE) published by the New England River Basin Commissions, 1973, and the Boston Harbor Islands Comprehensive Plan of the MAPC, 1972. All of the recreation planning documents are in agree- ment that present recreational facilities are inadequate and that future development and acquisition will be required. In the MAPC study area, present population levels require sane 31,363 ha (77,500 acres) of open space and existing acreage falls 3,849 ha (9,500 acres) short of this value. SCORP reports that the availability of recreation facilities on a per capita basis is worse in the Eastern Massachusetts region than for the state as a whole. While uniform standards for recreational requirements do not exist (the National Recreational Association and the Urban Land Institute both recommend 4 ha [ 10 acres]/l000 population while the city of Boston uses a 2 ha /1000 standard), it is evident that the amount of space dedicated to recreation in these areas is insufficient. This situation is typical of the normal availability of recreation resources in urban areas. In spite of these noted deficiencies, the acquisition of land for development into passive and/or active recrea— tional facilities has been an ongoing process for many years. Today, in the greater Boston metropolitan area, there exist some 27,519 ha (68,000 acres) of land designated as open 2—121 ------- space (MAPC, 1976). Many communities have utilized the Commonwealth’s Self Help Program, or funds from the U.S. Bureau of Outdoor Recreation to purchase such land. Within the study area, there are several large tracts of land operated by the MDC, such as the Blue Hills Reserva- tion, Middlesex Fells Reservation, and the Stony Brook Reser- vation. These serve much of the outdoor recreational needs of the area. State, federal and private organizations such as the Trustees of Reservations, Massachusetts Audubon, and local town commissions, have also managed to protect a sig— nificant amount of conservation and recreation land. In total, the holdings of these combined organizations and agencies within the study area amount to in excess of 9,307 ha (23,000 acres). A listing of the major properties either partially or wholly within the study area that are owned or operated by these groups is found in Appendix 2.13. Tourism is a valuable part of the area’s economy and many people are employed on both a full and part-time basis in the recreational and tourism sector. On the basis of both event and site attractions, the region has the highest ranking in the State for tourism. The region also has the highest ranking based on seasonal activity attractions, and the largest numer of sites of national significance in the State. Boston proper has a rating of 316 site attractions ( 8 percent of state total) and 200 event attractions 25 percent of state total). Quincy is also a highly rated tourist attraction (Massachusetts DCD, 1970). 2—122 ------- 2.14 SITES OF SPECIAL SIGNIFICANCE A. Historic Preservation Ar as . The State of Massachusetts is a treasury of historic place, all of which supply cultural benefits to the State. The eastern portion of the State is especially rich with historic sites. There are three main bodies of information containing documented and recorded his- toric sites: 1) the National Register of Historic Places; 2) the National Historic Landmarks, and; 3) the Massachusetts Historical Conunission Files. The National Register of Historic Places was established by the National Historic Preservation Act of 1966. Sites listed on this register are protected from adverse effects caused by federally funded or licensed projects, and are eligible for historic preservation grants-in—aid. A list of these sites present within the study area is presented in Appendix 2.14—1. The date of nomination of each site is given in parenthesis after each entry. Only those cornmuni- ties which contain recorded placed within their municipal boundaries are listed. Thirty-six of the forty-three towns (84 percent) presently served by the MDC have sites in the National Register. A number of sites on the National Register are given additional recognition by also being labelled as National Historic Landmarks. These sites are special because it is felt they contain cultural sigr ificance consistent with major themes in American history and are recognized as such through- out the entire nation, not just regionally. Therefore, while private groups, local, state or federal officials may nomi- nate a site to the National Register, only the National Park Service may nominate a site as a National Historic Landmark. National Register sites in Appendix 2.14-1 marked with an asterisk are also on the list of National Historic Landmarks. The files of the Massachusetts Historic CommisSiOn con- tain literally thousands of sites and districts which have been deemed by municipal historical commissions and societies throughout the state as being of local significance. Because of the sheer volume of these entries, it was not felt appli- cable to list them all here. However, as final sewer align- ments and facility sites are delineated, these local sources will be fully examined and recorded on an area-sepcific basis. B. Prehistoric Aboriginal Sites . A large number of Indian Sites within the state have been recorded by professional archaeologists and placed on record with the Massachusetts Historic Commission and the office of the State Archaeologist. 2—123 ------- Chapter 9, Section 27c of the Massachusetts General Laws stipulate that this information is to be regarded as conf i- dential, and therefore cannot be presented in inventory form here. As in the case with the local historic sites discussed above, however, these sources will be examined and discussed on an area—specific basis, as the proposed facility locations are determined. C. Natural Areas . While much of the project area is devel- oped, there remains a number of areas which deserve protec- tion from future degradation due to their inherent natural floral, faunal or physical significance. These areas would include such phenomena as waterfalls, bogs, swamps, rock outcrops or formations, islands, gorges, etc. Information concerning documented and recorded natural areas are avail- able from two sources. The National Registry of Natural Landmarks, of the National Park Service contains areas which are nationally significant and are especially valuable for illustrating or interpreting the natural heritage of the nation. All sites must be essentially undisturbed, reflecting relatively pris- tine aspects of nature. There is one locale within the MDC project area pending nomination to the National Registry. (There are only five other areas registered in the entire state, with one other area pending nomination). This area is the Lynnfield Marsh, located between Wakefield and South Lynnfield. The area is approximately 121 ha (300 acres) and is partly owned by the Massachusetts Audubon Society. In 1974, the Massachusetts Department of Natural Resources (now Department of Environmental Management) in association with the Massachusetts Audubon Society, the Trustees of Reser- vations and the Harvard Audubon Society, the Trustees of Reservations and the Harvard Graduate School of Design, Depart- ment of Landscape Architecture issued a report entitled “Massa- chusetts Landscape and Natural Areas Survey”. This study, although incomplete, surveyed and compiled an inventory of outstanding natural areas within the state, a number of which are located within the MDC Study Area. Appendix 2.14-2 con- táins a list of these areas by municipality, omitting those communities not surveyed or without “significant natural areas” as assessed in the inventory criteria (Wineman and LeBlanc, 1977). 2—124 ------- 2.15 SIGNIFICANT ENVIRONMENTALLY SENSITIVE AREAS One of the functions of an environmental inventory is to identify significant components of the environment which are sensitive to impact by the proposed action. In addition to significance and sensitivity, these features should be of some value to the area, contributing to the overall charac- ter of the region. Once identified, these features will be given priority in terms of selecting and evaluating project alternatives. A discussion of significant environmentally sensitive features in the study area follows. A. Geology . The greater Boston area contains over one hun- dred drumlins which are distinctive glacially-derived geologic features. Many of the islands in Boston Harbor are drumlins. The value of drurnlins is aesthetic and educational. They offer topographic relief in areas which are otherwise flat, and in certain locations, offer a place from which scenic views may be enjoyed. In addition, they offer the aspiring geologist an opportunity to observe the study these unique geologic features. B. Surface Waters . Surface waters within the study area include Boston Harbor, lakes and ponds, numerous streams, and six major river systems. These surface waters are highly valued as sources of water supply, aquatic habitat, wastewater disposal, recreation and transportation. The suitability of water resources for water supply, recreational use, and aquatic habitat is directly related to water quality. Water quantity is an important consideration from a water supply, transportation and aquatic habitat viewpoint. Water Quality in many portions of the study area is highly degraded due to existing point and non-point sources of pollution in and upstream of the study area. Flow in the rivers has been adversely affected by dams, surface with- drawals for industrial use, and groundwater withdrawal for domestic and industrial consumption. Both water quality and quantity, as well as their interrelationship, are significant environmentally-sensitive parameters and will be addressed. C. Recharge Areas . Recharge areas, or areas through which Surface runoff enters groundwater aquifers, are important for the maintenance of groundwater resources. These areas are sensitive to land development since increases in ixnper— Vious surfaces decrease the rate of recharge and may degrade its quality. D. Wetlands . Wetlands are universally recognized as an important part of the biological ecosystem. They are a 2—125 ------- significant component of the base of the marine and estuarine food chain. In addition to their biological importance, wet- lands are significant in moderating the hydrological varia- tions in river systems. Their capacity to retain, store, and siowiy release surface waters has been recognized by the Corps of Engineers, who have designated inland wetlands as Natural Valley Storage Areas. The Corps is attempting to acquire many of these areas to protect them from development. The state has also set up legislation to allow municipalities to desig- nate and protect their wetland resources. Floodplains, to a lesser extent, can be hydrologically valuable for the same reasons as wetlands. Both wetlands and floodplains are con- sidered significant, environmentally-sensitive areas. E. Steeply Sloped Areas . Areas with slopes exceeding 15 per- cent are generally considered to be critical for development purposes. Development in these areas often results in excessive erosion and runoff which affects the streams which receives the sediment load as well as degrading the area which has been eroded. Loss of suitable topsoil and stabilizing vegetation tends to result in long-term instability of the slope. The increased runoff rate will tend to increase variability in stream flow, increasing flows during peak flow periods and decreasing dry weather flows. F. Forest and Woodlands . These are a valuable resource which provide wildlife habitat, contribute to the aesthetic character of an area, and help to moderate climatic influences. They provide recreation and much needed open space. Development of these areas should be considered judiciously. G. Air Quality . The Boston Air Quality Control Region has been designated as a non-attainment area with respect to carbon monoxide, total suspended particulates, and photochemi— cal oxidants. This indicates that the region as a whole is exceeding allowable limits for these contaminants. Due to existing degraded quality, air resources must be considered as a significant sensitive parameter. H. Habitat of Rare or Endangered Species . A list of rare and endangered species for the study area has been presented. Due to the status of these species, their habitat preferences (also described) should be considered to be significant and sensitive. It is worthy to note here the value of the Boston Harbor Islands as wildlife habitat. These islands constitute a unique and rare habitat form which is due, in large part, to the inaccessibility of the Harbor Islands to people, and their proximity to Harbor feeding areas and flightways. These 2—126 ------- islands are used by several bird species for nesting sites. Productive Harbor Island habitat in uncommon because of the direct competition between human activity, which prizes these locations for summer homes, etc., and the native fauna. Such areas should be preserved. . Public Use/Cultural Resources Sites . These areas include all lands available for use (active or passive) by the general public as well as historic/archaeological sites which document and exemplify the region’s heritage. Due to the use and sig- nificance of these sites, they warrant classification as sig— nificant sensitive areas. Recreational areas are considered to be inadequate in terms of site availability in the study area. This places greater significance upon existing sites and sites proposed by the Boston Harbor Islands Plan and the MAPC Regional Open Space Plan. 2—127 ------- CHAPTER 3 ALTERNATIVE WASTEWATER MANAGEMENT SYSTEMS 3.1 INTRODUCTION 3.1.1. Method of Analysis and Approach The objective of this Environmental Impact Statement (EIS) is to determine the most environmentally acceptable, cost effective method of upgrading the MDC’s wastewater management system, including sewer interceptors, wastewater treatment facilities, and secondary sludge disposal facilities. The feasibility of utilizing inland satellite wastewater treatment plants as compared with continued centralized treatment at coastal facilities is to be investigated. A wastewater management system can be divided into several subsystems, such as those previously mentioned (sewer interceptors, wastewater treatment facilities and sludge disposal facilities). Numerous possible alternatives exist for each subsystem. Subsystem alternatives can differ from one another in several ways, including the number, locations, and types of facilities. Analyzing every possible wastewater management system which can be obtained by c nbining all of the subsystem alternatives would be a formidable task. In order to reduce the number of possible alternative systems to a manageable number, the formulation of alternative systems in this report will follow a systems analysis approach. This approach can be summarized as follows: 1. Divide the overall system into several major subsystems, such as wastewater treatment facilities, sludge disposal facilities, etc. 2. Divide each subsystem into major components, such as locations of facilities, treatment processes, etc. 3. List the alternatives available for each subsystem component. 4. Perform a preliminary screening whereby component alternatives which are obviously infeasible because of severe environmental implications, engineering difficulties or prohibitive costs will be eliminated from further consideration. 5. Combine the remaining component alternatives into subsystem alternatives. 3—1 ------- 6. Perform an intermediate screening of subsystem alternatives and eliminate the less feasible alternatives from further consideration. 7. Combine the remaining subsystem alternatives into system alternatives. 8. Perform a final screening of system alternatives and select the best system(s) based on environmental, feasibility, implementation, and economic factors. In this EIS, two separate systems will be developed; one which includes both inland satellite plants and coastal area plants (satellite system) and one which includes only coastal area plants (non—satellite system). These systems can be divided into the following subsystems and subsystem components: 1. Interceptor Sewers 2. Coastal Area Wastewater Treatment Plants a) Sites b) Effluent Discharge Locations c) Treatment Processes 3. Inland Satellite Wastewater Treatment Plants a) Sites b) Effluent Discharge Locations C) Treatment Processes 4. Sludge Disposal for Coastal Area Treatment Plants a) Treatment Processes b) Methods of Disposal 5. sludge Disposal for Satellite Treatment Plants a) Treatment Processes b) Methods of Disposal In the subsequent sections of Chapter 3, the various subsystem components and subsystem alternatives will undergo preliminary and intermediate screening, and the resulting feasible system alternatives will undergo final screening in order to determine the best wastewater management system(s) for the MSD service area. 3—2 ------- 3.1.2 Constraints and As sumptioris Affectthg Possible Alternatives A. Water Quality Objectives . The objectives of the Federal Water Pollution Control Act Amendments 1972 (Pub. L. 92-500) is “...to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” Major goals set forth by the Act include: 1) elimination of pollutant discharge into navi- gable waters by 1985; 2) attaining water quality which protects fish, shellfish, and wildlife, provides for their propogation, and allows for recreation in and on the water by 1983 (i.e. attain fishable - swimmable waters); and 3) prohibiting the discharge of toxic pollutants in toxic concentrations. All point source discharges are required by the Act to obtain a discharge permit which specifies the amount and nature of pollutants which can be discharged. These permits are based on a level of treatment to be achieved prior to discharge. Publically Owned Treatment Works (POTW) are required to provide secondary treatment of wastes. Secondary treatment was defined by the U.S. EPA in the Federal Regis- ter of July 26, 1976 as follows: The following paragraphs describe the minimum level of effluent quality attainable by secondary treatment in terms of the parameters biochemical oxygen demand, sus- pended solids and pH. All requirements for each parameter shall be achieved except as provided for in §133.103. (a) Biochemical Oxygen Demand (five day) (1) The arithmetic mean of the values of effluent samples collected in a period of 30 consecutive days shall not exceed 30 milligrams per liter. (2) The arithmetic mean of the values of effluent samples collected in a period of 7 consecutive days shall not exceed 45 milligrams per liter. (3) The arithmetic mean of the values of effluent samples collected in a period of 30 consecutive days shall not exceed 15 percent of the arithmetic mean of the values for influent samples collected at approximately the same times during the same period (85 percent removal). 3—3 ------- (b) SUspended SoU4s ( The arithmetic mean of the values for effluent samples collected in a period of 30 consecutive days shall not exceed 30 milligrams per liter (2) The arithmetic mean of the values for effluent samples collected in a period of 7 consecutive days shall not exceed 45 milligrams per liter. (3) The arithmetic mean of the values for effluent samples collected in a period of 30 consecutive days shall not exceed 15 percent of the arithmetic mean of the values for lnfluent samples collected at approximately the same times during the same period (85 percent removal). (c) pH. The effluent values for pH shall be main- tained within the limits of 6.0 to 9.0 unless the publicly owned treatment works demonstrates that: (1) Inorganic chemicals are not added to the waste stream as part of the treatment process; and (2) Contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0. The proposed upgrading of the MDC treatmen facilities is required, at the present time, to provide secondary treat- ment. The Federal Water Pollution Control Act, however, was amended by the Clean Water Act of 1977 (Pub. L. 99-217) to permit a waiver of the secondary treatment requirements for POTWs which discharge into marine waters. To obtain a waiver, the POTW must satisfy the eight, specific statutory require- ments outlined in Section 301(h) of the Act. Waivers apply only to the removal requirements for BOD 5 , suspended solids and pH. Toxic pollutant control is still required, and the POTW would, at a minimum, be required to remove these pollu- tants to levels equivalent to the toxic removal achieved by secondary treatment. All applicable Federal and State Water Quality Standards must also be met. In addition, it has been mandated by the Congress that applications for a waiver must be submitted to the Administrator of the Environmental Protection Agency by September 24, 1978. While recognizing the possibility of a waiver, it is not the purpose of this EIS to analyze the merits of such a waiver as it pertains to the MDC wastewater management activities. Until such time as a waiver is granted, the requirement for secondary treatment is applicable to the MDC. Consequently, alternatives to the recommended EMMA plan considered by thie EIS provide, at a minimum, secondary treat- ment of wastewaters. These facilities must also satisfy the Act’s provisions related to toxic pollutants. Under the Act, a specified mecha- nism for achieving this, is pretreatment of industrial wastes 3—4 ------- containing toxic substances which are discharged to the pub- licly owned system. However, it must be recognized that indus- try is not the only source of toxic pollutants, particularly metals. Domestic wastewaters have been shown to contain sig- nificant quantities of toxic metals (Klein, et al. 1974, Davis and Jackson, 1975) and a well implemented and monitored pretreatment program may not result in the reduction of these pollutants to acceptable levels. Toxic pollutants may limit the options for discharge locations or require a more sophis- ticated level of treatment at MDC facilities. Water quality standards of the Commonwealth of Massachu- setts classify the State’s waters according to their use (i.e. public water supply, fish and wildlife propagation, recreation) and establish criteria to support each designated use. These standards are designed to achieve the objectives of the Massa- chusetts Clean Waters Act and the Federal Water Pollution Con- trol Act. Effluents from the proposed MDC facilities must not violate the water quality criteria applicable to the waters into which they are discharged. In summary, the objective of this study is to develop the alternatives which provide the Metropolitan Boston Area with effective wastewater management while conforming with all applicable Federal and Commonwealth water pollution con- trol regulations. B. MDC Facilities Which Are Not Addressed in This EIS. The Wastewater Engineering and Management Plan for Boston Harbor- Eastern Massachusetts Metro olitan Area (EMMA Study) has pro— posed a comprehensive areawide wastewater management plan. The EMMA Study has considered all aspects of wastewater manage- sent planning to provide recommendations for the construction and/or rehabilitation of facilities needed for effective waste- water management. The findings and conclusions of that study have been formulated into the MDC’s Recommended Plan. This EIS is focused on those aspects of the MDC’s R commended Plan that deal with the transportation, treatment and ultimate dis- posal of municipal wastewaters. The factors considered are: 1) Interceptor system modifications required due to increases in wastewater flow volume and alterna- tive treatment plant sites. 2) Environmental and engineering feasibility of con- structing satellite treatment plants discharging to inland waterways. 3) Alternative treatment plant sites and treatment facility configurations for the major wastewater treatment plants in the vicinity of Boston Harbor. 3—5 ------- 4) Alternative techniques for the treatment and disposal of secondary sludge. 5) Wastewater treatment plant effluent discharge locations. This EIS does not address the following items whiøh are included in the EMMA Study: Infiltration/Inflow analysis; combined sewer overflow regulation; and primary sludge dis- posal. Infiltration/Inf low (I/I) analysis is required under Section 201 of the Water Pollution Control Act xnendments (Pub. L. 92-500) to determine the grant eligibility of waste- water treatment works. Facilities which are subject to ex- cessive I/I are not grant eligible. It is the respOnEibility of the grant applicant (the MDC) to demonstrate to the EPA that their interceptor system is not subject to excessive I/I, or to specify what remedial actions will be taken to eliminate sources of excessive I/I. These I/I studies are currently in progress, and are not included in this study. The Combined Sewer Overflow Regulation Plan has been removed from the MDC’s overall wastewater management plan by the U.S. EPA and is being treated as a separate water quality problem. The current plan for implementation of this program is to proceed directly to facilities planning and to perform an Environmental Assessment for each Combined Sewer Overflow Regulation project. A separate EIS related to primary sludge treatment and disposal is currently being prepared by the EPA. Therefore, the issue of primary sludge disposal is not being addressed in this EIS. C. Boston Harbor Islands Comprehensive Plan . In October of 1972 the Metropolitan Area Planning Council (MAPC) prepared for the Massachusetts Department of Natural Resources (now the Department of Environmental Management) the Boston Har- bor Islands Comprehensive Plan. This plan called for the aquisition of the more than thirty islands in Boston Harbor and their development into a recreational complex. Specific uses are delineated for the islands. In this development plan the islands are to offer both passive and active recreational opportunities to the public. Sixteen islands are currently part of the park system, being owned by either the DEN or the Dc. Since this plan was officially adopted by the state legislature, the Harbor Islands are now officially dedicated to conservation and recreation. 3—6 ------- n. Air Quality Objectives . The intent of the Clean Air Act is to protect the health and welfare of the citizens of the United States by preserving clean air where it exists, and by improving air quality in areas where air quality is degraded. A complex set of regulations exists to accomplish this goal. The law provides a range of means to accomplish the goals, including regulation of existing point sources, mobile sources, new source standards, and establishment of air quality control regions. The combination of these air quality constraints and objectives affect the sludge disposal aspects of waste— water management alternatives which can be considered for the greater Metropolitan Boston Area. The Boston Air Quality Control Region (AQCR) is in a status of non—attainment. Non-attainment means that one or more of the National Ambient Air Quality Standards (NAAQS) are being violated in the Boston AQCRas dstermined by moni- toring data. A 1976 Interpretive Ruling by EPA established the requirements for new sources in non—attainment areas. The following conditions must be met before a major new source may be approved. They are: 1) The new source must have an emission limitation which specifies the lowest achievable rate for that type of source. 2) All existing sources owned or controlled by the new source owner must be in compliance with all applicable State Implementation Plan (SIP) re- quirements. 3) Emission Offsets (reductions) are required from existing sources in the AQCR such that total emissions from the proposed source and existing sources are less than the present pollution load. 4) Emission offsets must provide a positive net air quality benefit in the region. 5) If SIP revisions are judged necessary by EPA to meet the NAAQS, no construction can be ini- tiated until such revisions have been approved by EPA (Federal Register, Vol. 41, No. 246 December 21, 1976). These provisions represent a stricter emissions limitation than the current regulations which affect new sources in uattaj entn areas. Under the same Interpretive Ruling, EPA designates a “major source” as any structure with allow- able emissions equal to or greater than 90,720 kg (100 tons) 3—7 ------- per year for particulates, sulfur oxides, nitrogen oxides, non-methane hydrocarbons and 907,720 kg (1,000 tons) per year for carbon monoxide (250 tons per year potential emissions for PSD). This designation establishes a two level system of review for major sources and smaller sources. The major sources would be subject to stricter emission limitations than the smaller sources, although the State may have the option to apply more stringent limitations to the smaller sources (Federal Register, Vol 41, No. 245, December 21, 1976). Under the same ruling it is suggested thatemissionoff- sets may be extended to smaller sources in certain areas, depending on the magnitude of the air quality problem. (See Section 2.8 for greater detail on the EOP nd PSD regula- tions). For “stable” air pollutants (i.e. SO 2 , particulate mat- ter, and CO), a case by case determination is to be made to determine if a new source will cause or exacerbate a NAAQS violation, based upon the best information and analytical techniques available. This determination should be indepen- dent of any general determination of non-attainment or judge- ment that the SIP is substantially inadequate to attain or maintain the NAAQS. This is because a violation in an AQCR may occur in only one limited section of the AQCR, thereby putting the entire region in violation of the standard. If a source seeks to locate in a “clean” portion of the AQCR and would not affect the area presently exceeding standards, or cause a new violation of the NAAQS, such a source may be approved (Federal Register, Vol. 41, No. 246, December 22, 1976). On the other hand, if a new source will degrade air quality in a “non—attainment” region, the five conditions set out above must be met. For an area not exceeding ambient air standards on a pollutant-specific basis for particulates and sulfur dioxide, limited increments of pollutant levels are permitted. Class II areas (Boston) are limited to the following increases in pollutant concentrations occurring over the baseline concen- trations (Federal Register, Vol 42, No.212, November 3, 1977): Table 3.1-1 Maximum Allowable Increase ( g/m 3 ) Particulate Matter: Annual Geometric Mean 19 24-hr. maximum 37 Sulfur dioxide: Annual Arithmetic mean 20 24-hr. maximum 91 3-hr. maximum 512 3—8 ------- Major new sources and major modifications must provide best avialable control technology for each pollutant subject toPSD regulation under the Clean Air Act. Theownerand oper- ator must demonstrate that emissions from such source will not cause, or contribute to, air pollution in excess of any ambient air quality standard in any air quality áontrol pro- gram. If emission offsets are required for a new source, EPA has determined that more than “one for one” emission offsets must be provided. Emission offset reductions must exceed the new source emissions so as to represent reasonable pro- gress toward attainment of the NAAQS. Rules and regulations for attainment and non-attainment regions limit certain alternatives which are being evaluated by this study. The incineration of sludge is especially affected by these regulations. The possibility of emission offsets, PSD review, the effect of the facility on the NAAQS, and the need to attain “the lowest achievable emission rate” may affect the feasibility of an incineration alternative. B. Limitations on Land Application of Sludge Products . Under the Resource Conservation and Recovery Act of 1976,(RCRA ) municipal wastewater sludge has been included within the defi- nition of solid waste. On February 6, 1978, EPA published classification criteria for solid waste disposal and utiliza- tion. Under these criteria, specific provisions address cad- mium, pathogens, pesticides, persistant organic chemicals, and potential for direct ingestion for sludge or solid waste applied to land used for the production of food crops. With regards to cadmium, two alternate approaches for controlling cadmium uptake by crops are proposed. Under the first approach four criteria are proposed: 1) The annual application rate for cadmium will be decreased from 2 kg/ha to 0.5 kg/ha by January of 1978 2) The maximum cummulative cadmium application shall not exceed the following: cuiumulative soil cation cadmium loading ion exchange kg/ha capacity 5 <5 10 5—15 20 >15 3—9 ------- 3) solid waste or sludge with a cadmium concentra- tion in excess of 25 mg/kg may not be applied to tobacco, leafy vegetables or root crops grown for direct human consumption 4) the pH of the soil must be maintained at 6.5 or greater Under the second approach, the cadmium levels in the crops or meats marketed for human consumption must be analyzed to demonstrate that cadmium is not accumulating to levels greater than that found in similar products grown locally on soils not receiving the sludge or solid wastes. A contingency plan must also be provided under this option, should the cadmium levels be found to be higher in foodstuffs from the sludge or solid waste augmented agricultural lands. In addition, the proposed criteria would require stabili- zation of sludge or solid waste applied to croplands and pro- hibit the application to lands where the material could be ingested by animals. In addition to the February 6, 1978 criteria, EPA is in the process of designating criteria for the identification of “hazardous” wastes under RCRA. Hazardous waste will be sub- ject to an elaborate “cradle—to-grave” regulatory procedure to ensure its safe disposal. Itis possible that some muni- cipal sludges may fall under the “infectious” or “toxic” criteria for a hazardous waste. If such is the case, the sludge can only be placed in a landfill designated to receive hazardous wastes. If the sludge, compost or ash from the MDC wastewater treatment plants fall under the forthcoming criteria for hazardous wastes, a new sludge management plan in conformance with the “cradle-to-grave” concept would be required - 3—10 ------- 3.1.3. Flow and Waste Reduction Measures The wastewaters generated in the MSD service area are currently collected and transported to wastewater treatment plants on Deer and Nut Islands for treatment prior to disposal into Boston Harbor. The EMMA Study estimated that wastewater treatment facilities would be required to treat an average quantity of about 2,218,000 m 3 /day (586 mgd) of wastewater by the year 2,000, and an average quantity of about 2,502,000 m 3 /day (661 mgd) of wastewater by the year 2050. When considering wastewater management alternatives for a system of this magnitude, it is prudent to consider the possibility of utilizing flow and waste reduction measures as a means of cost effective wastewater management. Two possible methods of flow and wastewater reduction are the elimination of infiltration/inflow and the use of water conservation measures. A. Infiltration/Inf low . Significant reductions in waste- water volu me could be realized through the elimination of extraneous flows entering the sewer system due to excessive infiltration and inflow. Infiltration is the seepage of groundwater into the sewer system through faulty pipe joints, broken pipes, or cracks in manholes. The rate of infiltration is governed by the depth of groundwater, groundwater level fluctuations due to precipitation, and the structural condition of sewerage facilities. Inf low constitutes the direct entry of storm runoff into a sanitary collection system through roof drains, foundation drains, sump pumps, manhole covers and other sources. The volume of these extraneous flows can be considerable. The Federal Water Pollution Control Act as Amended (Public Law 92—500), dated October 18, 1972, requires Construction grant appiicants to investigate the condition of their sewer systems. Title II, Section 201 (g) (3) of the Act states, “The Administrator shall not approve any grant after July 1, 1973, for treatment works under this section unless the applicant shows to the satisfaction of the Administrator that each sewer collection system discharging into such treatment works is not subject to excessive infiltration”. The final Construction Grant Regulations pertaining to the aforementioned were published in the Federal Register dated February 11, 1974. Sections 35.927, 35.927-1 and 35.927-2 of the Construction Grant Regulations include the following: “All applicants for grant assistance awarded after July 1, 1973, must demonstrate to the satisfaction of the Regional Administrator that each sewer system discharging into the treatment works project for 3—11 ------- which grant application is made is not or will not be subject ot excessive infiltration/inflow.... “The determination whether or not excessive infiltration/ inflow exists will generally be accomplished through a sewer system evaluation consisting of (1) certification by the State agency, as appropriate; and, when necessary, (2) an infiltration/inflow analysis; and, if appropriate (3) a sewer system evaluation survey followed by rehabilitation of the sewer system to eliminate an excessive infiltration/inflow defined in the sewer system evaluation. “The infiltration/inflow analysis shall demonstrate the nonexistence or possible existence of excessive infiltration/inflow in each sewer system tributary to the treatment works. The analysis should identify the presence, flow rate, and type of infiltration! inflow conditions, which exist in the sewer systems.... “For determination of the possible existence of excessive infiltration/inflow, the analysis shall include an estimate of the cost of eliminating the infiltration/inflow conditions. These costs• shall be compared with estimated total costs for trans- portation and treatment of the infiltration/inflow.... “If the infiltration/inflow analysis demonstrates the existence or possible existence of excessive infiltration/inflow, a detailed plan for a sewer system evaluation survey shall be included in the analysis.... “The sewer system evaluation survey shall consist of a systematic examination of the sewer systems to determine the specific location, estimated flow rate, method of rehabilitation and cost of rehabil- itation versus cost of transportation and treatment for each defined source of infiltration/inflow. “The results of the sewer system evaluation survey shall be summarized in a report. In addition, the report shall include: (1) A justification for each sewer section cleaned and internally inspected. (2) A proposed rehabilitation program for the sewer systems to eliminate all defined excessive infiltration/inflow.” In order to comply with the Construction Grant Regulations, a thorough study of the quantities and 3—12 ------- characteristics of infiltration and inflow is needed. The study should determine whether or not the cost of eliminating all or some of these flows by means of rehabilitating the sewer system is economically justifiable as compared to the cost of transporting these flows to, and treating them in, a wastewater treatment plant. Infiltration/Inflow studies are presently being undertaken by both the MDC and individual towns in the MSD service area in order to determine the most cost—effective means of handling these extraneous flows. In September, 1976, the MDC awarded a contract for the performance of an infiltration/inflow study of the MDC interceptor system tributary to the Deer Island Treatment Plant. A separate contract for the infiltration/inflow study of the MDC interceptor system tributary to the Nut Island Treatment Plant was also awarded by the MDC in September, 1976. The award of these two contracts by MDC was made in compliance with conditions in the EPA Region I permit issued to the Metropolitan District Commission in August, 1976. Draft reports of the infiltration/inflow studies for the Deer Island and Nut Island interceptor systems have been submitted to the EPA for their review and comment. The result of these two studies will be the determination of which portions of the MDC’s interceptor system are experiencing large amounts of infiltration/inflow. These areas will be investigated, and detailed recommendations regarding remedial actions and schedules of completion to remove that portion of the infiltration/inflow which is found to be cost effective to remove will be made. Another source of extraneous flow entering the MDC sewer system is seawater, which enters the combined sewer system tributary to the Deer Island Treatment Plant. Most of the seawater enters the sewers through faulty tide gates on sewer overflows, with an additional amount entering by infiltrating into sewers near the coastline. The MDC has recently completed a tide gate rehabilitation program; however, it is too early to evaluate the effects of this program at this time. It is estimated that infiltration/inflow and seawater entering the MDC sewer system presently account for more than half of the average flow reaching the treatment plants at Nut Island and Deer Island. Therefore, it is possible to significantly reduce the quantity of flow entering the MDC interceptors and reaching the MDC wastewater treatment facilities by rehabilitating the sewer System and the tide gates, thereby reducing the amounts of infiltration/inflow and seawater entering the sewerage System. However, the reduction of infiltration/inflow is dependent upon individual infiltration/inflow studies Concluding that sewer rehabilitation is a cost effective 3—13 ------- procedure, and a reduction in the quantity of seawater which enters the system is dependent upon the success of the tide gate maintenance and rehabilitation program. The infiltration/inflow studies arid the tide gate rehabil- itation and maintenance program have not yet progressed to the point where the amounts of flow quantity reduction can be estimated with any degree of certainty. It is recommended that the results of the infiltration/inflow studies and tide gate repair program be investigated at the time of facilities planning and, if at that time flows entering the MDC sewerage system have, in fact, been reduced or can be expected to be reduced by these efforts, the required capacities of interceptors, pumping stations, and wastewater treatment plants should be reduced accordingly. B. Water Conservation . The need for water conservation measures is increasing throughout the nation as sources of potable water become limited, the population increases and, with a rising standard of living, people tend to increase their consumption of water. It is possible to reduce water consumption while maintaining a high standard of living. The introduction of water conserving shower heads, toilets, kitchen sinks, more intelligent use of dishwashers and washing machines, and sensible practices of lawn watering and car washing can significantly reduce water consumption. Much of the water used in the home is discharged to the sewers and, therefore, any reductions in domestic water consumption would produce corresponding reductions in waste— water flow. As this study is focusing on wastewater treat- ment and disposal, further discussion of water conservation techniques will be restricted to those which have a direct effect on wastewater production. The quantity of domestic wastewater production could be reduced considerably with the use of several relatively simple and inexpensive flow reduction devices which are readily available. These devices Include aerators.or flow regulators which can be attached to water faucets, reduced flow shower heads, and either low flush type toilets or flow regulators which convert conventional toilets to low flush types. Aerators normally consist of a fine mesh screen which breaks up the water into fine droplets, thus entraining air. Wettability is increased and splash is decreased and, as a result, less water is required to produce the same degree of wetness and cleansing action. Flow regulators are devices which, when added to the water line, increase the frictional drag between the water and the pipe, thereby decreasing the flow. This type of 3—14 ------- regulator can be installed on the faucet as an aerator is installed, or can be inserted into the water pipe that supplies the faucet or shower fixture. Low flush or shallow trap toilets, which use approx— imately 13.2 liters (3.5 gallons) per flush, are available from most manufacturers. This represents a significant reduction over the conventional toilet which utilizes between 19 and 30 liters (5 and 8 gallons) per flush. The reduction in water used is possible through redesign of the siphon which permits more efficient flushing action while using smaller volumes of water. These units can be installed in new developments and in all newly renovated buildings for the same cost as conventional toilets. This can be accomplished through revisions in the local plumbing codes to require that these low flush type toilets be used in all new installations. Revisions of this type are becoming corni on as legislators are becoming aware of the importance of conserving water. Existing conventional toilets can be converted to use less water by installing either flow regulators which close the toilet flush valve faster, or dams which retain as much as 30 percent of the water volume in the tanks of tank type toilets. Both of these methods provide sufficient force for effective flushing action while reducing the volume of water used. Conversion, by either of these methods, requires only a nominal expenditure by the homeowner. Another simple method of reducing the flow of conventional tank type toilets is through the use of displacement devices. These devices displace a volume of water in the tank, thereby reducing the water volume used in flushing. One method that has been used is to place a brick or two in the tank. This method, although it reduces the flow volume, is not recommended as the bricks may start to crumble and foul the toilet mechanism. A better water displacement method is to fill a plastic bottle with water and place it in the toilet tank. The plastic bottle will displace its own volume of water, thereby reducing the amount of water in the tank. The plastic bottle will not decompose or foul the toilet mechanism. Individuals can determine the maximum amount of water which can be displaced while still providing effective flushing action. Other savings in water use are possible through sensible use of water consuming household appliances such as dishwashers and washing machines. By saving dishes to be washed until a dishwasher is fully loaded, it is possible to reduce the number of times the unit is used. This results in savings in water, fuel and electricity to heat the water and run the unit and detergent. Similar conservation 3—15 ------- techniques employed with washing machines can produce significant savings in water, energy and detergent. It is not always possible to save soiled laundry to completely fill the washing machine. For such cases, many machine manufacturers have incorporated a water level selection switch which permits the user to match the water used with the size of the clothing load to be washed. The use of washing machines and dishwashers designed to optimize water use is an effective means of conserving water. While it is not possible Lor individuals to redesign their appliances, they have the option of purchasing low water use appliances. If manufacturers realize that those appliances which conserve water and energy are preferred by the public, they will manufacture a greater variety of these appliances. Widespread action of this type by consumer groups can exert significant market pressure on the manufacturers to produce water and power conserving equipment. It is estimated that, through the use of the relatively simple domestic water conservation measures discussed above, domestic water use and wastewater production can be reduced by at least 76 liters (20 gallons) per capita per day. The related cost savings from reduced water supply, sewage management and heating charges would probably equal the initial cost of installing water conservation devices within the first year of use. After the first year, the average household should be able to save at least $60.00 per year in these charges. Implementation of water conser- vation by the methods previously discussed could meet with widespread public acceptance, since there is a minimum amount of inconvenience and a monetary savings to the individual water user. Appendix 3.1.3 contains a sample analysis of the water and cost savings associated with these conservation practices. Industrial pretreatment before discharge to the MSD system is currently required of certain industries to comply with their discharge permits. The MDC is currently engaged in an inventory of all industrial sources to determine the extent of their compliance with discharge requirements. Pretreatment can be modified or instituted to provide benefits to both the industrial organization and the MDC. This can be accomplished through wastewater reuse and recovery. Wastewater reuse and recovery is currently being utilized in many industries across the cou itry to meet wastewater discharge requirements and to reduce raw water intake requirements. Reuse of cooling water as process water, process water reclamation, monitoring of process water additions, and cooling water recirculation are all 3—16 ------- viable methods of industrial wastewater reuse. Through various combinations of physical, chemical and biological treatment processes, it is possible to recycle much of the industrial wastewater produced, thereby reducing both the volume and strength of the discharge. These reductions in wastewater reduce the transport and treatment require- ments, and costs, for the MDC, while they reduce industrial water charges, and often reduce the cost of the industrial process. Various by—products of industrial pretreatment are marketable items, such as paper products, recovered chemicals and animal feed, while the by—products of other treatment processes can be recycled in the manufacturing process itself. The success of a water conservation program will depend, to a great extent, on extensive public education programs to impress upon the general public the need for, and the benefits of, conserving water. This public education program can be accomplished through a joint effort of the MDC, local water supply agencies and conservation groups. Including brochures or newsletters which explain the economic and environmental benefits of water conservation with periodic water bills is one method of informing the public. Programs directed at school children can produce good results since children are easily impressed, they will most likely take the information home to their parents, and they can have a positive influence on their family and friends. In addition to the water conservation education program, a water conservation program will benefit from the adjustment of water rate schedules so that conservation efforts in the home will produce a savings in water bills. At present, many local water district rate structures encourage waste, as there is a minimum monthly charge for water use. The primary problem with this type of rate structure is that the quantity of water used which would result in the minimum charge would not be affected by a reduction in water consump- tion. Another form of water rate schedule which encourages Waste is the declining commodity rate. Under this system, the price per unit consumed decreases as consumption increases; i.e., the more you use, the less you pay. This type of rate Structure discourages conservation because the large volume user can get water for relatively low prices. Implementation of a uniform rate schedule for all water users based on actual consumption would provide reasonable economic stimulation for water conservation. With a uniform rate schedule,all water users, both domestic and industrial, can realize economic benefits from conservation efforts. A complete study of the social and economic effects of changes in water rate schedules is necessary before a decision can be made on whether or not to modify the current rate schedules. 3—17 ------- It is recommended that a water conservation effort be started immediately. If a concerted effort is made by the MDC, local water supply agencies, conservation groups, industry and the general public, a successful water con- servation program can be realized. The results of such a program should be investigated during facilities planning. If this investigation shows a reduction in the quantity of wastewater generated, the required capacities of interceptors, pumping stations, and wastewater treatment plants should be reduced accordingly. While it is possible that, because of the time required to produce results from a water conser- vation program, a significant reduction in wastewater quantities may not be realized at the time of facilities planning, a water conservation program may result in eliminating the need for expansion of facilities in the future. 3—18 ------- 3.2 PRELIMINARY SCREENING OF SUBSYSTEM ALTERNATIVES 3.2.1. Interceptor Sewer System, Pumping Stations and Headworks The purpose of an interceptor sewer system is to receive the wastewater from various local sewer systems and transport it to a treatment or disposal facility. Interceptor sewers are designed so that the wastewaters reach velocities which will prevent solid material from being deposited in the sewers and which will minimize the amount of decomposition which the wastewaters will undergo while in the interceptor system. If the wastewater is permitted to flow to the discharge point sluggishly, it will begin to decompose in the sewer system. Hydrogen sulfide gas is generated by wastewaters decomposing in the absence of air. In addition to producing foul odors, hydrogen sulfide is corrosive to the pipelines. Over a period of time, corrosion can cause serious deterioration in concrete pipe. Insufficient interceptor sewer capacity also prevents the local sewer systems from draining freely and causes the local sewers to back—up and store the wastewater until the interceptor sewer can accept the flow. Odor and corrosion would then be caused due to the decomposition of the wastewater in the local sewer system. For these reasons, it is important to maintain a properly operating interceptor sewer system, with adequate capacity to handle the wastewater generated, as an integral part of any wastewater management system. The existing MDC interceptor sewer system receives the wastewaters from 43 towns and cities, including the City of Boston, and transports it to the Nut Island and Deer Island wastewater treatment plants. The original interceptor system has been expanded over the years as required to keep pace with an ever expanding service area and an increasing population. The present system is currently overloaded in some areas and, as increased flows are to be expected from the existing service area and additional towns may be added to the MSD, the interceptor system will again require modifications and additions to provide adequate and safe service. The MDC interceptor sewer system can be considered as two separate systems. One system receives wastewater from the northern MSD service area and transports this wastewater to the Deer Island Treatment Plant. The other system receives wastewater from the southern MSD service area and transports it to the Nut Island Treatment Plant. 3—19 ------- Several wastewater management alternatives are being investigated for the treatment and disposal of the wastewater from an expanded MSD service area. These alternatives include expanding and upgrading the existing treatment plants, and constructing new treatment plants of various capacities at various locations. As would be expected, the locations and capacities of treatment plants have a direct effect on the interceptor modifications which will be required. Since all of the alternative wastewater management systems consider treating the wastewater from the northern MSD service area at a treatment plant in the vicinity of Boston Harbor, the modifications required for the northern interceptor system at locations not adjacent to the harbor will be identified for all alternatives. These requirements are listed in Table 3.2-1. Any additional modifications required which are dependent upon specific treatment facility locations will be discussed with the specific alternative systems later in this report. The variations of wastewater management system alter- natives has a larger effect on the southern interceptor system. Some alternatives consider transporting all of the wastewater generated in the southern MSD service area to a treatment plant in the vicinity of Boston Harbor, while other alternatives consider treating some of the wastewater at inland satellite treatment plants and the remainder at a treatment plant near the harbor. The southern interceptor system modifications which would be required for all alter- natives which include inland satellite plants are listed in Table 3.2-2. The modifications to the southern interceptor system which would be required for all alternatives which do not include inland satellite plants are listed in Table 3.2-3. Any additional modifications required which depend upon the specific locations of treatment facilities will be discussed with the specific alternative systems later in this report. A comparison of Tables 3.2-2 and 3.2-3 shows that a syste with satellite treatment plants would require less modifications to the southern interceptor system than would a system without satellite plants. This is because the satellite plants remove wastewater from the interceptor system at upstream locations, thereby reducing the flow, and capacity requirements, in the downstream sections. The interceptor relief and extensions which would be required for all alternative systems which include satellite treatment plants are shown in Figure 3.2—i. For alternative systems which do not include satellite treatment plants, the interceptor relief and extension requirements common to all such alternatives are shown in Figure 3.2—2. Pumping stations are a necessary part of this wastewater management system as they are needed to lift the wastewater flow from low—lying local sewer systems into the MDC 3—20 ------- interceptor sewers. The MDC operates ten pumping stations along the interceptor system. For this study, the existing capacity, future design capacity and the need to replace or rehabilitate each of the stations, as shown in Table 3.2-4, is as reported in the EMMA Study. The MDC operates four headworks; Ward Street, Columbus Park, Chelsea Creek, and the Winthrop Terminal Facility, which provide pretreatment for the wastewaters which will be treated at Deer Island. Pretreatment consists of coarse and fine screening and grit removal. The existing headworks have adequate capacity to handle the anticipated flows to the Deer Island plant, and therefore, no expansion is necessary The rehabilitation or repair work at these facilities is not included in the EMMA Study nor in this EIS, as these facilities are relatively new and any required repairs can be expected to be included in the existing maintenance budget. 3—21 ------- TABLE 3.2-1 INTERCEPTOR SEWER MODIFICATIONS FOR NORTHERN MSD SERVICE AREA Ref. No . ( - ) Interceptor Sewer Diameter cm. (in.) Length in. (ft.) 1 Milibrook Valley Sewer 91 (36) 3883 (12,740) 2 Wilmington Extension Sewer 76 (30) 2905 (9,530) 3 Reading Extension Sewer . 61 76 107 (24) (30) (42) 411 1664 414 (1,350) (5,460) (1,360) 4 Lynnfield Extension Sewer 30—53 (12—21) 1829 (6,000) 5 Stoneham Extension Sewer 30 (12) 1259 (4,130) 6 Wakefield Branch Sewer 38 107 (15) (42) 942 1664 (3,090) (5,460) 7 Stoneham Trunk Sewer 46 (18) 930 (3,050) 8 Wakefield Trunk Sewer 107 122 (42) (48) 2723 927 (8,935) (3,040) 9 North Metropolitan Sewer 137 (54) 610 (2,000) 10 North Metropolitan Sewer 152 (60) 792 (2,600) 11 CununingsviIle Branch Sewer 91 (36) 1515 (4,970) 12 Chelsea Branch Sewer 53 (21) 347 (1,140) 13 Revere Extension Sewer 30 76 (12) (30) 314 969 (1,030) (3,180) 14 Sommervi1J e—Medford Branch Sewer 61 107 (24) (42) 2277 280 (7,470) (920) 15 Weston—Lincoln Ext. Sewer 76—107 (30421 10180 (33,400) 16 South Charles Relief Sewer 91 107 122 (36) (42) (48) 2487 6062 1609 (8,160) (19,890) (5,280) 17 North Charles Metropolitan Sewer 61 91 (24) (36) 826 945 (2,710) (3,100) 3—22 ------- TABLE 3.2-1 (Cont’d.) INTERCEPTOR SEWER MODIFICATIONS FOR NORTHERN MSD SERVICE AREA 1. Reference Number - See Figures 3.2-1 and 3.2—2. Source: Metcalf & Eddy, Inc. , 1975i 18 f. No 1 Interceptor Sewer Diameter cm (in.) Length in. (ft.) South Charles River Sewer 91 (36) 213 (700) Charles River Crossing & Cross Connection 137 168 (54) (66) 884 1679 (2,900) (5,510) 3—23 ------- TABLE 3.2-2 INTERCEPTOR SEWER MODIFICATIONS FOR SOUTHE1 N MSD SERVICE AREA WITH SATELLITES Ref No. . (i-) Interceptor Sewer Diameter cm. (in.) Length m. (ft.) 19 Southborough Ext. Sewer 61—91 (24—36) 81 9 (26,800) 20 Ashland—Hopkinton Ext. Sewer 53—122 (21—48) 11186 (36,700) 21 Framinghain Extension Sewer 152 (60) 3101 (10,175) 168 (66) 6581 (21,590) 22 Upper Neponset Valley Sewer 61 (24) 3344 (10,970) 91 (36) 3152 (10,340) 23 Westwood Extension Sewer 76 (30) 3752 (12,310) 24 Walpole Extension Sewer 122 (48) 1503 (4,930) 152 (60) 3335 (10,940) 25 Sharon Extension Sewer 91 (36) 2256 (7,400) 26 New Neponset Valley and 61 (24) 472 (1,550) Stoughton Extension Sewers 76 (30) 692 (2,270) 91 (36) 1524 (5,000) 137 (54) 1501 (4,925) 198 (78) 152 (500) 27 Lower Braintree Connecting 61 (24) 227 (744) Sewer 152 (60) 877 (2,878) 28 Hingham Force Main 61 (24) 2316 (7,600) 29 Braintree-Weyiuouth Ext. Sewer 152 (60) 3123. (10,238) 1. Reference Number — See Figure 3.2—1. Source: Metcalf & Eddy Inc. ,1975i 3—24 ------- TABLE 3.2-3 INTERCEPTOR SEWER MODIFICATIONS FOR SOUTHERN MSD SERVICE AREA WITHOUT SATELLITES (26 ,800) (36 ,700) (10,175) (21,590) (10,970) (10,340) (12 ,310) (4,930) (10,940) (7,400) (1,550) (2,270) (5,000) (4,925) (500) (744) (2,878) (7,600) (10 ,238) (22,100) (17 ,100) (15,100) 2926 (9,600) 213 (84) 5029 (16,500) Ref. No. (1) 19 20 21 Interceptor Length Sewer (ft.) 22 Upper Neponset Valley Sewer 23 Westwood Extension Sewer 24 Walpole Extension Sewer 25 Sharon Extension Sewer 26 New Neponset Valley and Stoughton Extension Sewers Diameter _________________________________ cm. (in.) Southborough Ext. Sewer 61-91 (24-36) Ashland-Hopkinton Ext. Sewer 53-122 (21—48) Framingham Extension Sewer 152 (60) 168 (66) 61 (24) 91 (36) 76 (30) 122 (48) 152 (60) 91 (36) 61 (24) 76 (30) 91 (36) 137 (54) 198 (78) 61 (24) 152 (60) 61 (24) 152 (60) 183 (72) 198 (78) 183 (72) 198 (78) 8169 11186 3101 6581 3344 3152 3752 1503 3335 2256 472 692 1524 1501 152 227 877 2316 3121 6736 5212 4602 27 Lower Braintree Connecting Sewer 28 Hingham Force Main 29 Braintree-Weymouth Ext. 30 Wellesley Extension Sewer 31 New Neponset Valley Sewer 3—25 ------- TABLE 3.2-3 (Cont’d.) INTERCEPTOR SEWER MODIFICATIONS FOR SOUTHERN MSD SERVICE AREA WITHOUT SATELLITES Ref No. . (1) Interceptor Sewer Diameter cm. (in.) Length in. (ft.) 32 High Level Sewer 244 (96) 1189 (3,900) 259 (102) 4968 (16,300) 274 (108) 2530 (8,300) 1. Reference Number — See Figure 3.2-2. Source: Items 19 through 29: Metcalf & Eddy Inc., 1975i 3—26 ------- PAGE NOT AVAILABLE DIGITALLY ------- TABLE 3.2—4 MDC PUMPING STATIONS Year 2000 Peak Existing Firm Dry Weather apacity 3 Re 9 uirements EMMA Study Itein / Pump Station m 3 xlO /day (mgd) m xlO”/day (mgd) Recommendations a Reading .015 (4) .053 (14.0) Replace b Alewife Brook .244 (64.4) .117 (30.9) Rehabilitate c Charlestown .340 (90) .277 (73.3) Replace d East Boston Electric .189 (50) (Standby) Rehabilitate e East Boston Steam .397 (105) .076 (20.0) Replace Squantum .015 (4) .017 (4.4) Replace g Quincy .121 (32) .099 (26.2) Replace h Braintree-Weymouth .151 (40) .222 (58.7) Replace i Houghs Neck .005 (1.4) .008 (2.2) Replace j Hingham .010 (2.8) .031 (8.3) Rehabilitate 1. See Figures 3.2-1 and 3.2—2. Source: Metcalf & Eddy, Inc. , 1976 ------- 3.2.2. Coastal Area Wastewater Treatment Plants The determination of the most environmentally accept- able, cost effective method of upgrading the MDC’s waste- water treatment system requires the review and evaluation of various alternative systems of wastewater treatment plants. Whether satellite treatment plants are included or not, large treatment plants will be required in the vicinity of Boston Harbor. Therefore, it is necessary that consideration be given to alternative treatment plant sites, effluent discharge locations and treatment processes for these coastal area treatment plants. A. Sites . This analysis begins with a preliminary screening of sites in the vicinity of Boston Harbor which could —L possibly be used as the location of a major wastewater treatment facility. The sites which survive this preliminary screening process will then be combined into alternative “coastal area wastewater treatment plant” subsystems for further evaluation during the intermediate screening process. The list of sites which were evaluated in this stage include: Broad Meadows; Deer Island; Broad Cove, Kings Cove, and Lower Neck in the Hinghaxn-Weymouth area; Long Island; Moon Island; Nut Island; Peddocks Island; Spectacle Island; and Squantum Point. The locations of these sites are shown in Figure 3 . 2—3. A review of existing wastewater treatment plant designs providing secondary treatment indicates that providing an area of 0.267 x l0 hectares per m 3 /day (.25 acres per mgd) of wastewater treated (average daily flow) would be sufficient for preliminary screening purposes. Design flows for the year 2050 were used to determine ultimate plant area requirements so that adequate area would be provided for the possible future expansion of treatment facilities. The average daily design flows for the year 2050, as estimated in the EMMA Study, and the land area required for the necessary treatment facilities are: Est. Avg. Daily Approx. Area Flow, Yr. 2050 Req’d. m 3 /day (mgd) hectares (acres) Southern MSD service area, with satellites 568,000 (150) 15.2 (37.5) Southern MSD service area, without satellites 874,000 (231) 23.3 (57.8) Northern MSD service area 1,628,000 (430) 43.5 (107.5) Total MSD service area 2,502,000 (661) 66.8 (165.3) Broad Meadows . The Broad Meadows site is loc4ted at the head of the Town River Bay in Quincy. The site is primarily a filled tidal marsh which was used as a disposal area for material dredged from the Town River in 1939 and 3—32 ------- BOSTON BROAD MEADOWS SPECTACLE ISLAND MOON ISLAND ISLAND •7/ QUINCY BRAINTREE LEGEND A TREATMENT PLANT SITE CONSIDERED DEER ISLAND MILTON FIGURE 3.2-3 COASTAL TREATMENT PLANT SITES CONSIDERED ------- again in 1953. Some unspoiled tidal marsh land exists along the perimeter of the site adjacent to the bay. The ground surface is relatively level and covered primarily with Phragmites . Broad Meadows is bordered by residential and commercial structures on three sides and by the Town River Bay on the fourth, and is zoned for light industrial development. Currently, the Broad Meadows site is being considered as a site for the South Shore Community College. The proposed college would consist of a multiple building complex, roads, parking areas and recreational fields adequate for an enrollment of approximately 3000 commuting students. It is possible that the plans to construct the college at this site may be abandoned, and therefore, the site may become available for the construction of a wastewater treatment plant. Although there are residential areas in the vicinity of Broad Meadows, the site with a land area of about 44.5 hectares (110 acres), is large enough to accommodate a wastewater treatment plant which would serve the southern MSD service area, whether satellite plants were constructed or not, and maintain a buffer zone of at least 152 meters (500 feet) to the nearest structure. With effective architectural treatment of the structures and landscaping of the plant grounds and buffer zone, any objectionable appearance of a wastewater treatment facility can be minimized. The Broad Meadows site is adjacent to the existing High Level Sewer, which presently transports the wastewater flow from the southern MSD service area to the Nut Island Treatment Plant. The proximity of a new plant at Broad Meadows to the interceptor system would minimize the construction work (and cost) required to transport wastewater from the interceptor to a treatment plant on this site. Also, it would be possible to discharge the effluent from a treatment plant at Broad Meadows back into the High Level Sewer, which would carry the effluent tø Nut Island, thereby making it possible to utilize the existing outfall system which presently discharges into Boston Harbor in the vicinity of the Nantasket Roads Channel. Constructing treatment facilities on the Broad Meadows site would probably require pile foundations due to the unfavorable soil conditions associated with a filled marshland. The construction of a plant to treat the wastewater flow from the southern MSD service area at Broad Meadows would permit most of the treatment facilities presently on Nut Island to be abandoned and demolished, thereby making Nut Island available for other uses, such as recreational development. 3—34 ------- Deer Island . Deer Island is located north of the President Roads Channel of Boston Harbor, and is connected to the Town of Winthrop by a land bridge and roadway. The predominant feature of the island is an approximately 30 meter (100 foot) high drumlin located near the center of the island. South of the drumlin are the remains of Fort Dawes, which was abandoned in the mid 1940’s. Located north of the drumlin are the existing Deer Island Treatment Plant and a minimum security prison. The Boston Harbor Islands Comprehensive Plan (MAPC, 1972) calls for the development of the southern end of Deer Island as a recreational area. However, it should be noted that the MAPC, in preparing this plan, provided sufficient space on Deer Island for the treatment plant expansion recommended by the EMMA Plan. Had the EMMA Plan recommended a greater degree of expansion on Deer Island (as this study does), the MAPC recommendation may have been different. The undeveloped portions of the island are mostly occupied by early successional field, with some isolated growths of secondary woodland. Some areas of the island, particularly Fort Dawes, are devoid of any ground cover. The total land area of Deer Island, about 85 hectares (210 acres), is adequate to accommodate a wastewater treatment plant capable of treating all of the wastewater generated in the entire MSD service area. However, a treatment plant of this size would require utilization of the entire island for the plant site, including the drumlin area, the existing prison site, and the south end, in order to avoid any filling in of the harbor. A treat- ment plant large enough to accommodate only the wastewater from the northern MSD service area would require utilizing the area presently occupied by either the drumlin or the prison, in addition to the existing treatment plant site. The expansion of the plant into the prison area would require demolition of all prison facilities on Deer Island. Utilizing the area occupied by the drumlin would require the removal of the drumlin. Due to the relatively recent construction of the present Deer Island Treatment Plant (1968) and the fact that most of this plant’s facilities are in good condition, these facilities should be maintained and expanded as necessary to provide primary treatment to the wastewater generated in the northern MSD service area. Hingham-Weymouth . Consideration was given to the Construction of a secondary wastewater treatment plant to serve Braintree, Hingham, Holbrook, Randolph and Weymouth. Three locations in the Hingham-WeymOUth area which were considered as possible treatment plant sites are: Broad Cove in Hingham, Kings Cove in North Weymouth, and Lower Neck in North Weymouth. The design flow used for the determination of treatment plant area requirements 3—35 ------- was 105,980 m 3 /day (28 mgd), which approximates the wastewater flow which would be tributary to this plant in the year 2050. A treatment plant of this capacity would require about 2.8 hectares (7 acres) of land. Two of the locations, Broad Cove and Lower Neck, were not large enough to accommodate a treatment plant of this size. The third site, at Kings Cove, is large enough to accomm- odate such a plant and is near the existing Braintree- Weymouth interceptor. However, a treatment plant at Kings Cove would require an extremely long outfall to reach a suitable discharge location. In addition, the site is presently occupied by a low profile steel storage tank. A 105,980 m 3 /day (28 mgd) treatment plant in the Hingham—Weymouth area would reduce the area required at another site for a treatment plant to treat the remaining southern MSD service area wastewater by about 2.8 hectares (7 acres). The additional capital cost for having two plants treat the wastewater from the southern MSD service area as compared to one plant would be about $15,000,000. The additional operation and maintenance cost would be about $750,000 per year. Long Island . Long Island, with a land area of about 86 hectares (213 acres), is the largest of the islands located in Boston Harbor, and is connected to the main- land by a two lane causeway to Moon Island. The principal features of the island are the drumlin on its northern tip and Long Island Hospital. The hospital occupies the middle section of the island and consists of several buildings. South of the hospital is a cemetery of unmarked graves, a monument and cemetery for 79 Civil War dead, and an abandoned Army installation which is currently used as a storage facility by the Boston Library. The Boston Harbor Islands Comprehensive Plan calls for the development of Long Island as a major recreation facility in the Harbor due to its easy access by car, bus and ferry, and its size. The area south of the hospital is large enough, with about 49 hectares (120 acres) of land, to accommodate a treatment plant with sufficient capacity to provide primary treatment for the southern MSD service area and secondary treatment for both the northern and southern MSD service areas, whether satellite plants are constructed or not. If satellites are not constructed, the treatment plant would require about 49 hectares (120 acres) of land. This area is characterized as a mid-successional field with a fresh water marsh being found along a portion of the western shore of the island. This habitat supports a diverse population of wildlife species. The construction of a treatment plant on Long Island capable of giving primary treatment to the wastewater from 3—36 ------- the southern MSD service area and secondary treatment to the wastewater from the northern and southern MSD service areas would permit most of the existing Nut Island Treatment Plant to be abandoned and demolished, making Nut Island available for other purposes, such as recreational development. A small amount of expansion of the primary treatment facilities on Deer Island would be required . The use of the drumlin area, south end, or prison area of Deer Island would not be required. However, construction of such a plant on Long Island would require large submarine pipelines across Boston Harbor to carry wastewater from Deer Island and Nut Island to Long Island, would require relocation of the cemeteries on Long Island, and would result in the loss of a potential recreational area on Long Island. In addition, it is possible that a narrow strip of fill would be required along the shoreline of the island to provide area for an access road to the hospital. Moon Island . Moon Island is located between Quincy Bay and Dorchester Bay. The eastern half of the island contains a 30 meter (100 foot) high drumlin, and the western half is the site of the first major sewage disposal facility for the City of Boston. The tanks of this facility are still intact and are currently used to provide emergency relief for the combined sewer system of Boston during severe storms. This facility has no treatment capability, but does serve as a storage tank with a capacity of about 189,250 m 3 (50 million gallons) . The stormwater is discharged from the tanks to the harbor during outgoing tides. The drumlin is the current site of the Boston Police Department Firing Range and Boston Fire Department training facilities. The Harbor Island Compre- hensive Plan recommended conversion of the existing Moon Island tanks to a fish hatchery or a holding tank for the Boston Aquarium. The Plan recommends that the remainder of the island be developed as a recreation area. Moon Island with a land area of about 18 hectares 44.6 acres), is large enough to accommodate a wastewater treatment plant to serve the southern MSD service area without requiring any filling of Dorchester Bay or QuinCy Bay, if satellite plants are constructed along the Charles and Neponset Rivers. The treatment plant would Occupy almost the entire island. If satellite plants are not constructed, some fill would be required. Due to the shape of the island, and the necessity of maintaining a corridor for the roadway to Long Island, the plant layout Would be cramped and would not offer as much flexibility in operation as would be desired. The size and locations of the existing tanks are such that they could not be Utilized in a new plant. Extensive modifications to the 3—37 ------- present interceptor and pumping station network, or the construction of a pipeline across Quincy Bay which would transport wastewater to Moon Island from the existing interceptor system which terminates at Nut Island, would be required. A long outfall would also be required to reach an acceptable effluent discharge location. It is possible that, if Moon Island is not used as the site of a wastewater treatment plant, the existing tanks on the island could be incorporated into a combined sewer overflow regulation system for the City of Boston. Nut Island . Nut Island is located in the southern harbor area and is the present site of the Nut Island Treatment Plant. The Nut Island site was created by filling in the area between the original Nut Island and Houghs Neck peninsula. This site has a low, flat profile and a very stark appearance. The existing primary treat- ment facilities occupy most of Nut Island and, while the required primary expansion would result in only about 1.2 hectares (3 acres) of fill into Quincy Bay, the construction of secondary treatment facilities would require about 8.1 hectares (20 acres) of fill if satellite plants were constructed along the Charles and Neponset Rivers, and about 11.7 hectares (29 acres) of fill if satellite plants were not constructed..* The existing Nut Island Treatment Plant is in need of extensive renovation and modernization to provide efficient primary treatment. Nearly every portion of the treatment process requires some form of upgrading, renovation or replacement. Due to the extremely poor condition of the existing plant, it would cost about as much to revamp and expand the primary treatment facilities on Nut Island as it would be to construct new primary treatment facilities elsewhere. As discussed previously, it would be possible to reduce the amount of fill required for a secondary treatment plant on Nut Island by constructing an additional plant in the Hingham—Weymouth area. However, reducing the flow to a plant on Nut Island by the amount of flow which would be tributary to a plant in the Hingharn—Weymouth area would reduce the fill requirements at Nut Island by only about 2.8 hectares (7 acres), and at least 5.3 hectares (13 acres) of fill into Quincy Bay. Peddocks Island . Peddocks Island, located between Hull Bay and Quincy Bay, consists of five drumlins connected by low sand bars. The West Head of Peddocks Island, with about 20 hectares (50 acres) of land, has adequate space to accommodate a treatment plant which serve the southern MSD service area, if satellite plants are constructed. If * The acres of fill required are somewhat less than those presented in the EMMA Study due to utilization of rectangular rather than circular final settling tanks. 3—38 ------- satellites are not constructed, some fill would be required. According to the Boston Harbor Islands Comprehensive Plan, the West Head of the island is mostly undeveloped and is a valuable wildlife habitat. This area contains a Black—Crowned Night Heron rookery and a Snowy Egret rookery. (A “rookery” is a breeding area for a bird colony). The Boston Harbor area is one of three locations within Massachusetss known to contain Black- Crowned Night Heron rookeries. Neither species is, however, endangered. Because of the valuable habitat present on the West Head of Peddocks Island and the use of that habitat by bird populations, the Boston Harbor Island Comprehensive Plan has recommended that the West Head be preserved as a wildlife sanctuary with the remainder of the island to be developed for recreation. A treatment plant located on Peddocks Island could be connected to the existing interceptor system with a relatively short pipeline across the West Gut between Nut and Peddocks Islands. The site is relatively close to the existing Nut Island Treatment Plant outfall discharge location in the vicinity of Nantasket Roads. Locating a plant on Peddocks Island would require that a bridge or causeway be constructed between the island and the mainland in order to provide access to the plant. It would also result in the loss of the island as a wildlife refuge. Spectacle Island . Spectacle Island is one of the northern islands in Boston Harbor and consists of drumlins on the northern and southern ends connected by a low sandbar, giving it the appearance of a pair of spectacles. The island’s appearance has been significantly altered through its past use as a garbage dump. The natural low lying midsection of the island and its northern end are buried by garbage estimated to be as much as 30 meters (100 feet) deep. The southern portion of the island contains smaller piles of garbage and the ruins of small buildings. Although the island is no longer used as a garbage dump, fires are still reported to be smoldering deep within the garbage. The Boston Harbor Islands Comprehensive Plan recommends the reclamation of Spectacle Island as a recreational resource. This is to be done by extinguishing the fires, compacting the rubbish and developing a vegetative cover. According to the Plan, facilities to be developed on the island include bathing, beaches, nature trails and docking slips. The island is currently used by a variety of shore birds including Black-Backed Gulls, Herring u1ls, Black Crowned Night Herons, and serves as a breeding area for Glossy Ibis. Asuitable offshore habitat is essential for these species, hence loss of this island through the development 3—39 ------- of wastewater treatment facilities would result in a significant environmental impact. Spectacle Island, with a land area of about 39 hectares (97 acres) is large enough to accommodate a treatment plant which would treat the wastewater from the southern MSD service area, whether satellite plants are constructed or not. A treatment plant to serve the northern MSD service area would require some fill. However, if the wastewater from the northern service area received primary treatment at Deer Island, secondary treatment facilities could be placed on Spectacle Island without requiring any fill. Locating a sewage treatment plant on this site would require the construction of a bridge or causeway which would provide access to the island from the mainland. Also, it would be extremely difficult to construct a plant on 30 meters (100 feet) of garbage and, therefore, the garbage would probably have to be removed and disposed of. Locating a disposal site in the area for the huge amount of garbage presently on Spectacle Island would present a problem. In addition, extensive pipelines would be required in order to connect the existing interceptor system to a plant at this location. Squantum Point . The area called Squantum Point is located in northwest Quincy and is the site of an abandoned Naval air station. It is bordered by the Neponset River on the west and Dorchester Bay on the north. The site is about 28 hectares (70 acres) in size, relatively flat, covered with grasses and various shrubs, and has no special environmental significance. Most of the land being considered for a treatment plant site is owned by Boston Edisøn-iCo., and a portion is owned by Jordan—Marsh. Boston Edison currently has no plans for their land at Squantum Point, and has indicated a willingness to sell the property. The property owned by Boston Edison is large enough to accommodate a plant which would give primary and seáondary treatment to the wastewater generated in the southern MSD -service area if satellite plants were to be constructed on the Charles and Neponset Rivers. If satellite plants were not constructed, some of the property onwed by Jordan-Marsh would be required. Locating a treatment plant on this site would require the construction of a long pipeline to transport wastewater from the existing interceptor system to the plant. In addition, either a long outfall or another long pipeline connecting the plant with the existing Nut Island Treatment Plant outfall system would be required in order to discharge plant effluent to a satisfactory location in Boston Harbor. While the Squantum Point site is remote from existing residential areas, the area adjacent to the site is zoned for 3—40 ------- “planned Unit Development”, and a development of this type has been proposed on t1 e adjacent parcel. Elimination of Sites . ?rir c J ( S — Based on the information presented above, the following sites have been eliminated from further consideration for the reasons stated: Hingham-Weymouth . Three locations, Broad Cove, Kings Cove, and Lower Neck, were considered as potential sites in this area. Only one of these,Kings Cove, was large enough for a treatment plant of the capacity required. This alternative was eliminated because it would require an additional site and outfall, additional capital costs (about $15,000,000), additional operation and maintenance costs ($750,000 annually), and would result in only a minimal reduction in plant size that would be required at the principal plant serving the southern MSD service area. Moon Island . This alternative was eliminated due to the presence of three active land uses on the island which would be displaced by a wastewater treatment plant, and the potential use of Moon Island in a combined sewer overflow regulation program. Nut Island . Although Nut Island is the site of an existing MDC primary treatment plant, and this existing plant is recommended for secondary expansion by the EMMA Study, it has been eliminated as an alternative site for secondary expansion in this preliminary screening stage. This decision.is based on the adverse environmental effects which would result from the need to fill in Quincy Bay in order to create sufficient space on the site. The rationale behind this decision is discussed below. Historically, wetland areas and open water areas have been filled in and destroyed in order to create developable land for non-developable or “marginal” areas. This objective is very short sighted in the sense that a short term convenience is realized at the expense of a non—renew- able resource (proper land use planning could achieve alter- nate solutions). Furthermore, this action is, practically, irreversible. In the metropolitan area surrounding Boston Harbor, the motivation for harbor filling is clearly evident. Most of the land is developed and has high value. The pressure of urban expansion has created a need for developable land where little exists. The alternatives include displacement and re—development and, along water- front areas, conversion of open water areas into developable land by filling. In many cases, land creation is far cheaper and more feasible than re—development. Over the long term, these activities have serious effects. All fill projects are additive in their long term impact. While a 3—41 ------- single proposal may not, by itself, cause drastic environ- mental changes, the cumulative effects are often dramatic. In Boston Harbor, for example, fill projects have reduced the size of the inner Harbor by a significant increment (See Figure 3.2-4). For the construction of Logan Airport alone, over 800 hectares (2000 acres) of the harbor were filled. Considering the ecological, social, aesthetic and commercial value of our coastal areas, this trend (which is a result of individual fill projects, large and small), has had enormous impact and will continue to do so if left unchecked. Therefore, the alternative of filling from 8.1 hectares (20 acres) to 11.7 hectares (29 acres) of Quincy Bay to accommodate an expanded treatment facility cannot be recommended. To do so would represent an endorsement of a practice which has had severe impacts on the environment. The EPA, has published interim final guidelines for regulating the discharge of dredged or fill materials into navigable waters (Federal Register, Vol. 40, No. 173, Sept. 5, 1975). These guidelines state: “In evaluating whether to permit a proposed discharge of dredged or fill material into navigable waters, consideration shall be given to the need for the proposed activity, the availability of alternate sites and methods of disposal that are less damaging to the environ- In this case, the need for the expanded facility is clear. However, the proposed facility does not require direct water access, and other alternatives are available. Among the objectives to be considered in making a permit determination are: “(1) Avoid discharge activities that significantly disrupt the chemical, physical, and biological integrity of the aquatic ecosystem... (2) Avoid discharge activities that significantly disrupt the food chain... (3) Avoid discharge activities that inhibit the movement of fauna, especially their movement into and out of feeding, spawning, breeding, and nursery areas: (7) Minimize discharge activities that will degrade aesthetic, recreational, and economic values.” Another consideration outlined by the Regulations is: “Significant disruption of fish spawning and nursery areas should be avoided.” 3—42 ------- LAND CREATION IN BOSTON HARBOR 1800/1960 SOURCE: MAPC 1976 SOURCE: MAPC 1972 FIGURE 3.2-4 HISTORIC FILLING TRENDS IN BOSTON HARBOR ------- Filling a large area of Quincy Bay would eertainly disrupt the integrity of the aquatic ecosystem by the complete elimination of the ecosystem within the area in question. It has been reported (Chessmore, 1971) that Quincy Bay is used by the winter flounder (Pseudopleuronectes americanus) and several species of forage fish for spawning. Limited spawning of cod (Gadus inorhua) has also been reported. Winter flounder is an important game species in Massachusetts, providing recreation at a time of the year when few species are otherwise available. Forage species are an extremely important link in the estuarine food chain, supporting the larger game species. Filling in Quincy Bay could therefore contribute incrementally to a significant impact on the aquatic food chain, as well as on feeding, spawning, and nursery areas for the indigenous fauna. Filling will also degrade aesthetic and recreational values within the Bay. However, this must be compared to possible trade—off S at alternate locations. The previously cited regulations also state that “disposal sites for dredged or fill materials shall not be designated in areas of concentrated shellfish production.” The area of proposed filling is located in an area which is closed to shelifishing due to gross contamination. This contamination is caused by frequent overflows of raw sewage from the immediately adjacent Nut Island treatment plant. A study of the marine resources in Quincy Bay (Jerome, et al, 1966) indicates that Quincy Bay in general possesses very active and productive shellfish flats. The contaminated flats in which filling is proposed are not productive by comparison. 1.4 clams were found per cubic foot of substrate in the proposed fill area compared to 7.8 clams per cubic foot for the Bay as a whole. It is possible that existing contamination may have affected the productivity of the shellfish beds adjacent to the treatment plant. Expected water quality improvements could therefore improve shellfish productivity as well as open the area to harvest. Overall, the value of this and other parts of the Harbor to the aquatic ecosystem and to present and future generations is considered to outweigh the advantages of locating the facilities for secondary expansion at the Nut Island site. The preservation of Boston Harbor for future generations is dependent on present attempts to minimize filling activities. — Expansion of the existing Nut Island plant to a primary treatment plant capable of providing primary j, 4reatment oI the increased quantity of wastewater anticipated 1Y tI1 flhin the year 2050 would require only about 1.2 hectares (3 acres) of fill. While the magnitude of this amount of fill is far less than that necessary for secondary expansion, 3—44 ------- adverse environmental effects will still occur. However, for preliminary screening purposes, this alternative was not eliminated. Peddocks Island . This island was eliminated from con- sideration due to the wildlife value of the West Head, the intent to preserve the area as a wildlife refuge, and the need to construct an access bridge or causeway. Spectacle Island . This alternative was eliminated in this preliminary screening due to the difficulty and adverse environmental impacts associated with the removal of exist- ing refuse, the wildlife value of the island, and the need for an access bridge or causeway. To summarize, the following sites are still under con- sideration and will be evaluated in further detail in the intermediate screening stage of this study: Broad Meadows Deer Island Long Island Nut Island (expansion of primary treatment facilities only) Squantum Point B. Effluent Discharge Evaluation . The proposed expansion and upgrading of the MDC coastal area treatment facilities will alter the characteristics of the effluents currently discharged into Boston Harbor. Accordingly, the associated water quality impacts will change. This section projects effluent characteristics for the year 2000 facilities and evaluates their potential water quality effects. Secondary treatment facilities are required to effect an 85 percent reduction of BOD 5 and suspended solids, as required by Pub. L. 92-500 and this analysis assumes that the MDC facilities will achieve these removal rates. Present influent data and the EMMA Study Design Year wastewater char- acteristics were utilized as a baseline to project the char- acteristics of primary and secondary effuents. Table 3.2—5 presents a comparison of the present primary effluent and the projected secondary effluent for these parameters. Secondary treatment will significantly decrease the mass of BOD 5 and suspended solids discharged into Harbor waters, and as such is a positive impact upon Harbor water quality. Disinfection at the MDC primary plants, via chlorination, presently achieves a 99.9 percent reduction in coliform bac- teria. It is anticipated that chlorination of the secondary effluent will also result in a 99.9 percent coliforxn kill. However, chlorination of the secondary effluent should be more effective against human pathogens because of decreased 3—45 ------- suspended solids concentrations (viruses adsorbed on suspended solids during disinfection are more resistant to inactivation than those in free solution). Comparing present and future 99.9 percent coliform kills, the real value of the latter is greater. In this respect, secondary effluent will have a positive public health related impact upon Harbor water qual- i ty. Toxic pollutants (as defined by 43 FR 4108, January 31, 1970), in particular metals, are found in the influent and effluent of the MDC treatment facilities. Tables 3.2-6 and 3.2—7 present influent and effluent metals concentrations for the Nut Island and Deer Island plants. The data covers a 22 month period and is summarized from compliance monitor- ing reports submitted to EPA Region I by the MDC. A statistical analysis was performed on the data because of its great variability. For the influent concentration of each metal, the arithmetic mean and standard deviation were calculated, and a 95 percent confidence interval (±2 standard deviations) established. The data set was then examined for values falling outside the established range. Those that did were considered abnormal and discarded. The mean and stan- dard deviation were recomputed from the new data set, a new confidence interval established, and the data reexamined. When all values used to compute a mean fell into the corres- ponding confidence interval, that mean was considered repre- sentative of the expected influent metal concentration. These influent characteristics were used in the computation of their corresponding average influent concentrations. Table 3.2-8 summarizes these means, along with corresponding percent in- tervals. Removal efficiencies vary between facilities and among metals at each facility. A comparison of reported MDC metal removals and those reported for treatment plants across the country (Table 3.2-9) shows the MDC facilities to be typical. All treatmentp ants exhibit marked variations in metal rernov- als. Nevertheless, considerable amounts of toxic metals are being discharged from the MDC treatment plants. These data support the conclusion of the New England Aquarium (Gilbert, et al., 1972) that these facilities are a major source of metals to the Outer Harbor. Projections of metals content in the secondary effluent were made as follows. Primary removals were assumed to re- main constant, unless they were negative. In this event, the average mean primary removals reported in Table 3.2—9 were applied. Average reported secondary removals (Table 3.2-9) were added to the appropriate primary removals to obtain an estimated metals removal rate for secondary treatment. Asswfled toxic metal removals are summarized in Table 3.2-10. 3—46 ------- TABLE 3.2-s a COI ARISON OF PRIMARY NDC WASTEWATER AND SECONDARY EFFLUENTS TREATMENT PLANTS TOTAL -J 47.9 111.4 5.7x10 4 (1. 29x10 6 ) 50.1 68.6 8.74xl0 4 (1. 93x10 5 ) 1.45xl0 5 (3. 20xl0 5 ) 85 38.9 l.92x10 (4.23x10 ) 85 23 3.49x10 4 (7. 70xl0 4 ) 5.41x10 4 (1.19x10 5 ) 23.1 106.4 5.48x10 4 (1. 21x10 5 ) 30.8 100.6 1.28x10 5 (2.82x10 5 ) 85 27.8 1.37x10 4 (3.02xl0 4 ) 85 24.9 3.77x10 4 (8. 3 1x10 4 (—)4 . 37x 10 4 (9. 64 l04) 75.0% (—) 9. 03x1O (1. 99x10 5 ) 70.5% (—)l . 34x10 5 (2.95x1 0 5 ) 72.0% 1. See Tables 2.5—1 and 2.5—2 2. Design Conditions Year 2000 Metcalf 6 Eddy, 1975, j,k Primary’ SUSPENDED SOLIDS Southern Service Area Facility Northern Service Area Facility Primary 1 Removal Conc. Mass Percent mR/l KG/D ( lbs/d) Removal Conc. Mass Percent mg/l KG/D ( lbs/d) Change KC/D j1bs/d) Removal Conc. Mass Percent mg/i KC/D (lbsld) Removal Conc. Mass Percent mg/i KG/D ( lbs/d) Change KC/D (lbs/d) SOD 5 Secondary 2 (—)3.82x10 4 (8.42xl0 4 ) 66.6% (—)5.25x10 4 (1. 16xl0 5 ) 60.0% (—) 9. 07x1fl 4 (2.0x 10 5 ) 62.6% 1.82xl0 5 (4. 01x10 5 ) 5.14x10 4 (l.13xl0 5 ) ------- TABLE 3.2-6 NUT ISLAND TOXIC METALS CONCENTRATIONS Cadmium Chromium Copper Lead Mercury Nickel L) Zinc 12—75 1—76 2—76 3—76 4—76 5—76 6—76 7—76 8—76 9-76 10—76 11—7 12—76 1—77 2—77 3—77 4—77 5—77 6—77 7—77 8—7? 9-7? Avg. .005 .005 .0098 .0098 .016 .013 .01 .005 .10* .005 .01 .01 .01 .005 .06 .04 .18* .12 .005 .004 .02 .01 .036 .032 .01 .01 .008 .008 .01 .01 .008 .002 .004 .004 .032 .008 .014 .014 .052 .022 .020 .014 .012 .012 .0176 .0119 .03 .01 .018 .05 .0099 .045 .04 .04 .047 .08 .065 .06 —— —— .06 .04 .14* .10 .15* .05 .10 .09 .13* .10 .08 .05 .024 .012 .048 .024 .032 .044 .032 .040 .008 .048 .008 .048 .064 .050 .056 .035 .08 .08 .051 .041 .4 .07 .37 .08 .79 .07 .79 .16 .43 .23 .92 .16 .74 .08 .1O .10 ..OO .16 2.0* .7 .76 .56 .51 .46 .36 .50 .62 .82 .42 .50 .22 .27 .62 .34 .108 .59 .07( .10 .55 .11 .93 .88 .75 .40 .618 .292 .08 .08 .06 .04 .01 .01 .125 .10 .127 .20 .152 .15 .20 .10 .10 .05 .11 .10 .53* .15 .08 .04 .04 .03 .07 .01 .04 .02 .06 .04 .03 .02 .20 .16 .08 .04 .20 .16 .62* .16 .40 .12 .10 .06 .104 .074 .0002 .0001 .0001 .0005 .0003 .0006 .001 .0003 .001 .001 .000 .002 .ooi: .OO0 .000’ .000: .0001 .0001 .0005 .0001 .0001 .0002 .002 .001 .0004 .009 .0007 .0001 .003 .0006 .002 .001 .0174 .0028 .00 .00 .002 .0002 .006 .002 .0072 .0030 .0054 .0028 .00199 .00120 .76 .04 .88 .04 .85 .098 .64 .04 .86 .04 .44 .09 .23 .01 ..05 .42 .15 .58 1.25 .07 .96 .80 .90* 1.50 .93 1.14 .86 .72 .26 .12 .32 .15 .020 2.58 1.08 .0135 2.58 .04 .54 .04 .04 .68 .90 .55 .889 .291. .20 .73 .26 .44 .027* .54 .025 .29 .37( .76 .23k .92 .50 .48 .46 .37 .30 .29 .27 .13 .34 .18 .50 .32 .32 .20 .50 .42 .35 .22 .43 .29 .38 .30 .51 .46 .50 .46 .44 .42 .44 .28 .68 .46 .431 .376 All values mgfl Chromium values are total Chromium Top Entry: Plant Influent Bottom Entry: Plant Effluent Values from analysis of sample cooiposited daily over month. Daily portion taken from daily 24 hour composite then added to monthly composite. Avg — Arithmetic Avg. of Monthly Values *Data pair not used in calculation of average. See Text Discussion ------- 1.2—75 1—76 2—76 3—76 4—76 5—76 6—76 7—76 8—76 9—76 10—76 11—76 12—76 1—77 2—77 3—77 4—77 5—77 6—77 7—77 8—77 9—77 Avg. .020 .020 .02 .02 .02 .02 .002 .002 .006 .004 .16* .08 .04 .02 .008 .008 .02 .02 .06 .06 .024 .020 .02 .02 .03 .03 .02 .02 .012 .012 .02 .02 .02 .02 .10* .10 .016 .010 .018 .018 .025 .021 .021 .019 .08 .03 .14 .10 .10 .08 .01* .04 .08 .10 .12 .08 .10 .06 .14 .10 .25 .25 .12 .06 .20 .16 .10 .08 .13 .13 .10 .04 .16 .24 .15 .15 .15 .10 .15 .12 .17 .02 .20 .11 .30 .15 .147 .108 .30 .24 .10 .09 .21 .14 .04 .04 .30 .24 .04 .04 .21 .20 .08 .06 .23 .16 .06 .06 •44* .38 .40* .14 .50* .45 .25 .16 .20 .40 .20 .20 .28 .20 .14 .10 .20 .36 .70* 1.0 .28 .55 .12 .14 .06* .50 .25 .16 • .25 .44 .17 .17 .25 .44 .23 .23 .18 .39 .14 .14 .25 .44 .20 .23 .27 .36 .15 .0011 .0010 .30 .42 .11 .10 .20 .36 .31 .15 .24 .59 .10 .07 .28 .50 .3 .2 .246 .357 .157 .131 .0014 .0013 .ooi: .00l .001 .0009 .0013 .0013 .014* .0013 .0010 .0001 .0020* .0013 .0020* .0020* .001: .ooj. .001 .001 .0013 .0012 .0013 .0011 .0012 .0010 .0013 .0011 .0012 .0011 .0012 .0010 .13 .22 .0013 .0010 .0014 .0011 .0013 .0012 .0012 .0010 .00124 .0011 .08 .04 .06 .02 .08 .06 .04 .05 .05 .05 .10 .10 .16 .16 .12 .16 .06 .04 .20 .20 .12 .14 .16 .16 .20 .20 .08 .16 .14 .10 .10 .10 .92 .60 .10 .08 .08 .06 .15 .15 .213 .5 .115 .131 1.20 .44 .76 .34 .0 .54 .47 .37 .68 .43 .58 .40 .84 .61 .85 .73 .88 .52 1.16 .66 1.17 .45 .94 .72 .79 .47 .55 .38 .56 .61 .46 .31 .31 .20 .68 .38 .62 .66 .9 .42 .777 .488 Values from analysis of sample coniposited daily over month. Daily portion taken from daily 24 hour composite then added to monthly composite. All values mg/l Avg — Arithmetic Avg. of Monthly Values Chromium values are total Chromium Top Entry: Plant Influent *Data pair not used in calculation of average. Bottom Entry: Plant Effluent See Text Discussion TABLE 3.2-7 DEER ISLAND TOXIC METALS CONCENTRATIONS Cadmium Chromium Copper Lead Mercury Nickel Zinc ------- Future influent metals concentrations are a function of a number of variables, including the industrial pretreatment program and non-industrial sources to the MDC system. The pretreatment program requried by Pub. L. 92—500 will limit the input of substances which are not susceptible to treat- ment in the MDC facilities. In addition, limitations will be placed on pollutants which will, potentially, interfere with treatment. Current and future metals input to the MDC system from industrial sources is unknown and, therefore, any change due to industrial pretreatment cannot be quantified. In addition, significant quantities of metals are known to come from non—industrial sources. Table 3.2—11 summarizes recent studies which have quantified residential metals con- tributions. To evaluate the unknown inf].uent characteristics, five metals removal scenarios were developed. Scenarios A, B, C, D, and E assume, respectively, 0, 10, 25, 50 and 75 percent decrease in the present influent metals concentrations due to an industrial pretreatment program. Assumed removal rates were then applied to the metal levels in the influent. Tables 3.2-12 and 3.2-13 summarize these computations. In addition, dilution requirements for each projected effluent concentra- tion were calculated. Dilution requirements are based upon the recommended water quality criteria presented in Table 3.2-14. Specif i— cally, the minimum risk criteria was utilized to compute the required effluent dilutions. Minimum risk criteria are defined as the concentrations which present minimal risk of deleterious effects upon the marine environment (Committee on Water Quality Criteria, 1972). The intent in applying these criteria is “...to protect essential and significant life in water, as well as direct users of water...to pro- tect life that is dependent on life in water for its existence, or that may consume intentionally or unintentionally any edible portion of such life.” (Quality Criteria for Water, 1976). Given the inherent variability of influent characteristics and metals removal in treatment facilities, achievement of a minimum dilution ratio provides a necessary margin of safety for the harbor environment. The actual percent reduction in influent concentrations will probably fall between scenarios C and D (a 25 to 50 per- cent reduction). Based upon this analysis, effluent dilution in the 50:1 to 100:1 range, through utilization of an effec- tively designed diffuser(s), is viewed as providing a reason able margin of safety for the worst case metal concentration 3—50 ------- TABLE 3.2—8 MDC TREATMENT FACILITIES TOXIC METALS REMOVALS* NUT ISLAND DEER ISLAND Influent Effluent Removal Influent Effluent Removal Metal (mg/i) (mg/i) (Percent) (mg/l) (mg/i) (Percent) Cadmium 0.0176 0.0119 32.4 0.021 0.019 9.5 thromium 0.051 0.041 19.6 0.147 0.108 26.5 Copper 0.618 0.292 52.8 0.246 0.357 —45.1 Lead 0.104 0.074 28.8 0.157 0.131 16.6 Mercury 0.00199 0.00120 39.7 0.00124 0.0011 11.3 NIckel 0.889 0.291 67.3 0.115 0.131 43.9 Zi 0.431 0.376 12.8 0.777 0.488 37.2 *Influent and Effluent values derived from MDC Compliance Monitoring Reports to EPA Region I for period 12/75 through 9/77. See Text for discussion. 3—51 ------- TABLE 3.2—9 1 SUMMARY OF TOXIC METALS REMOVAL (percent) PRIMARY PLANTS 2 ACTIVATED SLUDGE PLANTS 3 Metal Mean STD. Dev. Max/Mm No. of Plants Mean STD Dev. Max/Mm No. of Plants Cadmium 8 17 76/0 31 17 27 88/0 44 Chromium 26 26 80/0 36 46 34 98/0 54 Copper 26 24 77/0 44 57 24 95/0 63 Lead 24 26 88/0 34 39 32 95/0 49 Mercury 27 29 75/0 21 39 32 99/0 34 Nickel 6 18 92/0 28 20 21 80/0 44 Zinc 31 22 88/0 38 58 25 99/0 58 1 Source: U.S. Environmental Protection Agency, 1977 2 Conventional primary treatment and primary treatment with pre—aeration 3 Primary sedimentation and activated sludge, including extended, step, high rate and Krauss modificat ions ------- TABLE 3.2—10 DESIGN YEAR ASSUMED TOXIC METALS PERCENT REMOVAL COASTAL AREA TREATMENT FACILITIES NUT ISLAND DEER ISLAND Metal Prinzary 1 Secondary 2 Total Primary’ Secondary 2 Total Cadmium 32.4 9 41.4 9.5 9 18.5 Chr nium 19.6 20 39.6 26.5 20 46.5 Copper 52.8 31 83.8 26.0 31 57.0 Lead 28.8 15 43.8 16.0 15 31.6 Mercury 39.7 12 51.7 11.3 12 23.3 Nickel 67.3 14 81.3 6 14 20.0 Zinc 12.8 27 39.8 37.2 27 64.2 1 Calculated values, see Table 3.2—8, unless percent removal negative. When removal negative, literature value assumed see Table 3.2-9. 2 Secondary removal assumed to be difference between activated sludge and primary values reported in Table 3.2—9. 3—53 ------- TABLE 3.2—il RESIDENTIAL METALS CONTRIBUTIONS New York City ,N.Y. Pittsburgh, 2 Pa. Muncie, I11 Metal Cadmium 49 63 Chromium 28 23 2.7 Copper 47 96 36 Lead 63 10 Mercury Nickel 25 19 13.3 Zinc 42 32 17 1)Klein, L.A. et al., 1974 New York entries represent percentage of total influent mass at NYC treatment plants during period January 1972 to September 1973. 2)Davis, J.A. III, and J. Jacknow, 1975 Pittsburgh entries are percentage of total influent mass to Allegheny County Sanitary Authority treatment facility for period January to June 1973. Muncie entries are percentage of total Influent mass to Muncie treatment facility for 1973, 3—54 ------- TABLE 3.2—12 DILUTION REQUIREMENTS SOUTHERN MDC SERVICE AREA TREATMENT FACILITY DISCHARGE INFLUENT CONCENTRATIONS, mg/i EFFLUENT CONCENTRATIONS, mg/i DILUTION REQUIRED 2 F ___________________________ METAL A B C D E A B C D E A B C 0 E Cadmium 0.018 0.016 0.013 0.0088 0.0044 0.011 0.0094 0.0076 0.0052 0.0026 52.7 46.8 38.1 25.8 12.9 Chromium 0.051 0.046 0.038 0.026 0.013 0.031 0.028 0.023 0.016 0.0078 0.62 0.56 0.46 0.31 0.16 Copper 0.618 0.556 0.464 0.309 0.155 0.100 0.091 0.075 0.050 0,025 10.0 9.0 7.5 5.0 2.5 Lead 0.104 0.094 0.078 0.052 0.026 0.058 0.053 0.044 0.029 0.015 5.8 5.2 4.3 2.9 1.5 Mercury 0.00198 0.00178 0.00149 0.00099 0.0005 0.00095 0.00086 0.00072 0.00048 0.00024 19.1 17.2 14.4 9.6 4.8 Nickel 0.889 0.800 0.667 0.445 0.272 0.166 0.150 0.125 0.083 0.042 83.1 74.8 62.4 41.6 21.0 Zinc 0.431 0.388 0.323 0.216 0.108 0.259 0.234 0.194 0.130 0.065 13.0 11.7 9.7 6.5 3.3 1. Scenario A: no change due to pretreatment 2. Ratio: Harbor Water : Wastewater B: 10% decrease in metals concentration C: 25% decrease in metals concentration D: 50% decrease in metals concentration E: 75% decrease in metals concentration ------- TABLE 3.2—13 DILUTION REQUIREMENTS NORTHERN MDC SERVICE AREA TREATMENT FACILITY DISCHARGE INFLUENT CONCENTRATIONS mg/i EFFLUENT CCE CENTRATIONS, mg/i DILUTION REQUIRED 2 METAL A 1 B C D E A B C D E A B C D E Cadmium 0.02. 0.019 0.016 0.011 0.005 0.0171 0.0155 0.0130 0.0089 0.0041 85.6 77.4 65.2 44.8 20.4 Chromium 0.147 0.132 0.110 0.074 0.037 0.079 0.071 0.059 0.040 0.020 1.57 1.41 1.18 0.8 0.4 Copper 0.246 0.221 0.185 0.123 0.062 0.106 0.095 0.080 0.053 0.027 10.6 9.5 8.0 5.3 2.7 Lead 0.157 0.141 0.118 0.079 0.039 0.107 0.096 0.081 0.054 0.027 10.7 9.6 8.1 5.4 2.7 Mercury 0.00124 0.00112 0.0009 0.0006 0.0003 0.00095 0.00092 0.00069 0.00046 0.00023 19.0 18.4 13.8 9.2 4.6 Nickel 0.115 0.104 0.086 0.058 0.029 0.092 0.083 0.059 0.046 0.023 46.0 42.0 34.4 23.2 11.6 Zinc 0.777 0.699 0.583 0.389 0.194 0.278 0.250 0.209 0.139 0.069 13.9 12.5 10.4 7.0 3.5 1. Scenario A: no change due to pretreatment 2. Ratio: Harbor Water : Wastewater B: 10% decrease in metals concentration C: 25% decrease in metals concentration D: 50% decrease in metals concentration E: 75% decrease in metals concentration ------- TABLE 3.2—14 WATER QUALITY CRITERIA* TOXIC 1ETALS Metal Minimal Risk Hazard Concentration, mg/i Concentration, mg/i Cadmium 0.0002 0.001 Chromium 0.050 0.10 Copper 0.010 0.050 Lead 0.010 0.050 Mercury 0.00005 0.00001 Nickel 0.002 0.010 Zinc 0.02 0.10 *SOjJRCES: Committeeon Water Quality Criteria, 1972 Quality Criteria for Water, 1976 3—57 ------- in scenario C. However, it must be recognized that, because removals are assumed, significant error may be present in this analysis. Actual percent removal for these toxic pollu- tants should be determined through a pilot plant study prior to facilities planning and incorporated into the diffuser design. The above summarized analysis quantifies dilution ratios necessary to safeguard the Harbor environment, given the existing data base and assumed reductions in metal con- centrations due to industrial pretreatment. In sununary, implementation of secondary treatment at the MDC coastal area treatment facilities will effect significant reductions in BOD5 and suspended mass discharge to the Harbor. In addition, disinfection should be more effective against human pathogens. To minimize the effects of toxic metals in the effluent, dilutions in the range of 50:1 to 100:1 are required. Wastewater Discharge Locations Since analysis of projected secondary effluent quality indicates a 50:]. to 100:1 dilution is required to minimize potential toxic metals impacts upon Harbor water quality, an assessment of potential discharge locations was performed to determine the range of dilutions achievable. The previous site evaluation process reduced the poten- tial locations for the southern service area facility to three: Nut Island, Broad Meadows and Squantum. Deer Island and Long Island were the remaining locations for the northern service area plant. In addition, treatment of all flows at Deer Island is a viable option. Based upon these remaining eites,four locations were chosen as potential discharge points. Discharge locations investigated were: A. President Roads off Castle Island for discharge from Squantum Point facility - approximate water depth 10.7 m (35 ft); B. Nantasket Roads between Rainsford and Peddocks Islands for discharge from a Nut Island, Squan- turn Point, or Broad Meadows facility - approxi- mate water depth 13.7 m (45 ft); C. President Roads off Deer Island for discharge from a facility on Deer Island or Long Island - approximate water depth 18.3-21.3 in (60-70 ft); D. Massachusetts Bay northeast off Deer Island for discharge from a facility on Deer Island or Long Island - approximate water depth 18.8- 21.3 in (60—70 ft). Figure 3.2-5 indicates these locations. 3—58 ------- LEGEND POTENTIAL DISCHARGE ‘OINT CURRET METER LOCATIONS D.er Islanâ •—NOAA 139 Low.II island Limit S c S.- otter ’ Harbor Light G. orges island I Crop. Island - —4 KILOMETERS 0 0.5 FIGURE 3.2-5 COASTAL POTENTIAL DISCHARGE LOCATIONS AREA TREATMENT FACILITIES . Ouincy Bay ENVIRONMENTAL ASSESSMENTCOUNC IL.INC. ------- Prior to discharge analysis an investigation of the renewal rates for Boston Harbor was undertaken. It is gen- erally accepted that renewal time for the Harbor is two tidal cycles. However, this is based on an average volume trans- port of 9062 m 3 /s (3.2xlOS cfs) into the Harbor during each flood tide and the assumption that inf lowing water contains no water which flowed out of the Harbor during the previous ebb tide. Water replacement is better computed utilizing net inflow. Accordingly, by volume continuity the net out- flow, Qout , must equal the sum of land drainage into the Har- bor, R, and the net sea water inflow, Qjn. Net circulation may be used as a measure of the effective Harbor renewal. The National Oceanic and Atmospheric Administration (NOAA) current charts (1974) were used to determine the aver- age flood current speeds and the net current speed and direc- tion (net implies averaged over one tidal cycle). NOA.A sta- tions 100, 101, 102, 103, 104— 105, and 106, shown in Figure 3.2-6, were used in this analysis. Average flood current speeds and net speeds are presented in Table 3.2-15. The net currents presented in Table 3.2-15 indicate the primary locations fornet inflow are through the southern half of the entrance to Presidents Roads and through the lower half of the entrance to Nantasket Roads. The net inflowing current speeds at these locations are approximately 15 per- cent of that for the flood currents and the net flows are esti- mated tQ be 7.5 percent of the average flood tide inflow or 679.7 mi/s (24,000 cfs). With a fresh water inflow on the order of 28.32 m 3 /s (1000 cfs) the time required to renew the Harbor water would be approximately 7 days. Although specula- tive, this estimate is more reasonable than the often cited one day renewal time. Effective dilution, therefore, takes on enhanced importance due to the long Harbor residence time. Calculation of the effluent dilution as the rising buoy- ant plume from each outfall diffuser port entrains the receiv- ing water was determined using the mathematical model devel- oped by Fan and Brooks (1967). The minimum dilution ratio along the centerline of the plume, the width of the plume, its trajectory, and the effect of vertical stratifications in the receiving waters are predicted. Minimum dilutions occur during slack water when current speeds approach zero. During this period the buoyant plume from each diffuser port will accumulate in a thickening sur- face layer. Sewage being discharged entrains older, previously discharged effluent rather than clean sea water, and high con- centrations of sewage will be found. Achievement of a minimum dilution in the required range specified a discharge location as being environmentally acceptable. 3—60 ------- LEGEND • CURRENT METER LOCATIONS Island Deer Flats Deer Island / / , ,- ——————————— ,___ ‘ Harbor Limit PRESIDENT ROADS • NO A’ ioó \____——-- NOAA 101 NOAA 102 • Gallops Lowefl - Is bn ,nd Island NOAA 103S. Island OA Georges NOAA 104” Rainsford ’ 105 -::: Island • / ‘Point NOAA 106 /” Moon Quincy Bay Island Grape Island 6 1 0 1 1 =-I K 110 METER S 0.5 0 0.5 -I FIGURE 3.2-6 BOSTON HARBOR CURRENT METERS ENVIRONMENTAL ASSESSMENT COUNCIL. INC. ------- TABLE 3.2—15 AVERAGE FLOOD CURRENT SPEEDS AND NET* CURRENT SPEED AND DIRECTION BOSTON HARBOR (Note: a negative current is into the currant is out) *Net implies average over one tidal cycle. SOURCE: NOAA, 1974 harbor; a positive Station Meter Depth Flood Current Net Current rn/sec (knots) in (ft) rn/sec (knots) 100 3.05 10.0 —.47 —0.91 0.04 0.08 100 10.67 35.0 —.47 —0.91 0.00 0.00 101 3.05 10.0 —.52 —1.00 —0.06 —0.12 101 10.67 35.0 —.56 —1.08 —0.12 —0.23 102 3.05 10.0 —.58 —1.13 —0.07 —0.14 102 10.67 35.0 —.50 —0.97 —0.08 —0.16 5 3.05 10.0 —.33 —0.64 —0.05 —0.10 103 3.05 10.0 —.43 —0.83 0.02 0.04 103 10.67 35.0 —.48 —0.93 —0.01 —0.02 104 3.05 10.0 —.47 —0.91 —0.01 —0.02 105 3.05 10.0 —.48 —0.93 0.04 0.08 105 10.67 35.0 —.39 —0.76 —0.05 —0.10 106 3.05 10.0 —.52 —1.00 0.01 0.02 106 10.67 35.0 —.47 —0.91 —0.05 —0.10 3—62 ------- The minimum dilution along the centerline of the plume may be shown to depend on the ratio of water depth to port diameter and on the densimetric Froude number F. Up [ (As/s) gD] where: = port exit velocity, rn/s g = acceleration of gravity, rn/s 2 As/s = receiving water specific gravity— effluent specific gravity receiving water specific gravity D = diffuser port diameter, m Although the mathematical model assumes that the effluent is discharged into water of infinite depth, Fan and Brooks (1966) have shown that the predicted dilutions do not differ signi- ficantly from experimental results obtained at the water surface. Preliminary diffuser design specifications for the MDC treatment plants were developed and are summarized in Table 3.2-16. Two values of As/s were chosen: 0.014 and 0.022. The former value is lower than would be expected for the dis- charge of sewage effluent with a specific gravity of 1.0 into sea water having a 28-30 percent salinity, but was chosen to account for the effects of salt water intrusion into the sewer system. It is assumed that port exit velocity remains constant and outfall sizes are varied to accomodate flow changes asso- ciated with the various site options. Table 3.2—17 summarizes predicted dilutions for each dif- fuser. It is interesting to compare the possible trade-off of increased water depth against increased length of diffuser. The 304.8 in (1000 ft) diffuser would have a minimum center- line dilution of 22:1 in 9.1 in (30 ft) of water for average flow. If the water depth were 12.1 m (40 ft) this dilution would then be increased to 32:1, which is exactly what could be achieved by the 609.6 in (2000 ft) diffuser in 9.1 in (30 ft) of water. There is only a slight difference in the calculated dilutions due to a 50 percent variation in As/s. Therefore, for the case of no stratification in the receiving waters, the performance of the diffuser is only slightly influenced by the density parameter, As/s. 3—63 ------- TABLE 3.2—16 PRELIMINARY DESIGN SPECIFICATIONS MDC TREAI}4ENT PLANT OUTFALLS Angle between velocity vector of effluent at discharge port and the horizontal, 4 = 00 AS/S 4.014 or 0.022 Diffuser I Diffuser II Length 304.8 m (1000 ft) 609.6 in (2000 ft) Number of Ports 100 200 Port Diameter 30.48 cm (1 ft) 21.55 cm (0.707 ft) Jet Velocity, Avg. Flow 78 cm/sec (2.56 ft/sec) 78 cm/sec (2.56 ft/sec) Peak Flow 186.2 cm/sec (6.11 ft/sec) 186.2 cm/sec (6.11 ft/sec) 3—64 ------- TABLE 3.2—17 COMPARISON OF DIFFUSER PERFORMANCE NOTE: E s/s 0.022 Dilution E (Peak) DIFFUSER I Water Depth Dilution for Dilution for Dilution QE (avg.) QE(Peak) Q (avg.) DIFFUSER II in (ft) 6.1 (20) 13:1 12:1 19:1 16:1 9.1 (30) 22:1 17:1. 32:1 25:1 12.2 (40) 32:1 24:1 49:1 35:1 15.2 (50) 44:1 31:1 65:1 46:1 18.3 (60) 57:1 39:1 87:1 58:1 QE = effluent flow ------- There is some evidence, however, that significant verti- cal stratification can occur in the region of an outfall at Point A*. The New England Aquarium (1973) made observations of salinity and temperature at the surface and at the bottom over a tidal cycle at the station labeled NEA 22 on Figure 3.2-5 The results of their observations show a salinity difference of 2 percent and a temperature difference of 3°C (5.4°F) can exist in this region of Boston Harbor. This stratification in salinity and temperature was modelled by assuming the density of the receiving waters decreased lin- early with height above the bottom from the value appropriate to sea water with salinity of 30 percent and temperature of 15°c (59°F) to the value for sea water with salinity 28 per- cent and temperature of 18°C (64.4°F). The effect of this stratification on the diffuser performance are shown in Fig- ures 3.2—7 and 3.2-8 and show that with either the 304.8 or 609.6 m (1000 or 2000 ft) diffuser and As/s = 0.014 the plume will not reach the surface. (It should be emphasized that the assumed linear density variation over the 9.]. in (30 ft) water depth would not be as effective in trapping the plume below the surface as other distributions may be. For example, a three layer model with uniformly high density water in the near bottom layer, a thin transition zone, and uniformly low density in the surface layer could be more effective in limit- ing the height of rise of the plumes. The result that a linear density variation over the entire water depth would trap effluent below the surface becomes very significant and indicates surveys to determine the potential for density stratification in the outfall area should be made before final design of the diffuser is established. Also apparent from Figures 3.2-7 and 3.2—B is that the density ratio as/s is a more important parameter when the receiving waters are stratified than in the case of no stratification. With As/s 0.022 the discharge from both 3048 and 609.6 in (1000 and 2000 ft) diffusers will reach the surface). The disadvantages of having the sewage effluent trapped below the surface due to the stratification in the receiving waters include a reduction in the effective height of rise of the effluent which decreases the sewage dilution, and a net upstream movement into the Inner Harbor as a result of the estuarine—type circulation which most likely exists in Boston Harbor, particularly in the vicinity of the mouth of the Inner Harbor. (In most estuaries a two layer net circulation, with a flow of high salinity water into the estuary in the lower layer and an outflow of lower salinity water in the upper layer is expected). Assuming that this is the case for *See Figure 3.2-4 for locations of alternative discharge points. 3—66 ------- 8 30 STRATIFIED AMBIENT 304.B M (1000 FT) DIFFUSER 6 SI S =.0 14 I I ’ 0 I I. 0 I- 0 U I UI UI II . 0 I 0 UI I 4 8 12 DILUTION RATIO 1S 4 2 0 8 6 4 2 0 I- U i U I I’ I- I I U I U. 20 10 0 30 20 10 0 $ DILUTION RATIO FIGURE 3.2-7 DISCHARGE POINT A DILUTION RATIOS ------- 8 STRATIFIED AMBIENT 609.8 N (2000 FT) DIFFUSER e 4 AVG. 2 L sis= 0.014 FLOW 0 20 10 0 4 8 12 16 20 24 DILUTION RATIO I- ‘U ‘U U. ‘U I I. / / / I / I / / I / 8 6 4 2 0 I / I / I / AVG. 30 20 10 0 c sis= 0.022 4 8 12 20 24 DILUTION RATIO DISCHARGE POINT A DILUTION RATIOS FIGURE 3.2-8 ------- the Inner Harbor implies that a subsurface sewage field, trapped by density stratifications, would have a net move- ment into the Inner Harbor. Current information (NOAA, 1974) was used to estimate the distance which a sewage field initially over a Point A outfall diffuser at high water slack would travel during the following ebb cycle of the tide. It is estimated that the total distance traveled would be about 5.6 kin (3.5 mi) and the leading edge would extend only 2.4 km (1.5 ml) into Massachusetts Bay past Deer Island. On the following flood tide it is likely that a significant portion of the field would flow back into President Roads. The degree of vertical density stratification appears to be less for Nantasket Roads (Point B) than for the Inner Harborendof President Roads. Observations of salinity and temperature made during the summer of 1967 throughout Boston Harbor by the Federal Water Pollution Control Administration of the U.S. Department of the Interior (1968) tend to confirm the lack of vertical stratification in Nantasket Roads. At station H-15, shown in Figure 3.2-5 salinity and temperature were observed at 1.5 m (5 ft) and at 16.5 in (55 ft) depths on 11 separate occasions. The average salinity at the 1.5 in (5 ft) depth was 28.33 percent while the average at 16.8 in (55 ft) depth was 28.50 percent. The average top to bottom decrease in temperature was 2°C (3.6 0 F). It is unlikely that the vertical stratification conditions in Nantasket Roads would be sufficient to trap the effluent below the sur- face. The tidal currents in the vicinity of the outfall at Nantasket Roads are stronger than those found at the Inner Harbor end of President Roads. This is especially true on the ebb tide when the peak current at the outfall site in President Roads (NOAA station 212) is only 0.31 rn/s (0.6 knots) while at NOAA station 105 in Nantasket Roads the peak ebb current is 0.67 in/s (1.3 knots). This higher range of currents in the vicinity of a Nantasket Roads outfall not only increases the maximum possible dilution in the near field about the outfall, but also insures that the effluent will be carried much farther out into Massachusetts Bay on an ebb tide. Starting with the sewage field over the outfall as the ebb begins, its movement is through the entrance to Nantasket Roads and then due east for 5.4 km (3.3 mi) into Massachusetts Bay. The degree of vertical density stratification at Presi- dent Roads off Deer Island appears to be comparable to that in Nantasket Roads and it is therefore, unlikely that the effluent will be prevented from reaching the surface. 3—69 ------- The tidal current speeds in President Roads near Deer Island, NOAA station 101, are approximately the same magni— tude as in Nantasket Roads, with a peak ebb speed being 0.62 rn/s (1.2 knots). It is not possible to use the current charts to trace the extent of the sewage field from the Deer Island outfall, into Massachusetts Bay since current observations do not extend far enough out into the Bay. One set of observa- tions of a near surface drogue released at the site of the present outfall off Deer Island is reported by the Federal Water Pollution Control Administration (1969). The drogue traveled only 4.0 km (2.5 mi) in a complete ebb tide. There was, however, a 12.9 rn/s (25 knot) northwesterly wind during these observations, which undoubtedly had an effect on the drogue’s trajectory. From the current charts is would be expected that with light winds, the effluent would travel in the north channel for a distance of at least 7.4 km (4.6 mi). The possibility of the occurrence of sufficiently large vertical stratification at Point D in Massachusetts Bay to trap the discharge from the diffuser below the surface is indicated by the data of Briggs and Madsen (no date), who took temperature profiles in the Bay a few miles offshore from Boston Harbor. A distinct thermocline existed at a depth of 6.1 m (20 ft). The average specific gravity in the bottom layer of water below the thermocline was 1.02558 while the average specific gravity of the upper (warmer) layer was 1.02250. Modelling the above values with a 609.6 in (2000 ft) diffuser, total water depth of 21.3 m (70 ft) and s/s= 0.022, the discharge will be trapped within the thermocline. However, the initial dilutionn for peak flo exceed 40:1 even though the discharge does not reach the surface. Comparison of Locations Discharge at Point A for a plant at Squantum Point has a number of disadvantages. The sewage field from this out- fall would overflow the effluent from a Deer Island outfall to President Roads at Point C during the ebb tide and, con- versely, the sewage field from a Deer Island plant discharging at Point C would overflow a Squantuin Point outfall at Point A during the flood. Therefore, President Roads can be viewed as a mixing zone within Boston Harbor for these two outfalls. In addition, during a significant portion of the flood tide the receiving waters over the Squantum Point outfall will in- clude effluent from a Deer Island plant and, consequently, the dilution of the Squantum Point effluent will not be with clean sea water but rather with diluted effluent from a Deer Island treatment plant. On the ebb tide the receiving waters over the outfall will be from the Inner Harbor and again the effective dilution of the effluent will be reduced due to the poor water quality of the receiving waters. 3—70 ------- The performance of an outfall discharging to the Inner Harbor end of President Roads (Point A) in terms of initial dilution is poor due to limited water depth, the poor quality of the receiving waters, and the relatively low tidal current speeds. There are two disadvantages of locating an outfall at Point B in Nantasket Roads. The first is that on flood tides there is a distinct possibility that the effluent will invade Hingham Bay and Hull Bay through the passage between Nut Island and Peddocks Island. The second disadvantage of locat- ing an outfall in Nantasket Roads and one off Deer Island in President Roads is the creation of two, rather than one, mixing zones within which water quality would be degraded. By separ- ating the two outfalls greater initial dilutions are achieved at each site, but at the same time contaminants are introduced into two distinct regions of the Harbor. It may prove preferable to have no discharge into the southern portion of the Harbor and use only the northern half, i.e. President Roads, as a mix- ing zone for the sewage effluent. Discharge at Point C would assure flushing of the efflu- ent out of the Harbor on the ebb tide; however, flow would travel into the Inner Harbor during flood tide. Satisfactory dilutions can be achieved at this point. Although the effluent will be trapped below the thermo- dine, discharge at Point D would eliminate a discharge to Boston Harbor while providing the necessary effluent dilution. In summary, Location A was found environmentally urisuit- able and was not considered further. Locations B, C, and D, were all found capable of providing the dilutions required to minimize water quality impacts upon Boston Harbor. Because the three locations have approximately equivalent environmental impacts, the selection of a discharge point(s) becomes a func- tion of the feasibility of reaching that point from a particu- lar site and the cost to do so. C. Treatment Processes . In accordance with the requirements established by the federal government under the Federal Water Pollution Control Act P nendments of 1972, (Pub. L. 92—500), the effluent from the coastal area wastewater treatment plants must meet the following criteria: The monthly average of 5-day biochemical oxygen demand (BOD) and suspended solids (SS) shall not exceed 30 mg/i or 15 percent of the inf].uent val- ues, whichever is less. The weekly average of BOD and SS shall not exceed 45 mg/l. The pH shall remain within the limits of 6.0 and 9.0. 3—71 ------- There are several treatment processes which can meet or exceed the above requirements, including; air activated sludge, pure oxygen activated sludge, rotating biological contactors, and various combinations of physical and chemical processes. Each method of treatment has its advantages and disadvantages. A proper selection can be made only after detailed wastewater treatability pilot tests and cost analyses have been made. The air activated sludge process has been selected as the treatment process for development of alternative systems in this study. This selection is only for the purposes of estimating costs and land requirements for comparison of alternative systems. One reason that the air activated sludge process has been selected is that it has been the most fre- quently used process for providing secondary treatment. In addition, air activated sludge was the process considered in the EMMA Study, and therefore, it is necessary to consider the same process in this study so that the treatment systems developed herein will be comparable to the systems developed in the EMMA Study. The various alternative treatment proces- ses should be investigated for applicability at each treatment facility during facilities planning. 3—72 ------- 3.2.3 Inland’ Satellite’ Wastewater Treatment Plants The wastewater management plan recommended by the EMMA Study includes the construction of two advanced wastewater treatment facilities in the southern MSD, in addition to a secondary treatment facility proposed at Nut Island. These two additional plants would treat wastewater to a high degree, using treatment processes beyond conventional secondary treatment. They would be located (one each) on the Charles and Neponset Rivers and would discharge their treated efflu- ent into their respective rivers. The EMMA St dy proposed an average daily design flow of about 117000 m /d (31 mgd) for the Charles River “satellite” plant and about 94600 m 3 /d (25 mgd) for the Neponset River facility. The use of these two plants would result in a reduction in the quantity of wastewater flowing to the proposed Nut Island plant in the year 2000 from 704000 m 3 /d (186 mgd) to 492000 m 3 /d (130 mgd). One advantage of a satellite system is related to treat- ment plant size. Expansion of Nut Island to accoinmodatea secondary treat- ment facility can only be accomplished by the placement of fill in Quincy Bay or the Harbor waters surrounding Nut Island. In the EMMA Study it was estimated that an upgraded primary and secondary treatment facility at Nut Island would require approximately 11.3 ha (28 ac) of fill if satellite facilities are constructed. Without satellite facilities, a total of 17 hectares (42 acres) of fill would be needed. The issue of filling Quincy Bay in order to accommodate an enlarged Nut Island treatment plant has proved to be a very controver- sial point, with citizens from the Quincy area expressing extremely vocal opposition to this plan. In this light, the satellite facilities offer a positive advantage by reducing the potential filling by 5.7 ha (14 ac). In the studies associated with this EIS, it was deter- mined that the area of fill required could be reduced by modifying the plant’s design. This modification would result in an approximately 2.4 ha (6 ac) differential in fill require- ments at Nut Island when comparing satellite versus non-satel- lite systems. More recently, the Massachusetts State Legislature enacted legislation which prohibits the expansion of Nut Island by filling the Bay. In this same time period, the studies associated with this EIS led to the conclusion that Nut Island should be eliminated from consideration because of the negative environmental effects associated with filling the bay (see Section 3.2.2). 3—73 ------- With Nut Island eliminated from consideration, the bene- fit of satellite plants reducing the size of a Harbor plant is not as significant. A second advantage of the “satellite” plan is that it would, in principle, help to maintain flow in the Charles and Neponset Rivers. Increasing water demands in the service area have been met and will be met, in part, by increased withdrawals of groundwater. Over a period of time, this action can reduce flow in the rivers draining the area. By discharging treated effluent to the river instead of to the Harbor, this effect can be mitigated. The third advantage associated with satellite facilities is a reduction in the need for interceptor relief. Many of the interceptor sewers now serving the MDC service area are old and in need of rehabilitation and/or replacement. In addition, certain sections of the interceptor system are cur- rently overloaded or are approaching their design limits. If satellite facilities are installed, the demands placed upon the sewers downstream of the facilities will be reduced, thus requiring a lesser amount of rehabilitation and relief sewers as compared to an alternative in which no satellite facility is installed. The significance of this is that interceptor relief is expensive and can result in significant environmental impacts through the installation of pipelines. It has been estimated that for the southern service area, about 58 km (36 ml) of interceptor relief sewers would be necessary if the satellite facilities are constructed and about 90 km (56 mi) would be required if satellite facilities are not constructed (see Section 3.2.1). A decentralized satellite system offers more flexibility in terms of future wastewater recycling, land application of effluent, and innovative small-scale sludge processing methods. This is a “potential” benefit which may or may not be realized. In this section of the EIS, the concept of satellite plants will be screened and evaluated (preliminary). The presentation of this evaluation process will be arranged in the order in which it occurred, beginning with the simultan- eous consideration of treatment plant sites, effluent discharge locations and treatment processes. A. Sites . While the EMMA Study endorsed the satellite con- cept in its proposed wastewater management plan, it did not make a specific recommendation for the locations of the satel— lite facilities. As a follow-up to the EMMA Study, the MDC organized two site selection committees to evaluate and suggest possible sites for the location of the satellite facilities. The mem— bers of the site selection committees were made up of repre- sentatives from those towns which would be directly affected 3—74 ------- by the proposed facilities. The general locus of the proposed facilities were derived from the EMMA Study. For the Charles River, just below the Cochrane Darn was selected as the dis- charge point based on prior water quality work done by the Division of Water Pollution Control, Commonwealth of Massa- chusetts. Hence, it was envisioned that the site should be located within a reasonable distance of the Darn. For the Neponset River facility, the Norwood-Canton area was chosen based on serving the area upstream and main- taining the discharge as far upstream as possible in order to maximize the flow augmentation benefits from the effluent discharge. No specific discharge point within this general area was specified. In October, 1976 the Site Selection Reports of the Middle Charles Site Selection Committee and the Upper Neponset Site Selection Conimittee were released. For the Charles River plant, some 19 sites were evalu- ated, all within a threemile radius of the Cochrane Darn. For the Neponset River plants, 10 sites were evaluated in the towns of Canton and Norwood. These sites are listed below and are illustrated in Figures 3.2-9 and 3.2-10 Fig- ure 3.2—9 does not show sites 11, 15, 16 and 18. Sites Evaluated in the Vicinity of the Cochrane Darn, Figure 3.2—9 Site 1 Stigmatine Fathers Property, Dover Site 2 Stigmatine Fathers Property, Dover Site 3 Clay Brook Road, Dover Site 4 Dedharn Street, near Carryl Park, Dover Site 5 WHDH Towers, Needham Site 6 Town Landfill, Needham Site 7 Powissett Farm, Powissett Street, Dover Site 9 Of f Eliot Street, near Broadmoor Sanctuary, Natick Site 10 Trustees of Reservations, Fisher Street, Needham Site 11 1 rnerican Can Plant, Needham Industrial Park (not shown) Site 12 Glen Street, opposite Site 9, Natick Site 13 Adjacent to Glenwood Cemetery, Natick Site 14 Pond Road, Wellesley Site 15 Kennedy Farm, Cutler Park, Needham (not shown) Site 16 Gravel Pits, Routes 128 and 20, Weston (not shown) Site 17 Wellesley Incinerator Site 18 Wellesley Office Park (not shown) Site 19 Wellesley County Club 3—75 ------- * J L41 ‘ ? ! \ * 1 / & , r b J f’ I - — $ c ? / —J I s r’ ) c: 5° c 9 I/I ••- :•- . - -_/ / ‘ ‘ - / (‘ i [ / 05 0 03 I • ‘ -: KILOMETERS T - FIGURE 3.2”9 SATELLITE SITES IN THE MID-CHARLES BASIN I — /,‘ / / 1 - L / . c -. r - ‘ I Lake’ \‘ ------- 05 9 o 5 O 5 FIGURE 3.2-10 SATELLITE SITES IN THE UPPER NEPONSET BASIN 05 K I LOME T ER S 9 MILES ------- Sites Evaluated ir the Norwood/Canton Area, Figure 3.2-10 Site 1 Corner of Route 1 and Union Street, Canton Site 2 Old Airport, Neponset Street, Canton Site 3 Norwood Drag Strip, Route 1, Norwood Site 4 Norwood Airport Site 5 Star Market Distribution Center, Univer- sity Avenue, Norwood Site 6 Industrial Area, Route 95 and Dedham Street, Canton Site 7 Industrial Area, Route 95 and Dedham Street, Canton Site 8 Southern portion of the Norwood Drag Strip, Route 1, Norwood Site 9 Knoll across river fromNorwood Airport, Canton Site 10 MDC Neponset River Reservation, Canton The Site Selection Committee reports contain rating sheets in which each site is ranked against a number of para- meters, such as land use considerations and transportation factors. (The full list of site selection criteria is con- tained in the committee reports). Furthermore, the ranking procedure used a qualitative scoring system (Excellent, Good, Average, Fair, Poor, Not Possible). Accompanying these rat- ing sheets was a general report and a series of minority reports. The Middle Charles River Site Selection Committee con- cluded that none of the sites evaluated met al1 of the cri- teria for the location of a treatment facility. The Commit- tee further expressed a reluctance to endorce the use of a riverbank site for treatment plant use. The Upper Neponset Site Selection Committee went some- what further and ranked the sites in four categories, as follows: Least Acceptable Sites 1, 5, 6 and 7 Less Acceptable Site 4 Less Objectionable Sites 3 and 8 Least Objectionable Sites 2, 9 and 10 These reports form the basis from which further site evaluation studies were conducted within the framework of this EIS. The first task in the site evaluation process consisted of the preliminary screening of sites which had been suggested by the Site Selection Committees. This screening procedure was based on the development of preliminary data for each site, 3—78 ------- including field visits. This preliminary information was then used to reject those sites which were unacceptable for one or more reasons. A reduced list of sites surviving this step will then be evaluated in greater detail in the inter- mediate screening stage. Factors which were used for a basis of rejection included: 1) Preservation of open space 2) Avoiding treatment plant construction in designated Natural Valley Storage Areas (Charles River Basin only) 3) Presence of ecologically valuable wetlands 4) Incompatibility with existing land uses 5) Extraordinary site development circumstances or use constraints 6) High wildlife value, scenic value or cultural value In addition to preliminary environmental data, some engineer- ing feasibility estimates were also made at this point. Two public workshops were held relative to the entire satellite treatment plant issue. Each workshop consisted of two sessions, one held in Wellesley (with emphasis on Charles River issues), the other in Canton (emphasis on Neponset River issues). The purpose of the initial two sessions, held February 1 and 3, 1977, was to inform the public of the exis- tence of the EIS study and to identify critical environmental issues that affected the preliminary screening of alternatives. The format of the workshops involved the organization of per- Sons attending into discussion groups which were then asked to discuss and respond to a series of questions. At the latter two workshop sessions, held in the same towns approximately eight weeks later, the tentative results of the preliminary screening were presented. Comments and suggestions were again invited. Following these sessions, adjustments were made in the site elimination choices. The following is a presentation of the results of the preliminary screening work, divided by river basin: Neponset River For the Neponset River satellite plant, a total of eleven sites were screened. This included the ten sites evaluated by 3—79 ------- the Upper Neponset Site Selection Committee plus one site, labelled “A”, which was suggested at the first workshop session in Canton. The preliminary screening process elimi- nated five of these eleven sites. These five sites are listed below along with reasons for their rejection. Site 1 - Corner of Route 1 and Union Street, Norwood . This site is located adjacent to Traphole Brook and is vege- tated with a mixture of various grasses (including Phragmites ) and mixed hardwood saplings. The site is more distant from the river than other sites and would require interceptor construction through a residential area. It is also bordered on two sides by Route 1. and Union Street. The wildlife value of the site is considered intermediate. Construction at this location may result in siltation of Traphole Brook. For this reason and the availability of clearly better sites, this site was eliminated from further consideration. Site 2 - Old Airport, Neponset Street, Canton . This site is an abandoned airport, is flat and at an elevation of 15.24m (50 ft). No significant active land uses are located immediately adjacent to the site. Several abandoned build- ings in a deteriorated condition occupy this location and it is zoned industrial by the Town of Canton. The aesthetic value of the site is low. During the flood of record, the area was inundated. On—site vegetation consists of mixed grass and sedges. To the immediate north and east is a large freshwater marsh area, with high wildlife value. Advantages of this site include compatability with exist- ing and proposed land uses, good access, minimal interceptor and outfall requirements, and minimal impacts on the natural environment provided that the marsh area is avoided and not disturbed. Disadvantages include the low-lying character of this site and its resultant potential for frequent and severe flooding. To overcome this problem, large scale filling would be required. it is estimated that about 290,000 m 3 (379,000 cu yd) of fill would be necessary. By elevating the floodplain in this area, flood magnitudes and durations in adjacent and upstream areas would be adversely affected. For these reasons, this site was eliminated from further con- sideration. Site 4 - Norwood Airport . This site is located between the Norwood Memorial Airport and the Neponset River. It is flat, is located at an elevation of 15.24 m (50 ft) and con- tains some heavy poplar, birch and maple growth. The site also involves some wetland species and is subject to flooding. Development of this location may conflict with the use of the airport. This site was eliminated due to the presence of other, more favorable locations. 3—80 ------- Site 10 — Area at the North End of 1—95 Interchange, Canton. This site slopes from east to west, with the eleva- ion changing from 45.72 in (150 ft) to 15.25 m (50 ft) and lies between the Neponset River Reservation and the Blue Hills Reservation. The western partof the site is occupied by a mature stand of mixed oaks, pine, sassafras and gray birch, while bordering an old field with mixed grasses, wild rose and hardwood seedlings/saplings. The site has inter- mediate wildlife value, access is good, and its aesthetic value is medium to high. The lower elevations of the site may be subject to flooding during severe storms. Advantages of this location include isolation from other land uses and good access. Disadvantages include significant impacts of the natural environment, aesthetic impacts and possible floodplain ele- vation. For these reasons, this site was eliminated from further consideration. Site “A’s - Off Pecunit Street, near Interchange 12 of Route 12:8, Canton . This site was suggested at the workshop session held in Canton on February 3, 1977. It was subse- quently evaluated and was found to be a lowland woodland with sections of inland wetlands located within the site. Exten- sive fill would be necessary prior to plant construction. Due to these conditions, this site was not considered further. To summarize, the preliminary screening process for potential Neponset Basin sites began with eleven sites and eliminated five of these. Sites 4 3, 5, 6, 7, 8 and 9 were still considered viable and were subject to a more detailed intermediate screening. Charles River For the proposed middle Charles River satellite treatment plant, the original nineteen sites evaluated by the Site Selec- tion Committee were used as the starting point for the pre- liminary screening work. The sites which were rejected in this phase are discussed below. Sites 1 and 2 — Stigmatine Fathers Property, Dover . These sites, located adjacent to the Charles River, are exceptional examples of a mature mixed pine-oak community. Many of the trees present are large, well-developed examples of their species. Excellent examples of hemlock and white pine are noteworthy on these sites. Additional tree species present include sugar maple, red maple and paper birch. Blueberry and lily-of-the-valley were also noted. Because of the mix- ture of connifers and hardwoods present on these sites, they provide excellent habitat for birds and a variety of other wildlife species. 3—81 ------- The Metropolitan Area Planning Council (MAPC), in their 1976 Regional Open Space Plan, recognized the scenic value of these sites. In their report, the MAPC states that the sites are “...one of the most scenic areas along the Charles River. It is a prime example of what the natural riverfront of the Charles River was 1ike. ’ (MAPC, 1976). The report goes on to recommend that the State acquire the land adjacent to the river to a depth of at least 152.4 meters (500 feet), if the entire sites is not purchased by the Commonwealth. In view of their scenic and wildlife value, as well as their potential recreational value, these sites were elimi- nated from further consideration. Site 3 - Clay Brook Road, Dover . This site is presently vacant and lies adjacent to a residential neighborhood. A small stream flows through the site, and it is heavily wooded with red maples and white pines. Since this site is a regis- tered wetland and has been designated as a Natural Valley Storage Area, it was not considered feasible for treatment plant development. Site 4 — Dedham Street, Dover . This site consists of an open field surrounded by heavy woods on its perimeter. It lies south of the riding stables near Carryl Park. This site has been willed to the Trustees of Reservations and so, for the purposes of this study, is considered to be dedicated open space (The Trustees of Reservations is an organization which, for many years, has been active in aquir— ing and preserving open space in Massachusetts). This fact, coupled with incompatible land use and rugged topography, eliminated this site from further consideration. Site 5 - WHDH Towers, Central Avenue, Needham . This site is an inland marsh ( Typha sp. and Phragmites sp.) which is located adjacent to the Needham Sanitary Lnadf ill. It is a designated wetland and Natural Valley Storage Area and, therefore, was eliminated from further consideration. Site 7 — Powissett Farm, Powissett Street, Dover . This site is presently occupied by an active farm, and consists of flat pasture land with numerous farm buildings. The site is to come under the control of the Trustees of Reservations via a conservation restriction and is, therefore, considered per- manent open space. Another negative factor associated with this location is its distance from the discharge point (Coch— rane Dam). Approximately 7.7 km (4.8 mi) of influent and effluent sewers would be required to pump wastewater to the site and effluent to the discharge point. This pumping would require a significant energy input since the site is approxi- mately 61 m (200. ft) higher than the existing interceptor sewer. These factors resulted in the elimination of this site from the evaluation. 3—82 ------- Site 8 Tow i of Dover , owissett Street, D ver . This site is an active landfill used by the Town of Dover. It is well screened from surrounding areas by rugged, forested land on its perimeter. However, this site is rather small and is even further from the discharge point than Site #7, above. Approximately 9.8 km (6.1 mi) of influent and efflu- ent sewers would be required. The site elevation, approxi- mately 83.8 in (275 ft), is about 55 in (180 ft) above the existing interceptor sewer. Further difficulties would result from the displacement of the landfill, thereby leav- ing Dover with a solid waste disposal problem. This site was, therefore, eliminated from further consideration. Site 9 - Elliot Street Farm, South Natick . This site consists of an open field, gently sloping down to the Charles River which lies adjacent to it. The Audubon Broadxnoor Sanctuary borders the site. The primary difficulties with this location are its extreme distance from the discharge point and its relatively small size. Approximately 16 kin (9.9 mi) of influent and effluent pipeline would be required. Since a reasonable setback from the Charles River would be recommended in order to preserve a natural “corridor” in this scenic section of the river, it would be necessary to expand the site in order to accommodate the needed facilities. Since an aquisition from the Broadinoor Sanctuary would be neither possible nor desirable, this site was eliminated from the evaluation. Site 10 — Fisher Street, Needhaxn . This site consists of a pasture with scattered clumps of hedgerows and trees, Red cedar, black oak, hickory and white pine were noted. The site is close to the discharge point and is surrounded on three sides by the Charles River. However, it is presently owned by the Trustees of Reservations and is, therefore, dedi- cated open space. The site is not considered feasible because of this fact. Site 11 — 7 merican Can Plant, Needham . This site is located in an industrial park and is presently occuped by an abandoned canning plant. The site has been purchased by a firm which is renovating and reactivating the facilities. This site was eliminated in consideration of this fact and because, due tO its distance to the discharge point, 13 km (8.1 ml) of sewers would be required. Site 14 — Pond Road, Wellesley . This site is vacant and is located between Pond Road and Paintshop Pond. It is heavily wooded, located in a park-like setting, and has very high aesthetic value. The site is also located approximately 3—83 ------- 5.64 km (3.5 mi) from the discharge point. It was eliminated from further consideration for these reasons. Site 15 - Kennedy Farm, Cutter Park, Needhain . This site was eliminated from further consideration because it is a Natural Valley Storage Area, is flood prone and is distant, 5.79 km (3.6 mi) from the discharge point. Site 16 — Gravel Pits, Route #128 and #20, Weston . This site was eliminated because of its extreme distance, 12.9 km (8 mi) from the discharge point. Site 17 — Wellesley Incinerator, Wellesley . This site is located at Interchange 55, Route 28. It is low and wet with adjacent higher ground. Red maples, silky dogwood, pepperbush, gray birch, blueberry and mixed oaks were noted. The wetlands which were found on this site and the availability of comparatively better locations resulted in its elimination from further consideration. Site 18 — Wellesley Office Park Wellesley . Utilization of this site would require the demolitiionof a newly constructed of f ice building and, therefore, it was eliminated from further consideration. Site 19 - Wellesley Country Club, Wellesley Avenue, Weiles].ey . This site is an active golf course. It was eliminated from consideration in order to avoid displacing an active recreational facility. To summarize, the preliminary screening process for treatment facility sites for the Middle Charles River faöil— ity began with nineteen sites, and eliminated sixteen of these. Sites 6, 12 and 13 were still considered viable and were subject to a more detailed intermediate screening. B. Effluent Discharge Evaluation Charles River The EMMA Study recommended an advanced wastewater treat- ment (AWT) facility discharge to the middle reaches of the Charles River and stated that the Cochrane Oain near Charles River Village was an advantageous discharge point. enits.*k ascribed to this ty were a reduction of flow’with — ghly treated effluen Addition of_ w to the Charles was e as being e1p i wafer quality in dry seasons. However, at the same time the report acknowledged the selected treatment process would not satisfy the dissolved oxygen (DO) criteria for the Charles River and additional removals of oxygen demand would be needed. (The Charles River is Class B 3—84 ------- water from Bridge St. in Dover to the Watertown Darn, the area of potential discharge. Class B waters are specified as “...suitable for bathing and recreational purposes, water contact activities, acceptable for public water supply with treatment and disinfection, are an excellent fish and wild- life habitat...” (Commonwealth of Massachusetts, 1974). A minimum allowable dissolved oxygen concentration of 5 mg/i has been established to maintain water of sufficient quality to allows for these uses. In addition, the D.O. standard must be met when the river is experiencing the 7 day, 10 year low flow (7Q10). This is the average daily flow for a 7 day period which has a 10 percent probability of occurring in any year. (Refer to Appendix 2.5.1). However, the magni— tude of the violation and an estimate of additional removals required were not presented by the EMMA Study. In order to quantify the impacts of the proposed Charles River Facility and determine if additional removals of oxygen demand would allow the discharge to meet Water Quality Criteria, water quality modelling of the Charles River was undertaken. The Massachusetts Division of Water Pollution Control (MDWPC) has a generalized water quality computer model (STREAM) developed for it by the consulting firm of Quirk, Lawler and Matusky Engineers in 1971. Subsequently, this model was calibrated and verified for simulation in the Charles River by the MDWPC (Erdmann, Bilger and Travis, 1977). The STREAM model was utilized to evaluate the effects of the proposed discharge upon the dissolved oxygen resources of the Charles River. Detail discussion of the model and modelling activities undertaken are contained in the report “Dissolved Oxygen Modeling Charles River Massachusetts” and its Addenda by Allen J. Ikalainen of the Systems Analysis Branch, Region I U.S. EPA*, which is found in Appendix 3.2.2. This section swmuarizes the results of modelling the proposed Cochrane Dam discharge. The reader is urged to review Sections III of the above report, which presents year 2000 river conditions utilized in the modelling. *Mr. Ikalainen is responsible for developing the low flow version of the STREAM model as well as all computer runs. In addition, he provided valuable insights into the complexities of the Charles River system. The work summarized by his report represents but a small portion of the total work per- formed. For the effort put forth in the preparation of this EIS he is gratefully acknowledged. 3—85 ------- Prior to analyzing the effects of the proposed discharge, baseline river conditions were modelled. Initially, the river was simulated without a MDC discharge. Profile Bi, Figure 12 (all figures referenced by this discussion are found in Appen— dix 3.2.2) indicates large D.O. deficits below the 5 mg/i standard upstream of the Cochrane Dam, with continued viola- tions of a smaller magnitude downstream to approximately river kilometer 32 (mile 20). It appears as though major problems in the River could occur in the future. Because the River entered the MSD - river kilometer 756 (mile 47) - in violation of standards, upstream river condi- tions were modified to constrain the River to meet standards. In order to accomplish this, discharges at the Charles River Pollution Control District (CRPCD) and the Medfield and Millis treatment plants were set a 1.0 mg/i SOD 5 , no NH 3 -N. In addition, all sediment oxygen demand between the CRPCD dis- charge and South Natick Dam was set equal to zero (the equiva— lent of dredging the river bottom). Profile Cl, Figure 12 presents the D.O. profile for this situation. All Case C simulations assume these river conditions (Table 10, Appendix 3.2.2., present the various cases modelled). The treatment train proposed by the EMMA Study for the Charles River satellite plant consists of conventional secon- dary treatment followed by biological nitrification for removal of nitrogenous oxygen demand, (The microbial trans- formation of ammonia nitrogen (NH 3 -N) to nitrate nitrogen (N0 3 -N) is termed nitrification. Approximately 4.5 mg of oxygen are required to oxidize 1 mg of NH3-N to N03-N. For a given wastewater, the total amount of oxygen required to transform all NH3-N to N03-N is termed nitrogeneous oxygen demand) and multi—media filtration. Table 3.2-18 presents EMMA projected influent BOD5 and NH 3 -N concentrations, typi- cal secondary effluent concentrations for these parameters, and the projected AWT effluent levels. In addition to model- ling effluent from this facility, an “advanced” sate1lite effluent was evaluated. The advanced satellite envisions the addition of breakpoint chlorination to the treatment pro- cess for removal of the NH 3 -N remaining after biological ni trif ication. The proposed EMMA discharge was modelled with the Charles River not meeting (Case Bi) and meeting (Case Cl) dissolved oxygen criteria upstream. Profile Bil, Figure 12 shows the discharge to cause further violations downstream of the Coch- rane Dam, while profile C].]. reveals the discharge would cause a violation by itself. In addition to the above cases, 18 additional variations of the Cochrane Dam discharge were modelled. These included both the EMMA and advanced satellite discharge, variations in reaction rate coefficients, in the area]. coverage of benthic demand in reaches downstream of 3—86 ------- TABLE 3.2—18 CHARLES RIVER SATELLITE TREATMENT PLANT INFLUENT - EFFLUENT CHARACTERISTICS B aD 5 NH3—N Influent 1 , mg/i 222 21 Typical Secondary, mg/i 30 15 Effluent Removal 86 29 Projected EMMA AWT, mg/i 5 1 Effluent X Removal 98 95 Advanced AWT Effluent, mg/i 5 0 Z Removal 98 100 1 lnfluent concentrations and percent removals based on flows and loads presented in Table 6—9, “Basic Design Criteria — Middle Charles River Advanced Wastewater Treatment Plant” of the EMMA Study Main Report (Metcalf and Eddy, 1975a). 3—87 ------- the discharge point, and placing the discharge both above and below the Cochrane Dam. The D.O. concentrations down- stream of the Cochrane Dam were below the Class B criteria in all cases. In addition, minimum dissolved oxygen concen- trations with a satellite discharge were always 1-2 mg/i less than the no satellite conditions. A satellite plant discharge at the Cochrane Dam was concluded to exacerbate a potentially serious future dissolved oxygen problem in the Charles River. These results led to the conclusion that a discharge to the Charles River at this location was environmentally unac- ceptable. Therefore, alternative discharge locations were evaluated. These included discharge at the S. Natick Dam and near the Medfield State Hospital which are, respectively 10.8 river kilometers (6.7 river miles) and 21.1 river kilo- meters (13.2 river miles) upstream of the Cochrane Dam. Dis- cussion of these discharge locations is presented in Section 3.3, Intermediate Screening. Neponset River The EMMA recommendations for a Neponset River advanced wastewater treatment facility was not accompanied by a speci- fied discharge location. The report simply stated that the flow should be discharged as far upstream in the watershed as possible to maximize flow augmentation benefits. It was fur- ther stated that the “...highly treated effluent should help the Neponset River by increasing flows in dry summer months.” (Metcalf and Eddy, 1975a). A quantitative analysis of the water quality impacts of this discharge was not included in the EMMA report and, therefore, an analysis was undertaken to define the potential water quality impact of the recom- mended facility. Preliminary screening indicated sites 3, 5, 6, 7, 8 and 9 remained viable. Discharge points for each site were de- fined and shown in Figure 3.2-11. Point A corresponds to sites 3 and 8, which were combined into one site; point B corresponds to sites 6, 7 and 9; and point C designates the site 5 discharge location. The Massachusetts Division of Water Pollution Control has a water quality model for the Neponset River. Unfortu- nately, the data necessary to utilize the model has not been fully developed and it could not be used for analysis of the proposed discharge. Therefore, the Streeter and Phelps equation was utilized to model the impact of the proposed discharge on the oxygen resources of the Neponset River. 3—88 ------- Dorch.ster lay WATEISHED LOCATION O9 Pond LEGEND * USGS. GAGING STATION FIGURE 3.2-11 POTENTIAL DISCHARGE PONITS NEPONSET RIVER AWT FACILITY 2 0 2 KILOMETERS Q MILES ------- The discharge volume was set equal to 1.10 m 3 /s (25 mgd) as presented by the EMMA report. In addition, two variations in effluent quality were modelled. Case 1 corresponds to the recommended EMMA level of treatment in which the discharge contained 5 mg/i of BOD 5 and 1 mg/i NH 3 -N. As in the Charles River modelling,an advanced discharge containing 5 mg/i BOD 5 and no NH 3 -N was also modelled and designated as Case 2. This analysis is found in Appendix 3.2.2, along with the resultant dissolved oxygen profiles for each discharge loca- tion. Case 1 discharge resulted in dissolved oxygen concentra- tions dropping to less than 1 mg/i for all locations, while the lowest Case 2 level was approximately 3 mg/i for locations B and C and 3.3 mg/I for A. For all discharge locations, Case 2 discharge results in a significantly higher dissolved oxygen concentrations in the river reaches modelled. In addition, discharge point A had slightly better dissolved oxygen profiles than the other points. Nevertheless, both cases violate water quality standards for these reaches of the Neponset River. The main branch of the Neponset River from the Town of Walpole downstream to its tidal secton is a Class C water- way. Class c waters have a dissolved oxygen criteria of “... never less than 3 mg/i” (Commonwealth of Massachusetts, 1974). Case 1 discharge violates the 3 mg/i criteria, while Case 2 results in the minimum allowable D.O. concentration. This analysis, however, does not account for the effects of ben— thic deposits, which may exert a major influence upon river dissolved oxygen àoncentrations. Specific data to quantity the effects of this parameter does not exist for this area of the Neponset River. However, during the MDWPC’s 1973 water quality survey a sampling station was established just below the confluence with the East Branch as well as at the Truman Highway Bridge in Milton. These stations bracket the majority of the Fowl Meadow Marsh, the area of interest to this analysis. Data from these statioDs from the 1973 survey indicate the average dissolved oxygen concentration of the river decreased by 0.6 mg/i as it tra- versed the marsh. Survey flows were approximately equal to the modelled low flow plus the treatment plant discharge. This implies benthic demand has a negative effect upon D.O. in the Neponset. Superposition of this effect, which is not anticipated to change in the future, upon the dissolved oxygen profiles resulting form Case 1 discharge would cause concentrations to approach 0 mg/i. Case 2 discharge would then violate the 3 mg/i Class C standard. 3—90 ------- The Neponset River in this area seems to be in a much better condition than its C classification implies. As was pointed out in Section 2.5, the marsh appeared to moderate upstream waste inputs. Although D.O. values declined and BOD 5 values generally increased, as would be expected in a river traversing a marsh, the average D.O. values never fell below 5 mg/i. During the 1964 survey by the Massachusetts Department of Public Health, Division of Sanitary Engineering the Nepon- set River in the Fowl Meadow Marsh area was found to be grossly polluted. Dissolved oxygen approached 0 mg/i while BODç exceeded 30 mg/i at many places (Water Quality Section, 1973). Comparison of 1964 data with that obtained during the 1973 survey by the MDWPC indicates: “...the water quality improved markedly between 1965 and 1973. This was accomplished by the cessation or diversion of many industrial dis- charges. Higher dissolved oxygen and lower BOD 5 have been the parameters most affected. The biggest improvement has been downstream from mile point 20 (beginning of Fowl Meadow Marsh).” (Water Quality Section, 1976). Any discharge to the Neponset in the area proposed by the EMMA report would result in a significant detrimental ixnpa t on the Neponset River’s dissolved oxygen resources and over- all water quality. In addition, all the discharge points analyzed are upstream of a major group ofwater supply wells (See Figure 2.5—18). It is very likely that these wells draw from the Neponset during low flows, given their proximity to the River and the nature of the aquifer. The potential for significant adverse health effects is created by utilizing any of these discharge point. In order to mitigate these impacts it would be necessary to move the discharge point downstream of point C. Such action reduces potential flow augmentation benefits considerably. In light of the great potential negative impact upon water quality, implementation of a Neponset River Satellite Plant is not recommended. C. Treatment Processes . The EMMA Study included a recommen- dation for the construction of two satellite treatment plants for the purposes of augmenting low flows in the Neponset and Charles rivers and for reducing the wastewater flow to the existing Nut Island Treatment Plant. It was proposed that both satellite treatment plants be designed to meet the fol- lowing monthly average effluent criteria: ROD 5 5 mg/l phosphorus 1 mg/l suspended solids 5 mg/i ammonia nitrogen 1 mg/i 3—91 ------- The average daily design flows for these plants as presented in the EMMA Study were: Upper Neponset Middle Charles TrEatment Plant Treatment Plant Year 2000 average daily flow 95382 m 3 /d 117335 m 3 /d (2.52 rngd) (31 mgd) Year 2050 average daily flow 133232 m 3 /d 172596 in 3 /d (35.2 mgd) (45.6 mgd) The unit processes proposed for this plant included pre— liminary treatment, primary settling, two stage activated sludge for BOD removal and nitrification, alum addition for phosphorus removal, multi-media filtration for effluent polish- ing, and chlorination for disinfection. Mechanical aerators were proposed to furnish the oxygen required for the first and second stage activated sludge aeration tanks. Flow equali- zation basins were proposed ahead of the multi-media filters to provide a uniform loading rate to the filters. As part of this Environmental Impact Statement, a brief review of alternatives to the processes recommended in the EMMA Study was conducted. Alternative treatment processes which were evaluated for the satellite treatment plants in- cluded oxygen activated sludge, activated sludge with powdered activated carbon addition, single step activated sludge nitri— fication, a ,bio1ogical system for phosphorus removal, rotat- ing biological contactors, a carousel oxidation ditch and land application. None of the alternative treatment systems considered provided significant advantages over that of the system proposed in the EMMA Study. It is believed that a more detailed review of the alternative treatment concepts would more appropriately be included in the detailed facility planning process. During the public workshops which were held to discuss the concept of satellite treatment plants, some concerns were expressed with regard to the degree of virus kill that one might expect from the treatment system recommended in the EMMA Study. A comprehensive literature search was performed to determine the relative efficiency of the various units with regard to virus removal or destruction. It was found that the viral removal data reported in the literature varied widely with the type of virus and the method of virus analy- sis. Table 3.2-19 presents the typical range of virus removal rates reported for various unit processes. The lower value of removal efficiency for chlorination represents that attained at low chlorine dosage rates, while the high values represent breakpoint chlorination. Breakpoint chlorination can attain levels of viral kill equivalent to ozonation. In order to estimate the viral removal efficiency for the level of treatment recommended in the EMMA Study at the satellite treatment plants the following removal rates were assumed for each process: 3—92 ------- TABLE 3.2— 19 TYPICAL VIRUS REMOVAL EFFICIENCY SELECTED WASTEWATER TREATMENT PROCESSES Process Primary Sedimentation Activated Sludge Activated Sludge with Alum Coagulation for Phosphorous Removal (Influent phosphorous level 4.5 ppm) Alum Coagulation Lime Coagulation Ferric Chloride Coagulation Rapid Sand Filtration (following coagulation) Rapid Sand Filtration (without coagulation) Chlorination Ozonation Nitrification DenitrificatiOn Reported Percent Removal 0—3 88—99.99 90—99 96—99.9 99—99.9 92-99.1 99 0—48 50—99. 999 99—99.999 4 8—79 9 5—99 3—93 ------- Unit Process Percent Removal of Virus primary sedimentation 0 activated sludge with phosphorous removal 96 activated sludge with nitrification 70 mixed media filtration without coagulants 20 disinfection normal chlorination 90 • breakpoint chlorination 99.99 ozonation 99.99 The re lting accumulative removal efficiencies were calculated to be 99.9 for the level of treatment recommended in the EMMA Study using normal chlorination at a dosage level of 8 mg/i and 99.9999 using breakpoint chlorination at a dosage rate of 12 mg/i or ozonation. By employing breakpoint chlorination or ozonation, the resulting virus concentration in the effluent would be only .0007 plaque forming units per liter (PFU/l) based on an initial concentration of 7000 PFU/1. As a result of the water quality modeling work performed for this EIS, it appeared that in some cases it might be necessary to reduce the BOD and ammonia concentrations even lower than assumed in the EMMA Study to satisfy required water quality dissolved oxygen levels. As a result, break- point chlorination was considered for ammonia removal as well as improved virus kill. Carbon columns were also investi- gated for BOD removal. For a basis of comparing the cost of the satellite sys- tem as proposed in the EMMA Study to the systems developed in this EIS, a detailed cost estimate was prepared for both the Middle Charles and Upper Neponset Treatment Plants. These costs, as presented in Table 3.2—20, reflect the unit processes recommended in the EMMA Study, exclusive of site preparation and sewer relocation. The costs for sludge dis- posal costs for the satellite plants are developed separately in a later section. The costs for the aeration tanks were based on a fine bubble diffused air system, instead of mechanical aerators, since a preliminary cost analysis showed that the diffused air system was more cost effective. Although the capital cost of the diffused air system is higher, this is more than offset by the reduced operating and maintenance costs of the diffused air system. An alum dosage rate of approximately 164 mg/i was assumed for phosphorous removal. 3—94 ------- TABLE 3.2-20 ESTIMATED COSTS FOR THE SATELLITE TREATMENT PLANTS Capital Cost O&M Cost Total Annual Cost ($1000) ($1000/yr) ($l000/yr) 1 - Upper Neponset EMMA System 38,400 2,080 5,059 EMMA System with breakpoint chlorination 38,400 2,115 5,094 EMMA Study with breakpoint chlorination and dechlorination 38,750 2,144 5,150 Middle Charles EMMA System 44,146 2,444 5,868 EMMA System with breakpoint chlorination 44,146 2,488 5,912 EMMA System with breakpoint chlorination and dechlorination 44,542 2,523 5,978 1) Sum of amortized capital cost and annual operation and maintenance cost. Capital cost is amortized assuming average life of 30 years and interest rate of 6 —.5/8 percent. 3—95 ------- Separate cost estimates were prepared for normal chlori- nation, breakpoint chlorination and breakpoint chlorination followed by dechlorination. The normal chlorination system was based on a chlorine dosage of 8 mg/i while the dosage for breakpoint chlorination of the filter effluent was estimated at 12 mg/i. The dechlorination costs were based on sulfur dioxide addition at a dosage rage of 2.5 mg/i followed by post aeration. 3—96 ------- 3.2.4. Land Application of Wastewater Treatment Plant Effluent Land application of treated municipal and industrial wastewater has been used to provide economic and environ- mental benefits from wastewater treatment and disposal. The benefits are obtained in the following ways: 1) An alternate wastewater disposal scheme becomes available. 2) A source of relatively reliable, low cost, pre—fertilized irrigation water is provided. 3) Water is conserved through wastewater recovery by groundwater recharge. In addition to these benefits, under certain conditions the application of wastewater to the lard provides an additional level of wastewater treatment by utilizing the physical and chemical characteristics of the soil to remove pollutants. The feasibility of land application of municipal wastewater depends upon the biological and chemical characteristics of the treated wastewater and the availability of sufficient land with desired chemical and physical properties to eliminate any adverse or unacceptable effects of the wastewater on groundwater and surface water quality. The most commonly used methods of land application are irrigation and infiltration techniques which have been adapted to wastewater application from agricultural use. Irrigation techniques include several types of sprinkling arrangements and surface loading measures such as the use of ditches or furrows. The attractiveness of this process lies in its potential for maximizing crop production by providing needed nutrients, and simultaneously filtering the applied effluent as it flows through the soil matrix. The applied wastewater is absorbed by the vegetation, evaporates into the atmosphere or percolates through the soil to the ground water. It is necessary for the treated wastewaters to be of sufficient quality to protect the ground water against contamination. If local restrictions require that the wastewaters be discharged to a surface water source, they can be collected underground by a sub- surface tile drainage field and pumped to the desired discharge location. If permitted to follow natural drainage patterns the wastewater would eventually reach some surface water source. Rates of wastewater application using irrigation methods vary from about 1.3 to 10.2 Cm/wk (0.5 to 4 ifl/wk), depending upon the characteristics of the wastewater, soil, vegetation and receiving waters. When using the rapid infiltration method of land application, the wastewater is generally applied to the soil 3—97 ------- through the use of shallow lagoons. The wastewater percolates through the soil and is either allowed to reach the ground- water or is collected by underdrains and discharged to surface waters. The objective is not to grow vegetation, but to renovate the wastewater as it passes through the soil, and to dispose of it. Rapid infiltration applic tion rates vary from about 10.2 to 305 Clfl/Wk (4 to 120 lfl/Wk), depending upon wastewater and soil characteristics. The feasibility of land application of secondary treatment plant effluent was evaluated by the Corps of Engineers in the Wastewater Engineering and Management Plan for the Boston Harbor-Eastern Massachusetts Metropolitan Area (EMMA Study), Technical Data Volume 5 “Land Oriented Wastewater Utilization Concept”. The result of this feasibility study was presented in the EMMA Study Main Report as Wastewater Management Concept 5. This plan required the construction of five inland satellite treat- ment plants which would discharge to land application sites approximately 40 kilometers (25 miles) outside the EMMA study area. The transportation of this wastewater to the sites of land application would require the construct- ion of a pumping station and force mains of sufficient capacity to transport the combined flow from the five satellites. Under this concept, the five satellite plants would treat a combined average flow of 681,000 m 3 /day (180 mgd.) The Deer and Nut Island treatment plants would be upgraded and expanded to treat the remainder of the wastewater from the MSD service area, and would continue to discharge their effluents to Boston Harbor. The comparison and evaluation of this plan with the four other wastewater management concepts considered in the EMMA Study resulted in the elimination of Concept 5 from further consideration due to high capital and operating costs and environmental considerations related to the construction of the necessary facilities and the operation of the land application sites. Additional problems associated with jurisdictional responsibilities of the MDC, as the land application sites are outside the MDC’S limits of activity, and the unprecedented use of land application of wastewaters on such a large scale made this alternative concept even more unfavorable. The systems under consideration in this EIS for implementation represent different configurations of treat- ment plants than did Concept 5 of the EMMA Study, but provide about the same volume of wastewater for land application. The MDC sewer system effectively divides the service area into a northern system a d a southern system. It would not be possible to include the wastewater from the northern system in any land application scheme due to its 3—98 ------- high degree of salinity. This high salinity is probably due to seawater intrusion into the northern interceptor system through faulty tide gates and the infiltration of seawater into the sewers in low-lying coastal areas. The southern system has two treatment plant options presently under consideration. One option includes the construction of two satellite treatment plants, one along the Charles River and one along the Neponset River, to supplement a coastal treatment plant that would discharge to Boston Harbor. The other option is to provide all treatment for the wastewater from the southern system at a coastal plant. The quantity of wastewater from the entire southern MDC service area is about the same as the quantity from the inland satellite plants of Concept 5 of the EMMA Study and, therefore, the results of that study are also valid for the wastewater management alter- natives currently under consideration. The excessive cost and adverse environmental effects associated with the discharge of about 681,000 m 3 /day (180 mgd) of wastewater from the MDC service area to land application sites in southeastern Massachusetts, as discussed previously, make t iis concept undesirable. As an alternative to the discharge of 681,000 m 3 /day (180 mgd) of wastewater outside the EMMA study area, discharge locations within the EMMA study area were evaluated for their wastewater load assimilative capability. For spray irrigation, it was assumed that wastewater would be applied at a rate of 5.1 cm/wk (2 ]-fl/wk) and that facilities would be operated for 26 weeks with storaqe capacity for 30 weeks of flow. For rapid infiltration, it was assumed that wastewater would be applied at a rate of 71 cm/wk (28 ‘ /wk) and that facilities would operate on a cycle of 14 days flooding and 7 days recovery, with storage capacity for 14 days of flow. These criteria were used by the Corps of Engineers in Technical Data Volume 5 of the EMMA Study. Including allowances for buffer zones, adminis- trative areas, pumping stations, roads and any other factors that reduce the land area at a particular site on which waste- water can be applied, the EMMA Study determined that the land requirements for the application of 3785 m 3 /day (1 mgd) of wastewater would be about 123 hectares (305 acres) using the spray irrigation method and about 7.4 hectares (18.4 acres) using the rapid infiltration method. These application rates will be used for the additional feasibility studies. The EMMA Study identified land areas available for spray irrigation and rapid infiltration within the study area. The location of these possible land application sites, both within and beyond the boundaries of the proposed extended MSD service area, are shown on Figure 3.2—12. 3—99 ------- Tables 3.2-21 through 3.2-25 list areas available and potential wastewater application rates for land application of wastewater in communities within the EMMA study area. The available land areas are those which meet the criteria for topography, soils, groundwater and land use necessary for land application of wastewater. As can be seen in Tables 3.2—21 through 3.2-25 and on Figure 3.2-l2most of the land application sites are suitable only for small flows and are spread over 30 municipalities within the EMMA study area, both inside and outside the MSD service area. Their combined total wastewater assimilative o vcuic bJcr ’ capacity is approximately 288,000 m 3 /day (76.1 mgd). This / represents approximately 40 percent of the average daily wastewater flow from the southern MSD service area. The remainder of the flow from the southern MSD service area must be discharged to surface and coastal waters depending on the treatment plant system selected. Only 45,000 m 3 /day (11.9 mgd) can be applied within the limits of the MSD service area. This represents approximately 6.5 percent of the wastewaters collected from the southern MSD service area. Using the data presented in Figure 3.2—12 and Tables 3.2—21 through 3.2-25, a conceptual design and estimate of pumping station, force main and land application facilities costs was made to determine costs for land application systems. Primary pumping and force main costs were based on straight line routes from the vicinity of Nut Island to four locations, each of which is surrounded by numerous land application sites. At the end of each of the, four primary force mains, a second- ary pumping station and network of smaller force mains is required to distribute the wastewater flow to each of the land application sites. Secondary pumping and force main costs were based on straight line routes from the termination of the major force main to each application site. These straight line distances represent an over- simplification of the transmission problems associated with the distribution of the treated wastewater to the land application areas. These costs provide a lower limit for transmission costs. The actual costs would be higher, depending upon the actual route selected for a particular force main. The capital costs for land application facilities include an allowance of $2,000 per acre for land acquisition. Operation and maintenance costs for the land application facilities include all costs associated with the application of wastewater once it has reached an application site. The power costs include the cost of all power associated with the primary and secondary pumping facilities. The following is a tabulation of the results of this analysis: 3—100 ------- SOURCE: NEW ENSLANO DIVISION U.S. ARMY CORPS OF ENGINEERS, 1775. N / \ J RST \ ,—..— 1(1111! v ‘\. NAV hI L ‘I I T • —, uuulJ ) / ‘S U(TNWfI / > S /‘ 3’ — — — — —.‘ f NITN I , 4, OIACUT P PP LL D*ST*E NUICI A*VtI IP$IICN •“9 - & •a •-— L,.-” \,. 0 — -- AIOOVEP ‘ P9II1D -‘ LOWIL I o “ - 1 fSSfx / T(51$$tJI’r A , 1 \ CN(1I5FOIO / — — .. NCFST!I \ / ‘ lMCN(5T(I’ — / ‘S -S.. •iw f*OIIG ) D*IV!IS I(V(ILY ‘ ‘ “ SM (Y) ITO •I1L(IIC* C I.CTM ‘S — \ / / / LITTIFTO I “- ‘ _—( CAI1ISL ..P.L\\_.. I(AOI5C yW,(1\ *KOy / _-‘ L TIEID ‘ $*ii MmfI Ao I IIIIIN ‘- . . c L iacasVII 4, / / I —- / COICOII ,4 L(IICTOI 7 *TN , SRS Mes ch sgtts • -.. PROPOSED CHARLES RIVER SATELLITE TREATMENT PLANT ( % / / , DEER ISLAND “K’LOCATION ISILAIDI D(STN ‘f • Boy I OS N 4 NUT ISLAND 1K ‘ ‘y UNI LIMIT OF ‘ ‘- ,‘-,-- -à “\ ‘ EXPANDED MSD • ‘ 01 0 “r- ’ I , 55 RNU P 1 , 1 1 110 1 ‘t ’1! SIENNI, DI V IP(5TM . < II [ TIU’ cow ssLr SERVICE AREA \ (— ( ‘ ç C’I*MUTlfl !W STw •o 0 r PILLIS (‘ “ AuDI \ —— Upyol ANOL!W’ / • O NILON \ \4 ’\ ‘\ ,g _9,p I IoIvni 9 , \ A. co .-‘ 0 - •\0 *T’*IICt ‘ 0 \ ucicmi ( D tAVOI - 0\5T SPAIN I P0 SWI(I.D ‘- A c.IoA ‘°__o 0 A 00 0 I .j (p j LI ..— / PROPOSED NEPONSET à’ OI° o “o RIVER SATELLITE UDISIOCI 1.11- DUXIURT MLL T* P O fUSION TREATMENT PLANT.. 0 Rhode Island LOCATION —m ‘ MltFAX •‘k: •IOCf 1*1( 1 LIMIT OF EMMA SCALE I” 10 MILES STUDY AREA LEGEND SPlAY IIIIIATI II IAPII IIFILTIATIII o 2141 ACHS • 2141 ACIIS A 5111 ACIIS £ 51.11 AC 1ES o 111.211 AC 1ES • 1IS-211 ACIES o 311+ ACIES • 3ll ACIES LIMIT OF EMMA STUDY AREA — — LIMIT OF EXPANDED MSD SERVICE AREA FIGURE 3.2— 12 POTENTIAL LAND APPLICATION SITES WITHIN THE EMMA STUDY AREA ------- TABLE L2-21 SPRAY IRRIGATION SITES WITHIN THE MSD SERVICE AREA Town ’ Ashland Dover Hingham Holbrook Hopkinton Sharon She rborn S toughton Walpole Total Available Area(i) hectares (acres ) 5.3 (13) 33.2 (82) 185.0 (457) 20.2 (50) 69.2 (171) 573.0 (1416) 28.3 (70) 128.7 (318) 142.0 (351) 1184.9 (2928) Average Daily Application Rate (ga ls.x10 3 ) (42.6) (268.8) (1,500.0) (164.0) (561.0) (4,643.0) (229.5) (1,042 .6) (1,150.8) (9,602.3) (1) New England Division, U.S. Army Corps of Engineers, 1975 a 161.2 1017.4 5677.5 620.7 2123.4 17573.7 868.6 3946.2 4355.8 36344.5 3—102 ------- (1) 86968.2 New England Division, U.S. Army Corps of Engineers, 1975 a TABLE 3.2-22 SPRZ Y IRRIGATION SITES WITHIN THE EMMA STUDY AREA AND OUTSIDE THE MSD SERVICE AREA Available Average Daily Town( 1 ) Area Cl) Application Rate hectares (acres) m (gals.x10 3 ) Bellingham 95.1 (235) 2916.3 (770.5) Boxford 81.7 (202) 2506.8 (662.3) Danvers 16.2 (40) 496.2 (131.1) Duxbury 79.7 (197) 2444.7 (645.9) Franklin 602.2 (1488) 18465.9 (4878.7) Hamilton 27.9 (69) 856.2 (226.2) Holliston 281.7 (696) 8637.4 (2282.0) Ipswich 102.8 (254) 3152.1 (832.8) Marshfield 258.2 (638) 7917.5 (2091.8) Medfie ld 86.2 (213) 2643.4 (698.4) Medway 106.0 (262) 3251.3 (859.0) Middleton 32.0 (79) 980.3 (259.0) Millis 14.6 (36) 446.6 (118.0) Norfolk 158.6 (392) 4864.5 (1285.2) North Reading 91.8 (227) 2817.2 (744.3) Norwell 264.7 (654) 8116.2 (2144.3) Pembroke 82.2 (203) 2519.3 (665.6) Scituate 112.5 (278) 3450.0 (911.5) Topsfie ld 63.5 (157) 1948.5 (514.8) Wrentham 278.4 (688) 8537.8 (2255.7) Total 2836.0 (7008) (22977.1) 3—103 ------- TABLE 3.2- 23 RAPID INFILTRATION SITES WITHIN THE 1 1SD SERVICE AREA Available Average Daily Town(’) Area(l) Application Rate hectares (acres) ( 1s.xl0 3 ) Hingham 17.4 (43) 8845.4 (2336.9) TABLE 3.2—24 RAPID INFILTRATION SITES WITHIN THE ENMA STUDY AREA ND OUTSIDE THE MSD SERVICE AREA Available Average Daily Town ( 1 -) Area( 1 ) A p1icatiOfl Rate hectares (acres) i t t - ’ (ga ls.x10 3 ) Boxford 44.5 (110) 22661.9 (5987.3) Duxbury 44.9 (111) 22833.4 (6032.6) Hanover 37.6 (93) 19130.5 (5054.3) Ipswich 41.7 (103) 211877 (5597.8) Marshfie ld 41.7 (103) 21187.7 (5597.8) Norwell 52.2 (129) 26536.3 (7010.9) Pembroke 45.3 (112) 23038.9 (6086.9) Total 307.9 (761) 156576.4 (41367.6) (1) New England Division, U.S. Army Corps of Engineers, 1975 a 3—104 ------- TABLE 3.2-25 SUBDIVISION OF LAND APPLICATION AREAS BY GEOGRAPHIC LOCATION FOR STUDY PURPOSES Northeast EMMA Sites MSD Sites Boxford Ashland Danvers Dover Hamilton Hingham Ipswich Holbrook Middleton HOpkintOn North Reading Sharon Topsfield Sherborn Stoughton Walpole Southeast EMMA Sites Southwest EMMA Sites Duxbury Bellingham Hanover Franklin Marshfield Holliston Norwell Medfield Pembroke Medway Scituate Millis Norfolk Wrentham 3—105 ------- Northeast EMMA Sites (outside MSD Limits) : Wastewater Application Rate. 56,526 m 3 /day (14.95 mgd) Average Distance from Nut Island 38.6 km (24 miles) Capital Costs: Primary Force Main $25,300,000 Primary Pumping Station 450,000 Secondary Force Mains 6,830,000 Secondary Pumping Stations 390,000 Land Application Facilities 7,500,000 Total Capital Costs $40,470,000 Annual Costs (Operation and Maintenance) Land Application Facilities $ 50,000 Power Cost 1,090,000 Total Annual (0 and N Costs) $ 1,140,000 Southwest EMMA Sites (outside MSD limits) : Wastewater Application Rate 49,800 m 3 /day (13.15 mgd) Average Distance from Nut Island 48.3 km. (30 miles) Capital Costs: Primary Force Main $26,500,000 Primary Pumping Station 445,000 Secondary Force Mains 11,900,000 Secondary Pumping Stations 375,000 Land Application Facilities 18,800,000 Total Capital Costs $58,020,000 Annual Costs (Operation and Maintenance) Land Application Facilities $ 107,000 Power Cost 970,000 Total Annual (0 and M) Costs $ 1,077,000 Southeast EMMA Sites (outside the MSD limits): Wastewater Application Rate 137,000 m 3 /day (36.2 mgd) Average Distance from Nut Island 28.9 km (18 miles) 3—106 ------- Southeast EMMA Sites (Continued ) Capital Costs: Primary Force Main Primary Pumping Station Secondary Force Mains Secondary Pumping Station Land Application Facilities $21,160,000 1,210,000 B, 250, 000 1,150,000 15,210,000 Total Capital Costs $46,980,000 Annual Costs (Operation and Maintenance) Land Application Facilities Power Cost Total Annual (0 and M) Costs $ 130,000 2,380,000 $ 2,510,000 MSD Sites : Wastewater Application Rates Average Distance from Nut Island 45,000 m 3 /day 32.2 km (11.94 mgd) (20 miles) Capital Costs: Primary Force Main Primary Pumping Station Secondary Force Mains Secondary Pumping Station Land Application Facilities $18,800,000 400,000 9,260,000 340,000 14, 270,000 Total Capital Costs $43,070,000 Annual Costs (Operation and Maintenance) Land Application Facilities Power Cost $ 84,000 660,000 Total Annual (0 and M) Costs $ 744,000 Utilization of all the available land application sites within the EMMA study area would undoubtedly incur juris- dictional problems for the MDC, as the bulk of the land application sites are beyond the MSD’s service area. The sites are located in 30 separate municipalities, 21 of which are outside the limits of the MSD service area. The towns which are outside the MSD service area have either already implemented their own municipal treatment systems or are part of smaller regional systems. Since these communities are not receiving any of the benefits of MSD wastewater treatment facilities, they would most likely not want to become depositories of MSD wastewaters. In view of these conditions, it is very likely that institutional problems would be a major obstacle to implementation of large scale 3—107 ------- wastewater disposal by means of land application. The disposal of about 288,000 m 3 /day (76.1 mgd) of wastewater by land application methods in the 30 separate municipalities would add more than $190,000,000 in construction costs and more than $5,000,000 per year in operation and maintenance costs to the wastewater management plan for the MSD service area. The additional amortized construction cost of the land application facilities in the entire EMMA study area over a 30 year period would be about $14,740,000 per year. Combining the additional amortized construction cost and annual operation and maintenance costs results in a total additional cost for land application of nearly $20,000,000. About 45,000 m 3 /day (11.9 mgd) of wastewater can be disposed of on land application sites within the MSD service area, at an additional construction cost of more than $43,000,000 and an additional operation and maintenance cost of more than $700,000 per year. The additional costs related to land application do not produce any savings in treatment costs, since secondary treatment of wastewater is required prior to land application. The additional amortized construction cost of the land application facilities within the MSD service area over a 30 year period would be about $3,335,000 per year. Combining the additional amortized construction cost and annual operation and main- tenance costs for the application of wastewater to land within the MSD service area results in a total additional annual cost for land application of about $4,000,000 per year. Land application of effluent from the satellite treat- ment plants on the Charles and Neponset Rivers was also investigated to determine its feasibility. Since the combined discharges of the two satellite plants would be less than the total wastewater application rate for the four major land application zones considered, it was decided to exclude the Northeastern EMMA area sites as a possible discharge location due to the high costs associated with transmission of wastewater from the satellite plants to that disposal area. In addition, about 40 percent of the sites in the Southwest EMMA area, which contains many sites of small capacity, need not be utilized in this analysis. The remaining areas (Southeast EMMA, MSD and 60 percent of Southwest EMMA) have sufficient wastewater assimilative capacity to accommodate the satellite plant discharge. A conceptual design of a land application system for the two satellite plants was prepared and estimates of construct- ion and operation costs were made. The system selected for economic evaluation provided for the transportation of the effluent from the Middle Charles River satellite plant to a distribution center at the Neponset River satellite plant. Force main and pumping station requirements to transport the wastewater to the three zones of application were determined. The estimated capital and annual operation and maintenance costs associated with these three main areas 3—108 o t1 o c1 d f ------- are presented below. Pipeline connection between the Middle Charles River and Upper Neponset River plants $12,000,000 Southwest EMMA Sites (outside MSD limits) : Wastewater Application Rate 30,300 m 3 /day (8 mgd) Average Distance from Upper Neponset River Plant 24.15 km (15 miles) Capital Costs Primary Force Main $11,900,000 Primary Pumping Station 270,000 Secondary Force Mains 5,440,000 Secondary Pumping Station 260,000 Land Application Facilities 11,800,000 Total Capital Costs $29,670,000 Annual Costs (Operation and Maintenance) Land Application Facilities $ 70,000 Power Cost 220,000 Total Annual (0 and M) Costs $ 290,000 MSD Sites : Wastewater Application Rate 45,000 m 3 /day (11.94 mgd) Average Distance from Upper Neponset River Plant 12.9 km (8 miles) Capital Costs Primary Force Main -- Primary Pumping Station -- Secondary Force Main $ 9,260,000 Secondary Pumping Station 340,000 Land Application Facilities 14,270,000 Total Capital Costs $23,870,000 Annual Costs (Operation and Maintenance) Land Application Facilities $ 84,000 Power Cost 110,000 Total Annual (0 and M) Costs $ 194,000 3—109 ------- Southeast EMMA Sites (outside MSD limits) : Wastewater Application Rate 137,000 m 3 /day (36.2 mgd) Average Distance from Upper Neponset River Plant 40.3 1cm (25 miles) Capital Costs Primary Force Main $30,000,000 Primary Pumping Station 1,210,000 Secondary Force Mains 8,250,000 Secondary Pumping Station 1,150,000 Land Application Facilities 15,210,000 Total Capital Costs $55,820,000 Annual Costs (Operation and Maintenance) Land Application Facilities $ 130,000 Power Cost 690,000 Total Annual (0 and M) Costs $ 820,000 Application of the effluent from the satellite treatment plants on land will eliminate the need for advanced waste treatment facilities, as secondary effluent is usually of sufficient quality for land application. The reduction in the level of treatment at the satellite plant sites from advanced wastewater treatment to secondary treatment results in a reduction in capital costs for satellite plant construction of about $32,000,000. However, land application of the satellite treatment plant effluent would require capital expenditures in excess of $121,000,000. Therefore, disposing of the effluent from the satellite plants by means of land application would result in a capital cost of over $89,000,000 more than the cost of disposal to the rivers. The reduction in the level of treatment at the satellite plants reduces the annual operation and maintenance costs of the two plants by nearly $2,800,000 per year. When this savings is compared with the operation and maintenance costs associated with land application of satellite plant flows of $1,304 per year, a net reduction in annual operation and maintenance costs of about $1,500,000 is acheived through land application of treatment plant effluent. The additional amortized construction cost for land application of satellite plant effluent within the EMMA Study area over a 30 year period would be about $6,900,000 per year. Combining the additional amortized construction cost and the net decrease in annual operation and maintenance costs results in a total additional annual cost for land application facilities of about $5,400,000 per year. This cost reflects the increased cost of land application of effluent from secondary treatment satellite plants above 3—110 ------- that of river discharge of effluent from advanced waste treatment satellite plants. Land application of satellite treatment plant effluent within the EMMA study area would present similar jurisdictional problems for the MDC that land application of coastal treat— inent plant effluent would present. Only about 20 percent of the satellite wastewater flow can be applied to land within the MSD service area. The remaining 80 percent must be discharged in towns outside the MSD service area. Application of that portion of satellite flow which could be assimilated by the sites within the MSD service area will reduce the cost of satellite treatment plant construction by nearly $10,000,000 by eliminating the need for advanced treatment for nearly 45,070 m 3 /day (11.9 mgd). The additional capital costs associated with land application are nearly $24,000,000. The reduction in plant cost partially offsets the high cost of land application facilities in the MSD service area. The reduced treatment required for that portion of the flow which will be applied to the land also reduces annual satellite plant operating costs by $630,000 per year, while the operation and maintenance costs for the land application facilities would be about $194,000 per year. The amortized additional capital cost of land application facilities over a 30 year period is nearly $1,100,000. Combining the amortized capital costs with the savings in annual operating and maintenance costs ($436,000 per year), land application of satellite plant effluent within the MSD service area increases annual southern MSD wastewater manage- ment costs by about $660,000 per year. Due to the significantly higher costs and the institutional problems associated with the land application systems, and the adverse environmental impacts which can be expected from the construction of the numerous pipelines and application sites required, land application has been eliminated from further consideration at this time. 3 111 ------- 3.2.5. Sludge Treatment and Disposal A systems approach was applied to identify the most attractive sludge management options. The inland satellite treatment plants and coastal area treatment plants were treated separately because of differences in the type and chemical characteristics of the sludge. Sludge from the inland plants will consist of a mixture of primary sludge, chemical sludge resulting from the phosphorous removal step, and biological sludge from the two-step nitrification process. Since a separate Environmental Impact Statement is addressing the disposal of primary sludge from the coastal area treatment plants, only secondary sludge from the coastal area plants was considered within the scope of this Environmental Impact Statement. The quantites and character- istics of the sludge were estimated for the four tributary service areas designated in the MDC’s recommended plan. The resulting sludge characteristics are presented in Table 3.2—26. The first step in the preliminary screening process was to identify all the available unit processes and operations applicable for sludge treatment, and to eliminate those which were deemed inappropriate for the coastal or inland treatment plant sludge. For convenience, the various unit processes and operations were classified into one of the following functional categories: A. Thickening B. Stabilization C. Dewatering D. Conversion E. Ultimate Disposal Although some unit processes and operations possess some characteristics which fall into several of these functional categories, for simplicity they were assigned to a single category. Table 3.2-27 lists the various processes and operations considered for sludge treatment in each of the functional categories. A. Thickening . “Thickening” refers to those processes which produce an increase in the solids content of sludge through a partial removal of the liquid fraction. The sludge output from the thickening process is still of a liquid consistency. The purpose of this step is to reduce the total volume of sludge for further processing and to improve the efficiency of subsequent treatment processes. 1. Gravit y . In gravity thickening, the sludge solids setUe to the bottom of a tank and form a concentrated sludge blanket. The sludge blanket is removed from the tank in a controlled 3—112 ------- TABLE 3.2-26 ESTIMATED SLUDGE CHARACTERISTICS Coastal Plants (Secondary Sludge Only) Inland Plants Deer Island Nut Island Middle Charles pper Neponset Sludge Quantity Metric tons/day (dry) 93.5 54.5 33.8 26.6 Short tons/day (dry) 103 60 37.3 29.3 Percent Volatile 67 72 60.7 60.3 Nitrogen Content (%) 6 6 4.6 4.6 Heavy Metals (mg/kg dry weight) Copper 1500 1340 631 654 Zinc 2482 316 1942 2011 Nickel 497 202 364 377 Cadmium 44 16 34 35 Lead 194 95 312 323 Mercury 6 3 6 6 Chromium 984 180 277 287 Note: All heavy metal concentrations are based on dry weight of sewage solids. The addition of chemicals to enhance dewatering will reduce heavy metal concentrations in proportion to the amount of solids added by the chemicals. ------- TABLE 3.2-27 ALTERNATIVE SLUDGE PROCESSES Thickening Stabilization Dewatering Conversion Ultimate Disposal Gravity Aerobic digestion Drying beds Incineration Landfill Air flotation Anaerobic digestion Vacuum filtration Pyrolysis Give away or market product Storage Pasteurization Horizontal belt Composting filtration Ocean disposal Wet oxidation Co-incineration Pressure filtration Land disposal Chemical oxidation Exotic processes (Purif ax process) Centrifugation Residue fusion H Heat treatment Heat drying (Porteous process) Chemf ix Chemical con— Puretec ditioning OrganiForm Irradiation Carver-Greenfie ld Solvent extraction (B.E.S.T.) ------- manner so as to obtain a high degree of solids concentration. Chemicals are sometimes added to enhance agglomeration. 2. Air Flotation . In air flotation, fine air bubbles are passed through the sludge. The bubbles adhere to the solid particles or are trapped in the particle structure, thereby increasing its buoyancy. The solids rise to the surface with the air bubbles, where they are skimmed of f. Chemicals are added to aid agglomeration. 3. Storage . Subsidence and concentration of solids naturally occurs when sludge is stored for long periods of time in lagoons or storage vessels. B. Stabilization . “Stabilization” describes those processes which reduce the offensive properties of sludge, such as odor, putrescence, and pathogenicity. Stabilization is usually accompanied by a reduction in the volatile content and an improvement in the dewaterability of the sludge. Most stabilization processes dissolve some of the solid constituents, resulting in an increase in strength of the liquid portion with regard to BOD, COD, etc. In this study, stabilization is used only to categorize those processes which can be applied to the sludge without previous extensive dewatering. 1. Aerobic Digestion . Aerobic digestion involves the biological oxida€ion of the volatile organic fraction of the solids in the presence of oxygen. This process is essentially an extension of the activated sludge process to the point where the microorganisms enter the “endogenous” phase and must utilize the sludge itself as a source of carbon. 2. Anaerobic Digestion . Anaerobic digestion involves the biological oxidation of the volatiles in the absence of oxygen. This process is normally conducted at about 35°C (95°F). A gas having a fuel value of about 22,000 kJ/m 3 (600 BTU’s/ft. 3 ) results from the conversion of the organic carbon to methane and carbon dioxide by the microorganisms which utilize the chemical bound oxygen as part of their metabolism. 3. Pasteurization . “Pasteurization” describes the prociss of heatin sludge to a prescribed temperature, and maintaining that temperature for a sufficient time to destroy pathogenic organisms. A typical past- eurization process might involve heating the sludge to 70°C (160°F), for a period of 30 minutes. Only a limited degree of volatile solids destruction and 3—115 ------- dissolving of solids is achieved by pasteurization. 4. Wet Oxidation . “Wet Oxidation” describes the oxidation of volatiles in the presence of oxygen and water at elevated temperature and pressure. In this process, compressed air or oxygen is mixed with the sludge to achieve “wet oxidation”. Since many of the sludge organics are dissolved in wet oxidation, a high strength liquid fraction results from this process. Wet oxidation also generally improves the dewaterability of the remaining solids. Wet oxidation is normally classified as low temperature and pressure, 150—205°C (300—400°F) and 2100—3400kN/m 2 (300—500 psi) or high temperature and pressure, 370°C (700°F) and 11,000 kN/m 2 (1650 psi). 5. Heat Treatment . Heat treatment, the conditioning of sludge at elevated temperature and pressure, is similar to wet oxidation, except that air or oxygen is not mixed with the sludge. The objective of heat treatment is to improve sludge dewaterability by dissolving and hydrolyzing the hydrated sludge fines. The “Porteous” process typically operates at temperatures of 1 5—204°C (350—400°F), and pressures of 1100—2100 kN/m (150-3 00 psi). As in the case of wet oxidation, a relatively high strength liquid fraction is generated. 6. Chemical Oxidation . “Chemical oxidation” describes the use of chemicals rather than oxygen to oxidize the volatiles. The most common chemical oxidation process is the “Purifax” process, which employs high dosages of chlorine to oxidize the organics. The reaction takes place in a closed reactor at a pressure of about 310 kN/m 2 (45 psi). This process generates a variety of non, or slowly, biodegradable organics. 7. Chemical Conditioning . Chemicals which reduce some offensive qualities and increase the dewaterability of sludge are usually added prior to the dewatering process. Ferric chloride functions primarily as a coagulant. Hydrated lime, which is almost always added with ferric chloride, destroys pathogens and controls odors. 8. Irradiation . Irradiation is a relatively new technology whiOh employs penetrating, ionizing radiation from either radioactive nuclear sources or electron accelerators to disinfect sludge. Presently, the Massachusetts Institute of Technology is conducting research on the use of an electron accelerator to disinfect sludge at the Deer Island Treatment Plant. Similar research is being conducted elsewhere utilizing beta and gamma emissions of radio—isotopes. In both cases of electron accelerators and radio—active material, disinfection properties appear to be enhanced 3—116 ------- by oxygenation prior to and during irradiation. C. Dewatering . “Dewatering” is used to describe those processes which remove a sufficient quantity of water from the sludge to change it physically from a liquid to a semi-solid. Sludge which has been subjected to a dewatering process will not flow and, therefore, can be handled basically as a solid material. Most dewatering processes incorporate the addition of chemicals such as ferric chloride, lime, alum or polyelectrolytes to improve the sludge dewaterability. 1. Drying Beds . Drying beds rely on natural evaporation and drainage to dewater the sludge. The most common type of drying bed consists of a sand or gravel bed equipped with a system of underdrains. Paved drying beds with limited drainage systems have also been used successfully at some treatment plants. 2. Vacuum Filters . Vacuum filters remove the moisture from sludge by applying suction to the underside of a filter media. The most common type is the rotary filter which has a filter belt attached to a rotating drum. The drum is partially immersed in the liquid sludge so that, as it rotates, a solid cake is formed on the filter belt. The vacuum is released at a specific point in the drum’s rotation, and the cake is scraped off before the filter belt is reimrnersed in the liquid sludge. 3. Horizontal Belt Filters . Horizontal belt filters are similar to vacuum filters, except that pressure is used to force the water from the sludge. The most common types employ two belts with the sludge sand- wiched between them. A system of rollers is used to apply pressure to the layer of sludge trapped between the belts, thereby dewatering the sludge as the liquid is forced through the filter media. 4. Filter Presses . Filter presses operate on the same principal as horizontal belt filters, except at much higher pressures. The filter press normally consists of several vertical plates mounted on a rigid frame. Liquid sludge is fed between the plates and the plates are mechanically pressed together, forcing liquid through drainage ports. When the cycle is completed, the plates are separated so that the solid cake will drop to a collection system located below the unit. Filter presses tend to yield a very dry sludge cake. 3 -117 ------- 5. Centrifuges . Centrifuges use centrifugal force to achieve a high rate of separation between the liquid and solid fractions of the sludge. Continuous rotating bowl centrifuges are the most common type used for sludge dewatering. Sludge is introduced at one end of the rotating bowl. As the centrifuge spins, the solids are collected along the periphery of the machine where they are continuously conveyed to the outlet. 6. Heat Drying . Heat drying employs elevated temp- eratures to increase the rate of evaporation of water from the sludge. An outside heat source must be provided to elevate the temperature of the sludge to a typical operating range of 370—540°C (700-1000°F). Most processes employ hot gases as the heat source, which can be placed in direct contact with the sludge or separated from the sludge through an intermediate heat exchanger. D. Conversion . “Conversion” is used to represent those processes which can impart a major change to the basic chemical and physical properties of the sludge itself. The product resulting from a conversion process does not resemble the material which is commonly associated with the word “sludge”. Most conversion processes produce some degree of stabilization, volume reduction, and further dewatering of the solids as part of the process. 1. Incineration . “Incineration” refers to the thermal oxidation of sludge to a sterile ash residue. Normally, the sludge is dewatered to an autothermic solid concentration, so that the burning process is self-sustaining and requires little, if any, supple- mental fuel. Sufficient air is provided to sustain complete combustion, with operating temperatures normally maintained between 7 60—925°C (1400—1700°F). The most common types of incinerator employed for sludge incineration are multiple hearth and fluidized bed reactors. Control devices to minimize emissions to the air can be added. 2. Pyrolysis . “Pyrolysis” refers to the destructive thermal distillation of sludge in an oxygen-deficient atmosphere. The volatile fraction of the sludge is either gasified and/or liquified during the process, leaving the remaining solids in the form of a residual char and/or slag. In some instances, the gas and liquid by—products of the process have a sufficient heat value for use as a supplemental fuel. Pyrolysis systems have been operated in the range of 480-1650°C (900-3000°F). While many pilot studies and demon- strations of pyrolysis units are currently underway, no large scale units have achieved satisfactory operation. 3—118 ------- 3. Composting . Composting is a process which achieves high levels of stabilization and volatile destruction through natural biological aerobic decomposition. The sludge is biochemically converted to a sterile humus material, which may be suitable as a soil conditioner. The microbial activity generates heat with temperatures reaching about 60—70°C (140-160°F), which is sufficient to destroy most pathogens. The most successful operation to date has been at Beltsville, Maryland, where composting is achieved by mixing raw sludge with a 20 percent moisture content with wood chips and piling the mixture in windrows, or continuous piles. Air is continuously passed through the piles via a system of pipes located at the base of the piles. The mixture is aerated for about 21-24 days, after which time the wood chips are removed. The remaining material is then aged for an additional 30 days prior to land application. 4. Co-incineration . “Co—incineration” refers to the incineration of a mixture of dewatered sludge and solid wastes. Co-incineration is normally carried out in conventional incinerators, such as the multiple hearth type. The mixing of sludge with solid wastes has the advantage of using some of the heat value of the solid waste to remove the residual moisture in the sludge. The product of the co—inciner- ation process is a sterile ash similar to that obtained by sludge incineration. In the context of this report, all the co—incineration processes considered also incorporate the generation of power and the recovery of inert materials such as glass, ferrous metals,and aluminum from the solid wastes. 5. Exotic Processes . Several processes which are applicable to sludge conversion have been proposed and patented by various companies. A brief summary of some of these processes follows: a. Franklin Institute Laboratory Residue Fusion Process . This is a thermal process which treats mixtures of shredded incinerator residue and dewatered sludge with a thermal process to yield a high quality aggregate. The process consists of a rotary kiln where complete burn—out is achieved followed by a high temperature 1200°C (2200°F), fusion furnace. The process is presently in the early stages of development. b. Chemf ix Process . This chemical fixation process involves solidifying the sludge with proprietary chemicals and is typical of many chemical fixation processes being marketed. The process produces a gelated solid material. 3—119 ------- c. Puretec (Barber—Coleman) . This process heat treats liquid sludge with id under pressure prior to dewatering. It is somewhat similar to wet oxidation but provides for heavy metal recovery from the liquid fraction. d. OrganiForm (Organics Inc.) . This process combines wet sludge with urea and formaldehyde to form a dry cake. The end product is dry, sterile, and high in nitrogen content. e. Carver-Greenfield Process . This process involves the use of multi—effect evaporation for sludge dehydration. The sludge is initially mixed with oil prior to entering, an evaporator, where the water is boiled off, leaving the solids suspended in the oil. The solids are then separated from the oil in a centrifuge and incinerated to produce steam. f. Solvent Extraction and DeJ ydration (Resources Conservation Co., BE.S.T. Process) . This process mixes wet sludge with an aliphatic amine to improve solids separation. The solids are recovered in ‘a centrifuge and the sludge cake is dried to obtain a sterile, low moisture product. E. Ultimate Disposal . “Ultimate Disposal” is used to describe the final destination of the sludge or sludge end product. The number of alternatives available for ultimate disposal is limited. In the final analysis, either the ocean or the land itself must serve as the final destination. 1. Landfill . “Landfill” refers to the controlled application or burial of large quantities of solid residue as a fill material at a designated site. The material is normally covered with earth on a daily basis to prevent the creation of nuisance conditions or health hazards. The material must be sufficiently dewatered to minimize leaching of dissolved materials to the groundwater. Leachate collection and monitoring systems are employed as a precautionary measure to prevent groundwater contamination. 2. Land Application . Land application is the controlled application of liquid or solid sludge or sludge products to the land, thereby returning nutrients to the soil. In the case of liquid sludge application, the soil serves to filter the solids from the liquid sludge before it reaches the ground- water. In the case of dry cake or compost application, the solids are mixed with the soil, increasing its friability and humus content. 3—120 ------- Land application has been practiced on areas such as agriculture croplands, grazing lands, golf courses forests, and strip mine reclamation projects. The applicability of this method of ultimate disposal is closely dependent upon public acceptance, the proximity of potential land application sites to the treatment plant, and sludge and soil conditioners. 3. Give Away or Market Product . Marketing and “Give Away” programs are possible, if the sludge has been treated by one of the conversion processes to produce a publicly acceptable end product. “Give Away” programs such as the Chicago Nu-Earth or Philadelphia’s Philorganic Program provide the sludge product free of charge to the general public for use as a soil conditioner. A marketing program, such as the Kellogg program in Los Angeles, or the Milwaukee Milorganite program, process the sludge into a high value soil conditioner or fertilizer, and sell it to the general public through a retail distribution system. 4. Ocean Disposal . “Ocean Disposal” refers to the dumping of the sludge or sludge products in the ocean. This can be accomplished via an ocean outfall or by a system of ocean-going barges. Presently, the EPA is attempting to phase out all ocean disposal of sludge by 1981. Elimination of Unit Processes for Coastal Area Treatment Plants A. Thickening . Since the sludge management program for the harbor plants is limited to secondary sludge only, gravity thickening and storage have been eliminated from further consideration. Both of these processes are of limited effectiveness when applied to secondary sludge due to the characteristics of such a sludge. Previous experience has shown air flotation to be the method of choice for the thickening of secondary sludge. B. Stabilization . Chemical oxidation by the Purifax process has been eliminated from consideration because of the high chlorine dosage required and the potential for generation of chlorinated hydrocarbons. The heat treatment and wet oxidation processes have not been effective for waste activated sludge. Therefore, no further consideration is given to these processes. Irradiation has been eliminated since it is still in research and development stages. C. Dewatering . The dewatering of waste activated (secondary) sludge by itself is seldom done. There is only limited operational data available on any dewatering process employ- ing 100 percent waste activated (secondary)sludge. 3—121 ------- Centrifuges, horizontal belt filters and vacuum filters were considered as equivalent processes for the purpose of this analysis. Each of these unit operations is capable of attaining similar solids concentration and solids capture. Differences in unit cost for these three alternatives are small and the choice of the preferred method should be determined during facilities planning. In this study, vacuum filtration was used for cost comparisons. The heat drying process was not considered economical for dewatering a sludge slurry of 3—4 percent solids concentration, due to the excessive amount of energy required. However, heat drying was considered as a conver- sion process to further reduce the moisture content following a mechanical dewatering process when considering the Give Away or Market Product option for ultimate disposal. D. Conversion . All of the unconventional or exotic processes have been eliminated because of the lack of extensive operation experience to demonstrate their practicability and cost—effectiveness. E. Ultimate Disposal . Ocean disposal has been eliminated because of EPA and public opposition to the use of the ocean for sludge disposal. The remaining unit processes which were considered for developing alternative sludge management systems for the coastal area treatment plants are shown in Table 3.2—28. Elimination of Unit Processes for Inland Satellite Treatment Plants A. Thickening . Sludge generated at the satellite plants consists of both primary sludge and secondary sludge. The secondary sludge includes biological sludge irom the first and second stage aeration processes, in addition to alum sludge precipitated in the first stage aeration clarifiers. Experience has shown that better solids concentrations and operation can be attained by segregating the primary sludge from the secondary sludge prior to the sludge thickening process. Air flotation has been selected as the method of choice for thickening of the secondary sludge, since this type of sludge is normally more amenable to air flotation thickening than other thickening processes. Gravity thickening and storage are of limited effectiveness when applied to waste activated (secondary) sludge. Gravity thickening has been selected as the method of choice for thickening of the primary sludge. Gravity thickening is more economical than air flotation and does not require the addition of polymers. Storage has been eliminated as a thickening process because of space constraints at the satellite plants. 3—122 ------- ( J TABLE 3.2-28 REMAINING SLUDGE PROCESS ALTERNATIVES FOR COASTAL PLANTS Thickening Stabilization Dewatering Conversion Ultimate Disposal Air flotation Aerobic digestion Drying beds Incineration Landfill Anaerobic digestion Vacuum filtration Pyrolysis Give away or market product Pasteurization Pressure filtration Composting Land application Chemical äondit- Heat drying Co-incineration ioning ------- B. Stabilization . At the satellite plants, it has been assumed that the thickened primary and secondary sludges will be blended prior to further processing. This will result in a more economical sizing of subsequent unit processes. Chemical oxidation by the Purifax process has been eliminated from consideration because of the high chlorine dosage required and the potential for generation of chlorinated hydrocarbons. High temperature, high pressure wet oxidation has been eliminated because of the numerous operating problems and high maintenance costs experienced with this process at other treatment plants. In addition, irradiation has been eliminated because it is only in the research and development stage. Low pressure wet oxidation and heat treatment employ similar equipment and incur comparable capital and operating and maintenance costs. The main difference between the two processes is that air is introduced to the reactor during wet oxidation. For simplicity of analysis, the term heat treatment has been used to describe a process which will operate at a temperature of about 195°C (380°F), and at a pressure of about l400kN/m 2 (200 psi). Low pressure wet oxidation can be substituted for heat treatment in any of the alternatives including this unit process. Pasteurization differs from heat treatment only to the extent that the process operates at lower temperatures and pressures. Heat treatment, however, provides the added benefit of eliminating the need for additional chemicals in subsequent dewatering steps, while providing pathogen destruction. Therefore, heat treatment was used in lieu of pasteurization for those alternatives involving a heat disinfection step. For combined sludges, experience has shown that anaerobic digestion is more cost—effective than aerobic digestion. While the capital cost of anaerobic digestion is higher than aerobic digestion, this is more than offset by the energy value of the gas produced during anaerobic digestion. Aerobic digestion has been applied mainly to secondary sludges or at small treatment plants. In addition, a higher degree of volatile solids reduction can be achieved by anaerobic digestion. Therefore aerobic digestion was eliminated in favor of anaerobic digestion for the satellite plant alternatives incorporating a digestion process. C. Dewatering . Centrifuges, horizontal belt filters and vacuum filters were considered as equivalent processes for the purpose of this analysis. Each of these unit operations is capable of attaining similar solids con- centration and solids capture. Differences in unit cost 3—124 ------- for these three alternatives are small and the choice of the preferred method should be determined during facilities planning. In this study, vacuum filtration was used for cost comparisons. However, belt filters and centrifuges can be substituted for vacuum filtration in any of the alternatives involving this unit process. D. Conversion . All the exotic or unconventional conver- sion processes have been eliminated because of the lack of extensive operating experience to demonstrate their practicability and cost-effectiveness. E. Ultimate Disposal . Ocean disposal has been eliminated because of EPA and public opposition to the use of the ocean for sludge disposal. The remaining unit processes which were considered for developing sludge management systems for the inland satellite treatment plants are shown in Table 3.2-29. 3—125 ------- TABLE 3.2-29 REMAINING SLUDGE PROCESS ALTERNATIVES FOR SATELLITE PLANTS Thickenin9 Stabilization Dewatering Conversion Ultimate Disposal Gravity Anaerobic digestion Vacuum filtration Incineration Landfill Air flotation Heat treatment Pressure filtration Pyrolysis Give away or market product Chemical condit- Heat drying Composting ioning Land application Resource recovery center Truck to coastal plant ------- 3.3 INTERMEDIATE SCREENING OF SUBSYSTEM ALTERNATIVES 3.3.1. Coastal Area Wastewater Treatment Plants The coastal area wastewater treatment plants sites considered which survived the preliminary screening process were: Broad Meadows; Deer Island: Long Island; Nut Island (for expansion of primary treatment facilities only); and Squantum Point. Combinations of possible degrees of treatment (primary only, secondary only, and both primary and secondary) at the various remaining alternative sites were developed into alternative coastal area wastewater treatment plant subsystems. These subsystem alternatives were then evaluated both with and without satellite wastewater treatment plants. In all alternatives that consider satellite plants one satellite plant would be located along the Charles River and one would be located along the Neponset River. The satellite plants would treat wastewaters from the outer areas of the southern MSD service area. Therefore, when satellite plants are considered, the coastal area plant treating the remainder of the wastewater generated in the southern MSD service area would receive less flow than when satellite plants are not considered. Each coastal area treatment plant alternative can be considered to be a combination of five elements, as follows: 1 - The location of primary treatment facilities for the wastewater from the northern MSD service area. 2 - The location of secondary treatment facilities for the wastewater from the northern MSD service area. 3 - The location of primary treatment facilities for the wastewater from the southern MSD service area. 4 - The location of secondary treatment facilities for the wastewater from the southern MSD service area. 5 — Inclusion or exclusion of inland satellite treatment plants. As a result of the preliminary screening process, the following coastal area wastewater treatment plant subsystem alternatives were developed: 3—127 ------- During the preliminary screening process it was determined that, due to the relatively recent construction (1968) and good condition of the existing Deer Island Primary Treatment Plant, these facilities should be maintained and expanded as necessary in order to provide at least primary treatment to the wastewater generated in the northern MSD service area. Therefore, all alternatives consider primary treatment facilities for the northern service area flow to be located on Deer Island. In order to facilitate the discussion of these alter- natives, each alternative will be referred to in an abbreviated form. For example, Alternative G, which consists of primary treatment facilities for the northern service area at Deer Island, secondary treatment facilities for the northern service area at Long Island, primary treatment facilities for the southern service area at Nut Island and secondary treatment facilities for the southern service area at Long Island, and does not include inland satellite treatment plants, would be designated: “Deer: Long/ Nut: Long — w/o Sat.”. Therefore, the sixteen alternatives under consideration in this section can be designated as follows: Deer! Broad Meadows: Broad Meadows - w/o Sat. Deer! Broad Meadows: Broad Meadows - w/Sat. Deer! Squantwn: Squantum — w,/o Sat. Deer/ Squantum: Squantum - w/Sat. Deer/ Long: Long - w,’o Sat. Deer! Long: Long - w/Sat. Long! Nut: Long - w ’o Sat. North Flow Loc. of Primary Alt. Treatment Loc. of Secondary Treatment South Flow Loc. of Loc. of Primary Secondary Treatment Treatment A Deer B Deer C Deer D Deer E Deer F Deer G Deer H Deer I Deer J Deer K Deer L Deer M Deer N Deer 0 Deer P Deer Brd. Head. Brd. Mead. S qua n turn Squantuxn Isi. Isi. Isi. Isl. Isi. Isi. Isi. Isl. Isl. Isi. Isi. Isl. Isi. Isi. Isi. Isi. Deer Deer Deer Deer Deer Deer Long Long Deer Deer Long Long Deer Deer Deer Deer Isi. Isl. Isi. Isi. Isi. Isl. Isi. Isi. Isl. Isi. Isl. Isi. Isi. Isl. Isi. Isi. Brd. Mead. Brd. Mead. Squantuin Squantuin Long Isi. Long Isi. Nut Isl. Nut Isi. Nut Isl. Nut Isi. Long Isl. Long Isi. Nut Isi. Nut Isi. Deer Isi. Deer Isi. Sats. or No Sats . No Sats. Sats. No Sats. Sats. No Sats. Sats. No Sats. Sats. No Sats. Sats. No Sats. Sats. No Sats. Sats. No Sats. Sats. Long Long Long Long Long Long Long Long Deer Deer Deer Deer Isi. Isi. Isi. Isi. Isi. Isi. Isi. Isi. Isi. Isi. Isi. Isi. A. B. C. D. ‘ E. F. ‘ G. Deer: Deer: Deer: Deer: Deer: Deer: Deer: 3—128 ------- H. Deer: Long/ Nut: Long - w/Sat. I. Deer: Deer/ Nut: Long - w/o Sat. J. Deer: Deer/ Nut: Long - w/Sat. K. Deer: Long/ Long: Long - w/o Sat. L. Deer: Long/ Long: Long - w/Sat. M. Deer: Deer/ Nut: Deer — w/o Sat. N. Deer: Deer! Nut: Deer - w/Sat. 0. Deer: Deer/ Deer: Deer — w/o Sat. P. Deer: Deer/ Deer: Deer — w/Sat. The sixteen subsystem alternatives listed above are described in more detail below. For intermediate screening purposes, the quantities of wastewater assumed to be flowing to the various plants are those which the EMMA Study estimated will be generated in the various portions of the MSD service area in the year 2000. These quantities of flow are: Total MSD service area 2,220,000 m 3 /day (586 mgd) Northern MSD service area 1,510,000 m 3 /day (400 mgd) Southern MSD service area without satellites 700,000 m 3 /day (186 mgd) Southern MSD service area with satellites 490,000 m 3 /day (130 mgd) Satellite areas 210,000 m 3 /day (56 mgd) A. Deer: Deer/ Broad Meadows: Broad Meadows - w/o Sat . In this alternative, the wastewater from the northern MSD service area would receive primary and secondary treatment at Deer Island and the wastewater from the southern MSD service area would receive primary and secondary treatment at Broad Meadows. The existing primary treatmer.t facilities on Deer Island would be expanded and secondary treatment facilities would be constructed. In order to expand and upgrade the Deer Island plant as required including provision for future expansion (year 2050), without adding fill to Boston Harbor, it would be necessary to utilize either the land presently occupied by the prison or the drumlin area. Utilizing the area occupied by the prison would require that all prison facilities be removed from the island. Utilizing the drumlin area would require the removal of the drumlin. The expansion of the existing Deer Island Primary Treatment Plant would enable most of the existing plant facilities to be utilized in the upgraded plant. The Brqad Meadows site has adequate area to accommodate a 700,000 m ’/day (186 mgd) plant with provision for future expansion (year 2050) and a buffer zone of approximately 152 meters (500 feet) to the nearest residence. The portion of the High Level Sewer between Broad Meadows and Nut Island would be utilized as a plant effluent conduit which would transport the effluent from the Broad Meadows plant to the existing Nut Island oütfalls. The hydraulic capacity 3—129 ------- of this portion of the High Level Sewer is adequate for average flows, but a relief conduit would be required to transport peak flows to Nut Island. Placing the plant at Broad Meadows would enable the existing Nut Island Primary Treatment Plant to be demolished. A pumping station would be required on Nut Island for effluent discharge into the existing outfalls during periods of above average flows and high tides. It is estimated that the pumping station would operate approximately 35 percent of the time. A lift station would also be required on Nut Island in order to lift the wastewater from the relief conduit to the outfall system. The remainder of Nut Island would then be available for other purposes, possibly for recreation. In addition, plant influent and effluent conduits would be required to connect the plant to the existing High Level Sewer, a new interceptor would be required to transport the waste — water from the Houghs Neck peninsula and the Braintree— Weymouth Pumping Station to the Broad Meadows plant influent conduit, and the existing Nut Island outfall system would require modifications. B. Deer: Deer/ Broad Meadows: Broad Meadows - w/Sat . This alternative is similar to Alternative A described above, except that approximately 30 percent of the wastewater from the southern MSD service area would receive tertiary treat- ment at two satellite treatment plants on the Charles and Neponset Rivers, thereby reducing the amount of wastewater requiring treatment at a plant at Broad Meadows. Therefore, a Broad Meadows treatment plant for this alternative-would be smaller than the corresponding plant in Alternative A, thereby increasing the buffer zone to the nearest residence to approximately 213 meters (700 feet). The High Level Sewer would have adequate capacity to transport the peak flow from this treatment plant at Broad Meadows to the Nut Island outfall system and, therefore, it would not be necessary to construct a relief conduit or a lift station as would be required in Alternative A. C. Deer: Deer/ Sguantum: Squantum - w/o Sat . In this alternative, the wastewater from the northern MSD service area would receive primary and secondary treatment at Deer Island and the wastewater from the southern MSD service area would receive primary and secondary treatment at Squantum Point. The facilities at Deer Island would be expanded and upgraded as described for Alternative A. The Squantum Point site is remotely located from existing residential areas. The site is of adequate area to accommodate a 700,000 m 3 /day (186 mgd) treatment plant with provision for future expansion (year 2050) and a buffer zone of more than 107 meters (350 feet) between the plant and a nearby marina. The buffer zone between the plant and the adjacent Jordan Marsh warehouse would be more than 91 meters (300 feet). 3—130 ------- The Squantum site is nearly 6.4 kilometers (4 miles) from the existing High Level Sewer, which is the main interceptor in the southern MSD service area. The High Level Sewer would be utilized to transport the plant effluent to the Nut Island outfalls, which would require modifications. It would be necessary to construct influent and effluent conduits between the High Level Sewer and the Squantum plant site. As the High Level Sewer would not have adequate capacity to handle peak flows from the plant, a relief conduit to Nut Island would be required. A lift station would be required on Nut Island to lift the wastewater from the relief conduit to the outfall system. In addition, a new interceptor to transport the wastewaters from the Houghs Neck peninsula and the Braintree —Weyrnouth Pumping Station to the Squantum plant influent conduit would also be required. The existing Nut Island Primary Treatment Plant could be demolished, and an effluent pumping station would be required at Nut Island to permit discharge of peak flows at periods of high tides. It is estimated that this pumping station would be required to operate approximately 35 percent of the time. D. Deer: Deer! Squantum: Squantum - w/Sat . This alter- native is similar to Alternative C discussed above, except that the quantity of wastewater reaching the treatment plant at Squantum would be reduced by about 210,000 m3/day (56 mgd) due to the addition of two satellite treatment plants on the Charles and Neponset Rivers. Therefore, the Squantum treatment plant for this alternative would be smaller than the corresponding plant in Alternative C, resulting in an increase of the buffer zone between the treatment plant and the marina to approximately 244 meters (800 feet), and between the treatment plant and the Jordan- Marsh warehouse to approximately 183 meters (600 feet). It would be possible to utilize the High Level Sewer without relief to transport the plant effluent to the Nut Island outfalls. E. Deer: Deer! Long: Long - w/o Sat . In this alternative, the wastewater flow from the northern MSD service area would receive primary and secondary treatment at Deer Island, and the wastewater from the southern MSD service area would receive primary and secondary treatment at Long Island. The expansion and upgrading of the Deer Island Treatment facilities is described in Alternative A. Long Island was, as a result of the preliminary screening, considered to be the most acceptable harbor island alternative site for treatment plant construction (not including Deer and Nut islands which are no longer true islands) from both environmental and engineering considerations. Construction of the treatment plant for the southern MSD service area at this location would require approximately 23.5 hectares (58 acres) of developable 3—131 ------- land on Long Island. Long Island has adequate area for the construction of a treatment plant of this size without requiring relocation of the cemeteries which exist on the island or filling of the harbor. Extensive regrading of the site would be required. A buffer zone in excess of 518 meters (1700 feet) could be maintained between the existing hospital on Long Island and the treatment plant. The site is remote from residential areas. A submerged pipeline would be required across Boston Harbor to connect the treatment plant on Long Island to the end of the existing interceptor system at Nut Island. It would be necessary to construct a headworks on Nut Island to provide preliminary treatment (screens and grit chambers) for the wastewater before it is transported to Long Island for treatment. The High Level Sewer would not have adequate capacity to carry peak flows to Nut Island. Therefore, a relief sewer to Nut Island would be required. A lift station would also be required on Nut Island to lift the wastewater from the relief sewer to the headworks. Although siting the plant on Long Island is contrary to the use of Long Island recommended in the Boston Harbor Islands Comprehensive Plan, it was felt that this alternative was justifiable as it provided compensating benefits. Most of Nut Island would become available for recreational development, there would still be considerable area for recreational develop- ment on Long Island, and filling of the bay would not be necessary. F. Deer: Deer! Long: Long — w/Sat . This alternative is similar to Alternative E, except that about 30 percent of the wastewater from the southern MSD service area would receive tertiary treatment at two satellite plants. The resulting decrease in wastewater which would reach Long Island reduces the treatment plant area requirements to approximately 154 hectares (38 acres), and the buffer zone between the treatment plant and the hospital would increase to more than 579 meters (1900 feet). A submerged pipeline across Boston Harbor, connecting the treatment plant on Long Island to the end of the existing interceptor system on Nut Island, and a headworks on Nut Island would be required, but would not be as large as those required for Alternative E. It would be possible to utilize the High Level Sewer without relief to transport the wastewater to the headworks on Nut Island. G. Deer: Long/ Nut: Long - w/o Sat . In this alternative, the wastewater from the northern M D service area and from the southern MSD service area would receive primary treat- ment at Deer and Nut Islands, respectively. The primary effluent from both primary treatment plants would flow to Long Island, where secondary treatment would be provided. The existing primary treatment facilities on Deer Island would have to be expanded due to the anticipated 3—132 ------- increase in the quantity of wastewater generated in the MSD. This expansion to the primary treatment facilities would be possible without encroaching on the land presently occupied by the prison or the drumlin, and without adding any fill to the harbor. Similarly, the existing primary treatment facilities on Nut Island would require expansion. This expansion on Nut Island would require about 1.2 hectares (3 acres) of fill. The construction of secondary treatment facilities on Long Island to treat the primary effluent from both the Deer and Nut Island primary treatment plants would require approximately 40.5 hectares (100 acres) of land. This area is available on Long Island, and a buffer zone of about 91.4 meters (300 feet) could be maintained between the treatment plant and the existing hospital. However, most of the area which was recommended for recreational development by the Boston Harbor Islands Comprehensive Plan would be utilized by treatment facilities. In addition, it would be necessary to construct submerged pipelines across Boston Harbor which would connect the treatment plants on Deer and Nut Islands to the treatment plant on Long Island. The High Level Sewer, which carries the wastewater to the Nut Island facility, would not have adequate capacity to carry peak flows. Therefore, a relief sewer to Nut Island would be required, and a lift station would be required on Nut Island to lift the wastewater from the relief sewer to the treatment facilities on Nut Island. H. Deer: Long! Nut: Long - w/Sat . This alternative is similar to Alternative G, except that the inclusion of satellite treatment plant would reduce the quantity of wastewater reaching the Nut Island and Long Island plants. It is possible that the necessary expansion of the primary treatment facilities on Nut Island could be accomplished without requiring any fill. The area required on Long Island for the secondary treatment facilities would be reduced to about 36.4 hectares (90 acres), and the pipeline across Boston Harbor from Nut to Long Island would be of a smaller size than would be required under Alternative G. It would be possible to utilize the High Level Sewer without relief to transport the wastewater to the Nut Island facilities. I. Deer: Deer! Nut: Long — w/o Sat . In this alternative, the wastewater from the northern MSD service area would receive primary and secondary treatment at Deer Island, and the wastewater from the southern MSD service area would receive primary treatment at Nut Island and secondary treatment at Long Island. The existing primary treatment facilities on Deer Island would require expansion and upgrading as discussed for Alternative A. 3—133 ------- The existing primary treatment facilities on Nut Island would require expansion in order to handle the increase in wastewater flow anticipated. This expansion would require approximately 1.2 hectares (3 acres) of fill. A relief sewer would be required to carry peak flows to the Nut Island facilittes, and a lift station would be required on Nut Island to lift the wastewater from the relief sewer to the plant. The construction of facilities on Long Island which would give secondary treatment to the effluent from the primary treatment plant on Nut. Is1ar d would require approx- imately 14.2 hectares (35 acres) of land. Most of the open space on Long Island would remain available for recreational purposes. Construction of a submerged pipeline across Boston Harbor from Nut to Long Island would be required to transport the primary effluent to the secondary treatment facilities. J. Deer: Deer/ Nut: Long - w/Sat . This alternative is similar to Alternative I, except that the construction of satellite plants would reduce the quantity of wastewater reaching the Nut and Long Island plants. The expansion of the primary treatment facilities on Nut Island could possibly be accomplished without requiring any fill, and the area required on Long Island for the secondary treat- ment facilities would be reduced to about 9.3 hectares (23 acres). The pipeline across Boston Harbor, from Nut to Long Island, would be smaller in size than would be required under Alternative I, and the High Level Sewer would not require any relief. K. Deer: Long/ Long: Long w/o Sat . In this alternative, the wastewater from the northern MSD service area would receive primary treatment at Deer Island and secondary treatment at Long Island. The wastewater from the southern MSD service area would receive primary and secondary treatment at Long Island. The necessary expansion of the existing primary treatment facilities on Deer Island would be possible without encroaching on the land presently occupied by the prison or the drumlin, and without adding any fill to the harbor. A submerged pipeline across the President Roads Channel would be required to transport primary effluent from Deer Island to the treatment facilities on Long Island. The treatment plant on Long Island would occupy approximately 46.5 hectares (115 acres) of land. This would require utilizing most of the available area south of the hospital at d approximately 2 hectares (5 acres) of fill for a roadway corridor to provide access to the hospital. 3—134 ------- Extensive regrading would be required, and a buffer zone of approximately 91 meters (300 feet) could be maintained between the treatment plant and the hospital. It would be necessary to relocate the cemetery which is presently on Long Island. The existing primary treatment facilities on Nut Island would be demolished. A headworks would be required to provide preliminary treatment for the wastewater before it is transported to Long Island. The High Level Sewer would require relief, and a lift station would be required on Nut Island. With the exception of the area required for the headworks and the lift station, the remainder of Nut Island would become available for other purposes, such as recreation. A submerged pipeline across the Nantasket Roads Channel would be required to transport the effluent from the headworks on Nut Island to the treatment facilities on Long Island. L. Deer: Long! Long: Long - w/Sat . This alternative is similar to Alternative K, except that the construction of satellite treatment plants would reduce the quantity of wastewater flowing to the treatment plant on Long Island. The area required on Long Island for wastewater treatment facilities would be reduced to approximately 40.5 hectares (100 acres), and the pipeline across the Nantasket Roads Channel would be of a smaller size than would be required under Alternative K. Although this alternative requires about 6.1 hectares (15 acres) less land that does Alternative K, it is anticipated that, due to the shape of Long Island and the limitations on treatment plant configuration, it would still be necessary to add about 2 hectares (5 acres) of fill and to utilize the land presently occupied by the cemetery. The High Level Sewer would not require relief, a lift station would not be required on Nut Island, and the required headworks on Nut Island would be smaller than would be required under Alternative K. M. Deer: Deer! Nut: Deer — w/o Sat . In this alternative, the wastewater from the northern MSD service area would receive primary and secondary treatment at Deer Island, and the wastewater from the southern MSD service area would receive primary treatment at Nut Island and secondary treatment at Deer Island. On Deer Island, the existing primary treatment facilities would be expanded and the required secondary treatment facilities would be constructed. In order to construct these facilities on Deer Island without adding fill to Boston Harbor, it would be necessary to utilize most of the island including the land presently occupied by the prison, the drumlin area, and more than half of the southern end which the Boston Harbor Islands Comprehensive Plan recommended being used for rec eationa1 purposes. 3—135 ------- Otherwise, depending upon which parts of the island were to remain unoccupied by treatment facilities, from about 4 to 24 hectares (10 to 60 acres) of fill would be required. It would be necessary to expand the existing primary treatment facilities on Nut Island, and this expansion would require about 1.2 hectares (3 acres) of fill. A relief sewer would be required to augment the capacity of the High Level Sewer, and a lift station would be required on Nut Island. In addition, it would be necessary to construct a submerged pipeline across Boston Harbor which would transport the primary effluent from Nut Island to the treatment facilities on Deer Island. N. Deer: Deer/ Nut: Deer - w/Sat . This alternative is similar to Alternative M, except that satellite treatment plants would treat about 30 percent of the wastewater from the southern MSD service area, thereby reducing the quantity of wastewater reaching the Nut Island and Deer Island treatment plants. The area required for treatment facilities on Deer Island would be reduced so that less than half of the area recommended for recreational development would be utilized by treatment facilities. The High Level Sewer would not require relief, and a lift station would not be required on Nut Island. Also, it is possible that the necessary expansion of the primary treatment facilities on Nut Island could be accomplished without requiring any fill, and the size of the pipeline across Boston Harbor would be smaller than would be required under Alternative M. 0. Deer: Deer! Deer: Deer — w/o Sat . This alternative represents the greatest consolidation of wastewater treatment facilities. The wastewater from the entire MSD service area would receive primary and secondary treatment at Deer Island. The existing primary treatment facilities on Deer Island would be expanded, and the required secondary treat— ment facilities would be constructed. In order to eliminate the need to add fill to Boston Harbor, the resulting treat- ment plant would occupy the entire island, including the land presently occupied by the prison, the drumlin area, and most of the southern end. On Nut Island, the existing primary treatment facilities would be demolished. A headworks consisting of screens and grit chambers would be required to provide preliminary treatment for the wastewater before it is transported to Deer Island. A relief sewer would be required to augment the capacity of the High Level Sewer, and a lift station would be required on Nut Island to lift the wastewater from the relief sewer to the headworks on Nut Island. With the exception of the area required for the headworks, 3—136 ------- and lift station, the remainder of Nut Island would become available for other purposes, perhaps recreation. It would be necessary to construct a submerged pipeline across Boston Harbor which would transport the wastewater from the headworks on Nut Island to the treatment facilities on Deer Island. p. Deer: Deer/ Deer: Deer - w/Sat . This alternative is similar to Alternative 0, except that the construction of satellite treatment plants reduces the quantity of waste— water flowing to the headworks on Nut Island and the treatment facilities on Deer Island. The area required for treatment facilities on Deer Island would be reduced so that approximately half of the land at the southern end of the island would be available for recreational purposes, and the size of the pipeline across Boston Harbor would be reduced. The High Level Sewer would not require relief, a lift station would not be required on Nut Island, and the headworks on Nut Island would be smaller than required for Alternative 0. 3—137 ------- 3.3.2. Elimination of Coastal Area Treatment Plant Subsystem Alternatives The previous section described 16 coastal area treatment plant subsystem alternatives (8 with and 8 without satellite plants) to be considered during the intermediate screening process. These alternatives were designated by the letters A through P. Alternatives E,F,K,L,O and P are similar to alternatives I,J,G,H,M and N respectively, with the exception that the former group of alternatives consider placing both the primary and secondary treatment facilities for the flow from the southern MSD service area at a single location, whereas the latter group consider primary treatment facilities for the southern service area at Nut Island, and secondary treatment facilities at a separate location. As discussed previously, the existing Nut Island Primary Treatment Plant is in need of extensive renovation and modernization to provide efficient primary treatment, as nearly every portion of the treatment process requires some form of upgrading, maintenance work, or replacement. Preliminary cost estimates indicate that it would cost about the same amount to revamp and expand the existing primary treatment facilities on Nut Island as it would to construct new primary treatment facilities elsewhere. In addition, separate primary and secondary plants would require additional facilities which would not be required for a combined primary and secondary treatment plant, such as an additional administration building and an additional pumping station to pump the effluent from the primary plant to the secondary plant. Also, it would require more men to operate and maintain separate facilities than to operate and maintain a combined facility. It is estimated that separate facilities would cost about $7,000,000 to $10,000,000 more to construct and at least $1,000,000 more per year to operate and maintain than would combined facilities. The difference in construction costs would probably be somewhat, although not completely, offset by the cost of demolishing the existing Nut Island treatment facilities. The demolition of the existing facilities would allow Nut Island to be utilized for other purposes. Based on the factors discussed above, alternatives G,H,I,J,M and N have been eliminated from further consider— ation. Alternatives E and F consider locating primary and secondary treatment facilities for the wastewater from the southern MSD service area on Long Island. Alternatives A and B consider locating these facilities at Broad Meadows, 3—1g8 ------- and alternatives C and D consider locating these facilities at Squantum. There are several factors which make utilizing Long Island unattractive as compared to locating the facilities at Broad Meadows or Squantum. These are: A large submarine pipeline would be required from Nut to Long Island. Access to Long Island is limited to the causeway which connects Moon and Long Islands with the mainland. Use of Long Island for wastewater treatment facilities would conflict with the Boston Harbor Islands Comprehensive Plan. Implementation problems can be expected when attempting to locate wastewater treatment facilities in the vicinity of Long Island Hospital. Therefore, alternatives E and F were eliminated from further consideration since more favorable sites exist. The best use of Long Island for the purpose of wastewater management would be to locate primary and secondary treatment facilities to serve the southern MSD service area and secondary treatment facilities for the northern MSD service area on the Island (alternatives K and L), thereby minimizing the impacts on both Deer and Nut Islands. (As discussed in Section 3.2.2.,due to the 4ood condition of the existing Deer Island Primary Treatment Plant, the wastewater from the northern MSD service area should continue to receive primary treatment at Deer Island). A comparison between these Long Island alternatives (K and L) and the alternatives which locate all coastal area treatment facilities on Deer Island (alternatives 0 and P) results in the following observations: Although both the Long Island and Deer Island alternatives require the construction of a tunnel across President Roads, the cross—sectional area of the tunnel required for the Long Island alternatives would be about 2 to 3 times the area required for the Deer Island alternative. The Long Island alternatives require facilities at two separate locations (Deer and Long Islands), whereas the Deer Island alternatives require facilities at only one location (Deer Island). The Long Island alternatives require two additional pumping stations, one for an average flow of 490,000 or 700,000 m 3 /day (130 or 186 mgd) at Nut Island and 3- l39 ------- one for an average flow of 1,510,000 m 3 /day (400 mgd) at Deer Island. The Deer Island alternatives require only one additional pumping station, for an average flow of 490,000 or 700,000 m 3 /day (130 or 186 rngd) at Nut Island. The Long Island alternatives would require using most of the land available on Long Island for treatment facilities, including land presently occupied by a Civil War Cemetery, an area which supports a diverse population of wildlife species, more than 40.5 hectares (100 acres) of land which is presently proposed for recreational facilities, and would require about 2 hectares (5 acres) of fill into Boston Harbor. In addition, treatment facilities would be located about 91 meters (300 feet) from Long Island Hospital. The Deer Island alternatives would require using most of the prison area, and south end. It would be possible, but not desirable, to build around the prison facilities. The addition of fill at Deer Island is not anticipated. Although the Boston Harbor Islands Comprehensive Plan recommends using the drumlin and south end of Deer Island and the open space on Long Island for recreational purposes, it did recognize the possible expansion requirements of the Deer Island Treatment Plant. In view of the above comparison, the Deer Island alternatives appear more attractive from economic, engineer- ing and environmental points of view and, therefore, alter- natives K and L have been eliminated from further consider- ation. The alternatives remaining after the intermediate screening process are the following: Alternative A . Primary and secondary treatment facilities at Deer Island to serve the northern MSD service area and primary and secondary treatment facilities at Broad Meadows to serve the southern MSD service area. Does not include inland satellite treatment plants. Alternative B . Similar to Alternative A, except that inland satellite treatment plants are included. Alternative C . Primary and secondary treatment facilities at Deer Island to serve the northern MSD service area and primary and secondary treatment facilities at Squantuiti to serve the southern MSD service area. Does not include inland satellite treatment plants. 3—140 ------- Alternative D . Similar to Alternative C, except that inland satellite treatment plants are included. Alternative 0 . Primary and secondary treatment facilities for the entire MSD service area at Deer Island. Does not include inland satellite treatment plants. Alternative P . Similar to Alternative 0, except that inland satellite treatment plants are included. 3—141 ------- 3.3.3. Inland Satellite Wastewater Treatment Plants A. Sites . The intermediate screening process for satellite treatment plants was conceived to be that part of the study in whiCh detailed environmental and engineering data were developed on a smaller group of sites in order to permit a comparison among these remaining sites and the selection of one site for each basin. However, t1 e results of the water quality analyses altered this strategy. Neponset River Six sites were evaluated for the proposed Neponset River treatment facility. Prior to the determination that the ef flu- ent discharge would not meet water quality standards, addi- tional data on these sites was developed. This data is pre- sented here for the record even though the concept of a Neponset River treatment facility was dropped at this stage. At the time that the decision to eliminate this facility was made, a selection among the six sites had not been made. Site 5 - Star Market, Norwood . This property is owned by the Star Market Company and is approximately 12.1 hectares (30 acres) in size. The site is bordered by the Star Market Distribution Center and by a golf course. It can be charac- terized as a flat, filled area vegetated by mixed grasses and brush. The wildlife value and aesthetic value of the site is low. Purgatory Brook flows adjacent to the site, but the site’s flood potential is low. Two easements traverse the site, a powerline easement and an MDC easement. Both road and rail access are excellent. If additional land were to become necessary for buffer- ing or to acconmtodate certain sludge options (such as com- posting), there appears to be suitable land lying west of the Star Market site. Advantages of this location include compatability with the industrial zoning of the area, adequate distance from residential areas, good access, and minimal impacts on the natural environment. The discharge point associated with this site would be located downstream of the Canton/Dedham Water Company well fields. The major disadvantage of this site is its location irnme- diately adjacent to a major food hand1 ,ng facility. The exist- ing Star Market facility is a 32,516 m (350,000 square feet) distribution center which services 61 food stores in four New England states. Since the danger of contamination via biologi- cal aerosols cannot be completed discounted, and in light of the great potential for exposure that this food distribution center 3—142 ------- offers, this must be considered a significant drawback to this site. In addition, the management of Star Market has voiced their opposition to this site on the basis of this sanitation hazard, the public’s perception of this hazard (and its potential ramifications on their business activity) and the fact that Star Market has included this site in their long range plans for contiguous expansion. Sites 3 and 8 - Old Drag Strip and Norwood Arena, Norwood . These sites are considered here as one, even though they were treated separately by the Upper Neponset Site Selection Commit- tee. In all, there exists over 28.3 hectares (70 acres) of land on this site which lie above flood elevation. The area is presently vacant with remnants of the arena and drag strip remaining. Vegetation consists mainly of mixed grasses and shrubs. Site preparation requirements would appear to be minimal. The site is bordered by Route ]., a lumberyard, an auto dealer (across the highway) and the Neponset River. The wild- life and aesthetic value of this location is low, and it is not subject to flooding. Road access is good but rail access 18 poor. The entire site has recently been acquired by Appendger, Inc. (Faded Glory) of University Avenue, Norwood. The com- pany has received approval by the town for a proposed indus- trial complex and plans to relocate at this location. Advantages of this location include compatability with existing land uses. The site can be adequately screened from residences across the river. Other advantages include good access, minimal interceptor and outfall requirements and minimal impacts on the natural environment. The main disadvantage of this site is that the place- ment of a treatment facility here may displace a planned industrial use. During the course of this study, Mr. David Aransky, an adjacent landowner expressed his interest in selling his property for the treatment plant site. Mr. Aransky’s property lies southeast of the Norwood Arena Site and on lower ground. The site comprises over 40.5 hectares (100 acres). The main disadvantage of this site is that it is subject to flooding during periods of severe runoff. The effect of filling in this area on present flood stages in adjacent areas has not been determined. If treatment facilities could be placed on this site without appreciably affecting flood conditions and wetlands in adjacent areas, this site would be feasible. 3—143 ------- Sites 6 and 7 — Dedham Street, Canton . This site (con— sidered as one) is a natural flat area with piles of dirt and debris scattered throughout. The site is located adjacent to 1-95, in an industrial area, Vegetation consists of mixed grasses and hardWood seedlings and saplings. Much of the site is bare and devoid of vegetation, and the wildlife and aes- thetic value is low. A small drainage stream crosses the northern part of the site, but it can be avoided. Flood potential is low. This site is currently slated for development by a local construction company. The owner has speculated that the devel- opment of the site may occur over a five year period. In this regard, concern has been raised at the public workshops over the economic loss to the town that would be incurred by devel- opment of the site for a non-taxable facility. Advantages of this locait.ion include compatability with the industrial area, good access (especially rail) and minimal impacts on the natural environment. Site 9 — Knoll Across River from Norwood Airport, Canton . This site consists of an open field and a knoll adjacent to Route 1—95. Its elevation ranges from 15.2 meters (50 feet) to 30.5 meters (100 feet) above mean sea level. It is situ- ated across the Neponset River from Norwood Airport and is in an isolated location. Owned by Roseland Properties Trust (University Road, Canton), the site includes a total of 32.4 ha (80 ac), although only 12.1 ha (30 ac) are located on the knoll above the maximum flood elevation. Vegetative cover includes a mixture of oaks, hickory, pitch pine and mixed grasses. Bedrock is present and accounts for the structure of the knoll. This has been identified as a part of the Warn— sutta formation, which is a fine—grained red sandstone. Of the sites being considered at this time in the Nepon— set Basin, primary construction-related impacts would be greatest at this location. However, these effects are not highly significant nor do they impact upon unique or endan- gered species. A minimal impact upon the local tax base is anticipated as this site does not have a high probability for development. Access by road and rail is presently poor but could easily be developed. Overall, this site has a significant advantage due to its isolated location. Environmental impacts are considered to be acceptable. Disadvantages include the presence of some steeply sloped areas in the vicinity of the knoll, and the need for extensive site preparation. 3—144 ------- Charles River For the Charles River, the water quality analysis con- ducted in the preliminary screening stage determined that the South Natick Darn was more appropriate as a discharge point than the Cochrane Dam. Since the distance from a potential site to the discharge point was a significant factor in the preliminary screening process, a shift in the discharge point would require a check on the previous elimination of sites to determine if any were eliminated based on distance from the Cochrane Darn. With a shift in discharge point, such sites might again be feasible. Site #9 (Off Eliot St., South Natick) . Site #9 is well located with respect to the new discharge point. However, the main reasons for elimination of this site relate more to site size than location. Therefore, the site remains infeas- ible with the relocated discharge point. Site #14 (Pond Road, Wellesley) . Site #14 was eliminated due to distance from the Cochrane Dam and the location, charac- ter, and value of the site itself. While this site is closer to the South Natick Dam than to the Cochrane Darn, it was determined that the site should still be considered in the eliminated category due to its previously mentioned high aesthetic value. Site #16 ( ravel pits, Routes 128 and 20, Weston) . Site #16 had been eliminated because of its extreme distance of nearly 12.9 km (8 mi) from the Cochrane Dam. This site is not much closer to the South Natick Dam (more than 11.3 km or 7 mi), and therefore, it remains in the eliminated cate- gory. Since the water quality analysis indicated that a dis- charge in the stream segment above the South Natick Dam would be desirable, and the original list of sites was selected using the Cochrane Dam as the proposed discharge point, it was felt that a search for new sites would be in order. In the swnmer of 1977, the EPA decided to organize a Site Evaluation Committee for the purpose of suggesting and evalua- ting sites associated with a South Natick Dam discharge. The committee was composed of two persons appointed from each of the following towns: Dover, Framingham, Medfield, Natick, Needham, Sherborn, and Wellesley. These are towns which could be potentially affected by the selection and development of the plant site. The canmittee held five meetings during the months of August through November, 1977. During that time the committee suggested 3—145 ------- and evaluated a number of sites. The committee was provided with technical support and data from EPA personnel, who attended the committee meetings. The sites which were considered included some of those evaluated by the original committee as well as new sites suggested by current committee members. A discussion of the sites evaluated by the committee follows, beginning with those sites previously discussed in Section 3.2.3. (Figure 3.3-1 shows the location of sites 26, 27, A-i and A—2.) Site 1/2 Sigmatine’ Fathers Prøperty . This site was suggested for re-evaluation by one of the committee members. It was thought that this location might be usable if facilities are confined to the”uplan& portions of the site. On inspection, this site was determined to be approximately 16.2 hectares (40 acres) in size and is bordered by a residential area on one side and the Charles River on the other sides. Buffer requirements would appear to significantly restrict the usable area present. Other considerations include the exceptional quality of the site’s vegetation and its scenic character. As noted in the preliminary screening section, the site is recommended for recreational usage in the MAPC Open Space Plan. After several meetings at which sites were suggested, dis- cussed, and evaluated, the committee at its October 13 meeting voted to eliminate a number of sites. This site was one of those eliminated, on the basis of its recreational and environmental qualities. Site 6 - ?Own of Needhain Sanitary Landfill . This site, one of three remaining after preliminary screening, is located off Marked Tree Road. It has been used for refuse disposal for many years and has a ten year expected life. The site has a usable area of about 16.2 hectares (40 acres) and is reasonably well buffered from surrounding land uses. Anticipated impacts on the natural environment are minimal and the use of this site, for a treatment facility would be comparable to its existing use. The principal effect of locat- ing a facility here would be the displacement of Needham’s present method of solid waste disposal. Concerns raised by the committee concerning this site included the accuracy of the foundation costs developed (since the plant would be located on an unstable landfill) and the possibility of the plant interferring with the nearby radio station (WHDR). At its October 13 meeting, the committee voted to con- tinue considering this site. Site 11 - merican Can Company Plant, Needham . This site is located in the industrial park on the east side of Route 128 at interchange 56. The site and adjacent median strip are rather small, and the site is slated for major 3—14.6 ------- ______ ____________________ O L Z j5 KILOMETERS Lake o1 0 / d Waban 27 : : ; 7j 1D / I. i/ ( -‘.., ø _ : i 4 Nat ‘\:.) 5 ‘ / - 3° rr - j, -- FIGURE 3.3 -1 ADDITIONAL SITES EVALUATED BY MID-CHARLES SITE EVALUATION COMMITTEE ------- industrial development. The committee voted to eliminate this site from further consideration. Site 12 len Street and the Charles River, Natick . This site is a large wooded area sloping from Glen Street to the Charles River, and encompassing a total area of approx- imately 38.5 hectares (95 acres). No structures are present. Mature hemlocks are plentiful. Problems associated with development at this location would result from the site’s significant slope, the occurrence of exposed bedrock through- out the site and the wet nature of the Bite. Vegetation present on the site is significant but not unique, although several trees are specimen size. The owner of the site has stated that he is in the pro- cess of applying a conservation restriction to a 30.5 to 45.7 meter (100 to 150 feet) strip of the site that borders the Charles River. Further, two parcels totaling approximately 18.2 hectares (45 acres) are being deeded to the Massachusetts Audubon Society. In the committee’s discussions, the site was cited as a scenic/conservation area similar to the Stigmatine Fathers Site. The site was voted down by the committee for similar reasons. Site 16 - Gravel Pits, Route 128 and 20, Weston . This site was reconsidered by the committee. As discussed previous- ly, it is too far from the discharge point to be feasible. This site was eliminated by committee vote. Site 26 — Eliot Hill, South Natick . This site occupies a wooded area locatedin the triangular area bounded by Cottage Avenue on the west, Morningdale Road on the north, and Wilford Road on the southeast. With a 152.4 meter (500 feet) buffer zone, insufficient land would be available for a treatment plant. In addition, this site is located in a scenic residential area. This site was eliminated by committee vote. Site 27 — Town of Natick Sanitary Landfill . This site is located southwest of West Street, just before its inter- section with South Main Street (Route 27), adjacent to the Sher- born Town line. Total area of the parcel is 16.2 hectares (40 acres). Available buffer around this site is adequate. As with the Needham landfill site, the major impact is expected to be the town’s loss of a solid waste disposal facility. In the committee’s discussion of this site, it was pointed out that it is located near a high school recreation field, a swimming pond, wetlands, and a skating rink. The committee voted to continue consideration of this site. Site A-i - Massachusetts Department of Corrections, Framingham . This site is an open field of approximately 28 3—148 ------- hectares (69 acres) located between Western Avenue and Merchant Road in Frainingham. It is owned by the State of MassathUSettS and has sufficient area to establish a suitable buffer zone. A treatment facility at this location would be generally compatible with the character of this area and, since it is owned by the State, would not remove ratable land from the local tax b 9 e. The site could be used for the construction of a 117000 in /d (31 mgd) facility, which would involve the pumping of wastewater to the site fromdownstream communities. As an alternative, the site could be used for a smaller facility, treating only the wastewater which is tributary to the facility from upstream communities. It is estimated that this “reduced flow” plant would have a capacity of 72000 m 3 /d (19 mgd). Wastewater generated downstream of this facility would transorted to the coastal area treatment plant. It was noted during the committee’s discussion of this site that the Town of Framingham plans to apply to the State for the aquisition of this site for industrial development purposes. Nonetheless, the committee voted to continue the consideration of this site. Site A-2 - Lincoln Properties, Natick . This site is located to the southeast of the intersection of West Central Avenue and Kendall Land in West Natick. The site is low, wet and has been approved for a subdivision development. T Natick Conservation Commission, which formerly endorsed this site, has withdrawn their approval. The committee voted to eliminate this site from further consideration. Site A-3 - Median St4p on Route 128, Dedham . This site includes the area within the median strip of Route 128, to Dedham Avenue, as well as acreage on either side of Route 128. Total acreage within the median strip is approximately 117.4 hectarea (290 acres), with an additional 101.2 hectares (250 acres) on either side of the highway. Advantages of this site include its large area, its iso- lation from other land uses, and the fact that the land is already in the public domain and not readily usable for other purposes. Road access is excellent. However, the site is located 9.7 kilometers (6 miles) from the discharge point. The committee voted to continue consideration of this site. Site A-4 Medfield State Hospital, Medfield . This site, not well defined, was suggested but not considered feasible because it is extremely distant from the interceptor sewer (which carries influerit wastewater), and the presence of wetlands. The committee voted to eliminate this site from further consideration. 3—149 ------- In its final meetings, the committee eliminated Site 6 (Needham Landfill) and Site 27 (Natick Landfill) and narrowed its considerations to Site A-i (Massachusetts Departmentof Corrections) and Site A-3 (Route 128 Median Strip). In its final report, the committee made it clear that it in no way condoned or approved of the concept of satellite plants nor did it necessarily agree that the South Natick Dam was the optimum discharge point. The report, which was unanimous except for the members from Medfield who chose to remain “mute” with respect to it, stated that it believed that all sites (other than Sites A-i and A-3) were unacceptable location for a sewerage treatment plant, and concluded as follows: “The Committee believes that the site which creates the least environmental damage is Site A-3, the Median Strip of Route 128. Site A-i, Framingham MCI, might be a possible site for a much smaller facility than the proposed 31-million gallon per day plant. However, the Committee feels that even a smaller facility at Site A-l might create significant envi- ronmental hazards.” “After considerable deliberation, the Committee has ser- ious reservations that any proposed Middle Charles River satel- lite sewerage treatment plant can be located in the area without creating major environmental (and, in the opinion of several Committee members, health) hazards. Consequently, we believe the EPA should direct its efforts to finding more acceptable alternative solutions to the problem.” At this time, the concept of a satellite treatment facility on the Charles River was found to be infeasible based primarily on water quality considerations (see Section 3.3..3B) Hence, all satellite—based alternatives in the EIS study were eliminated and, along with them, the selection of an optimum site became unnecessary. It should be noted, however, that the work of the Site Evaluation Committee was done on an advisory basis, forming an input to this EIS study. Therefore, recommendations of the committee as set forth in their final report do not necessarily reflect the opinions or judgements of EPA nor would they necessarily coincide with the final recommendations of this study had a satellite alternative been deemed viable. B. Effluent Dischar 9 e Evaluation . As discussed in Section 3.2.3B, an effluent discharge to the Charles River at the Cochrane Darn was concluded to worsen an already serious dis- solved oxygen situation in the downstream beaches. Conse- quently, alternative discharge points located above the S. Natick Darn, river kilometer 67.5 (river mile 42) and near the Medfield State Hospital, river kilometer 75.6 (river mile 47), 3—l5 ------- (Figure 3.3-2 ) were modelled to determine if a viable dis- charge location for a mid-Charles satellite plant exists. Discharge above the S. Natick darn was modelled to analyze the effects of the additional reaeration which would result as the effluent passes over the Darn and the short section of “rapids” below the Darn. (Examination of a Charles River pro- file [ New England Division, Corps of Engineers, 19721 shows the elevation change and length of the “rapids” below the S. Natick dam are approximately equivalent to those of the reach immediately downstream of the Cochrane dam). The Med- field location represents the most upstream point on the Charles within the proposed MSD. A discharge at this point would maximize the number of river kilometers receiving flow augmentation via the effluent discharge. The effluent volume and characteristics simulated were the same as those utilized during Preliminary Screening. In addition, a “reduced”discharge of 7.19x10 4 m 3 /d (19 mgd) was evaluated. This smaller discharge examines the impact upon the River of reducing the proposed satellite service area to include only the towns upstream of Site A-i in Framingham. The following section summarizes the results of the various cases simulated. Each case represents a variation in model inputs parameters and these, along with the other modelling details are found in Appendix 3.2.2. As in Section 3.2.3B, DO. profiles and their corresponding figure numbers are located in Appendix 3.2.2. Profile C2, Figure 13, which represents discharge at the Medfield location with the river meeting standards immediately upstream of the discharge point, shows the EMMA proposed dis- charge to violate water quality criteria within the impound- ments of the South Natick, Cochrane and Silk Mill dams. Con- versely, Profile E2 (a Medfield discharge with the River not meeting standards), reveals an improvement in D.O. concentra- tions as a result of the satellite plant flow; however, con- centrations are still depressed below the designated allowable minimum of 5 mg/l. Profiles C2 and C3, (the “advanced” dis- charge at Medfield) Figure 14, show the effect of removing all nitrogenous oxygen demand from the effluent. If the River was meeting Class B D.O. standards whep i entered the MSD, a satellite plant discharge of 1.l7xlO m /d (31 mgd), contain- ing 5 mg/i BOD 5 and no NH 3 -N would not cause a violation of water quality criteria. Discharge just above the South Natick damn caused down- stream dissolved oxygen conditions which were similar to those shown in the Medfield State Hospital discharge D.O. profiles. Consequently, it was concluded that discharge at either of these locations has the same effect upon oxygen resources in the Charles River. In addition, the reduced discharge caused lower dissolved oxygen concentrations than those resulting from a l.17x10 5 m 3 /d discharge. (:3 in d) 3-151 ------- FIGURE 3.3-2 ALTERNATIVE DISCHARGE LOCATIONS CHARLES RIVER SATELLITE PLANT WATERSHED LOCATION 2 0 2 K ILOMETERS 2 0 2 __ J l I — MILES Jamaica Pond Mother Brook Diversion Box Pond LEGEND * U.S.G.S. GAGING STATION DISCHARGE LOCATIONS: I ABOVE S. NATICK DAM II AT MEDFIELD STATE HOSPITAL Pearl ------- Subsequent to the modelling report of November 30, 1977, additional simulations were performed to determine the effects of a discharge on DO. concentrations at flows greater than the 7 day, 10 year low flow (see Appendix 3.2.2 for the Addenda to the modelling report). Flows approximating the expected average flow for the month of August in the year 2000 were simulated with all treatment plants on the Charles discharging effluents containing 5 mg/i BOD 5 and 1 mg/i NH 3 -N. The proposed satellite plant discharge was placed above the South Natick darn. The results of these simulations indicate D.O. concentrations fell to approximately 4 mg/i behind the Cochrane and Silk Miii dams, while the concentration behind the South Natick dam were depressed to roughly,. 2 mg/i. It appears as though D.O. concentrations less than the water quality standard of 5 mg/i may occur in the Charles River at flows considerably greater than the 7 day, 10 year low flow. Water quality modelling undertaken to evaluate alterna- tive discharge locations indicates a satellite plant discharge may (1) violate Class B water quality criteria (profile C2 Figure 14); (2) not violate these criteria (profile C3 Figure 14); or (3) increase D.O. concentrations, but not sufficiently to reach the desired 5 mg/i level. The above conclusions would apply as long as the discharge is at some point upstream of the South Natick dam. Water quality modelling is both a science and art and the results of any modelling program must be carefully inter— preted. The mathematical formulations used to describe natural systems, including their assumptions and limitations, as well as the input data utilized by the model, comprise the science of modeiling. The art of modelling is the inter- pretation of model output relative to its inherent limitations and the real world conditions it attempts to simulate. Conclusions (1) and (2) above are valid so long as the Charles River enters the MSD meeting standards. To do this, the Charles River Pollution Control District (CRPCD) and Medfield-Millis treatment plants would be required to dis- charge effluents containing 1 mg/i BOD 5 and no other oxygen demand. This represents a level of treatment equivalent to a water reclamation facility. The probability is extremely small that such an effluent limitation would be imposed upon these facilities. More importantly, all bottom material would have to be dredged from the River in order for it to exert no benthic oxygen demand. This would be a senseless undertaking, since organic solids deposition is a continuous process in any river. The possibility, therefore, of no benthic oxygen demand is essentially zero. In light of these factors, it does not appear logical to assume the Charles River would enter the MSD meeting standards. 3—153 ------- If the future dissolved oxygen profile during the 7 day 10 year low flow is approximately equivalent to profile Eli on Figure 13, then a satellite discharge is shown by profile E2, on Figure 13 to raise D.O. concentrations by 1-2 mg/l. This result assumes all treatment plants discharging to the River consistently achieve an effluent quality of 5 mg/i BOD 5 and 1 mg/i NH3. While it is not beyond the capability of an AWT facility to produce this level of effluent quality, it is questionable whether this level can be consistently achieved. This point was emphasized in a recent paper (Taylor 1978) on water quality criteria. Testimony by experts in the field of wastewater management before the Texas Water Quality Board indicated that, based upon an evaluation of existing systems around the country, the ability to operate a large treatment plant which consistently produces a level of efflu- ent quality equivalent to that assumed in this modelling is not proven. In addition, for a facility to achieve high levels of treatment on the average, it must be designed to per- form better much of the time. Considering flow variability, input pollutant and concentration fluctuation, and the uncer- tainties associated with the biological nitrification process, which is extremely sensitive, it is highly unlikely these levels of effluent quality can be met consistently. Given this situation it appears as though the effluent quality could possibly be worse than assumed by the modelling and, therefore, the improvement predicted by Case E2 may not materialize. It is also recognized that the modelling did not simu- late the non-point pollution processes such as solid waste leaching,which influence D.O. levels in the Charles River. These processes are significant in the Charles and have a negative influence on D.O. In addition, the benthic demands utilized are generally lower than would be expected in a river such as the Charles. It can be concluded that the assimulative capacity of the Charles River will be extremely stressed under low flow conditions by existing oxygen demands. A satellite plant represents a major new pollutant source for the Charles River, which will increase point source mass input the River of BOD5 from 329 to 586 kg/d (725 to 1293 lbs/d) and nitrogenous oxygen demand from 311 to 535 kg/d (685 to 1181 lbs/d) (See Table 7, Appendix 3.2.2). In addition,the fol— lowi.ngtablecompares the proposed discharge with River cjuality just upstream of the discharge. Imposition of this additional load upon the already stressed river system may effectively preclude the Charles from recovering from its present stressed condition. If River conditions improve such that standards are met, the satellite discharge is indicated to cause viola- tion of standards unless an extremely high level of treatment is achieved on a consistent basis. As the result of this 3—154 ------- COMPARISON OF AWT EFFLUENT AND CHARLES RIVER QUALITY Charles River’ Satellite Discharge 2 Flow, m 3 / 0.89 1.35 (ft 3 / s) (31.4) (47.7) Dissolved Oxygen, mg/i 3.1 6.0 BOD 5 mg/i 0.6 5.0 kg/d (lbs/d) 67 (148) 478 (1494) Nitrogenous Oxygen Demand mg/i 0.05 1.0 kg/d (lbsld) 17.5 (38.5) 535.8 (1181.5) Total Oxygen Demand, mg/i 1.1 11.9 kg/d (ibs/d) 84.6 (186.5) 1231.4 (2675.5) analysis, a satellite plant discharge:is seen as not improv- ing water quality in the Charles River and contributing to the maintenance of its present condition. The implementation of a satellite plant discharging to the Charles River isnot recommended. River conditions as modelled at river kilometer 80.3 (river mile 50), just upstream of Medfieid State Hospital discharge point, during 7 day, 10 year low flow. All upstream point sources have effluent quality of 5 mg/i BOD 5 and 1 mg/i NH 3 -N. recommended discharge and effluent quality. 3—155 ------- 3.3.4. Sludge Disposal for Coastal Area Wastewater Treatment Plants As discussed in Section 3.2.5., several stabilization, dewatering, conversion and ultimate disposal processes and operations remained as possible alternatives following the initial screening. Air flotation was selected as the method of choice for the thickening of secondary sludge. These unit processes and operations were assembled into process trains to develop a number of complete sludge management systems. Each system was developed by selecting appropriate unit processes which were compatible with an ultimate disposal or conversion process. All of the alternatives include air flotation thickening. The resulting alternative sludge management systems for second- ary sludge from coastal area treatment plants are described in this section and can be grouped under the following major options: A. Landfill B. Incineration or Pyrolysis — Landfill of residue C. Give Away or Market the Product D. Land Application E. Coincineration with Solid Waste A. Landfill . All of the system alternatives in this category would employ landfilling of dewatered sludge either at a facility owned and operated by the MDC, at the existing Plainville landfill at a fixed fee per ton of sludge disposed, or at a new privately owned and operated landfill at a fixed fee per ton of sludge disposed. The stabilization alternatives included in the evaluation were chemical conditioning, anaerobic digestion followed by chemical conditioning, and aerobic digestion followed by chemical conditioning. The dewatering alter- natives included vacuum filtration and pressure filtration. A line diagram of projects involving landfilling of sludge is shown in Figure 3.3-3. B. Incineration or Pyrolysis . All of the stabilization and dewatering processes considered for the landfill system were also considered for the incineration or pyrolysis system. Figure 3.3—4 shows the alternatives considered for incineration or pyrolysis systems. C. Give Away or Market the Product . Two basic approaches, compostil)g and heat drying, were considered for producing a high quality, dry sludge product for a give-away or retail market program. All of the stabilization and dewatering 3—156 ------- FIGURE 3.3-3 LANDFILL ALTERNATIVES DIRECTION OF FLOW ------- FIGURE 3.3-4 INCINERATION OR PYROLYSIS ALTERNATIVES DIRECTION OF FLOW ------- processes included under the landfill system were also considered for the give—away or market alternatives. Figure 3.3—5 shows the alternatives considered for giving away or marketing the sludge. D. Land Application . Pasteurization, aerobic digestion and anaerobic digestion, both with and without chemical conditioning, were considered for the stabilization of sludge for land application. Chemically conditioned thickened sludge was riot considered because of its potential pathogen content. Pressure filtration was not considered since vacuum filtration can produce a sludge cake of sufficient moisture content for incorporation into the soil. Figure 3.3-6 shows the alternatives considered for land application. E. Coincineraticr with Solid Wastes . The feasibility of coincineration of municipal sludge and solid wastes from the Boston metropolitan area was investigated in a separate study conducted by Stone and Webster Management Consultants, Inc., for the MDC. The stabilization and dewatering processes applicable to coincineration are identical to those discussed under the landfill system. Figure 3.3—7 presents a flow chart of the coincineration alternatives for the two sites identified in the Stone and Webster report. Elimination of Alternatives All of the alternative sludge disposal systems discussed above were evaluated for the disposal of sludge from the coastal area wastewater treatment plants. Through a series of successive screenings and eliminations, the total number of alternatives was reduced to five basic concepts. In some instances, alternatives were eliminated because of institutional or spacial constraints. In other cases, it was necessary to develop preliminary design data so that the economics of one alternative versus another could be compared. The rationale and criteria for elimination of alternatives are described below. A. Landfill . One option considered for a landfill operation was to transport dewatered sludge to the existing Plainville landfill located near the intersection of Interstate Route 495 and U.S. Route 1. The landfill currently contains 43 hectares (107 acres) , with an additional 121 hectares (300 acres) available for possible expansion adjacent to the site. The Plainville landfill is equipped with a leachate recovery system. The Department of Environmental Quality Engineering of the Commonwealth of Massachusetts has prescribed a limit of 15 percent by volume for the ratio of dewatered sludge to solid waste which may be disposed of at the landfill. Based cn discussions with the Massachusetts Department of Solid Waste Disposal, a tipping fee of $7.00 per wet ton of sludge 3—159 ------- FIGURE 3.3-5 GIVE AWAY OR MARKET ALTERNATIVES VACUUM FILTRATION DIRECTION OF FLOW ------- FIGURE 3.3-6 SLUDGE THICKENING LAND APPLICATION ALTERNATIVES DIRECTION OF FLOW AEROBIC DIGESTION ------- FIGURE 3.3-7 DIRECTION OF FLOW COINCINERATION ALTERNATIVES ------- has been assumed. At a ratio of sludge to solid waste of 15 percent by volume, and in order for the landfill to have a useful life of 20 years, it is estimated that only about 20 percent of the secondary sludge from the coastal area plants could be disposed of at an expanded Plainville landfill. There- fore, a second landfill option was considered. The second landfill option would involve a new landfill owned and operated by the MDC. It is estimated that the area required for 20 years of operation would range from 150 to 200 hectares (370 to 500 acres), depending upon the methods of stabilization and dewatering used. The sludge would be buried in trenches about 18 meters (20 feet) deep. A 30 centimeter (1 foot) layer of earth for every 60 centimeter (2 foot) depth of sludge would be provided, with a 152 centimeter (5 foot) layer of earth applied as a final cover. A third landfill option would be similar to the second, except that the new landfill would be privately owned and operated. It is assumed that the tipping fee for use of such a landfill would be the same as for the use of the Plainville landfill, which was assumed to be $7.00 per wet ton of sludge. Estimated costs for an MDC owned and operated sludge landfill were derived from construction bids for similar projects, and include the costs of equipment, buildings, roads and observation wells. Based on preliminary cost estimates, the alternative involving MDC operation of an independent landfill appears to be preferable to paying the projected tipping charge for use of a private landfill. Consequently, the landfill alternatives were premised on the MDC developing and operating their own sludge landfill site in the general vicinity of the existing Plainville landfill. A comparison of the costs of various alternatives for stabilization and dewatering indicated that the most economical alternative is chemical conditioning followed by filter press dewatering. A second alternative employing anaerobic digestion followed by chemical conditioning and pressure filtration was maintained to allow for an environmental assessment of the effects of undigested versus digested sludge on the landfill. B. Incineration or Pyrolysis . The two most common methods used for sludge incineration are the multiple hearth furnace and the fluidized bed furnace. Only the multiple-hearth furnace will be considered for detailed study for the following reasons: 3—163 ------- A multiple-hearth furnace can be modified to a pyrolytic reactor more easily than can a fluidized bed furnace. There is much more experience with multiple— hearth sludge incinerators. The multiple—hearth furnace has a lower potential for air pollution. The typical multiple—hearth furnace consists of a refractory lined vertical steel shell with a series of 4 to 11 refractory covered hearths surrounding a central shaft. The shaft has air—cooled rabble arms extending across each hearth which rake the sludge to expose its surface and promote downward movement of the sludge. Temperatures generally range from 540°C (1,000°F) in the top levels where the sludge is dried, 8700 to 980°C (1600 to 1800°F) in the middle or combustion zone, and 315°C (600°F) at the bottom. Exhaust gases generally exit at around 425°C (800°F) although they sometimes have to be heated in an afterburner to 760°C (1400°F) to burn off noxious gases. Ash from the furnace can be handled hydraulically or mechanically. Hydraulic systems are generally preferable because of simplicity. Space at the incineration site will be required for ash storage lagoons if a hydraulic system is used. Particulate and gaseous pollutants are released by sludge incineration. Gaseous pollutants can include hydrogen chloride, sulfur dioxide, oxides of nitrogen, and carbon monoxide. With the exception of mercury and possibly lead, metals are expected to remain in the ash and not be emitted with the off-gases. Emissions from sludge incinerators are generally controlled by scrubber equipment. The units were sized on hearth area requirement - bases to completely combust sludge solids. The sludge was assumed to be autogenous if the solids content was 30 percent or higher. The only fuel required would be for start—up. This would be a negligible quantity since 24 hour operation was assumed. The incinerators were provided with after burners and wet scrubbing exhaust gas cleaning systems. The afterburners were provided in case they are needed, but it was assumed that their use would not be required. It was assumed that the ash would be handled in the form of a slurry. The ash slurry would be stored in lagoons, from which the supernatant will be continuously decanted and recycled for treatment. The ash would be removed from the lagoons on a periodic basis, and trucked to the Plainville landfill for disposal. 3—164 ------- Pyrolysis of sludge may also be performed in the multiple—hearth type furnaces. Therefore, it was assumed that the type of units employed in this process would be the same as in the incineration alternative. The limited information available on this relatively new process indicates that the size of a pyrolysis installation would be approximately the same as an incineration installation. Since the amount of excess air used in pyrolysis is significantly less than that required for incineration, the amount of exhaust gases and potential air emissions should be lower. However, if the exhaust gases are burned in an afterburner, the saving in air pollution control equipment may not be significant. While many pyrolysis studies have been performed using refuse at large scale installation, relatively limited information is available on the pyrolysis of sludge even on a small scale level. In addition, the experience with the large scale refuse pyrolysis plants has not been entirely satisfactory. Based on the above discussion, no attempt was made to develop separate design bases and cost estimates for pyrolysis systems, and the incineration and pyrolysis concepts were treated as a single alternative. Any thermal sludge treatment process is sensitive to the moisture content of the sludge because of the direct relationship between the fuel requirement and moisture content. Since one of the major factors that determines the economics of an incineration alternative is the amount of supplemental fuel required, and due to the increasing shortage of fuel resources and increasing price trend for energy, it would be desirable to select stabiliz- ation and dewatering processes which require the least amount of fuel. As mentioned previously, it is anticipated that the sludge would be autogenous if the solids content was 30 percent or higher. Therefore, vacuum filtration and centrifugation, which can only be expected to produce a sludge with a solids content of about 15 percent, were eliminated as dewatering processes, and pressure filtration, which can produce a sludge with a moisture content of about 30 percent, was selected. Under the stabilization category, the alternatives developed included chemical conditioning of thickened sludge and digestion, either aerobically or anaerobically, followed by chemical conditioning. During the digestion process, a fraction of the volatile solids present in the sludge is destroyed, thus decreasing the heat content in the sludge. The digested sludge also requires relatively high chemical dosages prior to dewatering, thus increasing the inerts and decreasing the unit heat content. The benefit 3—165 ------- derived by the solids destruction achieved in the digestion process is more than offset by the decrease in heat content and increased operational costs associated with the digestion process. Therefore, the only stabilization process consid— ered compatible with incineration or pyrolysis was chemical conditioning of thickened sludge. C. Give Away or Market the Product . All three stabilization processes, chemical conditioning of thickened sludge, anaerobic digestion followed by chemical conditioning, and aerobic digestion followed by chemical conditioning, were included in preliminary cost estimates for the sludge management systems involving composting. Based on the comparative cost of aerobic versus anaerobic digestion, aerobic digestion was eliminated. Vacuum filter and centifuge dewatering were eliminated because they would produce a sludge cake with a solids concentration of less than 15 percent. This high moisture content would require a larger land area for the composting operation, and would incur higher operating costs because of the increased recycle stream and additional composting time that would be required. Taking cognizance of the limited land area available and the economics of the sludge disposal systems, only the filter press dewatering process, which would produce a sludge cake with a 30 percent solids concentration, was considered for cost development. Composting is a process which achieves high levels of stabilization and volatile destruction of sludge through natural biological aerobic decomposition. The sludge is biochemically converted to a sterile humus material suitable as a soil conditioner. The inicrobialactivity generates heat with temperatures ranging from 60 to 70°C (140 to 160°F) which is sufficient to destory most pathogens. Most composting processes fall under one of three basic types of systems; windrows, aerated static piles, and mechanical units of various designs which usually supply continuous mixing and positive aeration. In the windrow system the sludge is placed in piles which rely on natural ventilation and periodic turning to maintain aerobic conditions. The windrow is normally turned frequently using a specially designed vehicle (composter) . This turning results in some. heat loss. As a result, in cold climates it may be necessary to enclose the facility to maintain adequate temperatures. The equip- ment used for windrow composting includes a composter for turning the windrows, and a front—end loader for transporting the sludge. A pond and collection ditches are necessary to collect runoff from the compost site. The aerated static pile method has been developed t 3—166 ------- Beltsville, Maryland. In the static pile system, a blower and a system of perforated piping is used to aerate the piles, as opposed to the mechanical turning used in the windr w process. The dewatered sludge is mixed with a bulking agent to increase the prorsity so that air can be forced through the pile. Various bulking agents can be used including wood chips, bark chips, sawdust or unscreened compost product. Aerobic composting conditions are maintained by drawing air through the pile at a predetermined rate, by means of a pipe system located at the base of each pile. Typically, the sludge mixture is aerated for about 21—24 days, separated from the bulking agent and aged for an additional 30 days. The moisture content in the compost product ranges between 35 to 45 percent. The equipment required for the static pile system include: Front end loaders, composters, or pug mills for mixing sludge and bulking agent; Screens to remove the separated chips or bark and compost; and Blowers and pipes to draw the air through the piles. Mechanical methods have been developed for compoSting mixtures of sludge and solid wastes. These methods claim accelerated composting rates by providing a very controlled environment. Some of the more popular mechanical systems include the Fairfield Hardy System, the Eweson Bio Conversion System, the Dano Bio Stabilizer System and the Metro-waste Conversion System. While most manufacturers of mechanical systems claim accelerated composting rates, additional curing is often required to achieve the same level of stabilization achieved by the windrow and static pile method. In addition, none of the mechanical systems have been demon- strated for full scale cornposting of municipal sludge. For the purpose of cost estimates, an aerated static pile system has been selected. The mechanical systems have been eliminated because of lack of experience with municipal sludge. The static pile method was selected in favor of the windrow method to reduce heat loss in in the cold New England climate. It has been conservatively assumed that composting operations would be conducted only nine months per year to minimize the effect of cold winters. While cornposting operations can be conducted during the winter, freezing 3—167 ------- TABLE 3 .3-1 COMPARISON OF COMPOSTING METHODS Aerated Turned Windrow Static Pile Mechanical Process Advantages: May not require bulking agent Eliminates need to turn pile Possible reduction in coxposting time No need for blowers Lower land requirement Minimizes labor requirements Closer control of aeration rates Protected from weather Less sensitive to weather Excellent process control Bulking agent dilutes heavy metals Bulking agent dilutes heavy metals Disadvantages: Labor intensive Requires bulking agent Usually requires bulking agent. Possible odor problems with unstabilized sludge Requires blowers and air piping Highest equipment costs Requires corn— poster to turn windrows Limited operating experience with sludge in U.S. 3—168 ------- of condensate in aeration piping and operation of mechanical equipment can pose some problems. It was also assumed that there would be no cost associated with providing the bulking agent. This was based on using recycled dried compost or tree trimmings which could be obtained at no cost by the MDC. It is believed that such materials would be a satis- factory bulking agent for nine months per year operation. Acreage requirements were developed for composting 12 months of generated sludge during a nine month period and include storage facilities for the winter months, 24 days of composting time and 30 days for curing. It was determined that approximately .2 hectares (.5 acres) per dry ton per day of sludge generated would be required for 9 months per year operation including land for storage of dewatered sludge. If the composting operations were continued through the winter months, the land requirements could be reduced to approximately .14 hectares (.35 acres) per dry ton per day of raw sludge solids. If it is not possible to use recycled compost as the bulking agent or to obtain wood trimmings at no cost to the MDC, commercial wood chips could be purchased from pulping mills. At a typical cost of $6.00 per cubic yard, a wood chip to sludge volume ratio of 1:1, and a 20 percent makeup rate for wood chips, this would add approximately $4.14 per dry metric ton ($4.56 per dry short ton) of raw sludge solids to the cost of composting operations. The additional cost of screening the wood chips would be negligible in comparison to other operating and maintenance costs. The area requirements would be approximately the same, regardless of the type of bulking agent used, since bulking agent storage areas would be required in all cases. The heat drying process, employing a rotary kiln type dryer, was assumed to operate at 150°C (300°F). The loading rate and capacity of the dryer were based on equipment manufacturers’ information. The heat dried sludge was assumed to have a solids concentration of 95 percent. In this form, it may be conveniently bagged for marketing. Based on preliminary cost estimates, the heat drying alternative is decisively more expensive than the composting alternatives. It also consumes large quantities of fuel. Since both processes are capable of producing a high quality product which is suitable for a marketing or give-away program, heat drying was eliminated on the basis of the high cost and high energy consumption. D. Land Application . The disposal of primary sludge from the coastal area treatment plants by means of land application 3—169 ------- was investigated previously in separate studies by Havens and Emerson, Ltd., and Ecolsciences, Inc. Both studies eliminated land application as a sludge disposal alternative. The major factors contributing to this determination were the large amount of area required, over 8100 hectares (20,000 acres), which required the utilization of a large number of sites dispersed throughout Massachusetts, and the possible adverse effects of the sludge (particularly the heavy metal content of the sludge) on crops and groundwater. In addition, the requirements of utilizing many sites outside of the study area presented serious implementation and institutional barriers to this method of sludge disposal. There is no reason to believe that the situation would be any different with regard to the disposal of secondary sludge. In addition, discussions with the Massachusetts Department of Environmental Quality Engineering revealed that, at this time, the application of sludge on agricultural land is not permitted in Massachusetts. Therefore, the land application alternative for the disposal of sludge from the coastal area treatment plants was eliminated from further consider- ation. E. Coincineration with Solid Wastes . In November, 1976, Stone and Webster Management Consultants, Inc. submitted the results of a feasibility study concerning the coincin- eration of MDC’s primary sludge with solid waste collected by the Boston Public Works Department. The study invest- igated the location of a coincineration facility at either Deer Island or the City of Boston’s former incineration facility at South Bay. The study considered a solid waste to sludge ratio in the order of 10:1 as being technically feasible for a multiple hearth facility. The economics of both coincineration and separate incineration of sludge and solid wastes were evaluated. While the study concluded that coincineration was both technically and environmentally feasib1e, the economics favor separate incineration. This is largely a result of transportation costs between Deer Island and South Bay, and Federal grant structures. These grant structures provide 75 percent funding or sludge disposal, but none for saud waste disposal. Although the situation is somewhat different for secondary sludges, the basic findings are still valid. Based on this study and discussions with EPA, coincineration was not considered for disposal of the secondary sludge for the coastal area wastewater treatment plants. 3—170 ------- 3.3.5. Sludge Disposal for Inland Satellite Wastewater Treatment Plants As described in Section 3.2.5., several thickening, stabilization, dewatering, conversion and ultimate disposal processes remained after the initial screening. These unit processes were assembled into process trains to create a number of complete sludge management system alternatives. Each system alternative was developed by selecting appropriate unit processes which were compatible with an ultimate disposal or conversion process. The resulting alternative sludge management systems which were considered for the inland satellite plants are described in this section and can be grouped under the following major options: A. Landfill B. Incineration or Pyrolysis - Landfill of residue C. Give Away or Market the Product D. Resource Recovery Center E. Disposal at Coastal Area Plants F. Land Application All of the alternative systems include gravity thickening of primary sludge and air flotation thickening of secondary sludge. In systems which utilize heat treatment as the stabilization process, only vacuum filtration was considered for dewatering, since the combination of these two processes yields a relatively dry sludge cake (about 35 percent solids). A. Landfill . All the system alternatives considered in this category employ landfilling of dewatered sludge at the exist- ing Plainville landfill at a fixed fee per ton of sludge disposed. The stabilization alternatives deemed applicable with landfilling include chemical conditioning, anaerobic digestion followed by chemical conditioning, and heat treatment. The dewatering alternatives include vacuum filtration and pressure filtration. A line diagram of systems involving landfilling of sludge is shown in Figure 3.3-8. B. Incineration or Pyrolysis . As in the case of coastal area treatment plants, pyrolysis and incineration have been considered as interchangeable processes. All of the stabilization and dewatering processes considered for the landfill system were also considered for the incineration or pyrolysis system. Two of the options considered for this system involve incineration or pyrolysis of sludge from both satellite plants at a single site. Figures 3.3-9 and 3.3-10 depict the incineration or pyrolysis alternatives. 3—171 ------- FIGURE 3.3-8 LANDFILL ALTERNATIVES DIRECTION OF FLOW ------- FIGURE 3.3-9 ALTERNATIVES FOR INCINERATION OR PYROLYSIS AT BOTH INLAND PLANTS DIRECTION OF FLOW ------- FIGURE 3.3-10 ALTERNATIVES FOR INCINERATION OR PYROLYSIS AT ONE INLAND PLANT PRESSURE. FILTRATION PLANT ANAEROBIC TRUCK TO A DIGESTION PLANT B VACUUM __________ F 1TRATION HEAT T REATMENT SLUDGE THICKENING PRESSURE FILTRATION I INCINERA- PLANT ANAEROBIC TION OR LANDFILL B DIGESTION PYROLYSIS VACUUM FILTRATION HEAT TREATMENT DI RECTI OF FLOW ------- C. Give Away or Market Sludge Product . Two basic approaches, composting and heat drying, were considered for producing a high quality, dry sludge product for a give-away or retail market program. Under heat drying, a patented process which consists of belt filter dewatering to 20 percent solids followed by heat treatment was considered. For this process, a polymer would be added to the thickened sludge prior to the dewatering process. No stabilization processes were considered, since the temperatures reached in heat drying are sufficient for pathogen destruction. The product material would consist of heat pasteurized dry pellets at a solids content of approximately 95 percent. For the composting alternatives, all the stabilization and dewatering processes considered for the landfill system were initially included. Figure 3.3-11 shows the alter- natives considered for giving away or marketing the sludge. D. Resource Recovery Center . The Commonwealth of Massach— usetts has proposed locating a resource recovery center in the general vicinity of the satellite treatment plants. Alternative systems were considered which would dispose of the sludge from the satellite treatment plants at the proposed resource recovery center. All the stabilization and dewatering alternatives considered for the landfill system were also considered for the resource recovery center system. The resource recovery center alternatives are shown in Figure 3.3—12. E. Disposal at Coastal Area Plants . Figure 3.3-13 depicts alternative systems which were considered for transporting dewatered sludge from the satellite treatment plants to the coastal area treatment plants for disposal. F. Land Application . Pasteurization and anaerobic digestion, both with and without chemical conditioning, and heat treatment were considered for the stabilization of sludge for land application. Chemically conditioned thickened sludge was not considered because of its potential pathogen content. The dewatering processes considered were pressure filtration and vacuum filtration. In addition, the disposal of a liquid sludge, which would not undergo dewatering, was investigated. The land application alter- natives considered are shown in Figure 3.3—14. Elimination of Alternatives The alternative sludge management systems developed above, were further reviewed to reduce the number of alternatives to a reasonable number for final comparative analyses. While the unit processes included under each system are technologically compatible, some unit processes have obvious advantages over others, when considered in 3—175 ------- FIGURE 3 3-11 GIVE AWAY OR MARKET ALTERNATIVES DIRECTION OF FLOW ------- FIGURE 3.3- 12 RESOURCE RECOVERY CENTER ALTERNATIVES DIRECTION OF FLOW ------- FIGURE 3.3—13 DISPOSAL AT COASTAL AREA PLANT ALTERNATIVES DIRECTION OF FLOW COASTAL AREA L PLANTS ------- FIGURE 3.3-14 LAND APPLICATION ALTERNATIVES DIRECTION OF FLOW ------- light of the complete alternative. In some instances, alternatives could be eliminated during the screening process without the need for conducting detailed cost estimates. In others, it was necessary to prepare pre— liminary design data, so that comparative cost estimates could be developed. Through a succession of screening and elimination, the number of alternatives was reduced to nine basic concepts. The rationale and criteria for elimination of the other alternatives are discussed in this section. A. Landfill . Based on discussions with the Massachusetts Bureau of the Solid Waste Disposal, it was determined that the Plainville landfill would be the most suitable site for the landfill of dewatered sludge from the satellite plants. The site is located near the intersection of Interstate Route 495 and U.S. Route 1. The landfill currently contains 43 hectares (107 acres), with an additional 121 hectares (300 acres) adjacent to the site available for possible expansion. The site has been approved by the Commonwealth of Massachusetts Department of Environmental Quality Engineering and is equipped with a leachate recovery system. The Department of Environmental Quality Engineering has prescribed a limit of 15 percent by volume for the ratio of dewatered sludge to solid waste which may be disposed of at the landfill. Based on discussions with the Massachu- setts Department of Solid Waste Disposal, a tipping fee of $7.00 per wet ton has been assumed. At a ratio of sludge to solid waste of 15 percent by volume, it is possible to dispose of all of the sludge from the satellite treatment plants at an expanded Plainville landfill for a period of more than 25 years. Based on preliminary cost estimates, it appears that filter press dewatering of chemically conditioned sludge is the most cost effective landfill alternative. The anaerobic digestion followed by filter press dewatering alternative was retained to allow for an environmental assessment of the effects of digested versus undigested sludge on the landfill. B. Incineration or PyroJ ysis . The type of incinerators considered were multiple-hearth furnaces. The units were sized on the basis of the hearth area required to completely combust sludge solids. The sludge was assumed to be autogenous if the solids content was 30 percent or higher. Since sludge processing will most likely be performed on a two shift basis at the satellite plants, auxiliary fuel will be required to keep the unit at standby temperatures during the 8 hour period when sludge is not being processed. To ensure that sludge processing would not be interrupted during periods when maintenance work would be required, at least two incinerators were provided for each incineration alternative. As in the case of the coastal area plants, 3—180 ------- no attempt was made to develop separate design bases and cost estimates for pyrolysis systems, and the incineration and pyrolysis concepts were treated as a single alternative. Since any thermal process is sensitive to the moisture content of sludge, because of the direct relationship between the fuel requirement and moisture content, and since a solids concentration of less than 30 percent is not autoqenous, any combination of stabilization and dewatering processes not capable of producing a solids concentration of at least 30 percent should be eliminated from consideration. The only stabilization process considered which, when combined with vacuum filtration will result in a solids concentration of at least 30 percent, is heat treatment. Digestion was not considered desirable with thermal processes such as incineration and pyrolysis. Although the digestion process reduces the quantity of sludge to be incinerated, this is more than offset by the decrease in heat content of the digested sludge and the increase in capital and operating costs of the digestion process. The number of incineration or pyrolysis system alternatives, therefore, was reduced to four. Two of the remaining alternatives compare heat treatment followed by vacuum filtration with chemical conditioning of thick- ened sludge followed by pressure filtration, with inciner- ation or pyrolysis at each satellite plant. The other two remaining alternatives considered incineration or pyrolysis of the sludge from both plants at a single location. One of these alternatives involved pressure filtration of chemically conditioned sludge at both plants. Under the second centralized incineration alternative, heat treatment and vacuum filtration was substituted for filter press dewatering at the plant where the incinerator would be located to take advantage of the waste heat generated in the incinerator. Based on the comparative cost analysis, the centralized incineration alternative employing filter press dewatering at both plants was eliminated in favor of heat treatment at the plant where the incinerator would be located. C. Give Away or Market the Product . Alternatives utilizing the stabilization processes of chemical conditioning of thickened sludge and anaerobic digestion followed by chemical conditioning were included in the cost development for the sludge management systems involving composting. Heat treatment was eliminated because auxiliary fuel would be required, and the disinfection benefits associated with heat treatment are not required when followed by composting. Filter press dewatering of chemically treated sludge typically yields a sludge cake with a solids concentration 3—181 ------- of 40 percent. Experience in composting filter press cake in this range of solids concentration have not been completely successful at th Beltsville, Maryland demonstration project. Furthermore, since pressure filtration is more expensive than vacuum filtration, vacuum filtration was selected as the preferred method of dewatering mixtures of primary and secondary sludge for subsequent composting. The compost- ing method considered was the aerated static pile method using the recycled composted product or tree trimmings as the bulking agent. Based on the cost estimates developed, the composting of undigested sludge appears more cost effective than composting anaerobically digested sludge. However, both alternatives were retained because of potential differences in environmental impact. Also, based on the developed cost estimates, the heat drying alternative is decisively more expensive than the composting alternatives. It also consumes large quantities of fuel. Since both methods are capable of producing a high quality product which is suitable for a marketing or give-away program, heat drying was eliminated on the basis of its high cost and high energy consumption. D. Resource Recovery Center . At present, the Bureau of Solid Wastes has identifiedfour potential sites for the location of the proposed resource recovery center. It is anticipated that the facility would use some form of incineration or pyrolysis of a refuse derived fuel to generate power. Discussions with the Bureau of Solid Wastes have indicated that the facility would probably be able to handle a dry sludge cake at a cost of about $10 per wet ton. It is not possible to place an exact cost for sludge disposal or a limitation on compatible sludge moisture content at this time, since the specific technology which will be used at the proposed facility has not yet been determined. For the purpose of this study, it has been assumed that the facility would be located near the intersection of U.S. Route 20 and State Route 128. Due to the relatively high tipping fee of ten dollars per wet ton and the desirability to have a high caloric value, only filter press dewatered chemically conditioned sludge was considered under this category. Heat treatment was eliminated because of its high cost and the absence of a waste heat source at the satellite plants. Anaerobic digestion was eliminated because it reduces the caloric value of the sludge. Vacuum filtration was eliminated because it cannot produce as dry a cake as pressure filtration. Preliminary cost data confirmed filter press dewatering of chemically conditioned sludge to be the most cost effective resource recovery alternative. E. Disposal at Coastal Area Plants . Transporting inland satellite plant sludge to a coastal plant for disposal by landfill is not a viable alternative since landfill sites 3—18 2 ------- are located at inland locations. In addition, preliminary costs indicate that, when sludge is to be composted, it is more economical to compost at the location of sludge generation than to compost at a centralized facility. Therefore, the only method of disposal which is viable with transporting satellite plant sludge to a coastal plant is incineration. A comparison of preliminary costs showed that the alternatives of vacuum filtration and pressure filtration of chemically conditioned sludge are considerably less expensive that the other alternatives considered for sludge treatment prior to transport to a coastal area plant for incineration. Pressure filtration was selected as the more appropriate process, since it will result in a sludge cake with a solids content of about 40 percent as compared to a 20 percent solids content which would be achieved with vacuum filtration. F. Land Application . Both land application of liquid sludge and dewatered sludge cake were investigated as possible methods of ultimate sludge disposal. Liquid sludge has a solids concentration of less than 5 percent, and sludge cake has a solids concentration of from 20 to 40 percent, depending on the selected dewatering process. Application rates were based on typical nitrogen uptake rates. A value of 7.4 dry metric tons of solids per hectare per year (3.3 dry tons of solids per acre per year) was assumed as a typical rate of sludge application for both liquid sludge and sludge cake. Land application of liquid sludge or dewatered sludge cake involves the transportation of the sludge to selected tracts of land for either spray application or incorporation into the soil. Based on the quantity of sludge anticipated from the satellite plants, approximately 890 hectares (2,200 acres) of land would be required for the Upper Neponset satellite plant and 1210 hectares (3,000 acres) for the Middle Charles satellite plant. A preliminary survey indicates that there is insufficient land available in the vicinity of the satellite plants to accommodate a land application program. Land which is available and could meet the necessary criteria for land application is distant from the satellite plants and consists of fragmented small parcels. Furthermore, discussions with State officials at the Massachusetts Department of Environmental Quality Engineering has indicated that presently the State does not permit land application of sludge. Based on these factors, land application was not considered a viable alternative for the disposal of sludge from the satellite plants. 3—18 3 ------- 3.3.6. Discussion of the Remaining Sludge Management Systems As a result of the environmental assessment of the water quality impact of satellite treatment plant discharges, the satellite treatment plant concept was eliminated in favor of treating all the sewage at coastal area treatment plants. The remaining non—satellite sludge disposal systems and their associated costs and environmental parameters are presented in this section. As a result of the intermediate screening process, the number of feasible sludge management alternatives for non—satellite treatment systems has been reduced to five basic concepts. These basic concepts include: Landfilling of chemically conditioned, undigested, filter pressed secondary sludge (RFL) Landfilling of chemically conditioned, digested, filter pressed secondary sludge (DFL) Composting of chemically conditioned, digested, filter pressed secondary sludge (RFC) Composting of chemically conditioned, digested, filter pressed secondary sludge (DFC) Incineration of chemically conditioned, undigested, filter pressed secondary sludge (RFI) In order to facilitate the discussion of the numerous sludge management concepts, abbreviations have been assigned to each of 5 basic concepts and are shown in parentheses after each of the alternatives listed above. In all cases, it was assumed that primary sludge disposal would be handled separately and independently of secondary sludge disposal. Filter press dewatering was selected over vacuum filter dewatering in order to obtain a 30 percent solids cake concentration with secondary sludge. These five sludge management alternatives are shown in Figure 3.3-15. Detailed costs were prepared for the separate treatment and disposal of sludge from separate treatment plants serving the northern and southern MSD service areas and for the treatment and disposal of sludge from a single treatment plant serving the entire MSD service area. In addition, costs were prepared for dewatering sludge at separate northern and southern service area plants and hauling the dewatered sludge from one plant to the other for centralized disposal. Each of the five sludge treatment and disposal concepts were considered for the first two options. For the third option (separate dewatering-hauling-combined disposal), the 3—184 ------- FIGURE 3.3- 15 REMAINING SLUDGE DISPOSAL ALTERNATIVES MDC LANDFILL I ANAEROBIC I DIGESTIONt__ DIRECTION SLUDGE THICKENING CHEMICAL CONDITION- ING SLUDGE THICKENING PRESSURE FILTRATION CHEN I CAL CONDITION- ING SLUDGE THICKENING PRESSURE FILTRATION CHEMICAL CONDIT ION- ING MDC LANDFILL SLUDGE THICKENING PRESSURE FILTRATION INCINERA- TION OR PYROLYSIS CHEMICAL CONDITION- ING LANDFILL O1 ASH PRESS U RE FILTRATION COMPOSTING GIVE-AWAY OR MARKET OF FLOW ------- FIGURE 3.3-16 ALTERNATIVE PLANT CAPACITIES FOR SLUDGE TREATMENT AND DISPOSAL RESIDUE 400 MGD PLANT SLUDGE SLUDGE DISPOSAL FOR NORTHERN __________ TREATMENT CONVERSION SERVICE AREA AND DEWATERING OR DISTRIBUTION TRANS PORT DEWATERED SLUDGE TO CENTRALIZED SLUDGE DISPOSAL FACILITY RESIDUE 186 MGD PLANT SLUDGE SLUDGE DISPOSAL FOR SOUTHERN ___________ TREATMENT CONVERSION — OR DISTRIBUTION SERVICE AREA AND DEWATERING 586 MGD PLANT SLUDGE SERVICE AREA AND DEWATERING SLUDGE RESIDUE FOR ENTIRE ___________ TREATMENT __________ ___________ CONVERSION DISPOSAL OR DISTRIBUTION ------- landfill concepts were not considered, since there would be no further sludge processing required after sludge dewatering prior to landfill. The quantity of raw sludge solids processed, exclusive of chemical addition or recycle quantities, and the costs for each of the alternatives is shown in Table 3.3—2. The costs and quantities under the separate disposal option reflect the summation of the values for the northern and southern service area plants. Table 3.3-3 presents the fuel, power, manpower, chemicals, land area and other key elements for each of the 13 remaining non-satellite sludge management alternatives. Landfill Alternatives . Of the remaining alternatives, landfill of undigested, dewatered sludge represents the most economical alternative. As shown in Table 3.3-2, there is some economy of scale that can be achieved with this alternative with a single wastewater treatment plant as compared to separate wastewater treatment plants for the northern and southern service areas. Most of the economy of scale savings result from reductions in the unit cost of the dewatering equipment and the associated dewatering buildings. The landfill of digested, dewatered sludge is more expensive than the landfill of undigested, dewatered sludge because of the added cost of new digestion facilities. However, land requirements for the landfill of the dewatered sludge can be reduced by approximately 25 percent if the sludge is digested prior to landfilling. Digestion also would decrease the consumption of fuel, chemicals and trans- portation costs because of the lower sludge production. While the potential for odor production is reduced by digestion, the high lime dosage required to dewater undigested secondary sludge would also tend to mitigate odor problems. One potential disadvantage of digestion is that digested sludge does not dewater as well as undigested sludge. The use of stabilized sludge in a landfilling operation is normally required under most situations (Federal Register Vol. 42, No. 211 November 2, 1977) . The sanitary landfill must be operated so as to prevent nuisance odors. On this basis, any sludge which is labeled for landtilling, should be stabilized by means of digestion. The advantages of landfilling secondary sludge include low costs, minimal air emissions and low manpower, power and fuel requirements. The major disadvantages of landfilling secondary sludge include the commitment of large quantities of land for disposal of sludge at high loading rates and the problems associated with obtaining a site. The site must meet State and local requirements, and be acceptable to the general public. Sludge may be applied to a landfill in a liquid or a 3—187 ------- TABLE 3.3-2 Raw COSTS FOR NON-SATELLITE SLUDGE MANAGEMENT SYSTEMS Sludge Solids Processed Metric TPD (Short TPD) Amortized Capital Cost $1000/yr O and M Cost $1000/yr Total Annual Cost $100 0/yr Total Unit Cost $/metric T ($/short T) O i (‘ : r)o JH Alternative Capital Cost $1000 ( ) I -i OD RFL 166.7 (184) 40,549.0 3,065.0 5,689.0 8,754.0 144.2 (130.8) Separate DFL 166.7 (184) 54,811.0 4,143.0 5,647.0 9,790.0 160.9 (145.9) Treatment, RFC 166.7 (184) 47,173.0 3,566.0 5,509.0 9,075.0 149.5 (135.6) Separate Disposal DFC RFI 166.7 166.7 (184) (184) 59,798.0 65,117.0 4,520.0 4,922.0 5,483.0 6,532.0 10,003.0 11,454.0 164.4 188.5 (149.1) (171.0) Separate Treatment, Combined Disposal RFC DFC RFI 166.7 166.7 166.7 (184) (184) (184) 46,564.0 58,644.0 63,695.0 3,520.0 4,433.0 4,815.0 5,550.0 5,519.0 6,595.0 9,070.0 9,952.0 11,410.0 149.5 163.5 187.3 (135.6) (148.3) (169.9) Combined Treatment, Combined Disposal RFL DFL RFC DFC RFI 166.0 166.0 166.0 166.0 166.0 (183) (183) (183) (183) (183) 32,792.0 47,823.0 39,614.0 52,153.0 56,651.0 2,479.0 3,615.0 2,994.0 3,942.0 4,282.0 5,071.0 5,436.0 5,080.0 5,374.0 6,016.0 7,550.0 9,051.0 8,074.0 9,316.0 10,298.0 124.7 149.5 133.3 153.8 170.0 (113.1) (135.6) (120.9) (139.5) (154.2) ------- TABLE 3.3-3 ENERGY & RESOURCES CONSUMED BY NON-SATELLITE SLUDGE MANAGEMENT SYSTEMS Raw Sludge Solids Processed Metric TPD (short TPD) Labor Man- Hrs/D GJ/D (MBTU/D) Power GJ/D (KWH/D) Lime Metric TPD (short TPD) Alternative Land Required Ha (Acr) Fuel RFL 166.7 (184) 491 198.9 (491.0) 82.2 (77.9) 200.4 (54,700) 38.4 28.2 (42.3) Separate DFL 166.7 (184) 512 146.2 (361.0) 61.6 (58.4) 334.2 (91,220) Treatment, RFC 166.7 (184) 648 38.6 (95.4) 185.3 (175.6) 215.5 (58,815) (42.3) Separate DFC 166.7 (184) 605 29.7 (73.4) 138.7 (131.5) 345.2 (94,202) 28.2 (31.1) Disposal RFI 166.7 (184) 626 50.2 (124.0)* 37.7 (35.8) 314.7 (85,880) 38.4 (42.3) Separate Treatment, RFC 166.7 (184) 648 38.6 (95.4) 185.3 (175.6) 215.4 (58,788) 38.4 (42.3) Combined DFC 166.7 (184) 605 29.7 (73.4) 138.7 (131.5) 345.1 (94,183) Disposal RFI 166.7 (184) 573 50.2 (124.0)* 37.7 (35.8) 288.2 (78,650) 38.4 (42.3) RFL Combined DFL 166.0 166.0 (183) (183) 404 473 202.3 149.7 (500.0) 82.2 (370.0) 61.6 (77.9) (58 4) 183.7 315.0 (50,149) (85,980) 38.1 27.8 (42.0) (30.6) Treatment, RFC 166.0 (183) 583 38.5 (95.0) 184.2 (174.6) 198.7 (54,228) Combined DFC 166.0 (183) 576 29.6 (73.0) 138.2 (131.0) 325.9 (88,943) 27.8 (30.6) Disposal RFI 166.0 (183) 508 50.1 (123.8)* 37.6 (35.6) 271.5 (74,090) 38.1 (42.0) *Includes landfill required for ash disposal. ------- TABLE 3.3-3 (Cont ‘d) ENERGY & RESOURCES CONSUMED BY NON-SATELLITE SLUDGE MANAGEMENT SYSTEMS Fed 3 TPD TPD) Residue Volume m 3 /day (yd 3 /day) Wet Trips Per Day Truck Capacity 15.3m 3 22.9m 3 (20yd 3 ) (30yd 3 ) Alternative Metric (short Polymer Metric TPD (short TPD) Residue Weight Metric TPD (short TPD) Dry Separate DFL 7.1 (7.8) 0.29 (0.32) 158.3 (174.5) 658.9 (861.7) 43 29 Treatment, RFC 9.6 (10.6) 0.31 (0.34) 195.0 (215.0) 360.8 (471.9) 24 16 Separate DFC 7.1 (7.8) 0.29 (0.32) 144.2 (159.0) 266.8 (349.Q) 1.7 12 Disposal RFI 9.6 (10.6) 0.31 (0.34) 99.8 (110.0) 166.1 (217.3) 11 7 Separate Treatment, RFC 9.6 (10.6) 0.31 (0.34) 195.0 (215.0) 360.8 (471.9) 24 16 Combined DFC isposa1 RF1 7.1 9.6 (7.8) (10.6) 0.29 0.31 (0.32) (0.34) 144.2 99.8 (159.0) 266.8 (349.0) (110.0) 166.1 (217.3) 17 11 12 7 RFL 9.5 (10.5) 0.30 (0.33) 214.6 (236.6) 893.4 (1168.4) 58 39 Combined DFL 7.0 (7.7) 0.29 (0.32) 157.7 (173.9) 656.6 (858.8) 43 29 Treatment RFC 9.5 (10.5) 0.30 (0.33) 194.1 (214.0) 359.1 (469.7) 23 16 Combined DFC 7.0 (7.7) 0.29 (0.32) 143.3 (158.0) 2651. (346.8) 17 • 12 Disposal RFI 9.5 (10.5) 0.30 (0.33) 98.9 (109.0) 164.6 (215.3) 11 7 ------- dewatered form. The sludge may lso be raw or digested. Different problems will arise in landfilling of the sludge depending on the form of the sludge. An analysis to determine the most environmentally sound alternative for sludge landfilling will be discussed. Problems associated with landfilling of sludge include, increased leachate production, odors, public health consider- ations, compacting difficulties and nuisance. No specific guidelines exist for operation of a sewage sludge landfill; however, guidelines for proper design and operation for sanitary landfills apply. If a sanitary landfill accepting sludge is not operated by the wastewater treatment authority, a binding agreement should be required between the wastewater treatment authority and the operator of the sanitary landfill to assure compliance with EPA guidelines and criteria being developed under PL94-580 (EPA, 1977) Application of liquid sewage to sanitary landfills has been tested in the past. Odor and leachate problems were found. This would cause even a greater problem if heavy precipitation falls on a landfill. Since only dried sludge is accepted in Massachusetts, disposal of liquid sludge will receive no further considerations. Any disposal of sludge in a landfill requires a separate permit to be obtained by the landfill owner since sludge is designated as a special waste. It has been suggested that a new landfill site,for sewage sludge only, be developed. To accomplish this task a new site would have to be found. In light of public opposition to landfills in a community, this would be a difficult task. If such a site were found, it would require special permits and it would have to be a controlled landfill, assuming the sludge is designated a hazardous waste. Environmental concerns for such a fill would be similar to those for any landfill. Surface water and ground water pollution are of major concern in sanitary landfills. Precipitation is the principal source of moisture over a landfill site. Once the cover soil field capacity is exceeded, the moisture percolates down into the landfill material below and ventaully the field capacity may be exceeded. At this point the moisture, in the form of leachate, will percolate into the base soil of the landfill. Movement of leachate through soils depend on the composition of the soil, its permeability and the type of contaminant. Organic materials that are biodegradable do not travel far, but inorganic ions and refractory organics can. If leachate is determined to be a problem, a controlled 3—19 1 ------- landfill would be required. This would mean that leachate and runoff from the landfill would need to be collected and suitably treated to prevent pollution of ground surface waters. This can be accomplished by lining the landfill with a layer of clay or other impervious material. In Massachusetts today, only one small controlled landfill exists. The production of odors resulting from the application of digested sludge should be very similar to those associated with normal landfill operations. To control any odors which may be produced by the application of digested sludge, cover- age with soil as soon as possible after filling is necessary. The principal gases which will be produced due to de- composition are methane, nitrogen, carbon dioxide and hydrogen sulfide. Gas production will vary as the landfill ages and with the composition of the landfill. Methane gas is explosive, therefore, measures must be taken to prevent its accumulation. If the landfill is porous, the methane gas will escape through the surface of the fill to the atmosphere. However, if there is the possibility of methane pockets forming, the landfill must be vented. The potential presence of methane does not differ between ordinary landfills and those where sludge is added to the fill. Air pollutants from landfilling will be due to the sludge handling, soil covering and support vehicles. The equipment at the fill and the trucks delivering the sludge will be the sources of air emissions in addition to fugitive dust. Noise levels will also be raised due to the equipment. Exposure to pathogens in the sludge should be minimal at the landfill since it will have been digested prior to application. Bacteria, protozoan cysts, heirnirithic ova and viruses present in the sludge will be greatly reduced, but will not be totally eliminated. Landfill site workers may be exposed to some degree of hazard; however, few, if any, substantiated cases of disease due to landfill operations exist. Finally, it is essential for the community surrounding the landfill to be separated from the associated problems and possible nuisances of the landfill. Therefore, a buffer zone to screen the landfill is necessary. The buffer zone should screen the site from view with plantings and/or a berm which would also provide a barrier to limit noise and dust. Composting Alternatives . Next to landfill, the composting alternatives provide the most economical sludge disposal system. Six of the remaining alternatives for sludge disposal involve composting of either undigested, dewatered sludge or anaerobically digested, dewatered sludge. The anaerobic 3—192 ------- digestion step adds between $14 to $19 per ton to the cost of the composting operation. The only advantage of digesting the sludge prior to composting is to reduce the potential for odor generation during the composting process. Since undigested sludge has been successfully composted by the aerated pile method without significant odor generation, it is questionable whether the potential benefit derived from digestion prior to composting is worth the added cost. The effect of the economy of scale on composting can be gleaned from Table 3.3-2. By comparing the cost of composting for the separate treatment/separate disposal alternative to that of the separate treatment/combined disposal alternative, it can be seen that there is little cost savings for hauling dewatered sludge from the southern service area to the northern service area for centralized composting. The added transportation costs more than offset any savings resulting from a larger composting oepration. This is understandable since most of the costs associated with composting are operating costs, which tend to be directly proportional to the quantity of sludge processed. Table 3.3-2 does indicate however, that combined sludge dewatering and cornposting for a single centralized waste- water treatment plant is less expensive that the separate wastewater treatment alternatives. This is primarily a result of the economy of scale achieved with a large sludge dewatering facility, housed in a single building rather than separate sludge dewatering facilities for the northern .and southern service areas. The success of a composting operation is contingent upon finding a suitable outlet for the composted material. It has been assumed that certain high quality sludge products, such as shredded compost or heat dried sludge, could be distributed to the public by either a give-away or retail marketing program. For a give—away program, it has been assumed that the general public would pick up the sludge product free of charge at the coastal treatment plants. The product would be available in bulk for transfer to containers or trucks for general public distribution. For the give-away alternative, no cost would be incurred for sludge trucking or ultimate disposal. This program is similar to Philadelphia’s present Philorganic program and Chicago’s NuEarth program. For a retail market program, it was assumed that the sludge product would be prepared in 50 pound bags and distributed through retail outlets such as nurseries, garden supply stores, etc. This program is similar to the LA/OMA program in which composed sludge is privately distributed by the Kellogg Company, a Los Angeles based compost distributor. It has been assumed that the cost of bagging and distribution would be offset by revenues derived from the sale of the bagged product. A preliminary study of land suitable for compost appli— 3—19 3 ------- cation within the MSD service area was made. This study focused on large or institutional users and did not include small scale or individual users. Those areas which were considered for compost application were; parks (including the Harbor Islands), golf courses, parkway medians, military installation, prisons, airports, cemeteries and wildlife or natural preserves. Compost application was not considered for wetlands or 33 meter (100 foot) buffer zones around rivers and streams, areas with slopes in excess of 10 to 15 percent, cemeteries smaller than 1.2 hectares (3 acres), in- accessible woodlands and beaches or beach parks. The area suitable for compost application was approximately 4700 hectares (11,600 acres). Application rates of approximately 4.4 metric tons/hectares/year (2 tons/acre/year) are possible, based on the expected chemical composition of the composted sludge. At this application rate, it would be possible to apply approximately 20,700 metric tons (23,000 short tons) of compost annually to the large tracts of avail- able land area. While it would not be reasonable to assume that all of these large land area owners would elect to use compost as a soil conditioner, when the large volume user is combined with small users such as individual homeowners, industrial parks, landscape contractors and others, a considerable market for composted sludge as a soil conditioner can be expected. While it is difficult to project markets for sludge based compost in an area without a more formalized survey, it would appear that the MDC jurisdictional area and environs could support a market of 18,000—27,000 dry metric tons (20,000—30,000 dry tons) per year after 3 or 4 years of development. This market would include several sectors, one of which would be the reatil or consumer sector. Other sectors would be MDC—controlled or related municipal and county agencies, commercial nurseries, golf courses, and landscape contractors. Market projections for other cities throughout the U.S. are presented in Table 3.3-4. The major advantage of composting is that the sludge is converted to a useful product. The product therefore recycles a valuable resource by utilizing the nutrient and soil building properties of composted sludge. The major disadvantages of composting are the relatively large land requirements, the seasonal operation cycle, and the uncertain- ty of the market for the end product. Consequently, it would be desirable to conduct an extensive marketing survey prior to implementing an extensive composting program. At the present time, Energy Resources Company Inc., ERCO, is conducting a market survey for the MDC to determine user acceptance to cornposted sludge. Approximately 76.5 cubic meters (100 cubic yards) of compost have been produced from Deer Island raw primary sludge for test marketing. The compost is being distributed to a number of non-agricultural 3—194 ------- TABLE 3.3-4 ESTIMATED MARKET POTENTIAL FOR SLUDGE PRODUCTS Survey Area Colorado Springs Placerville Fort Worth Washington, D.C. Los Angeles Chicago 2,270 73,000 99,000 187 ,000 (2, 500) (80,000) (109,500) (205,500) Extracted from Ettlich, W.F. and A.K. Lewis, “Is There a Sludge Market?” Water and Wastes Engineering, Dec. 1976. Annual Market Potential Dry Metric Tons per Year (Short Tons per Year) 990 (1,090) 162 (178) 3—19 5 ------- potential users for testing and evaluation. Based on the results of the test marketing and user acceptance, ERCO will estimate the potential size of the compost market in the area. This study should be completed by the end of the third quarter of 1978. The aerated static pile method of composting was designed to reduce odor emissions into the atmosphere, eliminate costly digestion and reduce pathogen levels. This method allows the use of undigested sludge since it reduces malodors and destroys pathogens due to raised temperatures. There- fore, sludge digestion is unnecessary. In order for the composting operation to have no adverse effect on ground or surface water quality, an impervious layer of asphalt or other suitable material should be installed under the storage, drying, composting, mixing, dewatering and screening operations. The runoff and leachate should be collected and treated. Area must be provided for stockpiling the compost during curing and frr storing the final product until distribution. The impacts which may place the greatest limitations on the process include land availability, odor control and aesthetic impacts. The process is designed to operate in a manner whereby odors are minimized. The odors are kept to a minimum by drawing the effluent air from the compost through a pile of cured compost. At times, odors may be present in the vicinity of the composting area and may cause objections. Also, depending on the actual site, residences or business may be in full view of the composting area. Therefore, it is essential for the community surrounding the composting site to be separated from the associated problems and possible nuisances of the operation. A buffer zone to screen the site is necessary. The buffer zone should screen the site from view with plantings and/or a berm which would also provide a barrier to limit noise and dust. The static pile operation requires the use of front end loaders and trucks to move the compost materials and residues. Equipment used for these purposes will raise noise levels and air emissions. Various bacteria, protozoa, Helminthic parasites and viruses are found in sewage. Composting, when properly conducted, destroys the human enteric pathogens that are present in the sludge. However, the compost is not sterile. Successful composting depends on raised temperatures that will destroy the primary pathogens while not inhibiting the composting process itself. While composting destroys primary pathogens, certain thermophilic fungi and actinomycetes normally present in 3—196 ------- low concentrations can proliferate during the composting process (Burge, 1977) . These organisms can produce respiratory infections and allergic reactions to individuals susceptible to asthmatic reactions resulting in a potential occupational hazard to workers at the cornposting site. This impact can be readily mitigated by screening personnel with a history of health problems from consideration for composting jobs. Enclosure of the cabs in operating equip- ment and dust control measures can also reduce the exposure of the workers to spores of these secondary pathogens. Incineration Alternative. The incineration alternative represents the most expensive of the remaining sludge disposal alternatives. However, the amount of area required to landfill incineration ash is about one fourth of that required to landfill chemically conditioned dewatered sludge cake. Hence, if available land is at a premium, the reduction of land requirements could make the incineration alternative attractive. As in the case of the other alternatives, there is only marginal economy of scale to be gained by hauling sludge from the southern service area for centralized incineration. The main economy of scale savings are associated with the dewatering process and can only be achieved by constructing a single centralized wastewater treatment plant serving both service areas. It should be emphasized that the incineration costs as developed in this EIS reflect the costs of dewatering and incinerating secondary sludge separate and independent of primary sludge. If the secondary sludge were blended with primary sludge prior to dewatering, it may be possible to reduce the amount of chemical conditioning required, thereby reducing the costs of incineration somewhat from the costs reported in Table 3.3-2. Incineration processes have their drawbacks. Even with the most advanced air pollution control system, the incineration of secondary sludge will emit air pollutants. Thus the high cost and air emissions associated with incin- eration alternatives must be weighed against the high land requirements and public acceptance uncertainties of landfill alternatives, and the land requirements and market uncertain- ties of the cornposting alternatives. Air emission and air quality issues are of major concern. The Clean Air Act Amendments and various EPA rules and regulations related to air quality must be adhered to. An air dispersion study of the area was undertaken. The study included an air quality model for the air pollutants emanating from sludge incinerators at various locations within the study area. The air dispersion study is presented 3—197 ------- in Appendix 3.5.4. A general discussion of air pollution emissions from sewage sludge incinerators is presented here. Sludge incinerator systems have been shown to emit particulates, nitrogen oxides, sulfur oxides, carbon monoxide, hydrocarbons and small but measurable quantities of heavy metals and organic chemical compounds. The amount of a particular pollutant which is emitted is directly related to the characteristics of the sludge being burned. Sewage sludge, in general, contains organic material, carbon, phosphorus, and such major elements as silicon, sodium, potassium, magnesium, aluminum, iron, calcium and aminonium. A substantial number of minor elements may also be found, including, chromium, maganese, copper, nickel, mercury, lead, cadmium, zinc, boron, silver and cobalt. In addition to the sludge characteristics, operating procedures also determine the types and amounts of pollutants that may occur. Poor operating procedures may cause excess particulates to leave the incinerator or may ca zse hydro— carbons and carbon monoxide to form. Sulfur oxides are not emitted in significant amounts when sludge is burned, in comparison to other combustion processes, since the sulfur content (by dry weight) in sludge is generally 1 to 2 percent. Particulate emissions are generally a major problem in both multiple hearth and fluidized bed incinerators. The standards for discharge of particulate matter from sewage sludge incinerators allows not more than 0.65 grams per kilogram (1.3 lbs/ton) of dry sludge input. For uncontrolled multiple hearth incinerators, particulate emissions average about 50 grams per kilogram (100 lbs/ton) of sludge. Stack tests at existing sludge incinerators with control equipment have shown that the emissions standards can be met (EPA 1975). It is not anticipated that gaseous pollutant (nitrogen oxides, sulfur dioxide and carbon monoxide) levels would violate any regulations. As mentioned previously, sulfur dioxide levels are dependent upon sulfur levels in the sludge. With control equipment, sulfur dioxide levels are reported to be 0.4 g/kg (0.8 lb/ton), in contrast to 0.5 g/kg (1.0 lb/ton) uncontrolled. Sludge typically has a high nitrogen content due to the proteinaceous compounds and the ammonjum ion. The amount of nitrogen emitted from a controlled sludge incinerator is about 2.5 g/kg (5 lb/ton) versus 3 g/kg (6 lb/ton) for uncontrolled emissions (EPA 1975). Pesticides and PCB’s (polychlorinated-biphenyl) may occur as a wide range of concentrations in sludge as is summarized by a random selection of sludges below: 3—198 ------- Compound Range (mg/kg) Aidrin 16.2 (in one sludge only) Dieldrin 0.08 — 2.0 Chiordane 3.0 - 32.0 DDD n.d. - 0.5 DDT n.d. - 1.1 PCB’s n.d. — 105 n.d. - not detected The preceding data was obtained by the National Research Center, Cincinnati, Ohio as related by EPA (1974) . No pesticides were found in the sludge ash. Analysis also showed no pesticides or PCB’s in scrubber water. However, the study failed to determine whether or not they appeared in the gas stream leaving the incinerator. It therefore appears the materials are either destroyed via incineration or escape in the exhaust gas. Since all of these materials have some solubility in water, it is unlikely that no trace amounts would be present in the scrubber water. Thus, it appears that PCB’s and pesticides are destroyed. Other data also point to complete or near complete (99 percent) destruction of pesticides at temperatures near 900°C (1,652°F). PCB’s which are slightly more stable, were found to be totally destroyed at temperatures of 1315°C (2,400°F) for 2.5 seconds or 99 percent destroyed at 871—982°C (1,600—1,800°F) in two seconds. When oxidized in combination with sewage sludge, at an exhaust gas temperature of 593°C (1,100°F) , total destruction of the PCB’s was achieved (EPA 1975) The concentration of metals in sludge varies widely due to the source of the wastewater and the type of waste- water treatment. Subsequently, metal concentrations in the products of incineration (sludge ash, particulates and gaseous emissions) will vary depending upon the initial sludge metal content. Tests conducted at three incinerators showed that the ratio of a metal to fixed solids in the sludge was not always the same as its concentration in the ash. For example, if the ash showed a lower concentration of a metal than its concentration in the sludge on a fixed solids basis, this indicates that the particulate (or fly ash) should have a higher concentration of the metal than either sludge or ash (EPA Task Force Study, 1972). Table 3.3-5 gives a comparison of metals in the sludge to ash. Mercury vapor or a volatile mercury compound is discharged to the atmosphere in the exhaust gases from sewage sludge incinerators. There is strong evidence that 3—199 ------- TABLE 3.3-5 METAL TO FIXED SOLID RATIO FOR SLUDGE AND ASH FOR INCINERATOR TEST SITES (mglg) i.d. — insufficient data blank — not determined n.d. — not detected micrograms/gram multiple hearth incinerator fluidized bed incinerator Data on most elements were determined by emmission specto— graph by J. Kopp, Analytical Quality Control Laboratory. As, Sb, and Se were determined by neutron activation analysis at North Carolina State University (coordinated by D. von Lehmden, Analytical Branch, Division of Air Programs). Element Lake Tahoe, Calif.(MH) Barstow, Calif.(FB) Residue Residue Sludge Ash Ratio Ash Ratio Lorton, Va.(MH ) Residue Sludge Ratio Ag, Silver 0.6 L.d. 1 — 0.14 0.36 0.33 Al, Aluminum 27. 24. 0.88 16. 1.0 2.0 Ba, Be, Barium Beryllium 6.0 n.d. 3 1.1 n.d. 0.18 — 4.1 n.d. 0.37 - 0.75 — Ca, Calcium 62. 290. 4.6 46. 1.6 — Cd, Cadmium 0.37 0.20 0.57 n.d. — 0.71 Co, Cobalt 0.2 — n.d. — Cr, Chromium 2.0 0.3 0.15 2.9 0.17 0.86 Cu, Copper 2.6 1.3 0.5 2.5 0.68 1.0 Fe, Iron 18. 8.9 0.49 12. 0.91 0.86 Hg, Mercury 9.0* n.d. — 20.* K, Potassium 1.4 1.3 0.92 3.3 — 1.3 Mg, Magnesium 12.1 16.2 1.3 2.8 — 0.94 0 ° Mn, Na, Ni, Manganese Sodium Nickel 1.1 1.8 2 0.5 1.8 i.d. 0.45 1.0 0.18 n.d. 1.0 1.0 1.3 — P, Phosphorus 81. 84. 1.0 1.3 Pb, Lead 5.8 0.7 0.12 7.0 0.12 2.0 Sb, AntImony 1.3* 1.3* 1.0 Se, Selenium 12.3* 12.3* 1.0 Sr, Strontium 1.0 0.7 0.7 n.d. n.d. n.d. n.d. V, Vanadium n.d. 0.4 — n.d. 2.1 — n.d. n.d. - Zn, Zinc 1.6 1.6 1.0 2.4 1.4 0.58 0.8 0.7 0.88 0.05 16. 1.5 n.d. 73. 0.58 n.d. 0.5 1.7 11. n.d. 0.18 n.d. 0.85 0.15 8.1 1.2 n.d. 0.31 n.d. 0.7 1.6 50. 6.* 1.8 7.0 0.9 1.1 n.d. 45. 2.0 0.05 16. 0.9 n.d. 235. 0.22 n.d. 0.6 1.6 43. n.d. 2.3 6.6 0.9 1.4 n.d. 57. 1.0 (1) (2) (3) * (MN) (FB) Source: EPA Sewage Sludge Incineration 1972 ------- lead compounds are being classified into the fly ash stream and carried off by the combustion gases. It appears, however, that the lead is removed via scrubbers. Silver, barium, chromium and copper may show a similar effect, but more substantial data are needed. An analysis representative of particulates which leave the stack is presented for the Tahoe, Barstow and Lorton sewage sludge incinerators. The ratio of metal concentration in the particulates to the metal concentration in the sludge (fixed solids basis) is presented in Table 3.3-6. No precise quantitative relationships may be established from the data. However, there is reasonable agreement between samples. The literature indicates that discrepancies exist regarding the percentages of mercury which enter the atmos- phere. Several sources (EPA, 1972; Dewling, 1977; Olexsey, 1974) point to the complete vaporization of mercury into incinerator gases. Other data suggest between 10 and 35 percent release of mercury into the atmosphere. The data generated by Dewling (1977) shows, with the exception of mercury, 78—95 percent of the heavy metal contained in sludge is retained in the ash and all but 1 percent is removed by the scrubber. This data is indicative of incineration in general. A summary is provided in Table 3.3-7. Mercury is shown to be almost completely emitted to the atmosphere (97.6 percent) Due to the high emissions of mercury, a careful examination of the quantity of mercury emitted on a daily basis should be made. The EPA emission standard for mercury from sewage sludge incinerators is 3,200 grams (7.06 ibs) per day. It is estimatec . that the sludge from the northern MSD service area will contain about 6 mg/kg of mercury, and the sludge from the southern service area will contain about 3 mg/kg. Assuming all of the mercury is vaporized upon incineration, the incineration of all secondary sludge will result in emissions of about 701 grams (1.55 lbs) of mercury per day. This level, in addition to the 1634 grams (3.60 ibs) per day of mercury from primary sludge incinerators, is well within the EPA allowable limit of 3200 grams (7.06 ibs) per day. Airborne concentrations of metals are of concern since they are generally associated with particles in the respirable range (0.2u) and they may have toxic properties (Dewling 1977). Thus, the amount of heavy metals emitted should be controlled to within acceptable limits to avoid contamination to the environment. Many of the minor elements found in the sludge will be 3—201 ------- TABLE 3.3—6 CONCENTRATION OF METALS IN PARTTCULATES (mgf ) 1 R in ratio of metal concentration In partlculates to particulate concentration used In the calcul;it mu. 2 n.a. means “not analyzed” 3 Rerylllum concentration In given In micrograms pr r gram 4 n.n.i. means “not sufficient Information’ 5 n.j. means “no Information” rofl(Pfl t rat I on In the s lujd ’e . Med I an SOURCE: EPA Sewage Sludge Incineration 1972 Location Sample Elements South 1 Lake Tahoe Rarstow 1 Ag, Silver 0.2 n.a. 2 0.6 0.05 n.a. n.a. 0.6 n.a. n.s.i. 4 As, Arsenic <0.5 <0.3 <0.3 <0.3 0.3 <0.3 <0.3 <0.3 n.a. fl.5.I. Be, Beryllium 1.O 3 O.5 n.s.I. O.5 O.5 0.5 n.s.I. <0.5 n.s.f. Cd, Cadmium 1.0 1.0 1.5 2.6 0.1 0.08 0.1 n.s.f. <0.25 <0.8 Co, Cobalt 4.0 0.05 0.3 n.s.f. n.j. 5 0.4 0.05 n.s.f. 0.05 n.s.I. Cr, Chromium 1.0 0.1 0.4 0.2 0.5 0.4 0.6 0.2 0.5 0.7 Cu, Copper 1.0 0.04 0.8 0.1 2.0 1.8 2.5 0.7 1.3 0.8 Fe, Iron 4.0 28. 11. 0.6 5.0 12. 16. 1.0 17. 0.3 Mn, Manganese 0.5 0.6 0.3 0.4 11.1 0.1 0.2 0.6 0.4 0.5 Ni, Nickel 0.4 0.2 0.3 n.s.f. 0.1 0.05 0.1. n.s.f. 2.0 n.s.f. Pb, Lead 20. 7. 15. 2.6 1.0 0.1 0.9 0.1 9.0 4.5 Sr, Strontium 0.6 n.a. n.a. <0.4 0.2 n.a. n.a. n.s. f. n.a. n.T [ . V, Vanadium <0.2 <0.05 <0.05 n.s.f. <0.1 <0.05 0.1 n.s.I. <0.05 n.s.f. Zn, Zinc 40. 50. 55. 30. 2.5 8. 12. 36. 19. 74. ------- TABLE 3.3-7 FLUIDIZED BED INCINERATOR - HEAVY METAL MASS BALANCE % Weight Distribution (Normalized) Metal Ash Scrubber Stack Zinc 79 20 1 Copper 78 21 1 Lead 87 12 1 Chromium 95 4 1 Nickel 80 20 N.D. Mercury 0.4 2.0 97.6 Cadmium 80 20 N.D. N.D. — Not Detected Source: Dewling, 1977 TABLE 3.3-8 HEAVY METALS IN SLUDGE ASH (mg/kg dry weight basis) Silver 50 Boron N.D. Cadmium 200—500 Chromium 300-600 Cobolt N.D.-200 Copper 1,300—1,600 Mercury N.D. Manganese 200-900 Nickel N.D. Lead 700—1,000 Strontium N.D.-700 Zinc 700—1,600 N.D. - Not Detected Source: Dewling, 1977 3—203 ------- found in the ash in concentrations greater than the levels found in dried sludge. Except for mercury, metals generally remain in the ash or the fly ash. If the ash is about 25 percent fixed solids after ignition, it will have approximately four times the concentration of metals as did the dried sludge. These levels may range as high as 10,000 mg/kg, thereby posing a possible pollution threat upon ultimate disposal. Sludge ash data is difficult to find in the literature. However, Table 3.3-8 summarizes available eta1s concentration data. The incineration alternative presents a potential source of air pollution along with a sludge ash disposal problem. Enüssion controls are used to clean effluent gases before their release to the environment, thereby allowing air emission standards to be met. The incinerator ash must be disposed of in a properly designed landfill. When epositing ash in a landfill, leachate and runoff should be collected and treated and the site should be adequately monitored. As mentioned previously, an air dispersion study is presented in Appendix 3.5.4. The study provides computer estimates of air emissions for sludge incineration at various locations within the study area. The impacts of sludge incineration are discussed in Section 5.4. 3—204 ------- 3.4 FINAL SCREENING OF SYSTEM ALTERNATIVES 3.4.1. Non—Satellite Systems In the previous sections of this report, interceptor sewer, waste’ yater treatment and sludge management subsystems have been discussed as separate entities. In this section, these subsystems will be brought together to form alternative systems. Each alternative system will include interceptor sewer, wastewater treatment and sludge management facilities. As discussed previously, the least expensive means of sludge disposal would be landfilling undigested, dewatered sludge at an independent landfill owned and operated by the MDC. However, sludge should be digested prior to landfilling in order to stablize it and to reduce its volume. Due to the nature of the sludge, particularly the presence of heavy metals, leachate from the landfill would have to be prevented from reaching groundwater. This could be accomplished by lining the landfill area with a layer of clay or other impervious liner, and collecting and treating the leachate. Landfilling of sludge is the most land intensive sludge disposal method, requiring about 150 hectares (370 acres) of land to dispose of all the secondary sludge generated in the MSD service area. Transporting all the dewatered secondary sludge to an inland sludge landfill would require considerable truck traffic from the treatment plants to the landfill. Depending on the capacity of the trucks used, from 16 to 24 trucks would be required each day to transport the sludge generated from the treatment of wastewater from the northern MSD service area, and from 13 to 19 trucks per day would be required to trans- port the sludge generated from the treatment of wastewater from the southern MSD service area. For the alternative which includes treating all wastewater at Deer Island, 29 to 43 trucks per day would be required. Truck traffic would have the largest impact when transporting sludge from a plant on Deer Island, since it would mean that from 16 to 43 trucks would have to pass through the residential areas of Point Shirley and Winthrop each day. The impact of truck traffic would not be as great when transporting sludge from a plant at either Squantura or Broad Meadows, where the number of trucks required are less (13 to 19 per day) and the plants are located closer to major arteries. Due to the problems associated with leachate control, the large land area requirements, and the heavy volume of truck traffic required, methods of sludge disposal other than landfilling should be used where possible. The remain- ing feasible sludge disposal options available are composting sludge for a market or give away program, and sludge incin- 3—205 ------- eration with ash disposal in a controlled fill area. A Draft Environmental Impact Statement addressing the disposal of primary sludge from MDC wastewater treat— ment facilities prepared for EPA, Region I by the firm of Ecoisciences, Inc., concluded that “The MDC should not attempt to produce and sell a fertilizer product.” However, that conclusion was specifically made for the production and sale of fertilizer derived from stabilized primary sludge. It was stated in the primary sludge Draft EIS that a “review of other sludge fertilizer programs indicates that the established operations with successful marketing programs are those which dry activated sludge from secondary treat— ment processes”. While it would be desirable to conduct an extensive marketing survey to determine the possible market for composted secondary sludge prior to implementing an extensive composting program, such a survey is beyond the scope of this study. (The marketing study currently being conducted by Energy Resources Company, Inc. for the MDC should provide some insight into market potential for composted sludge) . Based on the experiences of other metropolitan areas and preliminary investigations during this study, it is estimated that, with an extensive promotional campaign, the MDC jurisdictional area could support a market of about 18,000 dry metric tons (20,000 dry short tons) of compost per year. The product could be utilized as a soil conditioner and applied to parks, highway median strips, golf courses, cemeteries, residential lawns and other landscaped areas. Other possible outlets are commercial nurseries and landscape contractors in the area. In addition to existing park lands, the Boston Harbor Islands Comprehensive Plan (MAPC 1972) recommends the development of the Boston Harbor Islands into major recreation and conservation sites. The combined land area of these islands provides another outlet for composted secondary sludge. The estimated compost market of 18,000 dry metric tons (20,000 dry short tons) per year would result in the disposal of about 25 percent of the secondary sludge generated at the MDC wastewater treatment plants. Based on th’e estimated sludge characteristics presented in Table 3.2-26, the sludge from the southern MSD service area wastewater will contain considerably lower concentrations of heavy metals than the sludge from the northern MSD service area wastewater. Since the quantity of secondary sludge generated from the wastewaters of either service area can more than fully satisfy the anticipated market for composted sludge, the compost should consist of sludge from the southern service area, as this sludge is of a better quality (lower heavy metals concentration) than the sludge from the northern 3—206 ------- service area. It is estimated that about half of the second— ary sludge generated from the treatment of the wastewater from the southern MSD service area could be disposed in the form of compost. As discussed previously, landfilling the secondary sludge generated from the treatment of wastewater from the northern MSD service area would require from 16 ro 24 trucks to transport the sludge to a landfill. The landfill would require an area of about 81 hectares (200 acres) . In addition, due to the characteristics of the sludge, particularly the heavy metals content, leachate and precipitation runoff from the landfill area would have to be collected and treated in order to prevent contamination of groundwater or surface water. The sludge from the northern service area cannot be di posed of as a composted product 1 since it was concluded that the available market would be utilized to dispose of sludge from the southern service area. A third alternative for disposing of the northern service area sludge is incin- eration. Although the Boston Air Quality Control Region is in a status of “non-attainment”, recent investigations by the Massachusetts Division of Air Pollution Control have determined that Deer Island is in a “clean zone” of the non-attainment” area. The incineration of the secondary sludge from the northern MSD service area would result in a residue of about 95 cubic meters (125 cubic yards) per day. This residue, which must be disposed of, is about 25 percent of the volume of sludge which would require disposal under the landfill option. It would be possible to dispose of the residue from incineration either on Deer Island or at a location near Deer Island, as will be discussed shortly. As a result of the preceding discussion, it is felt that incineration is the most practical method of disposing of the secondary sludge generated from the treatment of the wastewater from the northern MSD service area. The remaining half of the southern service area secondary sludge still requires a method of disposal. Land- filling of this remaining sludge would not have as severe impacts as would the landfilling of all the secondary sludge generated from the treatment of wastewater from the entire MSD service area or from the northern service area. An area of about 34 hectares (84 acres) of land would be required. Approximately 7 to 10 truck loads per day would be required to transport this sludge from the treatment facility to the landfill. In addition, due to the lower estimate of concentrations of heavy metals in the sludge from the southern service area and the smaller landfill area involved, the collection and treatment of leachate and runoff would be less involved than it would be at a landfill for the sludge from either the northern or entire service areas. If it is found that a larger market exists for composted secondary sludge than is estimated, the amount of sludge 3—207 ------- requiring landfilling would be reduced. The three non-satellite treatment plant system alter- natives which survived the intermediate screening process (see Section 3.3.2) will be described below, together with their respective sludge management and interceptor sewer requirements. Then, a comparative analysis will be made to compare the relative merits of the three systems in order to select an optimum non-satellite system which can, in turn, be compared to the plan recommended in the EMMA Study and a “No Action” alternative. A. Deer: Deer/Broad Meadows: Broad Meadows - w/o Sat . This alternative includes expanding and upgrading the existing Deer Island treatment plant to provide secondary treatment for the northern MSD service area wastewater flows, and the construction of a new treatment plant at Broad Meadows to provide secondary treatment for the wastewater from the southern MSD service area. Deer Island has a land area of approximately 85 hectares (210 acres). The existing primary treatment plant occupies about 8.9 hectares (22 acres) of land. The Suffolk County House of Correction prison is located to the north of the existing treatment plant and occupies about 9.3 hectares (23 acres). To the south of the treatment plant is the 30 meter (100 foot) high drumlin, which covers an area of about 13 hectares (44 acres) of land, part of which contains the remains of Fort Dawes. The remainder of the area on Deer Island consists of several parcels of open space. The expansion of the existing primary treatment facllit— ies and the addition of secondary treatment facilities at Deer Island to treat the wastewater from the northern NSD service area can be accomplished by expanding the plant site either northward or southward. A northward expansion would require utilizing the area presently occupied by the prison and would, therefore, necessitate removing the existing prison facilities. ExpandIng southward would require the construction of treatment facilities on the land presently occupied by the drumlin, and would necessitate removing the drumlin. A third option would be to expand the primary treatment facilities adjacent to the existing facilities and to construct secondary treatment facilities on the southern end of Deer Island, below the drumlin. This option was not considered because, in addition to the additional costs of constructing, operating and maintaining essentially separate facilities, there is not enough land area south of the drumlin to accommodate the necessary facilities, and about 6.1 hectares (15 acres) of fill would be required. The incineration of the secondary sludge generated 3—208 ------- 300 0 300 $00 SCALE IN FEET PRIMARY 100 0 100 ?O0 SETTLING •1 J-i _ i-- —I SCALE IN METERS AERATION TANKS AREA FOR SECONDARY SLUDGE ASH DISPOSAL AREA FOR PRiMARY SLUDGE ASH DISPOSAL SLUDGE MANAGEMENT BUILDING OUTLINE LEGEND EXISTING WASTEWATER TREATMENT FACILITIES OTHER EXISTING STRUCTURES NEW WASTEWATER TREATMENT FACLITIES REQUIRED —YEAR 2000 FUTURE EXPANSION - YEAR 2050 FIGURE 3 .4-I DEER ISLAND WASTEWATER TREATMENT PLANT FINAL TANKS CHLORINE CONTACT TANKS PUMPING STATION 0 I, LI FOR NORTH MSD SERVICE AREA ------- at the proposed treatment plant on Deer Island would produce about 95 cubic meters (125 cubic yards) of ash per day. This volume is based on a moisture content of 25 percent and a density of 800 kg/rn 3 (50 lbs/ft. 3 ), which are the anticipated characteristics of the ash at the point of disposal. Disposing of the ash by depositing it in a large basin to a height of 4.6 meters (15 feet) would require a disposal area of about 15 hectares (36 acres) for 20 years of operation. Including required berms and access roads, the overall area required for disposal of the ash would be about 20 hectares (50 acres). There is sufficient land on Deer Island to accommodate the required ash disposal facilities. If the treatment facilities are expanded southward, over the drumlin area, the ash would have to be disposed of in two separate areas; one located on the south end of the island and one located on the existing prison site. Expansion of treatment facililities northward, over the site of the prison, would leave enough area south of the treatment facilities for ash disposal. The area occupied by the drumlin and about half of the area south of the drumlin would be required for ash disposal. In either case, there would be some land available at the southern end of the island for the disposal of ash from primary sludge incineration. Since both options require the removal of both the prison and the drumlin, the better plan would be to expand the treatment facilities northward and dispose of incinerator ash south of the treatment plant, as shown in Figure 3.4-1. It would be necessary to collect any leachate and runoff from the ash disposal basin so that the metals in the ash do not reach the groundwater or Boston Harbor. This would require lining the basin with a layer of clay or other impervious liner and constructing a runoff collection system around the perimeter of the disposal area. The collected leachate and runoff would then be returned to the treatment facilities. The Broad Meadows site has a total land area of about 44.5 hectares (110 acres). Of this area, about 13.3 hectares (33 acres) along the southern edge of the site is tidal marsh land. The remaining 31.2 hectares (77 acres) of land above the marsh is an adequate area to accommodate the required treatment facilities and a cornposting operation to compost t least half of the secondary sludge generated at this treatment plant. However, locating both the treatment and composting operations on this site would result in facilities being constructed within about 46 meters (150 feet) of some residences and about 91 meters (300 feet) of the Broad Meadows School. In order to maintain a buffer zone of at least 152 meters (500 feet) between the treatment facilities and the nearby residences and school, the composting operation would have to be located off the Broad Meadows site. For this alternative, it is proposed that the northwest 3—210 ------- LEGENO REQIJRED FACILITIES - YEAR 2000 FUTURE EXPANSION- YEAR 2050 — - - — PROPERTY LINE FLOOD LINE (tOO YEAR) • — — MARSH EDGE BLOWER BUILDING FINAL SETTLING TANKS / / 0 SCMI I SCALE IM M(TEPI TOWN RIVER PAY INFLUENT STATION PRIMARY TANKS TOWN RIVER BAY 350 I00 PUMPING> ADMINISTRATION BUILDING ‘\ FIGURE 3.4-2 BROAD MEADOWS WASTEWATER TREATMENT PLANT ------- corner of Squantum Point be utilized for the composting operation. Composting half of the secondary sludge generated at the treatment facilities at Broad Meadows would require an area at Squantum Point of about 8.5 hectares (21 acres). The sludge would be transported from Broad Meadows to Squantum by barge via a circuitous path of about 19.3 kilometers (12 miles) around Long Island, or by truck (7 to 10 required per day) along major arteries for a distance of about 8 kilometers (5 miles). The remaining secondary sludge from the Broad Meadows facilities would require landfilling. A landfill area of about 34 hectares (84 acres) would be required. The proposed treatment plant at Broad Meadows is shown in Figure 3.4-2. As mentioned in Section 3.2.1, the present MDC inter- ceptor sewer system is currently overloaded in some areas and, as increased flow5 are to be expected from the existing service area and additional municipalities may be added to the MSD, the interceptor system will require modifications and additions to provide adequate service. The interceptor sewer system which serves the northern MSD service area would require the addition of about 51.5 kilometers (32 miles) of sewers ranging in size from 30.5 to 167.6 cent- imeters (12 to 66 inches) in order to relieve overloaded interceptors and to extend the northern interceptor system into municipalities which will possibly be added to the northern MSD service area. These required interceptors are listed in Table 3.2-1 and shown in Figure 3.2-2. The effluent from the Deer Island treatment plant would be discharged through the existing outfall system. The outfall system requires some repair work to restore it to its design capacity. Similarly, additions to the southern interceptor sewer system are required. Most of the additions would be required regardless of the location of the treatment plant to serve the southern MSD service area. Other interceptor sewer additions are dependent on the treatment plant location. The additions common to all alternative southern area plants include about 90.5 kilometers (56 miles) of sewers ranging in size from 53.3 to 274.3 centimeters (21 to 108 inches), as listed in Table 3.2-3 and shown in Figure 3.2-2. In addition, for this alternative, about 2740 meters (9,000 feet) of 35.6 centimeter (14 inch) diameter force main and 1220 meters (4,000 feet) of 182.9 centimeter (72 inch) diameter sewer would be required between Nut Island and the Broad Meadows site in order to transport wastewater from Houghs Neck and the Braintree-Weymouth pumping station to the treatment facilities at Broad Meadows. The wastewater from the High Level Sewer upstream of Broad Meadows would be 3—212 ------- BOSTON BOSTON HARBOR DEER 4 IS LAND MILTON QUINCY BAY BROAD MEADOWS QUINCY \_ . LEGEND BRA INTREE TREATMENT PLANT SEWER / EFFLUENT CONDUIT WITH FLOW DIRECTION AND SIZE PUMPING STATION OUTFALL EXTENSION AND SIZE TOWN BOUNDARY LINE FIGURE 3.4-3 COASTAL AREA FACILITIES REQUIRED FOR If DEER ISLAND - BROAD MEADOWS ALTERNATIVE ------- diverted to the treatment plant. The effluent from the plant would flow into the High Level Sewer downstream of the site, and would be transported to the outfall system at Nut Island. Since the High Level Sewer is not adequate to handle peak flows from this plant, a relief pipeline would be required. Preliminary investigations indicated that there is not adequate space to locate a relief pipeline parallel to the High Level Sewer through Houghs Neck, and therefore, the required 289.6 centimeter (114 inch) diameter relief pipeline would be routed under Quincy Bay, for a length of about 2,590 meters (8,500 feet). These modifications between Nut Island and Broad Meadows are shown in Figure 3.4-3. The relief pipeline crossing Quincy Bay would reach Nut Island at a lower elevation than the High Level Sewer and, therefore, a pump station would be required at Nut Island to lift the plant effluent from the relief pipeline to the outfall system. During periods of peak flow and high tide, the plant effluent from the High Level Sewer and the relief pipeline would require pumping in order to be discharged through the outfall system. Therefore, the existing raw sewage pumping station on Nut Island would be converted to an effluent pumping station. During periods of lower tides and average flows, the effluent would discharge through the outfall system by gravity. The modifications required at Nut Island for this alternative are shown in Figure 3.4-4. The existing Nut Island outfalls would be extended to a point in the harbor where there is about a 13.7 meter (45 foot) depth of water. This would require an extension of about 470 meters (1550 feet) for two of the existing 152.4 centimeter (60 inch) outfall pipes, and about 1585 meters (5200 feet) for the third existing 152.4 centimeter (60 inch) outfall pipe. Diffusers would be added to the end of each outfall pipe. Each of the ten pumping stations which are located along the interceptor system would be renovated or replaced in order to provide efficient and adequate capacities for future flows, as recommended in the EMMA Study. In addition to the above facilities, the overall wastewater management plan includes facilities which are not included as an integral part of this EIS. These include combined sewer overflow regulation facilities and primary sludge management facilities. Several combined sewer overflow regulation projects are included in the overall plan. These projects will provide collection, treatment and disposal facilities to replace the numerous combined sewer overflows which presently discharge to Boston Harbor and its tributaries. The primary sludge produced at the treatment plant serving the southern MSD service area will be pumped 3—214 ------- _J I SCALt IN PUT 0 I SCALE IN EXISTING INFLUENT PUMPING TO BE MODIFIED TO AN EFFLUENT PUMPING STATION LEGEND EXISTING FACILITIES TO BE DEMOLISHED D EXISTING FACILITIES TO BE MODIFIED NEW FACILITIES FIG. 3.4-4 NUT ISLAND FACILITIES EXISTING FACILITIES TO BE DEMOLISHED REQUIRED WITH A BROAD MEADOWS LIFT STATION D OR SQUANTUM PLANT ------- through a force main across Boston Harbor to Deer Island, where it will be dewatered and incinerated along with the sludge produced at the northern service area treatment plant, as recommended in a separate EIS. B. Deer: Deer/Squantum: Squantum - w/o Sat . This alter- native includes expanding and upgrading the existing Deer Island treatment plant to provide secondary treatment for the northern MSD service area wastewater flows, and the construction of a new treatment plant at Squantum Point to provide secondary treatment for the wastewater from the southern MSD service area. The wastewater treatment, sludge disposal, and inter- ceptor sewer facilities required for the northern service area are the same as discussed under Alternative A. The proposed layout of the Deer Island facilities is shown in Figure 3.4-1. The Squantum Point site has a total land area of slightly over 28.3 hectares (70 acres), of which approximately 50 percent is presently owned by Boston Edison. The remainder is presently owned by Jordan-Marsh. The area is large enough to accommodate a treatment plant to provide secondary treatment for the wastewater from the southern service area, but there is not enough additional area for a composting operation. For this alternative, it is proposed that Broad Meadows be utilized for composting. Composting half of the secondary sludge generated at the treatment facilities at Squantum Point would require an area of about 8.5 hectares (21 acres) at Broad Meadows. The composting operation would be located in the southwest corner of Broad Meadows so that it is as far away from the residential areas as possible. The sludge could be transported from Squantum to Broad Meadows either by barge or by truck. The remaining second- ary sludge generated at the Squantum Point treatment plant would require landfilling. A landfill area of about 34 hectares (84 acres) would be required. The proposed treat- ment facilities at Squantum Point are shown in Figure 3.4-5. The southern interceptor system requires the addition of about 90.5 kilometers (56 miles) of sewer pipe ranging in size from 53.3 to 274.3 centimeters (21 to 108 inches) in order to relieve and extend the present system, as listed in Table 3.2-3 and shown in Figure 3.2-2. In addition, an influent sewer is required to transport the incoming waste- water from the High Level Sewer to the treatment plant at Squantum Point. About 6500 meters (21,400 feet) of influent sewer, 3 meters by 4.3 meters (10 feet by 14 feet) in cross—section, would be required. In order to transport wastewater from Houqhs Neck and the Braintree-Weymouth pumping station to the influent sewer, about 2740 meters (9,000 feet) of 35.6 centimeter (14 inch) diameter force main and 1830 meters (6,000 feet) of 182.9 centimeter 3—216 ------- 300 0 300 600 SLUDGE SCALE IN FEET SCALE IN METERS CHLORINE CONTACT TANKS (If required) JORDAN MARSH WAREHOUSE PRIMARY SETTLING TANKS II -a.’, II 1J EFFLUENT STATION LEGEND AERATION TANKS PEQUIRED FACILITIES - YEAR 2000 FUTURE EXPANSION - YEAR 2050 LIMIT OF OPEN SPACE 100 0 100 200 4 BU TANKS I () 0 0 MARINA FIGURE 3.4-5 SQUANTUM WASTEWATER TREATMENT PLANT ------- (72 inch) diameter sewer would be required. The effluent from the Squantum Point treatment plant would leave the plant through two effluent pipelines. One effluent pipeline would be 365.8 centimeters (144 inches) in diameter, and would connect to the High Level Sewer downstream of the influent sewer connection. This pipeline would be about 6,500 meters (21,400 feet) in length. The second effluent pipeline, which is required during periods of high waste— water flows, would be 289.6 centimeters (114 inches) in diameter and would be routed under Quincy Bay to Nut Island. The length of this pipeline would be about 6,700 meters (22,000 feet). The sewer modifications required between Nut Island and Squantum Point are shown in Figure 3.4-6. A lift station would be required at Nut Island to lift the plant effluent from the 289.6 centimeter (114 inch) effluent piepline to the elevation of the High Level Sewer. The flow from both effluent pipelines would then enter the the Nut Island outfall system. During periods of peak flow and high tide, pumping is required to facilitate discharge through the outfall system. Therefore, the existing raw sewage pumping station on Nut Island would be converted to an effluent pumping station. As in Alternative A, the outfall system would be extended to reach deeper water. The modifications required at Nut Island for this alternative are shown in Figure 3.4-4. Each of the ten pumping stations which are located along the interceptor system would be renovated or replaced in order to provide efficient and adequate capacities for future flows, as recommended in the EMMA Study. As discussed in the description of the previous alter- native, combined sewer overflow regulation facilities and primary sludge management facilities, while not included as an integral part of this EIS, would be included in an overall wastewater management plan for the study area. C. Deer: Deer/Deer: Deer — w/o Sat . This alternative includes expanding and upgrading the existing Deer Island treatment plant to provide secondary treatment for the wastewater from the entire MSD service area. Due to the different heavy metal characteristics of secondary sludge from the northern and southern service areas and the decision to dispose of these sludges by different methods, it is necessary to keep the secondary sludge from the northern service area separate from the secondary sludge from the southern service area. In order to accomplish this, it would be necessary to keep the wastewaters from the northern and southern service areas separate and to process the secondary sludge from the two service areas separately. Constructing the facilities which would be required to 3—218 ------- -— \DEER ISLAND BOSTON HARBOR BOSTON 0 MILTON . QUINCY BRAINTREE LEGEND TREATMENT PLANT SEWER/EFFLUENT CONDUIT WITH FLOW DIRECTION AND SIZE PUMPING STATION OUTFALL EXTENSION AND SIZE TOWN BOUNDARY LINE FIGURE 3.4-6 COASTAL AREA FACILITIES REQUIRED FOR AND ‘ WEYMOU DEER ISLAND - SQUANTUM ALTERNATIVE ------- provide secondary treatment for the wastewater from the entire service area on Deer Island would require utilizing the areas currently occupied by the prison and the drumlin and all but about 7.3 hectares (18 acres) of the land south of the drumlin. Therefore, both the prison and the drumlin would have to be removed. Figure 3.4-7 shows the proposed treatment facilities at Deer Island. Whereas sludge dewatering and incineration would be accomplished on Deer Island, there is not enough area for the ash disposal and composting operations. However, since this alternative utilizes only one site for wastewater treatment, it would be possible to utilize one of the sites which were considered for treatment facilities in the previous two alternatives (Broad Meadows and Squantum Point) for the ash disposal and composting operations. A desirable aspect of utilizing an inland site, is that incinerator ash and dewatered sludge could be barged from Deer Island to either of these two sites. Due to the relatively isolated location of the Squantum Point site as compared to Broad Meadows, of which about half the perimeter is bordered by a residential area (private houses and a school are located adjacent to Broad Meadows), Squantum Point would be the better location for the ash disposal and composting operations. In addition, the travel distance for a barge between Deer Island and Broad Meadows is almost twice the travel distance between Deer Island and Squantum Point. The site proposed for ash disposal and composting operations is located at the northwest corner of Squanturn Point and is bordered on the east side by a marina, on the south side by the Jordan-Marsh warehouse, on the west side by the Neponset River, and on the north side by Dorchester Bay. The area consists of approximately 28.3 hectares (70 acres) of land, of which approximately 60 percent is presently owned by Boston Edison and the remainder is presently owned by Jordan-Marsh. The area which would remain for actual ash disposal and sludge composting (total area minus area required for berms, access roads and buffer) would be about 20 hectares (50 acres). The area required for the disposal of the ash generated by the incineration of the secondary sludge rom the northern service aera would be approximately 15 hectares (36 acres), based on an ash moisture content of 25 percent and density of 800 kg/rn (50 lbs/f t. 3 ). Composting half the sludge from the southern service area would require approximately 8.5 hectares (21 acres) of land. Therefore, it would be necessary to start disposing of ash on half the available area while composting secondary sludge from the southern service area on the remaining half. After about 14 years, it would be necessary to move part of the composting operation over the completed fill area and continue disposing of ash over the vacated composting area. However, it has been reported that during the normal ash filling operation, where equipment which is spreading new ash 3—2 20 ------- 300 0 3C0 60u TANKS ADM INISTRAT ION CHLORINE BUILDING FINAL SETTLING 00 0 SCALE IN FEET 00 200 SCALE IN METERS AERATION TANKS BLOWER BUILD ING FINAL SETTLING TANKS LEGEND STATION EXISTING WASTEWATER TREATMENT FACILITIES OTHER EXISTING STRUCTURES O NEW WASTEWATER TREATMENT FACILITIES REQUIRED - YEAR 2000 s FUTURE EXPANSION - YEAR 2050 ‘I INFLUEN PUMPING STATION MANAGEMENT BUILDING DRUMLIN OUTLINE AERATION TANKS AREA FOR PRIMARY SLUDGE ASH DISPOSAL FIGURE 3.4-7 DEER ISLAND WASTEWATER TREATMENT PLANT FOR TOTAL MSD SERVICE AREA ------- passes over previo s deposits, the ash compacts to a density of about 1280 kg/ma (80 lbs/it. 3 ) . If the conservative assumpiton is made that the ash will compact to a density of 1040 kg/rn 3 (65 lbs/it. 3 ) , then the area required for 20 years of ash disposal would be reduced to about 11.3 hectares (28 acres) , in which cast there would be enough area available for ash disposal and composting without it being necessary to move the composting operation. If it is found that there is a market for more than half of the southern service area secondary sludge, then some of the composting operation may have to be moved over an ash filled area. It would be necessary to collect any leachate and runoff from the ash disposal basin and composting area so that the metals in the ash and sludge do not reach ground or surface waters. This would require lining the fill and composting areas with clay or other impervious liner and constructing a runoff collection system around the perimeter of the work area. The collected leachate and runoff would then be returned to the interceptor sewer system. The remainder of the sludge produced in the treatment of the wastewater from the southern service area would require landfilling. If there is a market for 18,000 dry metric tons (20,000 dry short tons) of compost per year, a landfill area for de- watered, digested sludge of about 34 hectares (84 acres) would be required. The interceptor sewer system which serves the northern MSD service area would require the addition of about 51.5 kilometers (32 miles) of sewer pipe ranging in size from 30.5 to 167.6 centimeters (12 to 66 inches) in order to relieve overloaded interceptors and to extend the northern inteeceptor system into municipalities which will possibly be added to the northern service area. These required interceptors are listed in Table 3.2-1 and shown in Figure 3.2—2. Similarly, the southern interceptor sewer system would require the addition of about 90.5 kilometers (56 miles) of sewer pipe ranging in size from 53.3 to 274.3 centimeters (21 to 108 inches) in order to relieve and extend the present southern interceptor system (see Table 3.2-3 and Figure 3.2-2) In addition, some submerged pipelines would be required (see Figure 3.4—8). The portion of the High Level Sewer that passes through the Houghs Neck section of Quincy requires relief in order to be able to transport anticipated peak flows. Since there does not appear to be adequate space to locate a relief sewer parallel to the High Level Sewer through Houghs Neck, the required 289.6 centimeter (114 inch) relief sewer would be routed under Quincy Bay, for a length of about 2590 meters (8,500 feet). In order to transport the wastewater from the end of the southern interceptor sewer system at Nut Island to the treatment facilities on Deer Island, 3—222 ------- BOSTON BOSTON HARBOR DEER LAND 150” DEEP ROCK TUNNEL - 0 MILTON QUNCY QUINCY BAY 7—.— BRAINTREE LEGEND TREATMENT PLANT SEWER/EFFLUENT CONDUIT WITH FLOW DIRECTION AND SIZE PUMPING STATION OUTFALL EXTENSION AND SIZE TOWN BOUNDARY LINE NEW HEADWORKS FIGURE 3.4-8 COASTAL AREA FACILITIES REQUIRED FOR WEYMOUT THE ALL DEER ISLAND ALTERNATIVE ------- submerged pipleine would be required across Quincy Bay and along Long Island. From the northern end of Long Island a deep rock tunnel would be constructed to carry the wastewater to Deer Island. Two 274.3 centimeter (108 inch) diameter submerged pipleines would be required for a length of about 5800 meters (19,000 feet) from Nut Island to the northern end of Long Island, and the tunnel would be 381 centimeters (150 inches) in diameter and about 1520 meters (5,000 feet) in length. A headworks would, be required at Nut Island in order to provide screening and grit removal prior to transporting the wastewater from the southern service area across Boston Harbor to Deer Island. In addition, since the relief sewer crossing Quincy Bay will reach Nut Island at a lower elevation than the High Level Sewer, a lift station would be required at Nut Island to lift the wastewater from the relief sewer to the headworks. Most of the existing facilities on Nut Island could be demolished. The modifications required at Nut Island for this alternative are shown in Figure 3.4-9. In addition to utilizing the existing outfall system at Deer Island, a new outfall pipe would be required. This pipe would be 304.8 centimeters (120 inches) in diameter and about 640 meters (2100 feet) long. Diffusers would be added to the end of the outfall, which will be in the water at a depth of about 18.3 meters (60 feet) . The existing outfall system requires some repair work to restore it to its design capacity. Each of the ten pumping stations which are located along the interceptor system would be renovated or replaced in order to rpovide efficient and adequate capacities for future flows, as recommended in the EMMA Study. As discussed-in the description of the previous alter- natives, combined sewer overflow regulation facilities and primary sludge management facilities, while not included as an integral part of this EIS, would be included in an overall wastewater management plan for the study area. D. Comparative Analysis On inspection it can be seen that the Deer: Deer/Broad Meadows: Broad Meadows alternative (which will be referred to as the Deer Island-Broad Meadows alternative in this analysis) and the Deer: Deer/Squantum: Squantum alternative (which will be referred to as the Deer Island—Squantum alternative) closely resemble each other. Indeed, they can be considered as variations of the same basic concept. Since this is. the case, a two way comparison can be made between the two, with the better of the two then compared to the Deer: Deer/Deer: Deer (which will be referred to as the All Deer Island alternative). This approach avoids the confusion of a three—way comparison. 3—224 ------- so 0 10 ISO _J- j SCALE IN FEET - 0 25 0 P r .j- 25 . 50 LEGEND EXISTING FACILITIES TO BE DEMOLISHED D EXISTING FACILITIES TO BE MODIFIED NEW FACILITIES EXISTING FACILITIES TO BE DEMOLISHED FIG. 3.4-9 NUT ISLAND FACILITIES REQUIRED WITH TREATMENT FOR NEW SCREEN AND GRIT CHAMBER EXISTING SCREEN AND GRIT CHAMBER BUILDING TO BE MODIFIED SCALE IN METERS LIFT STATION D ENTIRE MSD SERVICE AREA AT DEER ISLAND ------- In locating sites for new treatment facilities, the number of facility sites to be used is of great importance, expecially in densely populated areas such as Boston. Wastewater treatment facilities are, unfortunately, thought of as bad neighbors and are generally not welcome by nearby residents. While this is not true in all cases, there is no doubt that facilities of the magnitude under discussion will significantly and unavoidably impact the settings in which they are located. Both the Deer Island—Broad Meadows alternative and the Deer Island-Squantum alternative would utilize three sites for the location of treatment facilities and the ash disposal and composting operations. As explained previously, if treatment facilities are located at Broad Meadows, then ash disposal and composting would be accomplished at Squantunt. Since the reverse is also true, these alternatives are similar in this respect. Sludge disposal plans for a plant at Broad Meadows or Squantum would remain the same for both alternatives. That is, primary sludge would be piped to Deer Island, and secondary sludge would be landfilled (50 percent) and composted (50 percent). The only differences that arise with regard to sludge disposal are the slightly longer primary sludge pipeline which would be required from Broad Meadows and the fact that truck traffic, moving digested, dewatered secondary sludge and compost from the sites would be routed over different local roads. Since secondary sludge must be transported from one site (where it is produced) to the other site (where it is composted) under either alternative, this is another area of similarity. In terms of outfall requirements, both alternatives require the repair of the existing Deer Island outf ails and the extension of the existing Nut Island outfalls. Since both alternatives would use the Squantum and Broad Meadows sites, these alternatives are again similar in this respect. One area in which these alternatives differ greatly is the need for additional interceptor construction (as opposed to the relief of existing interceptors). The Deer Island—Squantum alternative requires an interceptor sewer to convey influent from the High Level Sewer to the Squantum Point plant. This sewer is of substantial size, 3 meters by 4.3 meters (10 feet by 14 feet), and is over 6.4 kilometers (4 miles) inlength. In addition, a parallel effluent sewer, 366 cm. (144 inches) in diameter, would be required from the plant back to the High Level Sewer. A second effluent pipeline would be required for periods of peak flow. This effluent sewer would be routed under Quincy Bay to Nut Island. 3—226 ------- Since the High Level Sewer passes adjacent to the Broad Meadows site, influent and effluent sewer requirements to connect this site to the sewer are minimal. For the Deer Island—Broad Meadows alternative, an effluent sewer would also be required under Quincy Bay. However, this pipeline would be less than half the length required under the Bay from the Squantum plant. In order to assess the impact of these additional inter- ceptors which are required for treatment facilities at Squantum, a detailed field study was undertaken to select the best route for the parallel sewers and to evaluate the impact that construction of these sewers would have on the surrounding areas. The field evaluation (see Appendix 3.4 for a characterization, evaluation and detailed discussion of the alignments) indicated that the effects of sewer construction between the High Level Sewer to Squantum would be severe in spite of all reasonable attempts to reduce the impacts. Among the effects which are unavoidable are the removal of mature roadside vegetation, traffic disruption, and negative effects on local businesses due to extended street closures. The need for these additional sewers, including the longer subaqueous crossing of Quincy Bay, weighs heavily against the Deer Island-Squantum alternative. In addition to construction impacts, additional energy would be required on a continuous basis for wastewater pumping. It is estimated that the Deer Island-Squantum alternative would require about 5.9 million kilowatt hours per year of electricity over and above that required for the Deer Island— Broad Meadows alternative. Given these facts, the Deer Island—Broad Meadows alternative emerges as the clearly better alternative. Preliminary cost estimates (see Table 3.4-1) for the two alternatives show that the Deer Island—Squantum alternative involves approximately $3,500,000 per year additional cost (amortized capital cost and operation and maintenance cost) and confirms the choice of Deer Island—Broad Meadows as the better alternative. Prior to the election of a sludge management strategy, it was hoped that the use of the Squantum site for treatment facilities would completely avoid any need to use Broad Meadows. On the basis of sites alone, Squantum would be preferred since it is a more isolated location. About half of the Broad Meadows perimeter is adjacent to high density residential and commercial developments. However, the requirements for sludge processing now require the use of both sites, which then clearly favors the Deer Island—Broad Meadows alternative. When comparing the Deer Island-Broad Meadows and the All Deer Island alternatives, an immediate difference arises in the number of sites which are required. The Deer Island— 3—22 7 ------- TABLE 3.4-1 COMPARISON OF COSTS 1 All Deer Deer Island- Deer Island- Island Plan Broad Meadows Plan Squantum Plan Wastewater reatment Facilities 404,291,000 425,755,000 420,509,000 Secondary Sludge Management 58,78 ,QQO 64,144,000 64,144,000 Interceptor System 3 307,620,000 248,772,000 307,951,q00 Total Capital Costs 770,696,000 738,671,000 792,604,000 Amortized Capital Costs 4 59,783,000 57,299,000 61,482,000 Operation and Maintenance Costs 24,765,000 25,961,000 26,233,000 Total Annual Costs 84,548,000 83,260,000 87,±5Q,000 Applicant’s Share of Capital Cost (10%) 77,070,000 73,867,000 79,26,(, 000 Applicant’s Share of Amortized Capital Cost 5,978,000 5,730,000 8- --F72,000 Applicant’s Share of O & M Costs 24,765,000 25,961,000 26,233,000 Applicant’s Share of Total Annual Cost 30,743,000 31,691,000 3 i00 5,000 (1) Engineering News Record Construction Index = 2654 (2) Includes work at Nut Island and Outfall (3) Includes submerged pipelines, tunnel and related pumping stations (4) Assume average life of facilities = 30 years; Interest rate = 6—5/8 percent. ------- Broad Meadows alternative requires three sites while the All Deer Island alternative requires only two. The Broad Meadows site is not needed for the latter alternative. Of the three sites under discussion, Broad Meadows offers the greatest potential for environmental impact with respect to land use incompatibility. The fact that this site is not required under the All Deer Island alternative gives this system an immediate and significant advantage over the Deer Island- Broad Meadows system. The price which must be paid to eliminate one site is that a major harbor crossing is required. This component of the project also involves significant environmental impacts. For example, excavation of a trench in which the pipes can be constructed would displace benthic fauna. During construction, siltation would occur in and near the excavation area. Excess spoils would be generated from this excavation, presenting a disposal problem. Clean sand (if it is necessary) for backfilling the trench may present a storage problem. Finally, the type of construction is expensive. However, these construction effects are largely temporary. With time, the benthic community will become reestablished over the pipeline. Benthic fauna located adjacent to the trench which may be affected by siltation will also recover. Given the intensively developed nature of the Boston area, this type of construction, which can be done in open waters, may ultimately be preferable to the construction of large sewers in city streets. With all of the treatment facilities at Deer Island, further advantages in routine operation and maintenance activities can be realized. That is, a more efficient operation, in terms of manpower and costs, will be realized. It is estimated that operation and maintenance costs would be about $26,000,000 per year for the Deer Island-Broad Meadows alternative, and about $25,000,000 per year for the All Deer Island system. Energy costs also favor the All Deer Island system. It is estimated that this alternative would use about 7.5 million kilowatt hours less of electric power annually than the Deer Island--Broad Meadows alternative. With respect to outfall considerations, the All Deer Island system would require the construction of an additional outfall pipe into President Roads to handle peak flows. This is comparably offset (in terms of construction) by the extension of the Nut Island outfall system required under the Deer Island—Broad Meadows system. An important difference, however, is that the All Deer Island system would completely remove all sewage discharges from Quincy Bay and would add additional effluent flow into the President Roads. However, the Deer Island outfall will extend into 18.3 meters (60 feet) of water which will provide ample dilution. 3—2 29 ------- Amendments to Public Law 92-500 in December, 1977 (Public Law 92-217) allows the requirement for secondary treatment to be waived in certain coastal areas if eight specific statutory requirements are fulfilled. Should this occur in the Boston area, it is expected that some additional treatment beyond primary would be required (perhaps chemical treatment to reduce metal concentrations) and a longer ocean outfall would be needed to discharge the effluent out of the harbor. This modification would greatly favor the All Deer Island system, since a single outfall to reach offshore waters would be far more efficient than the extension of the two outfalls as would be necessary for the Deer Island-Broad Meadows alternative. Also, since secondary sludge would not be generated, there would be no need to utilize the Squantum site. This would reduce the number of sites used to one. Interceptor relief requirements for the All Deer Island and the Deer Island—Broad Meadows alternatives in the northern service area and in the southern service area upstream of Broad Meadows are the same. The differences in the two alternatives can be found in the Houghs Neck area. The changes to the interceptor system for the Deer Island—Broad Meadows alternative constitute a much greater impact on this locality because much of the interceptor work to be done will take place in the streets of Houghs Neck. The interceptor relief requirements for the All Deer Island option constitute a much less severe impact because the relief sewer is located under Quincy Bay. To summarize, the All Deer Island alternative is superior in terms of the number of sites required; the fact that the Broad Meadows site is not needed; operation and maintenance advantages; lower energy costs; and a more favorable outfall location. Deer Island—Broad Meadows is superior in terms of the need for new pipeline construction (the harbor crossing is not needed) In terms of estimated total annual cost, the two alternatives are relatively similar — about $83,300,000 for the Deer Island-Broad Meadows alternative and about $84,500,000 for the All Deer Island alternative (see Table 3.4—1) The All Deer Island alternative emerges as the better of the two alternatives and is the recommended non—satellite system. 3—2 30 ------- 3.4.2. Satellite Systems The purpose of this section was to select the best satellite system. However, the results of sections 3.2.3 and 3.3.3 indicate that satellite facilities on the Mid- Charles and Upper Neponset Rivers will not meet water quality standards. This fact renders a satellite system infeasible, and therefore, it was eliminated from consider- ation during the intermediate screening phase of this study. However, the plan recon mended by the EMMA Study, which is a satellite system, will be compared with the best non- satellite plan which was selected in Section 3.4.1. This satellite system, the EMMA plan, is described in Section 3.4.3. 3—2 31 ------- 3.4.3. EMMA Plan The MDC’S proposed wastewater management plan, as presented in the EMMA Study, includes secondary treatment plants at Deer and Nut Islands and two advanced wastewater treatment plants (providing a higher degree of treatment than secondary) at inland locations. The existing Deer Island primary treatment plant would be expanded and upgraded to provide secondary treatment to the wastewater from the northern MSD service area. The proposed facilities would be constructed to the north of the existing facilities, and would require removing the prison and filling about 5.7 hectares (14 acres) of Boston Harbor. This treatment plant would be capable of providing secondary treatment for an average daily wastewater flow of 1,514,000 m 3 /day (400 mgd), which is estimated to be generated in the northern service area in the design year 2000. The wastewater from the southern MSD service area would receive treatment at three treatment plants. One of these plants would be located on Nut Island. The existing Nut Island primary treatment plant would be expanded and upgraded to provide secondary treatment for an average daily wastewater flow of 492,000 m 3 /day (130 mgd). Nut Island is presently almost completely occupied by the existing treatment plant, and the additional facilities would be constructed on an area of fill of about 11.3 hectares (28 acres) in Quincy Bay. The remaining wastewater from the southern service area would receive treatment at two inland satellite advanced wastewater treatment plants. One of these plants would be located along the Charles River and would be capable of treating an average wastewater flow of about 117,300 m 3 /day (31 mgd) . The other satellite plant, located along the Neponset River, would have an average design capacity of about 95,400 m 3 /day (25.2 mgd). The specific sites of these two inland satellite plants have riot been selected. The sludge produced at the Nut Island plant would be pumped through a force main across Boston Harbor to Deer Island, where it would be dewatered along with the sludge produced at the Deer Island plant. The dewatered sludge would then be incinerated on Deer Island. The resulting ash from the incinerators would be stored on Deer Island and subsequently disposed of at an inland landfill. The sludge produced at the satellite plants would undergo incineration at each plant. Under this plan, modifications and additions would be made to the existing interceptor sewer system. About 3—232 ------- 5.15 kilometers (32 miles) of sewer ranging in size from 30.5 to 167.6 centimeters (12 to 66 inches) in diameter would be added to the northern interceptor sewer system and about 57.3 kilomters (36 miles) of sewer, from 53.3 to 198.1 centimeters (12 to 66 inches) in diameter, would be added to the southern interceptor sewer system. In addition, each of the ten pumping stations which are located along the interceptor system would be renovated or replaced in order to provide efficient operation and adequate capacity for future flows. The MDC’s proposed plan also includes several combined sewer overflow regulation projects which would provide collection, treatment and disposal facilities to replace the numerous combined sewer overflows which presently discharge to Boston Harbor and its tributaries. 3—233 ------- 3.4.4. No Action Alternative The purpose of evaluating a “No Action” alternative is to compare the benefits and adverse effects of a proposed action with a parallel set of benefits and adverse effects of doing nothing, or maintaining present practices. The No Action alternative assumes that no capital improvements will be made to the existing wastewater management system. Within the MSD system there presently exists about 362 kilometers (225 miles) of trunk sewers, serving over 8,000 kilometers (5,000 miles) of local sewers; 12 pumping stations (including two at wastewater treatment plants); four headworks; and two primary treatment plants. The two treatment plants, located at Deer Island and Nut Island, have a combined average daily design capacity of about 1,703,000 m 3 /day (450 mgd). Consideration of the No Action alternative implies the continued use of the present system’s facilities with its present levels of effluent discharge. The No Action alternative would provide for operation and maintenance of the existing interceptors, pumping stations, headworks and treatment plants in the MSD service area. No additional towns would be added to the service area and no interceptor relief would be provided. Present pumping station, interceptor and treatment plant capacities would remain limited. Present excess flows and future additional flows would exceed the capabilities of the present facilities. The Nut Island Primary Treatment Plant presently serves a population of about 634,000. During the fiscal year ending June 30, 1975, the verage daily flow entering the plant was about 522,000 ma/day (138 mgd), which was about 95,000 m 3 /day (25 mgd) above the average design capacity. Built in 1952, much of the original equipment is in need of repair or replacement. Assuming the plant is maintained at present levels, poorly treatment wastewater will continue to be discharged into Boston Harbor. Following digestion of the plant’s sludge, the unchlorinated sludge is disposed of through a pipeline extending into deep tidal water. The Deer Island Primary Treatment Plant, constructed in 1968, is in relatively good condition. The plant has an average daily design capacity of about 1,300,000 m 3 /day (343 mgd), and during the fiscal year ending June 30, 1975 treated an average of about 1,105,000 m 3 /day (292 mgd). However, it is anticipated that the quantity of wastewater reaching the plant will exceed the design capacity in the near future. The discharge from the facility is a mixture of chlorinated effluent and digested sludge which is released from the plant into President Roads. Three emergency outfalls exist for high flow periods. 3—234 ------- 3.4.5. Modified No Action Alternative This alternative includes specific plans which have been made, but are yet to be implemented, or are presently in the process o. being implemented. These include the regulation of combined sewer overflows and the treatment and disposal of the primary sludge generated at the wastewater treatment facilities. The combined sewer area consists of over 9700 hectares (24,000 acres) serving almost 900,000 people. Present combined sewer overflow regulation facilities consist of the following: 1. The East Boston Pumping stations and the North Metropolitan Trunk Sewer which have a capacity to divert about 454,000 m 3 /day (120 mgd) from upstream areas to Chelsea Creek or to the Deer Island Treatment Plant. 2. The 3oston Calf Pasture pumping station which diverts about 587,000 m 3 /day (155 mgd) of flow during periods of wet weather to the holding tanks on Moon Island prior to overflowing to Boston Harbor. 3. The Cottage Farm Chlorination and Detention Station designed to treat up to 882,000 m 3 /day (233 mgd) prior to overflowing into the Charles River Basin. 4. The Somerville Marginal Conduit Project which is designed to treat about 606,000 m 3 /day (160 mgd) prior to overflowing into the Mystic River tidal waters. 5. The Charles River Marginal Conduit Project presently under construction, to treat about 1,223,000 m 3 /day (323 rngd) prior to discharge to the Harbor. Approximately 125 combined sewer outlets presently discharge to Boston Harbor and its tributaries. The proposed Combined Sewer Overflow Regulation Program will provide a system to eliminate these discharges by collecting the flows and providing treatment and disposal facilities. Treatment will consist of screening, skimming, sedimentation, and chlorination. Under the primary sludge management plan, the sludge from the existing Nut Island Primary Treatment Plant will undergo digestion prior to being pumped through a force main across Boston Harbor to Deer Island. At Deer Island 2—2 35 ------- this digested sludge will be combined with the primary sludge from the Deer Island plant. The sludge will then be dewatered and incinerated at Deer Island. 3—236 ------- 3.5 COMPARISON OF SYSTEM ALTERNATIVES This section of the report is intended to compare and contrast the four remaining System alternatives. This will be done on the basis of environmental parameters as well as cost. This comparison will then permit the selection of a recommended plan. 3.5.1 Water Quantity As was stated earlier, a system alternative which employs satellite treatment facilities will tend to minimize any effects that sewering will have on basef low conditions in the Charles and Neponset Rivers. This will be a result of the discharge of treated effluent into the rivers on a continuous basis. Without satellite plants, wastewater is sent to the harbor and “lost” to local watersheds. This can, potentially, affect the river’s baseflow regime. The following rather detailed discussion explores the significance of water quantity as a determinant in selecting a system alternative. It should be noted that even though the “satellite system” was eliminated from further considera— tion, the EMMA Plan contains satellite facilities and, therefore gives significance to this discussion. Traditionally, river flow augmentation is provided to avoid the problems associated with the unpredictable nature of streamf low. Random periods of low flow stress the waste assimilative capacity of rivers, restrict recreational use, and, potentially, create water supply problems. Flow augmentation normally comes from surface impoundments or groundwater pumpage. It has been stated (Frimpter, 1973b) that a potentially severe flow problem exists in the Charles Watershed. In addition, utilization of the Neponset River for industrial water supply controls its flow characteristics (Metcalf and Eddy, 1969). Enhancement of the recreation potential, and other beneficial uses, of the lower Neponset has been re- ported (Commonwealth of Massachusetts, 1969) to depend upon augmentation of low flows. The proposed satellite plant wastewater discharges are a method of addressing the aug- mentation issue. The proposed satellite treatment plants are presented by the EMMA study as providing flow augmentation benefits for their respective rivers. Highly treated wastewater would enhance water quality during low flow periods and re- tention of water within its basin of origin would, by impli- cation, have a favorable impact on the water supply situation within the Charles and Neponset watersheds. However, as discussed in Sections 3.2 and 3.3 of this EIS, the pro- 3—2 37 ------- posed discharges have major adverse impacts upon water quality in both rivers during low flow situations. These adverse impacts must be weighed against benefits which might result from the increased flow during all times in order to determine the net impact upon the river systems. Consequently, a comparison of the satellite and non-satellite alternatives was performed to determine the effects of each upon the hydrologic budget of the Charles and Neponset watersheds. The analysis consisted of three steps: 1. Determining the effect of the discharge on flow over the course of an average year; 2. Development of water balances about each plant and its watershed; 3. Examination of flow records to determine if a historical trend toward streamf low reduction exists. Mean daily discharge for each month was extracted from U.S.G.S. flow records for the Charles River at Charles River Village and for the Neponset River at Norwood and Canton. The average year 2000 design flow from the satellite plants was then added to their respective river flow to derive an approximate flow after wastewater discharge. The corres- ponding percent increase in flow and the percentage of total flow consisting of wastewater were calculated. Tables 3.5-1 and 3.5—2 summarize the computations. Charles River flow increases ranged from 7.9 to 103.8 percent with the August, September, and October months ex- periencing the largest increases. Under these average flow conditions wastewater would make up a significant por- tion of the flow from June through October, a period of heavy recreational use. Flow increases for the Neponset River ranged from 20.7 to 141 percent, with July, August, September and October all experiencing more than a doubling of flow. Wastewater would make up a significant component (>20%) of river flow for all but one month during this average year. These increases would be greater during low flow periods. It can be con- cluded that both discharges would significantly alter the flow regime in their respective river. The desirability of having wastewater as a major com- ponent of flow for significant periods of time is question- able because of public health considerations. Downstream of any discharge point on either river are major water supply wells (see Figures 2.5-15 and 2.5—18) which are hydraulically connected to the rivers (Frimpter 1973b,c). The potential for adverse public health impacts is created by such a situation. Indeed, the Town of Wellesley voiced opposition to a Charles River discharge during the original satellite 3—2 38 ------- TABLE 3.5—1 Daily Mean Discharge ’ (ft /s) 6.8 (240) 9.9 (350) 17.0 (604) 14.2 (502) 8.8 (311) 5.0 (177) 2.3 (81) 1.4 (49) 1.3 (46) 1.7 (60) 4.3 (152) 6.5 (230) Waste Dischar e m 3 /s (ft /s) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) 1.35 (47.7) Total Flow m 3 /s (ft 3 /s) 8.15 (287.7) 11.25 (397.7) 18.35 (648.7) 15.55 (549.7) 10.15 (358.7) 6.35 (224.7) 3.65 (129.7) 2.75 (96.7) 2.65 (93.7) 3.05 (107.7) 5.65 (199.7) 7.85 (277.7) % Increase % Waste In In Total Flow Mean Discharge 16.6 19.9 12.0 13.6 7.4 7.9 8.7 9.5 13.3 15.3 21.3 27.0 37.0 58.9 49.1 96.4 50.9 103.8 44.3 79.4 23.9 3.14 17.2 20.8 Month EFFECTS OF PROPOSED SATELLITE PLANT DISCHARGE ON CHARLES RIVER FLOW January February March April May June July August September October November De cexnb er 1 Flow at Charles River Village Gage for Period of Record 1932—1973 ------- TABLE 3.5-2 ‘Total flow after confluence of and east Norwood Gage Period of Record 1940—1973 Canton Gage Period of Record 1953—1973 Month Daily Mean Discharge’ DISCHARGE Waste ON NEPONSET RIVER FLOW % Waste in % Increase In m 3 /s (ft 3 fs) m 3 fs (ft 3 /s) Total Flow January 3.1 (109) 1.2 (42.4) 4.3 (ft 3 / s) (151.4) Total Flow 27.9 Mean Discharge 38.7 February 3.9 (138) 1.2 (42.4) 5.1 (180.4) 23.5 30.7 March 5.8 (205) 1.2 (42.4) 7.0 (247.4) 17.1 20.7 April 45 (159) 1.2 (42.4) 5.7 (201.4) 21.1 26.7 May 3.2 (113) 1.2 (42.4) 4.4 (155.4) 27.3 37.5 , ° June July 1.7 1.0 (60) (35) 1.2 1.2 (42.4) (42.4) 2.9 2.2 (102.4) (77.4) 41.4 54.5 70.6 120.0 August 0.96 (39) 1.2 (42.4) 2.16 (76.4) 55.5 125.0 September 0.85 (30) 1.2 (42.4) 2.05 (72.4) 58.5 141.0 October i.o (35) 1.2 (42.4) 2.2 (77.4) 54,5 120.0 November 2.2 (78) 1.2 (42.4) 3.4 (120.4) 35.3 54.5 December 2.6 (92) 1.2 (42.4) 3.8 (134.4) 31.6 46.1 branches. ------- $ite selection process in 197€ because of potential virus contamination of its wells (see Appendix 3.5 1). A Charles River satellite plant would receive flows from six towns in the year 2000. Figure 3.5—1 presents a schematic of these sources, while Table 3.5-3 quantifies flows as developed by the EM1 A study (Metcalf and Fddy, l975c) Examination of Table 3.5-3 reveals approximately 75% of the total flow originates in two towns, Framingham and Natick. More importantly, 26 percent of the total design flow is extraneous I/I. Significant I/I reduction would, therefore, considerably alter the wastewater volume requiring treatment. Additionally, I/I reductions in Sudbury watershed towns would reduce the volume exported from this basin. Sources of water for each town were defined and Table 3.5—4 summarizes this data. In the development of this table, I/I was assumed to originate in a particular town’s watershed. However, in the case of Natick, a portion of these flows will come from the Sudbury River Basin and, therefore, its export figure is underestimated. This data indicates less than 40 percent of the projected flow originates within the Charles River Watershed. Approx- imately one—quarter comes from the Sudbury River Basin, while roughly 35 percent is MDC water. Augmentation of Charles River flow is a worthy objective, but it should not occur at the expense of the Sudbury River. Indeed, no further expansion of the MSD into the Sudbury should he allowed until detailed analysis of the effects of sewering to the harbor have been analyzed. This is especially significant because Sudbury towns presently sewered and those envisioned for future sewering lie at that basin’s headwaters. In the final accounting, it is the net difference in export between a satellite and non-satellite system which determines the impact of sewering upon the hydrologic bud- get of the Charles River Watershed. Four towns - Dedham, Natick, Needham and Wellesley — enter into this calculation. (All other towns within the watershed either return water to the basin via either septic tanks or upstream treatment plants, or receive MDC water and discharge it to MDC sewers.) Table 3.5-5 summarizes the watershed water balance computed with these municipalities. If the satellite facility is constructed 35.35xl0 3 m 3 /d (9.34 mgd) would be exported from the basin, while 84.56x10 3 m 3 /d (22.34 mgd) would leave the Charles watershed if all flows are sewereci to Boston Harbor. The net benefit, therefore, is the retention of 49.21x103m 3 /d (13.0 mgd) within the Charles watershed by the construction of a satellite plant. 3—241 ------- TABLE 3.5-3 YEAR 2000 WASTE FLOWS CHARLES RIVER SATELLITE PLANT Waste Flows Total Town 2 Flow Total Ashland 4.99 3.74 1.77 10.50 8.74 (1.32) (0.99) (0.47) (2.78) Dover 0.00 0.00 0.00 0.00 0.00 Framingham 33.23 5.57 13.70 52.50 43.66 (8.78) (1.47) (3.62) (13.87) Hopkinton 2.73 0.49 1.02 4.24 3.53 (0.72) (0.13) (0.27) (1.12) Natick 15.86 7.80 5.60 29.26 24.33 (4.19) (2.06) (1.48) (7.73) Sherborn 0.00 0.00 0.00 0.00 0.00 Southborough 2.16 0.83 0.80 3.79 3.15 (0.57) (0.22) (0.21) (1.00) Wellesley 11.01 0.61 8.33 19.95 16.59 (2.91) (0.16) (2.20) (5.27) TOTAL 69.98 19.04 31.22 120.24 (18.48) (5.03) (8.25) (31.77) % TOTAL 58.2 15.8 26.0 100.0 Waste Flow 1 - Domestic, Co m ercia1, and Minor Industrial Flows Waste Flow 2 - Major Industries and Other Industrial Flow I/I - Infiltration and Inflow Entries - m 3 /d (mgd) SOURCE: Metcalf & Eddy, Inc., 1975c 3—242 ------- TABLE 3.5-4 SUMMARY OF YEAR 2000 SOURCES TO CHARLES RIVER SATELLITE Water Source Charles Sudbury ____ Watershed Watershed _______________ 10.50 (2.78) 13.70 (3.62) 4.24 (1.12) Flow entries m 3 /d x 1O 3 (mgd) *Sudbury losses due to I/I Entries total flows from Table 3•5-3 assumed to originate at indicated source CONTRIBUTING PLANT MDC Water District Town Ashland Dover Frami ngham* Hopki nton Natick Sherborn Southborough* Welles 1 ey Total Flow % Total Flow 0.00 29.26 (7.73) 0.00 19.95 (5.27) 49.21 (13.00) 40.92 Total Flow 10.50 (2.78) 0.00 52.50 (13.87) 4.24 (1.12) 29.26 (7.73) 0.00 3.79 (1 . 00) 19.95 (5.27) 120.24 (31.77) 38.80 (10.25) 2.99 (0.79) 41.79 (11 . 04) 34 .75 0.80 (0.21) 29.26 (7.73) 24.33 3—24 3 ------- TABLE 3.5-5 YEAR 2000 WATER BALANCE CHARLES RIVER WATERSHED Vol ume Local Export Always Town Waste Flow I/I Capacity Volume Exported Dedham 1 12.64 7.15 6.93 14.08 14.08 and Westwood (3.34) (1.89) (1.83) (3.72) (3.72) Natick 23.66 5.60 34.67 29.26 (6.25) (1.48) (9.16) (7.73) Needham 17.83 8.40 12.87 21.27 21.27 (4.71) (2.22) (3.40) (5.62) (5.62) Wellesley 11.62 8.33 28.39 19.95 (3.07) (2.20) (7.50) (5.27) TOTAL 65.75 29.48 82.86 84.56 35.35 (17.37) (7.79) (21.89) (22.34) (9.34) Entries 3fd x (mgd) 1. Dedham and Westwood are served by the Dedham Water Co., which has wells in the Chaires and Neponset Watersheds. Local capacity set equal to that of the Bridge Street wells in the Charles Watershed. Dedham’s additional needs come from White Lodge wells in Neponset watershed. Total Dedham 3 Water Co. capacity, 29.14 x rn 3 /d (7.7 mgd) exceeds total demand, 20.70 x 10 m 3 /d (5.47 mgd). See Table 3.5-6 for definition of terms 3—244 ------- TABLE 3.5-6 DEFINITION OF TERMS CHARLES RIVER WATERSHED WATER BALANCE COMPUTATIONS Waste Flow = Sum of domestic, conTnercial, and all industrial flows. = Infiltration and Inflow. Local Capacity = Capacity of existing township water supply system (Frimpter, 1973b). The Dedhani Water Co. supplies Dedham and Westwood, which lies in the Neponset River Watershed, from wells in both watersheds. Dedham’s local capacity re- ported is the pumping capacity of the Dedham Water Company’s Bridge Street wel is. Export = The volume of water discharged by a town to the MDC interceptor system. It is computed as: Export = Waste Flow + I/I if Local Capacity > Waste Flow OR Export = Local Capacity + I/I if Waste Flow > Local Capacity Total Export is the volume discharged out of the watershed if no satellite facility is constructed. Always Exported = The volume discharged out of the watershed if a satellite plant is constructed. 3—245 ------- BOUNDARY CHARLES RIVER WATERSHED SUDBURY WATERSHED WELLESLEY FRAMINGHA ...... : i<. SOUTHBOROUGH NATICK ’.. .. I CHARLES RIVER TO CHARLES RIVER SATELLITE ______ PLANT ASHLAND —. HOPKINTON SHERBORN* * DOVER * LEGEND WATER SOURCE • FRAMINGHAM AND SOUTHBQROUGH SUDBURY WATERSHED EXPORT SUDBURY WATER VIA I/I MDC WATER DISTRICT ___ • CONTRIBUTE NO FLOW - - CHARLES WATERSHED UNTIL 2020 FIGURE 3.5-1 WATER SOURCES CHARLES RIVER SATELLITE PLANT YEAR 2000 ------- The proposed Neponset satellite would receive flows from five towns in the year 2000. Figure 3.5-2 schematically re- presents these sources and Table 3.5-7 summarizes corres- ponding flow quantities (Metcalf and Eddy, 1975c). Projected flow is fairly evenly distributed over the five towns. A large portion of the total flow is I/I, as was the case in the Charles, and its reduction would produce a smaller wastewater volume requiring treatment. Table 3.5-8 presents water sources for these towns. Unlike the Charles, 95 percent of the flow to a Neponset facility would originate within the Neponset watershed. SIX towns - Canton, Norwood, Sharon, Stoughton, Walpole and Westwood - determine the net effect upon the Neponset watershed when the non-satellite and satellite systems are considered. Table 3.5-9 summarizes the year 2000 water balance around the Neponset basin utilizing these towns. (Other municipalities within the Basin receive MDC water and discharge to the MDC sewer system or discharge within the Basin via septic tanks.) Construction of the Neponset River satellite facility would result in an export of 16.35x10 3 m 3 /d (4.32 mgd) of Neponset Basin water to Boston Harbor, while eliminating a satellite plant will increase the export to l07.20xl0 3 m- /d (28.32 mgd) . The net benefit of a satellite plant, therefore, is the retention of 90.84x10 3 m 3 /d (24.0 mgd) within its basin or origin. Historically, towns within the metropolitan Boston area have joined the MSD as growing populations presented waste- water disposal problems. At the same time, however, commun- ities water supply needs generally outstripped local capacities and these towns also tied into the MDC water system. The net effect - positive or negative - of this trend is probably negligible. The additional export of 49.2x10 3 m 3 /d (13.0 rngd) and 90.84x10 3 m3/d (24.0 mgd) respectively, from the Charles and Neponset basins to Boston Harbor has potential for long term negative impacts, the most important of these are decreased groundwater availability for water supply and reduction of base flow in these rivers. These impacts would be most severe when the region is experiencing a drought. During these periods without precipitation, river flow will drop to its base flow level. Base flow is that portion of flow coming from groundwater storage. For a given aquifer and its associated recharge area, groundwater storage will naturally fluctuate as a function of the random precipi- tation inputs. However, if storage has been reduced by 3—2 47 ------- Waste Flow 1 = Domestic, commercial and minor industrial Waste Flow 2 = Major industries and other industrial flows I/I = Infiltration and Inflow Entries m /d x 10 (mgd) SOURCE: Metcalf and Eddy, 1975c TABLE 3.5-7 SUMMARY OF YEAR 2000 FLOWS NEPOMSET RIVER SATELLITE PLANT Waste Flows 2 I/I Town Canton 12.45 (3.29) 5.22 (1.38) 4.09 (1.08) Norwood 11.58 (3.06) 5.15 (1.36) 9.27 (2.45) Sharon 3.22 (0.85) 1.29 (0.34) 1.21 (0.32) Stoughton 9.92 (2.62) 3.75 (0.99) 4.58 (1.21) Walpole 9.08 (2.40) 19.38 (5.12) 4.13 (1.09) Total 46.25 (12.22) 34.79 (9.19) 23.28 (6.15) % Total 44.3 33.4 22.3 Total Flow 21.76 (5.75) 26.00 (6.87) 5.72 (1.51) 18.25 (4.82) 32.59 (8.61) 104.32 (27.56) Total 20.9 24.9 5.5 17.5 31 .2 100 3—24 8 ------- TABLE 3.5-8 SUMMARY OF YEAR 2000 SOURCES NEPONSET RIVER SATELLITE PLANT Total Town Water Source Flow Neponset MDC Watershed Water District Canton 21.76 21.76 (5.75) (5.75) Norwood* 20.63 5.37 26.00 (5.45) (1.42) (6.07) Sharon 5.72 5.72 (1.51) (1.51) Stoughton 18.25 18.25 (4.82) (4.82) Walpole 32.59 32.59 (8.61) (8.61) Total Flow 98.95 5.37 104.32 (26.14) (1.42) (27.56) % Total 94.85 5.15 100 Entries m 3 /d x (mgd) *Assljnes Norwood supplies 11.35 x M 3 /d (3 mgd) from local water, and remainder fr MDC —249 ------- TABLE 3.5-9 YEAR 2000 WATER BALANCE NEPONSET RIVER WATERSHED Vol ume Local Export Always Town Waste Flow IfI Capacity Volume Exported Canton 17.67 4.07 11.51 15.60 0.00 (4.67) (1.08) (3.04) Norwood 1 16.73 9.72 11.36 20.63 0.00 (4.42) (2.45) (3.0) (5.45) Sharon 4.51 1.21 14.00 5.72 0.00 (1.19) (0.32) (3.7) Stoughton 13.67 4.58 11.73 16.31 0.00 (3.61) (1.21) (3,1) wa lpo le 2 28.46 4.13 13.25 32.59 0.00 (7.52) (1.09) (3,5) Westwood 3 8.06 2.57 22.22 23.28 23.28 and Dedham (2.13) (0.68) (5.87) (6.15) TOTAL 89.10 25.85 84.07 107.79 23.28 (23.54) (6.83) (22.21) (28.48) (6.15) Entries m 3 /d x (mgd) See TABLE 3.5-10 for footnotes. 3—250 ------- TABLE 3.5-10 FOOTNOTES TABLE 3.5-9 1. Norwood served by Metropolitan Water District. Local capacity used for emergencies; however, Norwood is pre en ly reactivating wells to allow for the r use to supply 11.36 x lO m /d (3 mgd). Therefore, 11.36 x 1O3 m /d (3 mgd) of waste flow is assumed from local supplies. 2. Surface water withdrawals for industrial consu ption is assumed equal to Walpole major industrial flow 11.59 x i 3 m /d (4.51 mgd), local capacity 13.25 x 1O 3 m /d (3.5 mgd) ‘ local demand 11.39 x lO M /d (3.01 mgd): Export = Total Waste + I/I. 3. Westwood and Dedham are served by the Dedham Water Co., which has wells in the Charles and Neponset watersheds. Local capacity set equal to that of the White Lodge wells in the Neponset watershed. Total Dedhacn Water Co. cap city 29.14 x i 3 m 3 /d (7.7 mgd) exceeds total demand 20.70 x i 3 m’ /d (5.47 mgd). Westwood export set equal to its waste flow + I/I and the amount of Dedham’s demand 5.71 x iü m 3 /d (1.51 mgd), not satisfied by Bridge St. wells. Waste Flows, I/I, Export Volume, and Volume Always Exported defined in Table 3.5-6. 3—25 1 ------- NEPONSET AWER WATERSHED BOUNDARY NORW000.. CANTON NEPONSETI I TO NEPONSET R%V€R SATE LLITE [ PLANT WALPOLE \ ST OUGH TO N SHARON LEGEND MDC WATER - NEPONSET RIVER WATER FIGURE 3.5-2 WATER SOURCES NEPONSET RIVER SATELLITE PLANT YEAR 2000 ------- withdrawals for water supply and if this water is exported from the basin in sewer pipes, the base flow of a river could be expected to decrease. There appears to be a general perception that the Charles River has experienced major base flow reduction and will experience severe flow problems in the near future unless flow augmentation is instituted. Historical flow records were examined to determine if such a trend is discernabie. The seven day period with the lowest average flow during a water year is generally considered as base flow. Table 3.5-li summarizes Charles River “base flow” for the period 1938-1973 as measured at Charles River Village gage station of the U.S.G.S. In addition, the average discharge is included as a measure of water input for the year. The conclusion drawn from this data is that base flow appears random and if a long term trend towards base flow reduction does exist, it is masked by natural fluctuations. Future flow problems have been predicted by a U.S.G.S. open file report (Frimpter, 1973b Appendix 3.5.1) Assuming that increased water demand would be met with local sources and all wastewater is sewered to Boston Harbor, the report predicted that in 1990: .if the st.reamf low regulation remains unchanged, if the water consumption increases as predicted, and if sewage is discharged outside the basin, the flow in the Charles River at Waltham will be expected to approach zero for approximately 9 days during an average year. However, because the maximum monthly demand is expected to be 1.2 times greater than the average demand and is expected to occur when stream- f low is lowest, the flow of the river will be expected to approach zero for approximately 14 days during an average year.” River flow at Waltham is assumed to be reduced by the total amount (0.297m 3 /s [ 10.5 ft 3 /sJ) of additional withdrawal for water supply, with the resultant predictions of no flow conditions. (A no flow condition should not be envisioned as the bed of the Charles River becoming dry. Significant volumes of water are stored behind the many dams along the lower Charles and it is unlikely these will dry up. The no flow situation, therefore, should be looked upon as a situation in which water is not passing over the spiliways of the dams along the river). Although these predictions were presented as preliminary and this is the only known quantification of the problem, this report has been quoted to substantiate the need for augmentation of Charles River flow. 3—25 3 ------- TABLE 3.5—11 HISTORICAL FLOWS CHARLES RIVER AT CHARLES RIVER VILLAGE 1 Water Year runs fran it ends. (i.e. Oct. Oct. 1 to Sept. 30 and is 1, 1937 to Sept. 30, 1938 designated as the year in which is Water Year 1938). Water 1 Year 1938 Avg. m 1 /s 12.716 Flow ft 3 /s 7 Day Flow m 3 7s 1t /s 1.756 62 Period 7 Day in Which Low Occurred Oct. 13-19, 1937 499 1939 9.034 319 0.906 32 Sept. 22—28, 1939 1940 6.174 218 0.991 35 Sept. 4-11, 1940 1941 5.069 179 0.510 18 Sept. 24—30, 1941 1942 5.551 196 0.340 12 Oct. 10-16, 1941 1943 8.043 284 0.481 17 Sept. 24-30, 1943 1944 4.729 167 0.481 17 Sept. 5-11, 1944 1945 9.317 329 1.586 56 Sept. 11-17, 1945 1946 9.997 353 1.614 57 July 16-22, 1946 1947 6.429 227 1.416 50 Sept. 14-20,1947 1948 9.034 319 0.935 33 Sept. 24-30, 1948 1949 1950 1951 5.749 5.013 8.128 203 177 287 0.396 0.595 0.850 14 21 30 Aug. Aug. Oct. 25-31, 1949 13-19, 1950 1-7, 1950 1952 10.054 355 0.793 28 Sept. 10-16, 1952 1953 8.808 311 0.340 12 Oct. 22-28, 1952 1954 9.997 353 0.510 18 Oct. 16-22, 1953 1955 11.866 419 0.963 34 Aug. 5-11, 1955 1956 13.197 466 0.850 30 Aug. 24-30, 1956 1957 6.429 227 0.176 6.2 Aug. 18-24, 1957 1958 10.195 360 0.127 4.5 Oct. 1—7, 1957 1959 11.186 395 1.473 52 Sept. 23—20, 1959 1960 9.544 337 0.906 32 Sept. 5-11, 1960 1961 9.997 353 1.133 40 Sept. 8-14, 1961 1962 8.751 309 0.850 30 Sept. 14-20, 1962 1963 8.326 294 0.453 16 Sept. 10-16, 1963 1964 7.052 249 0.453 16 Sept. 6-12, 1964 1965 4.220 149 0.396 14 Sept. 6-12, 1965 1966 3.313 117 0.340 12 Aug. 28-Sept. 3, 1966 1967 7.986 282 0.793 28 Oct. 10-16, 1966 1968 8.977 317 0.651 23 Aug. 30-Sept. 5, 1968 1969 7.845 277 0.736 26 Aug. 30-Sept. 5, 1969 1970 10.478 370 0.850 30 Aug. 5-11, 1970 1971 6.853 242 0.481 17 Aug. 20-26, 1971 1972 10.563 373 0.538 19 Oct. 1-7, 1971 1973 11.158 394 0.244 86 Sept. 11-17, 1973 3—2 54 ------- The above conclusion is based upon analysis of a flow- duration curve developed using discharge data for the period of record 1932-1968 recorded at the U.S.G.S. gaging station in Waltham. (A flow-duration curve is prepared by counting the number of average daily flows which occurred within a given range. The lower limit of this range is then plotted against the percentage of days in the period of record this flow was exceeded.) Discharge at Waltham, according to this flow-duration curve, (Figure 3-1, Appendix 3.5.1) was equal to or less than 0.297 m 3 /s (10.5 fti/s) 2.5 percent of the time during the 36 year period of record analyzed. However, prior to 1954, low flows at Waltham were completely regulated by the Boston Edision Power Company dam just upstream of the gage (U.S. Geological Survey, 1976). The effect of this regulation upon flow was analyzed by developing flow duration curves for the entire period of record (1932—1973), as well as the regulated (1932-1953), and unregu- lated (1954-1973) portions. Figure 3.5-3 presents these curves. The skew towards lower flows occurring more frequently exhibited by the entire period, and regulated period curves is the result of active regulation. To illustrate the influence of regu- lation, the occurrence of 0.297 rn 3 /s (10.5 ft 3 /s) was investi- gated. During the period of record, average daily flow was less than 0.297 m 3 /s (10.5 ft 3 /s) on 469 days. Of this total, 389 days (83 percent) occurred from 1932-1954. While 80 days (17 percent) in the unregulated period had average flows of this magnitude or less. Within the unregulated period, only six years experienced average daily flows of 0.297 m 3 /s (10.5 ft 3 /s) or less. In addition, 73 days (91 percent) are clustered into three years. These years 1966 (14 days), 1965 (27 days), and 1957 (32 days) represent, respectively, the first, second and third driest years (based on average annual flow) in the 20 year unregulated period analyzed. Furthermore, 1966 and 1967 are the driest years in the entire period of record for the Waltham gage. The future low flow hydrology of the Charles F iver will be influenced by a number of factors not previously considered. The most significant of these is the presence of point source discharges upstream of the NDC service area. Discharge from th se sources is expected to increase approx- imately 48.lxlO 3 m /d .(12.7 mgd) - from l9.68x10 3 m 3 /d (5.2 mgd) in 1973 to 67.75xl0 3 rn /d (17.9 mgd) in 2000. These upstream communities draw groundwater from public wells scattered throughout the Upper watershed (see Figure 2.5-13b) and many private wells. Groundwater withdrawals from wells distant from the river will adversely influence the Charles only after a significant time lag. Conversely, the water will rapidly reach the river via the sewer systems. The net effect can be considered as augmentation of river flow by pumping groundwater storage. These upstream sources roughly balance the export volume and the flow situation in the Charles can 3—255 ------- 2.83 (100) 0 -J U- -1 - - - -4- - V -- b ii H iH -ii .i - iiiiii .- ———--—- .-—— . — ——-——— EE H H 0.0283 ; _______ (1) 0.01 0.05 0.1 0.2 0.5 1 2 40 30 20 10 - I - 100 RECbRD __ FIGURE 3.5-3 FLOW DURATION CURVES U.S.G.S. GAGING STATION AT WALTHAM, MASS. ‘999 999990 99 99 98 95 90 80 70 6c H 1- . HI. • . H _ _T — — - 1 4 ± - 05 0.2 0 1 0.05 001 - . f .-= -H ______ • I -1-- - - -- ( 1000) jIj I II. ______ Eii IE1 H1i : ____ PERi - F REC 1954-197.8 . . - _____RIEC 1 O21 - 0.283 (10) - - i :i L —t - : : 4- ±1—Hi ±- 1 : ::::j: 4- .. - - - __ -+ I ii: . 5 10 2 99 9095 PERCENTAGE OF TIME FLOW EXCEEDS INDICATED VALUE ------- be anticipated to remain relatively constant. In addition, implementation of water conservation methods, reduction in I/I and more effective management of the Mother Brook diver- sion are techniques which can be utilized to ensure low flow problems in the lower Charles watershed do not develop. In summary, it is felt that the benefits of flow augmenta- tion to the Charles River by an additional point source dis- charge, are not sufficient to warrant the degradation in water quality that such a discharge would cause. Given the option of Harbor discharge, the risks involved with a Charles River satellite discharge are not offset by the benefits to be derived. While recycling of water within a basin is a worthy objective of a wastewater management plan, it should not be done at the expense of water quality considerations. Indeed, recycling is occurring in the Charles upstream of the study area. As a result of this, water is conserved during times of drought and water quality is frequently degraded. Adding an additional 120.24x10 3 m 3 /d (31.77 mgd) point source to the river does not appear to be environ- mentally sound. The expenditure of resources on advanced waste treatment would be best applied to existing point sources in the river to maximize the water quality and quantity benefits of their operation. The water quantity/ f low augmentation issue is extremely difficult to project and is by no means closed. However, it is felt that a system without satellite plants will best protect the over- all environmental concerns within the study area. The Neponset River is actively regulated for industrial water supply and this controls its low flow characteristics. In addition, the only upstream discharges are industrial cooling waters. Sources of water to make up for export to the Harbor are not readily available as in the Charles watershed. Between 1970 and 2000, export of Neponset water to Boston Harbor would increase by approximately 45.42xl0 3 m 3 /d (12 mgd). The loss of this water is a negative impact asso- ciated with non—satellite alternatives. However, as pre- viously discussed, significant water quality impacts will be caused by a Neponset discharge. Major water supply wells lie immediately downstream of the most likely discharge points, creating public health concerns. The water quality related impacts are more severe than the water quantity impacts and, therefore, an all harbor alternative is preferable. The potential to mitigate those impacts through an alternative augmentation system should be investigated. The active regulation of the Neponset for industrial water supply 3—25 7 ------- could be coordinated with flow needs such that both are satisfied during drought conditions. In addition, major I/I reductions and water conservation should be emphasized as * ethods to mitigate quantity related impacts. Such actions will have greater long term benefits for the Neponset River Watershed than augmentation with wastewater. Water quantity impacts associated with the no action or modified no action alternatives are approximately equiv- alent to those of a non-satellite system. 3—258 ------- 3.5.2 Wate 4 Each of the remaining system alternatives has associated water quality impacts. The following discussion summarizes these impacts. No Action . The No Action alternative would have severe water quality impacts on Boston Harbor and throughout the EMMA study area. Continued degradation of the entire Harbor would occur. In addition, various sections of the intercep- tor system would continue to be overloaded. As future in- creases in wastewater generation further overload these sec- tions, and cause additional sections to become overloaded, wastewater overflows within the service area can be expected to increase. These overflows will continue to violate water quality standards. Also, in the near future, the design capacities of the present treatment plants will be surpassed, reducing the treatment efficiency below present levels. Modified No Action . Modified no action will have a bene- ficial effect upon Harbor water quality because sludge dis- charge will be discontinued and combined sewer overflows will be controlled. However, the problems associated with insufficient interceptor hydraulic capacity and overloaded primary treatment facilities will continue to have a detri- mental water quality impact. During periods when the hydrau- lic capacity of the system is exceeded, overflows would vio- late water quality standards. Discharge of primary effluent to Boston Harbor would continue to add significant amounts of toxic metals. In addition, it is unlikely that the present outfalis achieve acceptable dilutions. EMMA Study . There are major adverse water quality impacts associi ed with this alternative. Wastewater discharge by satellite plants cause dissolved oxygen problems in both the Charles and Neponset Rivers. At the Harbor, secondary treat- ment would remove additional toxic metals; however, effective dilution is required to reduce these pollutants to “safe” levels. It is not known if the proposed outfall modifications and locations car achieve safe dilution levels. Deer Island_Plan. Elimination of proposed satellite dis- charges would prev significant water quality impacts (See Sections 3.2.3B and3.3.3B). Similarly, the removal of the Quincy Bay overflow would benefit water quality in Quincy Bay. Treatment of all flow at Deer island allows the discharge to be placed in a location which will assure proper dilution. In addition, should MDC obtain a waiver of secondary treatment requirements, an all Deer Island Plan allows for discharge into the deep waters of Massachusetts Bay. 3—259 ------- In summary, the Deer Island Plan is the only system alter— native evaluated which meets water quality standards. This plan will generally improve areas of existing water quality degradation. With respect to water quality considerations, the Deer Isaind Plan is the best of the four system alterna- tives. 3—260 ------- 3.5.3 Biota Deer Island Plan . This alternative will cause various impacts on the biota in the vicinity of Construction. The severity of the impact of the wastewater treatment facili— ties and influent and effluent lines leading to the Deer Island facility will be discussed. Deer Island has a total land area of some 85 ha (210 acres), portions of which are owned by the City of Boston, the MDC and The U.S. Government. Located on the island is a City of Boston Prison, the MDC’S Deer Island Wastewater Treatment Plant and what is left of Fort Dawes, a U.S. Govern- ment installation. The remains of several past uses exist in various areas of the island. The dominant physical feature of the site are the drurnlins which occupy portions of the island. The major drumlin rises to an elevation of over 30.5 meters (100 feet) and is composed of a mixture of glacial materials. Access to the site is very poor, being limited to the narrow streets of Point Shirley and Cottage Hill. During the site development phase, displacement of exist- ing wildlife and vegetation will occur. Vegetation found through- out most of the proposed area of expansion is characterized as being that of an early successional field. Some isolated patches of secondary growth woodland are found, and portions, particu- larly at Fort Dawes, are devoid of any ground cover. Neither habitat nor wildlife species on the site are considered unique. The most dominant features of Deer Island are the drumlins. If all treatment is provided at Deer Island it will not be possible to prevent drumlin removal. However, it is projected that the Deer Island site can be developed without the need to fill, providing that the drumlins, prison and/or Fort Dawes properties are made available. The Squanturn site will be used for ash disposal and corn- posting under the Deer Island Plan. The site is approximately 28.3 ha (70 acres) in area and is located on the old naval airfield at Squantum. The site was vacated by the Navy in 1953 and the area being considered for composting and ash disposal has remained vacant since that time. Today remnants of the old runways still exist. Squantum is located on what appears to be a filled wet- land where a bulkhead (of wood and/or steel and concrete) was erected and the inner area was filled. The site is flat and vegetation is limited principally to low growing grasses. Access is provided via Morrissey Boulevard and Squantum Street. Site development will cause displacement of existing wild- life and vegetation. The vegetation on the site is composed of a mixture of grass with a variety of other annuals, 3—261 ------- shrubs and trees being found scattered throughout. Some Phragmites are found on the site, but no wetland species are present except beyond the bulkhead where some wetland vegeta- tion (apparently Spartina alterniflora ) can be found. The habitat is not rare or unique and is not thought to support any rare or endangered species. The proposed use of the site will displace both vegetation and wildlife from the site. Overall magnitude of the impact from such action is minimal. In considering an all Deer Island alternative, the need for an influent sewer across Boston Harbor from Nut Island, a relief sewer across Quincy Bay to a pumping station on Nut Island and an additional outfall from Deer Island arises. Any construction across the Harbor will disturb the marine environ- ment in the path of the construction to some degree. The actual effects and the degree to which they will influence the Harbor environment can vary. Many factors will influence the extent of the detrimental impacts to the Harbor due to the construction. These include: the construction technique utilized, the physical character- istics of the Harbor in the vicinity of the crossing, the disposal of construction spoils, the duration of construction activity and the season of the year. The construction of the pipe across the Harbor will result in both short-term and long-term impacts. The immediate effects of the project on the Harbor would consist of destruction of flora and fauna, loss of habitat and increased turbidity and subsequent disruption by sedimentation in the vicinity of construction. Non-mobile benthic organisms in the path of the sewer, such as hydrozoans, bryozoans and algae will suffer at least temporary loss of habitat. In addition, fine spoils material would be suspended in waters surrounding the construction area. This would cause undesirable environmental effects including siltation, temporary reduction of photosynthetic activity and possible mortality to certain flora and fauna. The suspended material may also be contaminated with heavy metals. Siltation would alter the habitat on either side of the pipeline cut, with the greatest effect nearest the cut and diminishing effects with increasing distance, depending upon tidal effects. Areas where tidal currents have greater velo- city will cause a wider distribution of silt than those areas with lower velocities. Since two 2.75 meter (9 foot) diameter pipes are to be constructed across the Harbor, and a 4:1 ratio of horizontal footage to vertical footage is required to make the cut, large volumes of material will be disturbed. These large quantities of spoils, if improperly disposed of (e.g. side casting of spoils), would pose a significant detrimental environmental effect or. the Harbor. 3—262 ------- Disruption of benthic organisms such as clams, crabs, and worms would occur as long as sedimentation continues, however, they should adjust themselves to the level of the sedi- mentwithin a short time period after turbidity is reduced. Recovery time may be longer if the water is cold since animals are more sluggish. The impact of the proposed plan on shellfish and other benthic organisms is dependent on the method of dredge spoils disposal. If dredge spoils are deposited on the bay bottom adjacent to the trench, shellfish and other benthic organisms both in the path of the pipeline and in adjacent areas will be disrupted. If dredge spoils are removed and deposited on an existing spoils site, disruption of adjacent benthos would be minimized, but some of those organisms contained in the spoils would be destroyed. Overall, the most damaging effects will occur to benthic sessile forms, burrowing benthic animals and to aquatic plants directly in the path of construction. This, in conjunction with the possible disturbance of heavy metal-contaminated sediments will pose the most significant environmental effects. However, as mentioned previously, these effects are short term in nature. The overall effect of the project on the estuarine community will be beneficial. After completion of the con- struction activities, benthic organisms will resettle and develop on the new bottom substrate. In the area of the present Nut Island outfall, water quality would improve. This would be due to the elimination of the treatment plant outfall and plant overflows. This should result in increased recreational uses of Quincy Bay and surrounding areas. Shellfish production would also be positively affected. Areas which are now condemned or need depuration may possibly become open areas, depending upon recovery time for the environment and other pollution inputs still entering the harbor. Water quality at the present Deer Island outfall will also be improved due to improved treatment efficiency. At this location, however, heavy metal levels may accumulate in the benthic sediments over time. Other water quality para- meters should not violate standards. Disposal of spoils from the various pipeline trenches will influence the biota wherever the material is deposited. If the Foul Area Site is used, whatever biota exists at this site will be covered. This should cause minimal impact, since dumping of contaminated wastes has occurred for over a decade at this site. A final consideration with respect to biotic impacts is the issue of interceptor relief. As has been mentioned pre- viously, the Deer island Plan (a non-satellite system) will 3—26 3 ------- require approximately 23 miles of relief above and beyond the relief requirements of the EN? A Plan. This relief work involves the Wellesley Extension Sewer, the New Neponset Valley Sewer, and a segment of the High Level Sewer. While this FIS study did not attempt to select specific alignments for the relief sewers (which will be done during facility planning), a reasonable estimate of the biotic impact can be made. In each case, the relief sewers will roughly parallel the existing sewers. Deviations from this condition will occur to avoid other utilities, structures, or obstacles and to minimize environmental impacts (a result of facility planning). However, for the purpose of a rough cut analysis, a parallel alignment was assumed, regardless of the type of area beinc traversed. Furthermore, a 22.9 m (75 ft.) right-of-way was assumed where the sewer passes through undeveloped areas. A 15.2 rn (50 ft.) right-of-way was assumed through developed areas. With these assumptions, the amount and type of area impacted was calculated and is presented below: Wellesley Neponset High Extension Valley Level Total ha (ac) ha (ac) ha (ac) ha (ac ) Wooded 12.9 (31.9) 15.7 (38.8) 0.7 (1.8) 29.3 (72.5) Wetlands/Water 1.3 (3.2) 1.1 (2.6) 0 2.4 (5.8) Developed 3.6 (8.9) 9.6 (23.8)13.2(32.6) 26.4 (65.3) Open 2.6 (6.5) 1.2 (3.0) 2.2 (5.3) 6.0 (14.8) Impacts of sewer construction through areas designated as open will be minimal. Restoration of the impacted areas to their original state will be rapid. Construction through wetland/water areas is much more likely to result in adverse environmental impacts. It is expected that facilities planning will reduce the area to be impacted by a substantial amount. Controlled construction and restoration procedures can further mitigate impacts on aquatic and wetland biota. Wooded areas are quite variable in terms of the amount of impact which can be expected. The productivity of a wooded area is often significantly increased by the clearing of a right-of-way. Clearing results in the formation of an ecotone, or transition zone between two habitat types. These zones are known to support a greater diversity and density of wildlife compared to either habitat type alone. In areas where woods are present in scattered parcels, ecotone benefits already exist and the main value of any parcel may be aesthetic. Here, clearing will have a greater impact. Again, during facilities planning, emphasis should be given to avoiding routes which impact significantly upon unique, scenic, or otherwise valuable woodlands. 3—264 ------- It is not generally advisable to replant trees in all easements as a matter of course. However, if scenic or unique woodlands are impacted, barrier screening can greatly mitigate these effects. Finally, construction through developed areas results in the greatest amount of short-term disruption to local residents. Biotic impacts are few and result mainly from the loss of roadside vegetation. Judicious routing of sewers can avoid most mature specimens, however. Overall, the impac of relief sewer construction are mostly short-term in nature and are readily controllable through the facility planning process. EM A Study . Implementation of the EMMA study will alter the biotic community at the proposed facility sites. This will include land based impacts as well as impacts on marine resources. Two satellite plants were proposed, one for the Upper Neponset River and one for the Middle Charles River. No specific sites were chosen under this plan, therefore, no quantitative impact analysis can be made. However, it was determined that approximately 32 and 28 acres of land (in- cluding buffer zones) would be required for the Neponset and Charles plants respectively. The majority of the land on the proposed sites would be dedicated to wastewater treatment and sludge processing facilities. The acreage dedicated to treatment facilities would be permanently lest as far as its ecological value is concerned. Wildlife displacement and vegetative losses at the plant sites would be dependent upon the site locations. The buffer zones may still possibly provide productive wildlife and vege- tation habitat. In addition to the 70 acres of land which would be permanently committed, some additional land may be impacted through the construction of interceptor and outfall connec- tions (depending on the specific site). It should also be noted that the selection of satellite sites has been studied and deliberated at great length both in this study and in the EMMA study, by two site evaluation committees, and by the public through workshop sessions. In spite of all this effort no clear indication, of an optimal (or even satisfactory) site has emerged. Basically, this is a result of the essential incompatibility of such a. facility in an area like the Middle Charles. To locate a facility there, near the discharge point will result in hiotic, aesthetic, and land use impacts. This very significant fact should be remembered in forthcoming discussions about acreage trade—offs among the various alternatives, 3—265 ------- Water quality impacts will be associated with the effluent characteristics of the two plants along with the location of the effluent discharge. Since a specific site for effluent discharge was not determined, water quality effects and subsequent impact on the biota due to water quality are discussed generally. Water Quality Modeling of the Neponset and Charles rivers indicates effluents from the proposed satellite plants cause dissolved oxygen problems in their respective rivers. In the Neponser, the recommended discharge will cause a violation of applicable water quality criteria, with D.O. concentrations dropping to less than 1.0 mg/i. However, the situation for the Charles River is not so clear. Class B water quality criteria for dissolved oxygen could be met by a satellite plant discharge above the S. NatickDarn if the river water quality were to meet standards where the river enters the MSD. This condition will not occur, however, because the present Benthic Oxygen demand in the upstream reaches will not dissappear. Even though the Charles River, as modelled, is predicted to be in violation of standards without a satellite plant, discharge by the proposed facility would worsen an already critical dissolved oxygen problem. Such low D.C. levels would pose even more severe constraints on the indigenous aquatic populations. Oxygen is as important to aquatic organisms as it is to terrestrial ones. However, oxygen gas is poorly soluble in water: water containing 10 mg/i of “D.C.” is rich in oxygen. Depletion of even a few mg/i of D.O., therefore, can subject aquatic species to the same suffocating stress as air-breathing animals experience in a stuffy, enclosed atmosphere. In fact, almost any reduction in D.O. levels can reduce somewhat the effeciency of oxygen uptake by aquatic organisms, which reduces an animal’s ability to survive other stresses of its environinent(just as a shortness of breath weakens one). Lowered dissolved oxygen concentrations may not kill an adult fish outright, for instance, but may interfere with its growth, reproductive activity, or the survival of the eggs and young. In addition, many fish species require healthy populations of lower organ- isms as food and the dissolved oxygen concentrations must be sufficient to maintain these insects and other inver- tebrates. Maintaining a healthy, balanced ecosystem, and therefore, good populations of fish, may be difficult when the decay of material such as wastewater, consumes a major portion of a river’s dissolved oxygen. There is some disagreement among authorities as to a precise, minimum dissolved oxygen concentration needed to sustain a balanced fish community, consisting of a 3—266 ------- related with confidence to maintaing a good fish population. “To allow for the differences among require— ments affected by species and other variables, the dissolved oxygen criteria are based on the concen- tration that will support a well-rounded population of fish (Ellis, 1937) as it would occur under natural conditions. A population of fish is composed of a number of different but more or less inter- dependent species, of different feeding and repro- ductive habits, but which will include game and pan fish (bass, pike, trout, perch, sunfish, crappie, depending upon the location), some so—called rough or coarse fish (carp, buffalo, bullhead, sucker, chub), and large numbers of smaller ‘forage’ fish (e.g., minnows). Theoretically it should be possible to base oxygen criteria on the needs of the most sensitive component of such a population, but there is not enough information for this at present; that is why the criteria must be based on oxygen concentrations known to permit the main- tenance and well—being of the population as a whole. “The requirement that the data be applicable to naturally occurring populations imposes limits on the types of research that can be used as a basis for the criterion. Aside from a few papers on feeding, growth, and survival in relation to oxygen concentration, very little of the laboratory- based literature has a direct bearing; field data are in general more useful. Field studies have the disadvantage that the numbers of variables encountered in the natural environment (temperature, pH, dissolved solids, food supply, and the like, as well as dissolved oxygen) make it necessary to be conservative in relating fish cibundance arid distribution to oxygen concentration alone, but enough observations have been made under a variety of con- ditions that the importance of oxygen concen— tr tion seems clear. “Field studies, in which fish catches have been related to dissolved oxygen concentrations measured at the same time, indicate that a dissolved oxygen concentration of 3 rng/l is too low to main- tain a good fish population (Thompson, 1925; Ellis, 1937; Brinley, 1944), this finding is supported by 3—26 7 ------- diversity of species and general types of fish (such as game fish, pan fish and rough fish). By implication, such a minimum D.O. level would also maintain the rest of the organisms in the aquatic system. On one hand water quality criteria developed by the National Academy of Science and National Academy of Engineering for the Environmental Protection Agency (Committee on Water Quality Criteria, 1972) state: “There is evidently no concentration level or percentage of saturation to which the 02 content of natural waters can be reduced without causing or risking some adverse effects on the reproduction, growth, and consequently, the production of fishes inhabiting those waters. Accordingly, no single, arbitrary recommendation can be set for dissolved oxygen concentrations that will be favorable for i1 kinds of fish in al]. kinds of water, or even one kind of fish in a single kind of water. Any reduction in oxygen may be harmful by affecting fish production and the potential yeild of a fishery.” The allowable minimum recommended in this reference is 4 mg/i, except when naturally occurring concentrations are less. In that case, no depression below the naturally occurring minimum is recommended. The value of 4 mg/i was chosen by the National Academy Committee because the literature reviewed indicated subacute or chronic damage to fish below this level. The accumulated evidence also revealed appreciable effects on embryonic and juvenile sur- vival and growth of several fish species at oxygen concen- trations below this level. Representing a more conservative approach, water quality criteria recently published by the U.S. Environmental Protection Agency (1976) specify 5 mg/i as the minimum consentration which will maintain a good fish population. The E.P.A. discusses this criterion as follows: “A discussion of oxygen criteria for fresh- water fish must take into account these facts: (1) fish vary in their oxygen requirements according to species, age, activity, temperature, and nutri- tional state; (2) they are found from time to time, and can survive for a while, at oxygen concen- trations considerably below that considered suitable for a thriving population; and (3) although there is much literature on the oxygen consumption of fish and the effects of varying oxygen concentrations on behavior and survival, few investigators have employed methods or sought endpoints that can be 3—2 68 ------- laboratory observations that in the vicinity of 3 mg/liter and below feeding is diminished or stopped (Lindroth, 1949; Mount, 1960; Hermann, et al. , 1962), and growth is reduced (Hamdorf, 1961; Itazawa, 1971), even when the lowered oxy- gen concentration occurs for only part of the day (Stewart, et al., 1967). “A dissolved oxygen concentration of 4 mg/i seems to be about the lowest that will support a varied fish population (Ellis, 1937), even in the winter (Thompson, 1925), and for a well-rounded population including game fish it should be above that. Both Ellis (1937) and Brinley (1944) set the minimum for a well rounded population at 5 mg/I. It should be pointed out, however, that Thompson found the greatest variety of species at 9 mg/i, Ellis found good populations more fre- quently at 6 than at 5 mg/i, and Brinley reported the best concentrations for game fish populations to be above 5 mg/i. “Fish embryonic and larval stages are espe- cially vulnerable to reduced oxygen concentra- tions because their ability to extract oxygen from water is not fully developed and they can- not move away from adverse conditions. Although many species can develop at oxygen concentra- tions as low as 2.5 to 3 mg/l, the effects of a reduced oxygen concentration even as high as 5 or 6 mg/i can cause a partial mortality or at the least retard development (Brugs, 1971; Siefert et al. , 1973, 1974, 1975; Carlson et al. , 1974; Carison and Siefert, 1974; Garside, 1966; Gulidow, 1969; Hamdorf, 1961). Unless it is extreme, how- ever, the retardation need not be permanent or detrimental to the species (Brannon, 1965; Eddy, 1972). For most fish, maintaining a minimum of 5 mg/i in the water mass in the vicinity of the embryos and larvae should suffice.” Extensive information was not found on the present bio- logical populations, especially of fish, in the Charles River. A 1973 survey by the MDWPC (Erdmann, Bilger and Travis, 1977) showed bottom dwelling invertebrate communities consisting largely, but not exclusively of pollution—tolerant species. (These organisms have a better natural ability to tolerate low dissolved oxygen levels). A 1969 survey (Massachusetts Division of Fisheries and Game, 1970) showed the middle reaches of the Charles River to have a fairly diverse fish 3—26 9 ------- community, consisting of pickerel, bass, perch, bluegills, pumpkinseeds, carp, suckers and others. Although not the most abundant in numbers, coarse fish such as carp or suckers, accounted for a large proportion of the total weight of fish collected during the survey. This could be due to man in— duced pollution effects, or the natural characteristics of the Charles River may be favoring these fish species. Regardless, it seems clear that the River has at least the potential to support a healthy, balanced ecosystem. The future D.O. concentrations of the Charles River, how- ever, are indicated to be stressed by the existing oxygen demands entering the River. Adding a new, major point source is likely to have a significant, adverse impact on the present, or the potential, fish populations of this system. 3—270 ------- 3.5.4. Air Quality Sludge produced by the Deer Island Plan would be kept separated according to its origin (northern or southern service area). All of the sludge from the northern system would be incinerated along with all of the primary sludge from the southern service area. The secondary sludge from the southern system would be sent to Squantum for transfer and disposal. One half of this secondary sludge would be composted at Squantum and the other half would be transferred to a landfill. Incineration of the sludge would add significant quantities of pollutants to the atmosphere. The estimated yearly maximum allowable emissions (emission rate based on maximum rated capacity using new source performance standards and AP-42 controlled emission factors) in kilograms (tons) for Deer Island are: particulates 117,936 kg (130), sulfur dioxide 302,098 kg (333), nitrogen dioxide (as NO 2 ) 609,638 kg (672) and hydrocarbons 69,854 kg (77) Long term and short term analyses of air quality were conducted. On an annual basis it was estimated that the maximum annual concentration of pollutants would occur 800m (2624.8 ft) east of the Deer Island site. It is estimated 4.1 pg/rn 3 of sulfur dioxide and 1.2 pg/rn 3 of total suspended particulates will be added to the back- ground level pollutants. The estimated maximum 24 hour concentrations will be 10.2 pg/rn 3 for particulates and 34.2 pg/rn 3 for sulfur dioxide. The 3 hour maximum is expected to be 137.8 pg/rn 3 for sulfur dioxide. It should be noted that due to prevailing winds, the maximum con- centrations occur over water. None of the above concen- trations would exceed the Prevention of Significant Deterioration standards set by EPA for a Class II area. It is expected, according to the air quality model (Appendix 3.5.4), that the effect of the emissions on areas designated as being in non—attainment will be negligible for annual concentrations. Sulfur dioxide levels will meet the 24 hour standards, however, 24 hour particulate levels are projected to violate the secondary NAAQS for par ticulates. Under the EMNA study all of the secondary sludge would be incinerated. Sludge from the harbor plants would be in- cinerated at Deer Island and each satellite plant would in- cinerate its own sludge. 3—2 71 ------- Based upon the incineration of all the sludge, the estimated yearly maximum allowable emissions in kilograms (tons) were calculated for the EMMA Plan. The estimated emissions for all incinerator sites were calculated to be: 141,523 kg (156) particulates, 399,168 kg (440) sulfur dioxide, 793,800 kg (875) nitorgen oxides and 88,906 kg (98) hydrocarbon. In the EMMA plan greater air emissions levels are found than under the Recommended Plan. This is due to the fact that half of the secondary sludge from the southern system in the Recommended Plan is being composted and half is being landfilled instead of being incinerated. Thus greater quantities of air pollutants would contribute to the ambient air concentrations due to the EM M Plan. An analysis was made of emissions from the combination of incinerators located at the Deer Island, Charles River and Neponset River plants. This analysis provides estimates for the annual ground level concentrations of sulfur dioxide and total suspended particulates. The total suspended particulates estimates for the Deer Island, Neponset River and Charles River facilities, were 1.5, 2.3 and .06 .ig/m 3 , respectively. Sulfur dioxide levels for the three plants were estimated to be 5.0, 0.09 and 1.7 g/m 3 . Incinerating sludge at the Neponset and Charles sites would expose a larger population to the added pollutants of incineration. Aithougn the emission increments are not ex- pected to violate any standards, these emissions will be generally “upwind” of populated areas and thus, less desirable. This is in contrast to Deer Island where most emissions are expected to be blown over water. Based on the lower quantities of emissions and site location, the Deer Island alternative would have less of an impact on air quality than the EMMA Plan. The No Action and Modified No Action alternatives would both have fewer emissions than either the EMMA or Deer Island plans. The No Action alternative would not involve any additional emissions. Air quality would not be influenced, since no sludge would be incinerated. This alternative would have the least effect on air quality. 3—272 ------- The Modified No Action alternative would include the incineration of only primary sludge. This is part of the on-going plans for the MDC wastewater management scheme. Incineration of primary sludge is assumed in both the EMMA and Deer Island alternatives. Since secondary sludge is not incinerated in the Modified No Action alternative, this alternative would have significantly less emissions than either of the aformentioned plans; however, it would create more emissions than the No Action alternative. 3—273 ------- 3.5.5 Socio—econornic Effects The primary socio-economic impacts associated with each of the alternatives are related to employment resulting from the construction activity required for each. In addition, the construction related employment should result in in- creased commercial activity in the immediate vicinity of the construction staging areas. Both of these beneficial impacts should accrue for the duration of the construction phase. Assuming that the Deer Island and the EMMA Plan have approximately equivalent man power requirements for construc- tion, it would appear that their respective impacts would be quite similar. However, differences will emerge due to the two additional construction sites required under the EMMA Plan. Under this alternative, construction employment would take place at four distinctive locations; Deer Island, Nut Island, in the Charles River and Neponset River watersheds. Under the Harbor Plan, construction activity would be concentrated on and around Deer Island and Nut Island. The effect of this employment concentration in the Harbor area could result in more positive impacts on inner city residents with skills in the building trades. Also, the utilization of minority contractors and subcontractors should be greater under the Deer Island Plan than under the EMMA Plan due to the proximity of Deer Island and Nut Island to the urban core of Metropolitan Boston. The No Action alternative will not result in these bene- ficial, employment related impacts, since no construction would take place. The Modified No Action alternative would require sub- stantially less construction than either the Deer Island Plan alternative or the EMMA alternative. Therefore, the probable employment related impacts would be proportionally less than either the Harbor or the EMMA alternatives. There is also potential for adverse fiscal impact on local governmental units. This is associated with the acreage requirements for the implementation of the alterna- tives. Use of land for sewerage treatment facilities, a tax exempt public use, reduces the tax base in the rnunici- palities in which the facilities are located. The extent of this impact will depend on the amount of currently pri- vately owned land to be consumed and the current and future assessed value of that land, as well as these magnitudes relative to the entire municipality. Neither of the No Action alternatives would result in the removal of any privately owned land from municipal tax rolls. 3—274 ------- The Deer Island Plan alternative will result in the consumption of about 28.3 ha (70 acres) of privately owned land at the Squantuin site in Quincy. The remaining land required for this alternative is already publicly owned. The EMMA Plan alternative would require the acquisi- tion of 30 to 32 ha (75 to 80 acres) of private land for the construction of the two satellite plants on the Charles and Neponset Rivers. No comparisons can be made, however, between the Harbor and EMMA alternatives in terms of either absolute or rela- tive loss of tax ratables resulting from acquisition since specific sites have not been delineated under the EMMA Plan. 3—2 75 ------- 3.5.6 Construction—Related Transportation Impacts In order to assess primary impacts against the transpor- tation/accessibility factor, the affected construction points for each of the various alternatives must be identified, as well as the nature of the access routes into these areas, and the type of vehicular traffic these routes would be expected to carry. The following discussion will outline these details and contparatively evaluate the varying alternatives. No Action . By the nature of this alternative, no con- struction, and therefore, no induced transportation/access impact would be realized. Modified No Action . This strategy entails storm sewer overflow relief in the Boston core area along the r ystic, Charles arid Neponset Rivers as well as around the harbor face. Additionally, a primary sludge incinerator is proposed for Deer Island, as well as ongoing interceptor relief in the core area. Aside from the Deer Island site, specific construction areas cannot be identified for the storm sewer overflow relief and interceptor renovation. This is due to the fact that measures to correct overflows have only recently been initiated, and the relief program operates interrnittantly on a “need” basis. It is felt that construction pertaining to these tasks would not lead to any extended severe impacts on the viability of the affected transportation links in the metropolitan Boston area. Construction of the primary incineration facility at Deer Island would not require maThr topographic alteration of the facility site, and would, therefore, engage a work force strictly for construction purposes only. It is not expected that the crew required for this task would be large enough to overload the carrying capacity of the through routes into the Deer Island site. Storm sewer overflow and interceptor renovation would entail short-term intensified activity at a number of small sites located sporadically around the metropolitan core. Due to a limited duration at each site and the discrete un- connected spatial character of the sewer relief projects, major accessibility and/or through-traffic impacts would not be expected to occur. EMMA Study . This alternative concentrates construction activities into four areas: 1) Deer Island (construction of a 17.5 m 3 /s (400 mgd) treatment plant including the filling of 5.7 ha (14 acres) of harbor and removal of the prison facility), 2) Nut Island (construction of 5.7 m 3 /s (130 mgd) treatment plant and the filling of 11.3 ha (28 acres) of harbor), 3) Mid Charles River Watershed (construction of 31 rngd treatment plant, and 4) Upper Neponset River Watershed (construction of 1.1 m 3 s (25 mgd) treatment plant). 3—27 6 ------- Examination of access routes into Deer Island indicates that the work force required for implementation of the proposed facility would severely stress the traffic handling capability of these roads. Intensive development in spatially restricted land areas (Beachrnont, Cottage Hill and Point Shirley sections of Winthrop) has led to a very disorganized and constrictive road system leading to Deer Island. A similar case may be made for access to the Nut Island site. However, the range of construction activities at that location is much smaller, comparatively, and the roadway pattern is less restrictive and more organized in the Houghs Neck and Central Quincy area. Therefore, while a significant impact is expected on local traffic and accessibility into the proposed Nut Island facility, it would not be of the mag- nitude of that associated with Deer Island construction. Facility construction in the Charles and Neponset Basins will tend to affect through-traffic flow, as opposed to local- ized access inconvenience associated with facility implemen- tation in the Harbor area. Especially in the Mid—Charles Basin, with a limited number of secondary transportation cor- ridors, reductions in the vehicular flow rate may be expected, due to slow moving construction equipment and additional con- gestion due to the influx of workers into the work area. Deer Island Plan . This strategy concentrates construc- tion activity into three major areas, all within the Boston Harbor area: 1) Deer Island (25.7 in3/s (586 mgd) treatment plant, including the removal of the drumlin and removal of the prison facility), 2) Nut Island (dismantle existing facility and construction of headworks and pump station), 3) Squantum (construction of 4.6 m (15 ft.) berm enclosing compost and ash fill area). Construction of the subaqueous connection between Nut and Deer Islands may potentially have a negative impact on ship traffic into Boston Harbor, although this should be avoidable through proper construction management. In any event, the northern portion of Long Island (in addition to areas within Nut and Deer Islands) has been preliminarily designated as a staging point for this proposed action. In regard to the Deer and Nut Island areas, transportation/ accessibility impacts for this strategy are expected to be similar in severity to those expected with implementation of the EMNA plan. Vehicular flow impairment would most likely be less significant for construction in the Nut Island area, due to the swaller size and reduced complexity of the pro- posed facilities. In the area of Houghs Neck, where a relief interceptor is proposed to be lain under Sea St. (Near Manet Avenue) and out into the harbor to Nut Island, impacts on vehi- cular flow and local access are expected to be severe, but only for the short period of time necessary to cross the roadway. 3-277 ------- Impacts in the Deer Island area, however, would be more serious than those expected with construction of the proposed EMMA facility, due to the increase in facility size. Disturbance to the free flow of vehicular traffic is not expected to occur to any significant degree in the Squan— turn area. In direct opposition to the other sectors affected by construction of the Deer Island alternative, the Squantum area is virtually free from residential development (limiting access inconvenience) and is directly served by major through routes (Routes 3, 3A and Morrissey Blvd). Comparison of Alternative Strategies . It is readily apparent that both the No Action and Modified No Action alter- natives yield no or minimal primary impacts against the trans- portation/accessibility factor. The EMMA plan and the Deer Island alternative are similar in that they exhibit a magni- tude of disturbance far above those encountered with the initial two alternatives. Both the EMMA and Deer Island alternatives will severely affect transportation flow in the Deer Island area. It is felt that transportation impacts generated by the Harbor plan will not greatly exceed those of the EMMA plan, because the excavated drumlin material is proposed to be barged out, thus eliminating a potential large increase in vehicular traffic. Additionally, the traffic flow capacity differential between the two proposed Deer Island facility alternatives is not expected to greatly affect the size of the generated work force (and associated traffic flows) due to their great size and the economies of scale inherent in projects of that magni- tude. For the EMMA plan, during construction, it is estimated that an average work force of 750 men, with a peak manpower level of 1500 men would exist. The Deer Island plan would call for approximately a 2000 man construction force at peak operations, and an average work force of about 1000 men. Traffic patterns will be significantly affected by both the EMMA plan and Deer Island alternative in the Nut Island/Houghs Neck area; however, the time of disturbance will be less with the Deer Island alternative. The overall magnitude of impact upon the transportation factor is expected to be less for a Deer Island alternative as the impacts associated with the construction of Charles and Neponset STP’s outweigh those associated with construction at Squantuin. In addition, the concentration of facilities at Deer Island may render the delivery of materials, equipment, and/or manpower by barge feasible, thereby greatly mitigating transportation effects. Transportation impacts arising from the channel dredging of Boston Harbor are difficult to assess. However, with the exception of minimal disturbance at Long Island, it is not felt that this action will affect any areas other than those already disturbed by the proposed facility construction. 3—27g ------- TABLE 3.5-12 COMPARISON OF COSTS 1 All Deer Capital Costs Island Plan EMMA Plan Wastewater Treatment 404,290,900 503,400,000 ’ Facilities 2 Secondary Sludge Management 58,784,500 33,892,l00 Interceptor System 3 307,620,000 l32,532,l00 Total Capital Costs 770,695,400 669,824,200 Amortized Capital Costs 6 59,782,800 51,958,300 Operation and Maimtenance Costs 24,765,200 30,447,000 Total Annual Costs 84,548,000 82,405,300 Applicant’s Share of Cap. 77,069,500 66,982,400 Cost (10%) Applicant’s Share of 5,978,300 5,195,800 Amortized Cap. Cost Applicant’s Share of 24,765,200 30,447,000 0 & M Costs Applicant’s Share of Total Annual Cost 30,743,500 35,642,800 (1) Engineering News Record Construction Index = 2654 (2) Includes work at Nut Island and Outfall (3) Includes submerged pipelines, tunnel and related pumping stations. (4) From EMMA Study, adjusted to ENR CI of 2654. (5) Includes satellite treatment plant, and satellite sludge management adusted to account for primary sludge (6) Assume average life of facilities = 30 years; Interest rate = 6-5/8 percent 3—27 9 ------- 3.5.7 Aesthetics Removal of the drumlin from Deer Island would present a permanent significant aesthetic impact on Boston Harbor. The drumlin, which rises 100 feet above the harbor provides a good vantage point for viewing the harbor activities. Presently little use is made of the drumlin area due to a lack of accessibility. Although other views of Boston are available from Point Shirley, they do not afford as pan- oramic a view. From Boston, the drumlin on Deer Island is clearly evident. Under the Deer Island Plan, the treatment plant would take the entire island, therefore necessitating re- moval of the drumlin. No objective value of the site is quantifiable since each individual may place a different value on the drumlin’s scenic qualities. Significant water quality improvements will occur as a result of the Deer Island alternative. Concurrent with an improvement of overall water quality will be an increase in the opportunity for recreational use of the entire Harbor. The Nut Island site, in specific, would accrue large benefits from this plan. A recreation area could be placed at the present Nut Island facility site and other harbor islands could be put to greater recreational use. Therefore, it is felt that drumlin removal is an acceptable negative impact in light of the overall benefit which will result from the Deer Island alternative. 3.5.8 Costs Table 3.5-12 shows the estimated costs for facilities which were considered in this EIS. These include the costs of the interceptor sewer system (including related pumping stations, submarine pipelines, and the deep rock tunnel), wastewater treatment plants, and secondary sludge management facilities. These costs, both capital (construction) and operation and maintenance, are shown in Table 3.5-12 for the EMMA Plan and the All Deer Island Plan )the No Action and Modified No Action alternatives do not include any of these facilities). The capital cost of the EMMA Plan was based on costs developed in the EMMA Study, which were adjusted to May 1978 costs. Estimates of all other costs were developed during the course of this study and are discussed further in Section 4.1.6. As shown in Table 3.5-12, the All Deer Island Plan would cost about $101,000,000 more to build than the EMMA Plan. 2 mortizing the construction costs over the average life of the facilities (estimated to be 30 ye.ars) at an annual interest rate of 6—5/8 percent results in the amortized capital costs of the All Deer Islan d Plan being 3—280 ------- about $7,800,000 per year more than the amortized capital costs of the EMMA Plan. This is considerably offset by the fact that operation and maintenance costs are about $5,700,000 per year less for the All Deer Island Plan than for the EMMA Plan. This is due primarily to the relatively high operation and maintenance costs of the advanced wastewater treatment satellite plants included in the EMMA Plan. The result is that the total annual cost of the All Deer Island Plan is about $2,100,000 more per year than the total annual cost of the EMMA Plan. Since the capital costs would be eligible for 75 percent Federal aid and 15 percent State aid, the Applicant’s share of the capital costs is 10 percent. However, the Applicant’s share of operation and maintenance costs is 100 percent, since these costs are not grant eligible. Taking these factors into account, the All Deer Island Plan would cost the Applicant about $4,900,000 less annually than the EMMA Plan. 3.5.9 Conclusion With respect to water quality considerations, the non- satellite system (the Deer Island Plan) is the only system alternative which will meet water quality standards. This system will not affect water quality in inland streams and will greatly improve the quality of the existing effluent discharges. The EMMA Plan will similarly improve the aual- ity of the harbor discharges and will reduce their volume somewhat. The EMMA Plan, however, will cause degradation of water quality in the Charles and Neponset Rivers. A Neponset River discharge will cause its dissolved oxygen standard to be violated, while the Charles River discharge will significantly increase the magnitude of projected water quality violations. The No Action alternative will result in the continued degradation of harbor waters. Modified No Action will cause an improvement in ambient water quality conditions but degradation in the vicinity of the existing primary discharge will persist. Overall, the Deer Island Plan is the best of the four system alterna- tives with respect to water quality. In terms of water quantity, the Deer Island Plan and both “No Action” alternatives will have a similar effect. That is, they will result in the export of water from the Charles and Neponset watersheds in the form of sewage. For the Charles River watershed, this loss will be approximately offset by additional point source discharges to the river. For the Neponset River, an estimated export of 45.42x10 3 m 3 /d (12 mgd) per day has been projected. The EMMA Plan, since it will result in the discharge of treated effluent to the rivers, will have a lesser impact on low river flows. In fact, the EMMA Plan will result in substantially higher dry weather river flows than have occurred in the past, but at the expense of water quality. 3—281 ------- The effects of the No Action alternative on the area’s biotic communities will represent a continuation of present trends. That is, organisms associated with polluted waters will remain. Increased degradation of water quality as a result of increased pollutant loads will continue to damage the harbor’s flora and fauna as well as the public’s use of them. Modified No Action will improve the situation except in the vicinity of the existing primary outfalls. Both the EMMA Plan and the Deer Island Plan will further improve biotic conditions. The EMMA Plan and the Deer Island Plan will further improve biotic conditions. The EMMA Plan will require the use of two additional sites for facilities construction and specifies the filling of Quincy Bay to expand the Nut Island plant and the filling of Boston Harbor to expand the Deer Island plant. This is considered to be a major impact. The Deer Island Plan avoids filling the harbor but requires the complete use of Deer Island plus a major bay crossing. Also, additional inter— cepter relief is required for the Deer Island Plan. In terms of construction-related impacts, both the Deer Island Plan and the EMMA Plan will cause more disturb- ance than either No Action alternative. While each of these systems will produce its own set of characteristic construction impacts, they cannot be easily separated on this basis in terms of a value judgment. As far as air quality characteristics are concerned, the No Action alternative would result in the least air emissions followed by the Modified No Action alternative. The Modified No Action alternative represents an increase in emissions to the ambient air due to the incineration of the primary sludge, but it would not include the incinera- tion of the secondary sludge. Comparisons of the emissions from primary and secondary sludge incineration at the Deer Island Plan and EMMA Plan sites, indicates the Deer Island Plan would have less air quality impact. This is based upon the lower quantities of emissions and the site loca- tion of the Deer Island Plan. This differential is offset, however, by the need to establish a landfill for disposal of digested sludge under the Deer Island Plan. On the basis of the preceding comparison, the best of the four system alternatives can be selected. The No Action alternative, while it is economical and impacts upon air quality the least, is not considered feasible. Existing primary sludge discharges to the Harbor, poor operation of existing facilities, gross and visible pollution from the Nut Island facility, and persistent bacterial contamination of the Harbor render this alternative untenable. 3—282 ------- The modified No Action alternative will improve water quality conditions and benefit the harbor’s biota in a general sense, but the gross pollution from the existing primary out- falls and by-passes will persist. Pollution from sludge dis- charges will be abated, however. This plan is significantly less expensive than either the Deer Island plan or the EMMA plan and will be more favorable in terms of air quality impacts and primary construction-related impacts. The alternative is rejected, however, on the basis of permitting unacceptable water quality conditions to persist. The EMMA plan and the Deer Island plan both further improve water quality conditions in the Harbor. As described previously, these alternatives vary in terms of their specific impacts, but they can be separated on the basis of several significant parameters. These include: 1. The violation of water quality standards in the Neponset River and a further deterioration of the Charles under the EMMA plan. 2. The need for 42 acres of fill in the Harbor under the EMMA plan. 3. The need for a major harbor crossing, additional interceptor relief and drumlin removal under the Deer Island plan. Beside these factors, the other levels of impact are generally similar with some trade-off s existing between the alternatives. Costs are approximately equal. While Item #3 above represents significant impacts, they can be justi- fied in light of the magnitude of the problem and its solü- tion. Except for drumlin removal, these effects are short term. Items *1 and #2, however, represent long term impacts which are considered unacceptable. The solution to a waste— water management problem should not be resolved by causing other water quality problems. The loss of 40 acres of the Harbor likewise represents an irreversible impact which should not be accepted if there exists any alternative. We therefore, select the Deer Island Plan as the best of the four system alternatives. 3—283 ------- CHAPTER 4 THE RECOMMENDED PLAN 4.1 DESCRIPTION 4.1.1. General Description The wastewaters from the member municipalities of the MDC’s Metropolitan Sewerage District (MSD) would be treated at a wastewater treatment plant located on Deer Island. Provision has been made for the possible addition of the Towns of Dover, Hopkinton, Lincoln, Lynnfield, Sharon, Sherborn, Southborough and Weston* to the 43 municipalities presently making up the MSD. The northern and southern interceptor sewer systems, and related pumping stations, would be expanded and modified as required to handle the peak flows anticipated from an expanded MSD. The wastewater from the southern inter— ceptor sewer system would receive preliminary treatment at a headworks on Nut Island (screening and grit removal) and would then be transported to Deer Island through a conduit which would be constructed across Boston Harbor. At Deer Island this wastewater would be pumped into the treatment plant. Most of the wastewater from the northern interceptor sewer system receives preliminary treatment at three headworks and then enters the Deer Island plant at a main pumping station. The remainder of the northern wastewater enters the plant at a separate headworks (Winthrop Terminal Facility) where it receives pretreatment and is pumped to the effluent conduit from the main pumping station. The main pumping station and the headworks on Deer Island would be upgraded and expanded as required. The treatment i 1ant on Deer Island, which presently provides primary treatment to the wastewater from the northern MSD service area, would be expanded and upgraded to provide secondary treatment to the wastewater from both the northern and southern service areas. The secondary sludge generated at the treatment plant would be aewatered and then disposed of by a combination of incineration followed by ash disposal, composting followed by giving away or marketing the compost product, and landfilling. The ash disposal and composting operations would be accomplished at Squantum Point. The primary sludge generated at the treatment plant was the topic of a separate HIS which recommended it be incinerated at Deer Island. *Durina 1977 the Town of Weston voted against joining the MSD. 4—1 ------- 4.1.2. Flow and Waste Reduction Measures For the purposes of this study, the quantities of wastewater which will require collection and treatment in the year 2000 (design year) are assumed to be those which were estimated in the EMMA Study (prepared for the MDC by Metcalf and Eddy, Inc.). T iese quantities were estimated to be about 2,220,000 m /day (586 mgd) for the average daily flow and 5,235,000 mi/day (1,383 mgd) for the peak flow. Possible methods of reducing the volume of wastewater requiring collection and treatment should be investigated during facilities planning. One method of flow reduction is the elimination or reduction of infiltration and inflow which enters the sewerage system. Infiltration/inf low studies currently underway will, when completed, identify those areas where the cost of eliminating infiltration/ irif low by means of rehabilitating the sewer system is economically justifiable as compared to the cost of trans- porting these flows to, and treating them in, a wastewater treatment plant. From data presented in Technical Data Volume 2 of the EMMA Study, it is estimated that approx- imately 680,000 m 3 /day (180 mgd) of the average daily flow and 1,135,000 m 3 /day (300 mgd) of the peak flow is due to infiltration. The results of the infiltration/inflow studies would be investigated at the time of facilities planning, and if these studies result in the removal of infiltration and inflow into the system, the design flows should be adjusted accordingly. Another method of reducing the quantity of wastewater in the sewerage system is water conservation. The intro- duction of water conserving shower heads, toilets, and kitchen sinks, and more intelligent use of dishwashers and washing machines can significantly reduce water consumption. It Is estimated that, through the use of relatively simple domestic water conservation measures, domestic wastewater production can be reduced gy at least 20 gallons per capita per day. The related cost savings from reduced water supply, wastewater management and heating fuel charges would probably equal the initial cost of installing water conservation devices within the first year of use, after which time the home owner would realize an estimated savings of at least $60.00 per year. An extensive public education program should be implemented to impress upon the general public the need for, and the benefits of, conserving water. Also, a detailed study of the water rate schedules of the MSD member municipalities should be made. A water conservation program will benefit from the adjustment of water rate schedules so that conservation efforts in the home will produce a reduction in water bills. In addition, the possibility of forcing conservation measures 4—2 ------- by legislative means should be investigated. For example, legislation requiring new residences to install low flush toilets would be a large step toward the water conservation goal. The results of these efforts should be examined during facilities planning. If it is found that water conservation efforts have resulted in a reduction of domestic wastewater flows, the design flows should be adjusted accordingly. Even if a significant reduction in the volume of domestic wastewater is not realized at the time of facilities planning, a water conservation program may result in eliminating the need for expanding facilities in the future. In Technical Data Volume 2 of the EMMA Study, the quantities of average and peak residential, commercial and industrial wastewater flows and infiltration are estimated for each of the municipalities included in the expanded MSD. These sources account for an average daily flow of about 2,025,000 m3/day (535 mgd) in the year 2000. The remaining flow of about 195,000 m 3 /day (51 mgd) which is estimated will enter the system on an average day can be accounted for b the fact that, in 1972, an average of about 185,000 mi/day (49 mgd) of seawater entered the northern sewerage system, mainly through inoperative or broken tide gates. The MDC has recently completed a tide gate rehabilitation program. The results of that program should be investigated during facilities planning, and the design flows adjusted accordingly. Using the values estimated in Technical Data Volume 2 of the EMMA Study for peak industrial and infiltration flows and applying a peak factor of 2.0 to the average residential and commercial fl ws results in a peak flow for the MSD of about 4,288,000 m- /day (1133 mgd) in the year 2000. A higher value, 5,235,000 m 3 /day (1383 mgd) was used for design purposes in the EMMA Study. The difference of 947,000 m 3 /day (250 mgd) consists of about 757,000 m 3 /day (200 mgd) from the northern system and about 190,000 m 3 /day (50 mgd) from the southern system. The use of the higher peak flows was based on the assumption that “the full capacity of the incoming sewer system would be utilized in the future during storm runoff periods” (EMMA Study, Technical Data Volume 10, page 3-1) . This seems to be a reasonable assumption. Presently, about 45 percent of the population and 20 percent of the area tributary to the MSD sewerage system are served by combined sewers. Combined sewers, which collect storm- water runoff as well as sanitary wastewater, transport large quantities of stormwater to treatment plants. The combined sewers are located in the northern service area. During rainfalls, the runoff entering the combined sewers would cause the tunnels and sewers entering Deer Island to reach full capacity. The southern system does not contain any combined sewers. However, it is reasonable to assume that, during periods of rainfall, the sewers in the southern 4—3 ------- system will experience significant quantities of stormwater inflow. Using a desing peak flow of 5,235,000 m 3 /day (1,383 mgd) in the design of the wastewater treatment facilities would result in providing secondary treatment for about 947,000 m 3 /day (250 mgd) of storm related flows. The design of certain facilities, such as primary settling tanks and aeration tanks, are based on average daily conditions (flow and biochemical oxygen demand). Other facilities, such as pumping stations, final settling tanks (usually), and chlorine contact tanks, are designed based on peak flow conditions. It would be possible to reduce the peak flow entering the treatment plant by about 15 percent by diverting the excess flow due to storm runoff from the combined sewers to a combined sewer overflow regulation facility. This would result in a reduction of required pumping equipment, final settling tanks and chlorine contact tanks as well as power required for pumping and chlorine required for disinfection. However, pumping and chlorination would be required for the diverted flow at the combined sewer overflow regulation facility. Therefore, anticipated savings would be limited to the reduced number of final settling tanks required. A better optio.i would be to let the stormwater enter the treatment plant and allow the excess flow to by—pass the secondary treatment facilities. It is not known at this time whether the Federal and State regulatory agencies would permit such a plan, and this should be investigated during facilities planning. The excess peak flows due to stormwater inflow into the southern sewerage system should be addressed by the infilt- ration/inflow studies discussed previously. As discussed above, the following four methods are available to significantly reduce the quantity of wastewater requiring treatment: Sewer rehabilitation to reduce the amount of infiltration and inflow entering the sewer system where it is shown to be cost-effective by Infiltration/Inflow studies. Water conservation measures. Tide gate repair program to reduce or eliminate seawater which presently enters the system. Removal of excess flows due to storm runoff in combined sewers, or by-passing this excess flow around the secondary treatment facilities. Each of these flow reduction measures should be given serious consideration during facilities planning. The 4—4 ------- success of any or all of these measures would result in a significant reduction of facilities required for the collection, transportation, pumping, and treatment of was tewater. 4—5 ------- 4.1.3. Interceptor Sewer System The wastewaters from the MSD service area will be collected and transported to a central wastewater treat- ment facility on Deer Island. Due to increasing population, increases in water use and the possible expansion of the service area to include additional communities, increased wastewater flows are to be expected. The criteria used in evaluating the adequacy of the present interceptor sewer system was to test the ability of the system to transport 1970, 1980, 2000, 2020 and 2050 flows. If the 1970 or 1980 flows showed insufficient existing interceptor capacity, relief capacity was determined on the basis of 2020 flows. If the interceptor section was inadequate for the year 2000 flows, relief capacity was determined on the basis of 2050 flows. This was the method of analysis used in the EMMA Study interceptor system analysis. Significant portions of the EMMA Study analysis are directly applicable to the Recommended Plan of this EIS. The analysis and recommend- ations for relief of the northern MSD interceptor system have been incorporated into this Recommended Plan. The analysis and recommendations related to the portions of the southern interceptor system upstream of the EMMS Study satellite plant locations in the Charles and Neponset River Valleys have also been incorporated into this Recommended Plan. A hydraulic analysis of the interceptors downstream of the EMMA Study satellite plant sites was performed to determine the adequacy of these interceptors to transport increased flows to the new headworks on Nut Island. This analysis indicated that the entire Wellesley Extension Sewer, Neponset Valley Sewer, and High Level Sewer down- stream of its junction with the Neponset Valley Sewer required relief. The relief capacity requirements were determined using a 50 year design life criteria. Relief sizes are based on the assumption that the r lief pipes would be installed parallel to existing facilities and at the same slope. In final design more economical or appropriate arrangements may be selected. Special consideration should be given to the route selection and installation of the large diameter relief interceptors that are required in urban areas. In many cases, it may not be possible to construct the relief lines in the same streets as existing sewers due to utility congestion. In those instances, it will be necessary to construct the relief sewers on adjacent streets. The High Level Sewer relief downstream of the Braintree- Weymouth Pumping Station required special consideration due to the space restrictions on Houghs Neck. There did not appear to be any available area to construct the relief interceptor on the peninsula itself and, therefore, the relief conduit was located under Quincy Bay. This install- ation requires an additional pumping station at Nut Island 4—6 ------- PAGE NOT AVAILABLE DIGITALLY ------- to lift the wastewater in the relief conduit to the Nut Island headworks. The relief conduit under Quincy Bay will only be used at times when the wastewater flow rate exceeds the capacity of the High Level Sewer in Houghs Neck. After the wastewater has received preliminary treat- ment at the Nut Island headworks, it will flow to Deer Island by gravity via a submarine pipeline and deep rock tunnel system under Boston Harbor. The pipeline and tunnel will have usfficient capacity to transport flows anticipated in the year 2050. The submarine pipeline portion of the transmission system consists of two-274 centimeter (108 inch) diameter reinforced concrete pipelines buried under the harbor bottom, between Nut Island and the north end of Long Island. Between the north end of Long Island and the southern tip of Deer Island, a deep rock tunnel 380 centimeters (150 inches) in diameter will pass beneath the President Roads Channel. A drop shaft on Long Island and an uptake shaft on Deer Island are required because of the great depth of the tunnel. The influent pumping station for the southern wastewater flow will be located in the uptake shaft at Deer Island. The locations of the interceptor relief work and new wastewater pipeline construction are shown on Figure 4.1—1. The sizes, lengths and costs of each of these facilities are shown on Tables 4.1-1 and 4.1-2 in Section 4.1.6. 4—9 ------- 4.1.4. Wastewater Treatment Plants In the Recommended Plan, the wastewaters from the MSD service area will be treated at a central treatment facility on Deer Island. In order to meet the NPDES permit require- ments for acceptable wastewater discharges, secondary treat- ment is necessary. This level of treatment will provide monthly average concentrations of BOD and suspended solids which are no more than 30 mg/l. For the MSD service area, effluent characteristics of 30 mg/i BOD and suspended solids correspond to treatment efficiencies of approximately 85 percent removals. Secondary treatment includes pre- liminary treatment, primary settling or sedimentation, biological aeration, final settling or sedimentation, and disinfection. For the purpose of this study, it has been assumed that the air activated sludge method of secondary treatment will be utilized. Each of the phases of treat- ment, and its counterpart in the Recommended Plan, will be described below. Due to the different heavy metal character- istics of secondary sludge from the northern and southern service areas and the decision to dispose of these sludges by different methods, it is necessary to keep the secondary sludge from the northern service area separate from the secondary sludge from the southern service area. In order to accomplish this, it is necessary to keep the wastewaters from the northern and southern service areas separate and to process the secondary sludge from the two service areas separately. Detailed design information can be found in the Bases of Design in Appendix 4.1.4. Preliminary treatment consists of screening and grit removal. Screening is accomplished through the use of bar screens or gratings which trap large objects as the waste— water passes through them. These large objects (bottles, sticks, large rags, etc.) could cause severe damage to pumps and other equipment if allowed to flow into the plant. Grit removal is necessary to remove sand and other small, heavy particles from the wastewater. This is usually accomplished in small settling tanks where the flow velocity is reduced just enough to permit the heavy particles to drop out, but keep the remainder of the solids suspended in the wastewater. Removal of grit is necessary to protect mechanical equipment from excessive abrasion and wear, and to prevent grit from accumulating in the piping and the various tanks in the plant. Although pumping is not a treatment process, it is generally included after preliminary treatment in a waste- water treatment plant. The purpose of the pumps is to lift the wastewater from the level of the sewers into the treat- ment plant facilities (i.e. pirmary settling tanks). It is common practice to pump the wastewater at the beginning of the plant and allow it to flow through the different treatment phases in the plant by gravity, if possible. 4-10 ------- In the Recommended Plan, preliminary treatment is provided at separate headworks. There are presently four operating headworks in the MSD service area; Ward Street, Columbus Park, Chelsea Creek, and the Winthrop Terminal Facility on Deer Island. An additional headworks on Nut Island is being proposed in the Recommended Plan. The three major headworks, Ward Street, Columbus Park and Chelsea Creek, are all of modern design and construction and have adequate capacity for the peak dry weather waste- water flows for the year 2050, which is the limit of our planning period. These headworks do not have sufficient capacity for wet—weather peak flows, which they are presently receiving. When their capacity is exceeded, they overflow into surrounding water-courses. This current overflow practice emphasizes the need for combined sewer overflow management, as it will eliminate the overloading of the headworks. No additional work is proposed at these three locations in the Recommended Plane They are expected to continue in their present mode of operation by providing preliminary treatment to wastewaters prior to discharge to the Boston Main Drainage Tunnel and the North Metropolitan Relief Tunnel for transport to Deer Island for treatment. The Winthrop Terminal Facility on Deer Island is currently increasing its pumping capacity of 454,200 m 3 /day (120 mgd) , while ts capacity for screening and grit removal is only 227,100 m /day (60 mgd). Wastewater in excess of the screening and grit removal capacity discharges to a plant bypass conduit which discharges directly to the Harbor. This presently occurs during periods of peak wet weather flow In the Recommended Plan, this practice of discharging untreated wastewaters to the Harbor will be discontinued, and sufficient pumping, screening and grit removal capability will be provided for 511,000 m 3 /day (135 mgd), which is the estimated flow that will reach this headworks in the year 2000. The previously described facilities are all for the northern service area wastewater flow. The southern service area wastewater flow will receive preliminary treatment at a new headworks to be located on Nut Island. This new headworks will consist of the renovated and modernized screening and grit removal system of the present Nut Island plant (as proposed by the EMMA Study) and additional screening and grit removal capability required to adequately handle the design flows. After receiving preliminary treatment at Nut Island, the wastewaters from the southern service area will flow by gravity to the Deer Is land Treat- ment plant via a submarine pipeline — deep rock tunnel system. Screenings, skimmings, and grit collected at the various headworks will be trucked to Deer Island and incinerated in the sludge incinerator. When the southern service area wastewaters reach Deer Island they will be lifted into the treatment plant through 4—11 ------- a new influent pumping station. This pumping station will be located over the uptake shaft of the deep rock tunnel which passes under the President Roads Channel to Deer Island. The pumping station will have eight raw sewage pumps powered by electric motors, with sufficient capacity to pump peak flows utilizing only seven of the pumps. The eighth is provided as a spare. Space will be provided for one additional pump which will be needed for the year 2050 flows. The wastewaters which enter the Deer Island plant via the two existing rock tunnels will be pumped at the present Deer Island Main Pump Station. Following the recommendations of the EMMA Study, the nine existing pumps will be switched from dual-fuel engine drive to electric motor drive. One additional pump will be provided at this station to provide standby capacity. Since the capacity of this pumping station is fixed by the capacity of the deep rock tunnels under the Harbor, no future additions are envisioned. Primary settling (or sedimentation) is used to permit small suspended particles to settle out of the wastewater. This is accomplished by providing quiescent conditions in large settling tanks. In this portion of the treatment process, approximately 20 percent of the biological pollutants and 40 percent of the suspended solids in the wastewater will be removed. The sludge (settled solids) which collects on the bottom of the tank is collected and pumped to the sludge management facility for further treatment and ultimate disposal. The existing primary treatment facilities on Deer Island are being maintained in the Recommended Plan wastewater treatment facility. The existing eight primary settling tanks are being supplemented with eight additional settling tanks for the northern service area wastewater flow, with provision for one settling tank to be added for the year 2050 flows. The wastewater from the southern service area will enter separate primary settling tanks. Eight tanks are required and provision is made for the addition of two settling tanks for the projected increases in flow for the year 2050. The sludge that is produced in the primary treatment phase is not utilized in the composting operation. The two waste sludge streams (one from the northern flow primary settling tanks and one from the southern flow primary settling tanks) are combined at the sludge management facility for processing and disposal as recommended in a separate Environmental Impact Statement that addresses primary sludge management. Biological aeration is the process in which wastewater becomes the food for a community of bacteria and other 4—12 ------- single-celled organisms (biomass) . During this phase of treatment, the biomass consumes the biological waste materials as food for cell growth and reproduction. This process takes place in the aeration tanks. In order to keep this natural system operating, it is necessary to add oxygen. The oxygen is added by bubbling air into the bottom of the aeration tank. In order to ensure complete uitilization of all incoming food sources (biological waste materials) by the biomass, surplus biornass is added to the aeration tank. This surplus biomass is supplied by returning some of the sludge that is withdrawn from the final settling tanks to the aeration tanks. If there are adequate bacteria to consume all the available food sources, then all of the biological waste materials will be consumed by the biomass, which is the object of this phase of secondary treatment. Biological aeration is accomplished in the wastewater treat3nent facility of the Recommended Plan using the air activated sludge process. There are twenty aeration tanks provided to treat the wastewaters from the northern MSD service area. These aeration tanks also provide adequate capacity for the year 2050 projected loading from the northern service area. The southern MSD wastewaters are treated in eleven aeration tanks. Provision is made for two additional tanks which will be required to handle the projected increase in pollutant loading from the southern service area in the year 2050. These facilities are designed to accommodate both the influent wastewater BOD and the recycled biomass. Each aeration tank will have air distribution piping and diffusers on the tank bottom to bubble air into the waste- water. In addition to providing oxygen to support biological activity in the aeration tank, the air bubbles also agitate the wastewater, mxiing the recucled biomass with the waste— water and preventing solids from settling out in the aeration tanks. The air is provided by low pressure blowers located in a central blower building which supplies all process air to both the northern and southern portions of the plant. Final settling (or sedimentation) is used to remove the biomass from the wastewater. In this phase of treatment, the remaining settleable solids are removed in large quiescent settling basins. The effluent that flows from these tanks generally contains less than 15 percent of the pollutant load of wastewaters entering the plant. sludge collected in this phase of treatment is recycled to the aeration tanks to provide the excess biomass and is also wasted to the sludge management facility for further treatment and ultimate disposal. The northern MSD wastewaters, after passing through the 4—13 ------- aeration tanks, will flow to the final settling tanks. Thirty final settling tanks are provided to provide the necessary quiescent conditions. There is no need for additional final settling tanks to be added in the future for the northern service area flow, since the present and future peak flows are the same. The southern service area wastewaters will pass through fifteen final settling tanks, with provision for adding a sixteenth tank in the future. The sludge that is collected from the northern flow final settling tanks is recycled to the northern flow aeration tanks for process control or wasted to the sludge management facility where it will be dewatered and incin- erated. The sludge collected from the southern flow final settling tanks is recycled to the southern flow aeration tanks or wasted to the sludge management facility for conditioning and dewatering prior to composting and land— filling operations. Disinfection of treated wastewaters is practiced to kill nay harmful organisms in the wastewater (virus, bacteria) which can spread water—borne diseases. This is commonly achieved through the addition of chlorine, in the form of sodium hypochiorite, to the wastewater. The amount of chlorine added is carefully monitored and controlled to provide the desired disinfection without wasting chlorine. The chlorinated wastewater is held in a detention tank for a minimum of 15 minutes before it is discharged to the plant outfall. This contact time is sufficient to achieve the disinfection desired. In the Recommended Plan wastewater treatment facility disinfection is provided in a common chlorine contact chamber. This is the first time that the wastewaters from the northern and southern service areas are combined in the plant. The chlorine contact tank is designed to provide 15 minutes detention time at periods of peak flow. No future expansion is contemplated because the increase in peak flow is such that there is only a 2 percent decrease in detention time. The size of this facility reflects a conservative design approach, since no allowance for detention in the plant outfall system, either in the land portion on Deer Island or the marine portin, was made. At the time of facilities planning, reductions in the size of the chlorine contact tank should be considered, using outfall detention time in conjunction with chlorine contact tank detention time. An effluent pumping station will follow the chlorine contact tanks. This pumping station will have 16 pumps with space provided for an additional pump to be added when the wastewater flow increases in the future. The pumping station is designed so that there is always one space pump available in the event of a mechanical failure. The number of pumps that are in operation at any one time will be 4—14 ------- LEGEND EXISTING FACILITIES To BE DEMOLISHED D EXISTING FACILITIES TO BE MODIFIED NEW FACILITIES - J A ISO - SCALE * FUT * 25 0 2 5 I-I J-LI- 1 —I EXISTING FACILITIES TO BE DEMOLISHED NEW SCREEN AND GRIT CHAMBER EXISTING SCREEN AND GRIT CHAMBER BUILDING TO BE MODIFIED SCALE IN METERS LIFT STATION D 00 FIG. 4.1-2 NUT ISLAND FACILITIES REQUIRED FOR RECOMMENDED PLAN ------- governed by the wastewater flow through the plant and the water elevation in the Harbor. At times of peak flow and high tides, all pumps except the spare, will be required to be in operation. At times of lower tides and lower flows, as few as four pumps will be required. The existing Deer Island outfall system is not adequate for the increased flows. An additional 3.05 meter (10 foot) diameter outfall with diffusers is required to meet the increased hydraulic loading. The EMMA Study contained recommendations for outfall renovation and modification which have been incorporated into the Recommended Plan. If the outfall system is modified as recommended in the EMMA Study and the additional outfall is added, there will be sufficient capacity to meet the peak flow demands effectively. The existing and additional outfalls should be investigated during facilities planning to ensure that the outfalls discharge to deep enough water and the diffuser system is adequate to provide the necessary dilution of effluent. The two sites undergoing substantial changes in the Recommended Plan are Nut Island and Deer Island. The changes at Nut Island include the construction of a waste- water pumping station and additional grit chambers, while most of the existing treatment plant facilities are to be demolished. Examination of the proposed Nut Island Head- works facilities on Figure 4.1-2 indicates that most of Nut Island will be available for recreational development once the existing primary facilities are phased out of operation and demolished. The modifications at Deer Island constitute the Recommended Plan’s most significant changes to the Boston Harbor area. Due to the size of the wastewater treatment facility, the entire island will be required for plant construction. The proposed layout of the Deer Island plant is shown on Figure 4.1-3. This will require the relocation of the existing prison facilities and the demolition of all prison structures, the removal of the Deer Island drumlin, and the removal of all buildings and topographic features ‘south of the drumlin. 4—16 ------- 300 0 300 600 TANKS ADMINISTRATION BUILDING CHLORINE STATION FINAL SETTLING LEGEND EXISTING WASTEWATER TREATMENT FACILITIES OTHER EXISTING STRUCTURES NEW WASTEWATER TREATMENT FACILITIES REQUIRED - YEAR 2000 FUTURE EXPANSION - YEAR 2050 STATION 100 0 SCALE IN FEET 100 200 SCALE IN METERS AERATION TANKS BLOWER BUILDING FINAL SETTLING TANKS DRUMLIN OUTLINE AERATION TANKS AREA FOR PRIMARY SLUDGE ASH DISPOSAL 0 ‘U, Lu FIGURE 4.1-3 RECOMMENDED PLAN DEER ISLAND FACILITIES ------- 4.1.5 Secondary Sludge Disposal The Recommended Plan will utilize three means of sludge disposal; incineration, composting to a marketable product, and direct landfill of dewatered and digested sludge. Figure 4.1-4 presents a solids bal- ance and flow diagram for the sludge management phase of the Recommended Plan. The selection of these methods of disposal was based on the characteristics of the sludges produced and on a desire to provide an acceptable alternative to incineration of all sludge produced. The characteristic of the sludge which most affects which disposal means are feasible is its chemical composition. It is estimated that the secondary sludge generated in the treat- ment of wastewaters from the northern MSD service area would contain higher heavy metals concentrations than the secondary sludge generated in the treatment of the southern service area wastewaters. Since the primary restriction related to sludge disposal systems such as compost- ing is related to heavy metals concentration, it was decided to use the southern secondary sludge for composting. The volume of southern secondary sludge produced would more than adequately supply the antici- pated market for compost in the MDC area. The remaining portion of the southern secondary sludge will be landfilled. The secondary sludge from the northern service area will be incinerated and the ash will be land— filled. In order to take advantage of these factors in formulating the plan for sludge disposal, it was decided to separate the portions of the treatment plant so that the northern sludge would not be mixed with the southern sludge. It should be noted that although these recommendations are only related to the disposal of secondary sludge, the primary treatment facilities must also be separated to prevent the wastewaters from mixing. The method of ultimate disposal of the primary sludge is the subject of a separate Environmental Impact State- ment and therefore is not included in this report. The sludge that is removed from the final settling tanks is secondary sludge. Some of this material is returned to the aeration tanks for process control. The sludge that is to be wasted is pumped from the final settling tanks to the sludge management facility. At this stage in sludge processing, air flotation thickening is used to increase the solids content of the sludge. Separate thickeners are required for the northern and southern sludge processing. Following the thickening process, lime and ferric chloride are added to the southern wastewater sludge that is to be composted at Squantum Point. Following the chemical addition and conditioning this sludge is passed through pressure filters which will remove additional water. The sludge cake that remains will be loaded into containers for barge shipment to the composting site at Squantum Point. The sludge to be composted is approximately 23 percent of the total secondary sludge produced or approximateiy 50 percent of the secondary sludge produced in treating the southern service area wastewaters. 4—18 ------- ‘(.‘(A “ () () FROM NORTHERN SERVICE AREA SECONDARY SLUDGE FROM SOUTHERN SERVICE AREA I- z 0 a- 2 4 C i) 0 I— LU a: 4 0 LU N.J a: LU 2 4 I— 2 0 0 (BuLKING AGENT MAKEUP) TRUCK TO MDC LANDFILL LANDFILL - HS2 UANTUM LEGEND 00 DRY SOLIDS - METRIC TONS/DAY DRY SOLIDS — SHORT TONS/DAY 0% PERCENT SOLIDS CONCENTRATION 28.8 I(3 1.8) 75% 40.9 (45.1 ) 75°Jo RECYCLED COMPOST (BULKING AGENT) r 17.6 VOL. SQL i (I9,4)DESTROYED 46.4 I r ———‘ (51.2) I I I COMPOST I- z a 1 Li I— _____________ - u 46 . 4 ‘(5I.2) I I COMPOST 3O%¶ ____________ 6.7 I (7. 75% (BULKING AGENT) RECYCLED WOOD CHIPS z 0 I- J a: I- (1) 0 I- LU x a: 4 34.7 (38.3) 3O% L J 12.2 VOL. SOL. (13.5) DESTROYED RECYCLED SUPERNATANT SOLIDS SECONDARY SLUDGE -.9’ (7] r DESTROYED RECYCLED SUPERNATANT SOLIDS WOOD CHIPS OR TREE TRIMMINGS FIGURE 4.1-4 SLUDGE MANAGEMENT FLOW DIAGRAM AND SOLIDS BALANCE ------- After thickening, the remaining 50 percent of the southern second— ary sludge is taken directly to anaerobic digestors where, in the ab- sence of oxygen, microbial activity produces a stable end product by utilizing the sludge as a source of food. It has been assumed that the fuel value of the gas produced during the digestion process would balance the fuel requirements for maintaining the digesters at 35° C (95° F) . Following digestion, the residue is chemically conditioned with ferric chloride and lime to aid in dewatering. After chemical addition, the digested sludge is passed through pressure filters for additional dewatering. After dewatering, the digested sludge will be loaded into containers, barged to Squantum Point, and then trucked to an MDC operated sludge landfill. Approximately 34 metric tons (38 short tons) on a dry weight basis, or 170 m 3 (227 cubic yards) of digested sludge will be landfilled each day. The secondary sludge that is produced in the treatment of the northern service area wastewaters is conditioned chemically with lime and ferric chloride after it passes through the flotation thickeners. The sludge is then passed through pressure filters where it is dewatered into a “cake”. This “cake” is then broken up and fed into multiple hearth sludge incinerators where it is burned. The incinerators in- clude afterburners and wet scrubbing exhaust gas cleaning systems. Under normal operating conditions it should not be necessary to use the afterburners. The ash that remains and the particulate matter that is collected in the air pollution control equipment is pumped in slurry form into a temporary holding tank. The ash is permitted to drain and is then loaded into containers for barge shipment to Squanturn Point where it will be used as a landfill material. Storage space at Deer Island for both sludge ash and sludge for composting and direct landfill is provided for inclement weather periods when daily barge shipments are not possible. The composting and ash landfilling operations at Squantum Point will occur within the confines of an earth embankment enclosed area. This enclosed area will be lined with a layer of clay or other imper- vious material which will prevent any leachate from the ash landfill or composting operation from mixing with the local groundwater. A leachate collection system will be constructed to collect all rainfall that falls on the site and discharge it to the MDC Squantum interceptor which will return it to the treatment plant. There is sufficient area available at Squantum Point for twenty years of northern secondary sludge ash storage and a composting operation. After several years of opera- tion of the landfill, it may become necessary to compost sludge on top of the completed portions of the landfill. When the landfill reaches its design height of 5 meters (15 feet) it will be covered with topsoil and converted to a recreational area. During the operation of the land- fill and composting area, the embankment surrounding the area will con- ceal the operation from surrounding areas. Landscaping of the exterior slopes and top of this embankment will also screen the filling and com- posting operations. Approximately 58 metric tons (63 short tons) of dry sludge solids or 91 m 3 (125 cu. yards) of ash material will be 4—20 ------- 300 0 300 600 0 SCALE IN FEET SCALE IN METERS ASH DISPOSAL AREA ADMINISTRATION AND MAINTENANCE BUILDING MARINA FIGURE 4.1-5 SQUANTUM POINT ASH LANDFILL AND SLUDGE COMPOSTING AREA zoo 200 400 JORDAN MARSH WAREHOUSE / ------- landfilled at Squantum Point each day. The compost production rate will range from about 29 to 41 metric tons (32 to 45 short tons) of dry sludge solids, or 52 to 74 m 3 (70 to 98 cu. yards) per day depending on the type of bulking agent used. This composted material is expected to be absorbed by a market which will be developed among the MDC, land- scapers and private citizens who can use the composted sludge as a soil conditioner.. Figure 4.1—5 shows the required facilities for the sludge Qomposting and ash landfill operation at Squantum Point. 4—22 ------- 4.1.6. Costs of Recommended Facilities The cost of a wastewater management system includes both capital (construction) costs and operation and maintenance costs. In order to effectively evaluate the true costs of a wastewater management alterna- tive, it is necessary to determine both the annual operation and main- tenance costs and the construction costs amortized over the life of the facilities. Annual operation and maintenance costs were determined from esti— mated manpower requirements to staff the facilities, plant maintenance costs for both structures and equipment, electric power consumption, fuel oil and chemical requirements. Manpower requirements were esti- mated for effective operation and maintenance of the facilities, using the manpower requirements of the EMMA Study as a basis. Electric power consumption was estimated for the various pumping systems in the plant, process air blowers, small motors, lighting and ventilation require- ments. Fuel oil quantities were based on estimates of fuel oil needed to heat the plant facility and for sludge incineration start-up. Chemical quantities were determined using estimates of chlorine for disinfection and ferric chloride and lime for sludqe conditioning and processing. Using the estimated quantities and the following unit costs, based on May 1978 prices, operation and maintenance costs were determined: Manpower $14,500/man year Electric Power $0.0475/kwhr Fuel Oil $0.40/gallon Chlorine $157/ton Ferric Chloride $220/ton Lime $62/ton Plant maintenance costs were based on a percentage of the construc- tion cost of a structure or the purchase price of mechanical equipment. Capital or construction costs were based on the design of the var- ious facilities of the wastewater management system using current con- struction costs and equipment prices. An additional allowance is made for unforseen contingencies and engineering costs. There were no allowances for land acquisition or administrative costs in any of these estimates. The cost of interceptor sewer work was based on the estimates of sewer construction costs found in the EMMA Study. Using EMMA Study costs per unit of length for a given pipe diameter and depth, it was possible to estimate sewer construction costs. These costs were in- creased by 25 percent to include an allowance for contingencies which are encountered in underground work and for engineering costs. These costs were then updated from their January 1975 base to the May 1978 cost base of this EIS. Costs of treatment plant related pumping stations were estimated from conceptual estimates of different capacity pumping stations and actual construction cost data. It was assumed that the pumping station 4—23 ------- would provide a 10 meter (30 foot) lift and would have adequate standby pumping capability. An allowance of 50 percent for contingencies and engineering costs was also included. These costs also reflect May 1978 construction costs. Outfall and submarine pipeline costs were based in part on the EMNA Study cost estimates, conceptual cost estimates and construction cost data. It was assumed that no rock would be encountered that would require blasting, and that there would be no severe weather restrictions related to the marine work. A 25 percent contingency and engineering cost allowance was also included. Since the wastewater treatment plant is the single most expensive item in a wastewater management system, the estimate of its cost re- quires the most attention. Estimates of structural and mechanical costs were made from preliminary designs for each of the major treatment plant facilities. Estimated quantities of earthwork, concrete, piping, architectural costs and prices for major items of equipment such as pumps, blowers, sludge collection systems, air diffusers and inciner- ators were also obtained. Economies of scale in concrete work due to the large volume of repetitive work, and in equipment sizing due to the large capacities involved were also considered. Plumbing, heating, ventilating and air conditioning and electrical installations were also included. Due to the overall complexity of a wastewater treat- ment plant, an allowance of 35 percent was included for contingencies and engineering costs. Cost estimates for the various phases of the Recommended Plan are shown on Tables 4.1-1 through 4.1-5. A summary of costs for the Recommended Plan is shown in Table 4.1-6. 4—24 ------- TABLE 4.1-1 INTERCEPTOR SEWER MODIFICATIONS FOR NORTHERN MSD SERVICE AREA Estimated Cost Ref Interceptor Diameter Length (Millions No. Sewer cm. (in) m. (ft) f $ (2) 1 Milibrook Valley Sewer 91 (36) 3883 (12,740) 4.5 2 Wilmington Extension Sewer 76 (30) 2905 (9,530) 3.8 3 Reading Extension 61 (24) 411 (1, 350) On— Sewer 76 (30) 1664 (5,460) Going 107 (42) 414 (1,360) 4 Lynnfield Extension Sewer 30—53 (12—21) 1829 (6,000) 0.4 5 Stoneham Extension Sewer 30 (12) 1259 (4,130) 0.4 6 Wakefield Branch 38 (15) 942 (3,090) Sewer 107 (42) 1664 (5,460) 1.2 7 Stoneham Trunk Sewer 46 (18) 930 (3,050) 0.2 8 Wakefield Trunk Sewer 107 (42) 2723 (8,935) 122 (48) 927 (3,040) 5.8 9 North Metropolitan Sewer 137 (54) 610 (2,000) 0.8 10 North Metropolitan Sewer 152 (60) 792 (2,600) 1.2 11 Cuuimingsville Branch Sewer 91 (36) 1515 (4,970) 1.2 12 Chelsea Branch Sewer 53 (21) 347 (1,140) 0.1 13 Revere Extension 30 (12) 314 (1,030) Sewer 76 (30) 969 (3,180) 4.1 14 Soxnmerville—Medford 61 (24) 2277 (7,470) Branch Sewer 107 (42) 280 (920) 5 .4 4—25 ------- TABLE 4.1-1 (Continued) Estimated Cost Ref., Interceptor Diameter Length (Mi11iq No. Sewer cm. (in) rn (ft) of $) 15 Weston—Lincoln Extension Sewer 76—107 (30—42) 10180 (33,400) 4.5 16 South Charles 91 (36) 2487 (8,160) Relief Sewer 107 (42) 6062 (19,890) 122 (48) 1609 (5,280) 6.8 17 North Charles 61 (24) 826 (2,710) Metropolitan Sewer 91 (36) 945 (3,100) 1.5 18 South Charles River 91 (36) 213 (700) Sewer, Charles River 137 (54) 884 (2,900) Crossing & Cross 168 (66) 1679 (5,510) 15.3 Connection Total for Northern System 57.2 (1) Reference Number — See Figure 4.1—1 (2) Cost Index - ENR 2654 (May, 1978). Source: Metcalf & Eddy, Inc. , 1975 i 4—26 ------- Re f. No. (1) TABLE 4.1 —2 INTERCEPTOR SEWER MODIFICATIONS FOR SOUTHERN MSD SERVICE AREA Interceptor Sewer Estimated 19 20 Southborough Extension Sewer Ashland-Hopkinton Extension Sewer 61—91 (24—36) 8169 (26,800) 53—122 (21—48) 11186 (36,700) 2.9 5.3 21 Framingham Extension Sewer 152 (60) 168 (66) 3101 (10,175) 6581 (21,590) 27 . 2 22 Upper Neponset Valley Sewer 61 (24) 91 (36) 3344 (10,970) 3152 (10,340) On- Going 23 Westwood Extension Sewer 76 (30) 3752 (12,310) 2.9 24 Walpole Extension Sewer 122 (48) 152 (60) 1503 (4,930) 3335 (10,940) 14 . 4 25 Sharon Extension Sewer 91 (36) 2256 (7,400) 1.5 27 Lower Braintree Connecting Sewer 61 (24) 152 (60) 227 (744) 877 (2,878) 0.5 28 Hingham Force Mai 61 (24) 2316 (7,600) 0.6 29 Braintree-Weymoutri Extension Sewer 152 (60) 3121 (10,238) On- Going 30 Wellesley Extension Sewer 183 (72) 198 (78) 6736 (22,100) 5212 (17,100) 23 . 2 Cost Diameter cm. (in) Length m. (ft) (Millions of $) (2) 26 New Neponset Valley 61 (24) 472 (1,550) Sewer and 76 (30) 692 (2,270) Stoughton Extension 91 (36) 1524 (5,000) Sewer 137 198 (54) (78) 1501 152 (4,925) (500) 2.3 31 New Neponset Valley 183 Sewer 198 213 (72) (78) (84) 4602 2926 5029 (15,100) (9,600) (16,500) 29.0 4—27 ------- TABLE 4. 1-2(Contjnued) Estimated Interceptor Sewer Length m. (ft) 33 Submarine Pipeline & Tunnel System 2@274 (2@108) 381 (150) 6863 (22,500) 1678 (5,500) 57 . 2 20.0 Total for Southern System (1) Reference Number — See Figure 4.1—i (2) Cost Index — ENR 2654 (May 1978) Source: Items 19 through 29: Metcalf & Eddy Inc., 1975 i 232.6 Ref No. 32 High Level Sewer Diameter cm. (in) Cost (Milli of $) 244 (96) 1189 (3,900) 259 (102) 6005 (19 700) 274 (108) 2591 (8,500) 289 (114) 2593 (8,500) 45.6 4—28 ------- TABLE 4.1—3 MDC PUMPING STATION CONSTRUCTION COSTS Item(l) a b C a e f g h 1 j Pump Station Reading Alewife Brook Charlestown East Boston Electric East Boston Steam Squantum Quincy Braintree-Weymouth Rough’s Neck Hingham EMMA Study Recommendation Replace Rehabilitate Replace Rehabilitate Replace Replace Replace Replace Replace Rehabi. litate Cost ( Miilons/$ ) (2) On-Going .85 7 .24 .44 1.77 On-Going 2 . 68 3 . 52 .25 1 . 07 17.82 (1) See Figure 4.1-1 (2) ENR Cost Index = 2E54 (May 1978) Source: Metcalf & Eddy, Inc. , 1976 4—29 ------- TABLE 4.1-4 TABULATION OF COSTS FOR THE RECOMMENDED PLAN WASTEWATER TREATMENT FACILITY Item ________ Nut Island Headworks & Primary Plant Demolition Winthrop Terminal Facility Raw Sewage Pumping Stations Primary Settling Tanks Aeration Tanks Final Settling Tanks Sludge Pumping Facilities Blower Building Operations/Administration Building Chlorine Contact Tank/Chlorination Equipment Outside Piping/Site Development Channels, Conduits and Galleries Effluent Pumping Station Outfall Landscaping/Roads Electrical and Instrumentation Sludge Management Facilities Drumlin Removal/Extraordinary Site Development _____ All prices reflect construction costs of May 1978 (ENR Index = 2654) Cost (Millions of $) 16.43 .73 13.37 27. 07 82.03 73 . 54 1; .47 40.49 7.63 7.16 22.42 15.50 22.36 7 .61 2.59 31.47 58.79 16.42 463. 08 4—30 ------- TABLE 4.1-5 RESOURCE REQUIREMENTS AND OPERATION AND MAINTENANCE COSTS OF THE RECOMMENDED PLAN Resource Wastewater Treatment Sludge Manage- Requirements Plant ment Facility Manpower 298 86 Chlorine -Tons/Year 7 .135 Fuel Oil-Gallons/Year 706,000 224,214 Electric Power-Kwhr/Year 196,571,000 27,482,675 Lime -Tons/Year 14,600 Ferric Chloride-Tons/Year 3,504 Polymer-Tons/Year 113 Annual Operation & Maintenance Costs ($ Million) $17.14 $6.31 Interceptor System & Related Pumping Stations Annual Operation & Maintenance Costs ($ Million) $1.31 Total Annual Operation & Maintenance Costs ($ Million) $24.76 Note: If it is necessary to purchase wood chips to serve as a bulking agent for the composting operation, approximately 9,000 cubic meters (12,000 cubic yards) of wood chips would be required per year. At a cost of $6.00 per cubic yard for wood chips, the resulting in- crease in the annual operation and maintenance costs for the sludge management facility would be about $72,000 per year. 4—31 ------- TABLE 4.1-6 COST OF RECOMMENDED PLAN 1 Wastewater Treatment Facilities 2 Secondary Sludge Management Interceptor System 3 Total Capital Costs Amortized Capital Costs 4 Operation and Maintenance Costs Total Annual Costs Applicant’s share of Cap. Cost (10%) Applicant’s Share of Amortized Cap. Cost Applicant’s Share of 0 & M Costs Applicant’s Share of Total Annual Cost 404,290,900 58,784,500 307,620,000 770,695,400 59,782,800 24,765,200 84,548, 000 77,062,500 5,978,300 24,765,200 30,743,500 Engineering News Record Construction Index = 2654 May 1978) Includes work at Nut Island and Outfall Includes submerged pipelines, tunnel and related pumping stations Assume average life of facilities = 30 years; Interest rate = 6-5/8 percent (1) (2) (3) (4) 4—32 ------- CHAPTER 5 ENVIRONMENTAL IMPACTS OF THE RECOMMENDED PLAN 5.1 INTRODUCTION This section of the report will describe the specific environmental impacts associated with the proposed plan. While this plan has been described in detail in Chapter 4, it is helpful to outline those components of the project in terms of the impacts they are expected to cause. First, being a wastewater management project, water quality will be significantly affected. The project will do this by replacing two existing discharges of primary effluent in Boston Harbor by one larger, secondary effluent discharge. Therefore, the amount of pollutants being dis- charged will be reduced and the present site of one primary discharge will be eliminated. Other components of the over- all project will eliminate the present practice of discharging primary sludge into the harbor and will help eliminate com- bined storm sewer overflows into the Harbor. Also, the present practice of by-passing raw sewage from the treatment plants during periods of peak flow will be eliminated by expanding the hydraulic capacity of the treatment facilities. The net effect of these actions will be the improvement of water quality in Boston Harbor. However, some short term adverse effects will occur during construction of the facilities (i.e. siltation from dredging activities). As a consequence of employing secondary treatment (which will benefit water quality) a new problem will be created. That is, a “secondary” sludge will be generated in large volume which will require disposal. The proposed plan recommends disposal of this sludge in three ways. The second- ary sludge resulting from treatment of wastewater originating in the northern service area will be incinerated at Deer Island. This will result in air quality impacts. Inciner- ator ash will be transported to Squantum for landfilling. One half of the secondary sludge from the southern service area will be digested at Deer Island, then transported to Squantuin where it will be loaded on trucks and transported to a sani- tary landfill for final disposal. This landfill will have to be specially designed in order to provide for the containment and collection of leachate. Furthermore, it will require a special permit from the Commonwealth of Massachusetts to operate as a “sludge—only” landfill. Since no landfills suitable for this purpose presently exist in eastern Massachusetts, it is expected that the MDC must locate and establish a suitable facility. Other than specifying the approximate acreage of this landfill (which will indicate the magnitude of the land require- ment) and discussing general localized water quality effects, no further specific environmental impacts can be projected at this time. 5—1 ------- The other half of the secondary sludge which will be generated from the southern service area’s wastewater will be transported to Squantum, composted, and made available to the general public for their use. Composting is intended to represent both an environmentally acceptable method of sludge disposal and a means by which resources (nutrients, organic matter) can be “recycled.” Provided that all the generated compost is properly utilized, this should indeed be the case. However, beyond the discussion of compost disposal given in Section 3.3.6, no further details can be given due to the dispersed nature of compost disposal. However, should com- post be stockpiled or stored improperly, leachates rich in nutrients and metals may form and could cause environmental damage. Another component of the project which will cause en- vironmental impact is the permanent consumption of land by the proposed facilities. This will result in the loss of land for other uses and the temporary displacement of pres- ent biotic communities. Essentially all of Deer Island and 28.33 ha (70 acres) at Squantum Point will be committed for permanent use. It should be noted, however, that when land- fill operations at Squantum (for ash disposal) result in a 4.57 m (15 foot) thickness of ash throughout the site, the area will be covered with topsoil and will revert to other uses, perhaps recreational. Deer Island, however, will be permanently committed. The proposed plan will also require the removal of the drumlins on the Island for the develop- ment of treatment facilities. Loss of the drumlins is ex- pected to cause negative aesthetic impacts. The project will also cause socio—economic impacts as a result of the use of Squantum Point. This will be a re- suit of the removal of this tract from the pool of taxable land since the MDC-owned operation would not be taxable. Further, the facility may affect the value of adjacent par- cels which are zoned for PUD use. During the construction of relief sewers, road closings may temporarily affect local businesses along the construction routes. Positive impacts will result from improved water quality, especially near Quincy Bay, which enhance the recreational use of the Harbor. Another component of the project which will result in environmental impacts is the need for interceptor relief. The need for new sewers to relieve existing overloaded sewers is an inevitable requirement with old facilities. Thus, interceptor relief can be considered to be a part of the normal maintenance associated with an existing system. 5—2 ------- As such, relief work is required in any circumstance. There- fore, this study does not deal with the specifics of inter- ceptor relief alignments. Specific alignment corridors, detailed costs, and environmental impacts should be evaluated during the facility planning process. Even though relief is required for any configuration of facilities, without satellite plants, the need for relief is somewhat greater. Approximately 36.8 km(23 ml) of additional sewer (Wellesley Extension Sewer and New Neponset Valley Sewer) will require relief. While this is now known in concept, the specific detailed alignments for this sewer have yet to be studies and selected. Section 3.5.3 presents a first cut analysis of the impacts of the relief sewer on various land use categories. This Construction will cause significant, localized short term effects. Finally, the construction and operation of the facili— ties will cause environmental effects due to the movement of materials, machinery, personnel, etc. It will be helpful to describe the details of these activities for the value of the information as well as for reference in the subsequent evaluations. For the purposes of discussion in this chapter, the “project” is considered to include the treatment facilities, outfalls and specific interceptor modifications resulting from the recommended configuration. For the construction phase, the following activities will be undertaken: Excavation for Bay Crossings-In order to install a submarine pipeline from Nut Isiand to Deer Island, a relief sewer across Quincy Bay, and a new outfall line into Presi- dent Roads, substantial excavation in Boston Harbor will required. It is estimated that a total of 1.68 million m (2.2 million yd 3 ) of excavated material will be generated. If some of this material is suitable for use as backfill, it may be stored either on Squantum or at another land based storage site. If this material is not suitable for backfill, it should be disposed of at an offshore site known as the “foul area”. This is an area where the dumping of wastes has been practiced for years. Disposal of dredge spoils here should, therefore, result in minimal impacts on the marine environ- ment. As 3 suming an average barge capacity of 1146.9 rn 3 (1500 yd ), approximately 1410 barge trips will be needed to transport these spoils to the disposal site. Assuming a maximum of 48.27 km (30 miles) per round trip over a total duration of two years, an average of 2.7 barge trips will be needed per working day. A total of 68,061 barge kilometers (42,300 barge miles) will be involved., 5—3 ------- Drumlin Removal—In order to construct treatment facil- ities at Deer Island, removal of drumlin material from the site is required. Some of this material will be used at Squantum for the construction of berms. If suitable for trench backfill, additional fill may be stored at Squantum or in the harbor until needed for backfill purposes. Remain— ing drumlin material can be offered to the public for fill on a give-away basis. Whatever remains may have to be dis- posed of at the “foul area”. In any event, the removal of 2,293,800 m 3 (3,000,000 yd3) of material will require approximately 2,000 barge trips. Over a period of one year, this will average 7.7 barges/day. Assuming that an average round trip is 48.27 barge km (30 barge miles) approximately 96,450 barge km (60,000 barge miles) will be required. Materials Delivery-With all treatment facilities located at Deer Island, the delivery of materials will be facilitated by the use of water transportation. This will greatly minimize the effects of construction in Winthrop and other communities which may lie along main access routes. The materials to be delivered to Deer Island (and other loca- tions) include the following: Cement - It is recommended that a batch mix plant for concrete production will be operated on Deer Island. Cement deliveries will be barged in (from out of the area) at the rate of one barge per month. Aggregate - One barge delivery per day of aggre- gate is anticipated during the active con- struction phase. This is expected to come from a local off-loading facility which may receive aggregate by rail. At 16.09 barge km (10 barge miles) per round trip, this would require 4183.4 barge km (2,600 barge miles) per year. Mechanical and Heavy Equipment - It is anticipated that this material can be barged to the site at a rate not exceeding one barge trip per day (average). This would amount to ap- proximately 4183.4 barge km (2,600 barge miles) per year. Pipe - Pipe will be delivered to appropriate staging areas (near Deer Island, Long Island, and Nut Island) by truck at an average rate estimated at 3 trucks per day during active pipe—laying periods. At an average of 80.45 km (50 miles) per trip (within the MDC area), this will amount to 241.35 km (150 miles) of travel per day. 5—4 ------- Backfill Delivery - As a worst-case condition, the en- tire volume of needed backfill may have to be purchased and transported to the construc- tion site. It is not expected that this will occur since the drumlin material and/or dredge spoils may prove to be suitable material for this purpose. However, in the worst case, app 1 oximatelv 1.45 mi)lion m 3 (1.9 million yd ) of backfill will be needed. Over a period of two years, this would require 1,300 barge trips (2.5 barge trips per day) which is equivalent to 10,458.5 barge km (6,500 barge miles) per year. Personnel - While the project will positively impact on the local economy by the creation of jobs, the movement of workers into and out of the construction sites each day may adversely affect local communities by increasing the local traffic flow and by increasing air emissions. These effects will be most significant at Deer Island where the labor force is expected to reach 2,000 workers during the peak construc- tion period. If each worker drove his (or her) own vehicle to the site (worst—case conditions), 2,000 additional vehicle trips per day through Winthrop would result. If the average distance travelled per round trip is 48.27 km (30 miles), then total local travel would amount to 96,450 vehicle km (60,000 vehicle miles) per day for the peak period. Other locations where workers will be employed, in con- nection with this project, include Nut Island, Long Island and Squantuin. The peak personnel requirement, and vehicle kilometer (mile) increment for these locations (using the same assumptions) is shown below: Peak Total Vehicle Total Vehicle Location Work Function Labor Force kni/Day Miles/Day Nut Island Headworks Construction 150 7,240.5 4,500 Bay Crossing Staging Area Long Island Bay Crossing Stagling 40 1,930.8 1,200 Area Squantuin Landfill, Ccinposting 30 1,448.1 900 Area Construction 5—5 ------- For the long—term operational phase, the logistical re- requirements are considerably less stringent. They are summa- rized below: Ash Transportation - As Chapter 4 indicates, incinerator ash resulting from the burning of secondary sludge from the northern service area will be transported to Squantum for landfilljng. This will be accomplished by barge, the ash being held in bulk containers The total volume of ash to be transported is about 91.75 m 3 (120 yd 3 ) per day. Sludge Trans ortation — Similarly, secondary sludge from the southern service area will be transported to Squantum from Deer Island. This will amount to 405.24 m 3 (530 yd 3 ) per day and will also be shipped by barge in bulk containers. Both the sludge and the ash from a single day’s operation can be shipped to Squantum in one barge. From Squantum, digested sludge will be trucked to a remote landfill site. Approximately 10 truck trips per day will be needed to move this material. For the purpose of impact assessment a round trip travel distance of 128.7 km (80 miles), to an unspecified site, was assumed as a worst case condition. This equals 1287.2 truck kin (800 truck miles) per day. Also, composted sludge will be made available to the public (as well as to institutions, agencies, and com- mercial organizations) at the Squantum site. Approximately 18,144,000 kg (20,000 tons) of compost will be produced annually. If this material is removed from the site in vehicles with an average capacity of 450 kg (one half ton) approximately 40,000 vehicle trips will be required annually to pick up compost. This is equivalent to 110 vehicles per day or 5,309.7 vehicle km (3,300 vehicle miles) per day (at 48.27 km (30 miles] per day). Materials Delivery - During operation the treatment facility will require several chemicals (chlorine, ferric chloride, lime and polymer) on a continous basis. It is recommended that these materials will be trucked to Squantum (8 trucks per day or 643.6 truck km [ 400 truck miles] per day) then barged to Deer Island via return barge from the sludge/ash shipment. Fuel oil will be trucked directly to Deer Island at the rate of one oil delivery per week. Personnel - Approximately 300 persons will be required to staff the Deer Island facility. At worst, this will amount to 300 trips per day through Winthrop, totalling 14,481 vehicle km (9,000 vehicle miles) per day. This value does not represent a net increase, however, since signifi- cant staff already travels to the existing treatment plant and prison facility. 5—6 ------- At Squantum, the operating staff will be small, amount- ing to 15 persons (724 vehicle km [ 450 vehicle miles] per day). The following sections in this chapter will further detail the impacts and effects described above. 5—7 ------- 5.2 WATER QUALITY IMPACTS Implementation of the Recommended Plan will eliminate the discharge of primary effluent and sewage overflows from the southern portion of Boston Harbor. Cessation of the Nut Island treatment plant operation should yield an immediate aesthetic improvement in Quincy Bay due to the elimination of wet weather plant bypasses which discharge floating debris and solids to near shore areas. Elimination of the contitL- uous primary effluent discharge removes significant pollutant inputs from the southern portion of the Harbor and thus will have a long term positive impact upon its water quality. Productive shellfish beds, presently adversely influenced by these discharges should, over time, become useable. The discharge of all MDC secondary effluent into President Roads will impact Boston Harbor by changing the mass of pollutants it receives. Table 5.2-1 summarizes the differences in pollutant discharge between the present primary and future secondary effluent. Wastewater volume discharged into President l oads will increase by 85 percent, yet the total mass of BOD 5 and SS de- crease by 53 and 32 percent respectively. The mass discharge of three toxic metals - chromium, copper and zinc - decrease while cadmium, mercury and nickel increase. This occurs if one assumes the pretreatment program removes 25 percent of the present influent mass of toxic metals. Pretreatment removal, as well as removal by the secon- dary facility, cannot be quantified at this time. Actual removals will depend upon the success of the ! DC in imple- menting and enforcing its pretreatment program and the ability of its secondary facility to remove the toxic materials. The figures in Table 5.2—1 do illustrate the need for reducing toxic metals inputs to the c system. Unless inputs are reduced, high concentrations of toxic metals in northern Boston Harbor can be expected to continue. Toxic metals are sure to be present in the proposed discharge due to input from non-industrial sources and variations in removal efficiency within the secondary facility. Effluent must be properly diffused into Harbor waters to prevent water quality impacts. The magnitude of dilution required for the various toxic metals is summarized in Table 5.2—2. These dilutions assume metal mass discharges found in Table 5.2—1 and, since these are expected to vary, dilution requirements will vary accordingly. Nevertheless, dilution in the 50:1 to 100:1 range is required to avoid potential impacts. 5—8 ------- TABLE 5.2—1 COMPARISON OF POLLUTANT DISCHARGE INTO PRESIDENT ROADS Present Northern Year 2000 Service Area Total NSD Average Primary Plant Secondary Plant 2 Change % Change Flow m 3 /d 1200000 2218000 (+) 1018000 85.4 (mgd) (316) (586) (270) BOD 5 kg/d 128000 58123 (—) 69870 53.4 (lbs/d) (282240) (128160) (154080) SS kg/d 87400 59667 (—) 27730 31.7 (lbs/d) (192717) (131565) (61151) Cadmium kgld 22.7 25.0 (+) 2.3 10.1 (lbs/d) (50.1) (55.16) (5.1) Chromium kg/d 129.0 105.4 (—) 23.6 18.3 (lbs/d) (284.6) (232.5) (52.0) Copper kg/d 426.7 173.8 (—) 252.9 59.3 (lbs/d) (940.9) (383.2) (557.7) Lead kg/d 156.6 153.5 (—) 3.1 1.9 (lbs/d) (345.2) (338.5) (6.7) Mercury kg/d 1.32 1.54 (+) 0.22 16.7 (lbs/d) (2.9) (3.4) (0.5) Nickel kg/d 156.6 177.2 (+) 20.6 13.2 (lbs/d) (345.2) (390.7) (45.4) Zinc kgld 583.3 452.7 C—) 130.6 22.4 (lbs/d) (1286.1) (998.2) (288.0) 1. See Tables 2.5—2 and 3.2—5 for flow, BOD, and SS. Metals values calculated with effluent concentrations, Table 3.2—8. 2. Assumes 85 percent removal of total influent mass of BOD and SS, See Tables A4.1—l and A4.l—2 of Appendix 4.14 Total mass of metals calculated using Scenario C concentrations, See Tables 3.2—12 and 3.2—13. 5—9 ------- TABLE 5.2-2 DILUTION REQUIR 2IENTS YEAR 2000 DEER ISLAND SECONDARY PLANT METAL DILUTION * Cadmium 56.5 hromium 0.9 Copper 7.8 Lead 6,9 Mercury 14.0 Nickel 40.0 Zinc 10.2 *Dilution required such that minimum risk criteria are not exceeded. See section 3.1.2B 5—10 ------- Previous analysis (Section 3.2.2B) has indicated a properly diffused discharge to President Roads will not violate water quality criteria. However, the analysis assumed a single discharge point rather than the three out- falls presently envisioned. The hydrodynamics of President Roads should be studied prior to design in order to optimize the dilution of a three outfall system. In addition, all outfalls must include diffusers to insure proper near field dilution of the wastewater. Water quality impacts can be minimized if the outfall system is designed to achieve the greatest dilution in excess of 50:1 that the hydrodynamics of President Roads will permit. The discharge of chlorinated secondary effluent into Boston Harbor can have significant water quality impacts. Residual chlorine in wastewater discharges has been shown to have detrimental effects upon aquatic life. Major prob- lems, as summarized in a recent report to the Congress by the Controller General (1977), include: “Major fish kills occurred in the lower James River in Virginia in 1973 and 1974. The Virginia Insti- tute of Marine Science investigated the kills and attributed them to chlorine residuals from sewage treatment plants. Overall, 5 to 10 million fish probably died over a 3-week period in 1973. The species affected included bluefish, striped bass, weakfish, and menhaden. Following a reduction in the levels of residual chlorine in the sewage of effluent, dead fish counts dropped from thousands to tens within 2 days. A similar experience occured the following year. In addition, when the chlorine was cut back, the oyster season was unusually successful while other estuaries enter- ing the Chesapeake Bay were no more productive than usual. “A major fish kill due to chlorine residuals from sewage treatment plants was noted by the California Fish and Game Department in 1972 in the Sacramento River of California. Estimated losses of eggs, larvae, and fingerlings were in the millions for salmon, and in the billions for striped bass and shad. Sturgeon and catfish were also killed. The California Fish and Game Department reported that the fish lost would have been a significant portion of the State’s fishery resources. For kincr salmon alone, the Fish and Game Department estimates the loss at $1,123,200. 5—il ------- “In studies of San Francisco Bay published in 1972 and 1974 (made because of periodic fish kills and deteri- oration of the fisheries there), sanitary engineering researchers at the University of California at Berkeley suggested that chlorine in watewaters may be the largest single source of toxicity entering San Francisco Bay. The researchers concluded that chlorinated sewage, even after secondary treatment, is harmful to aquatic life. The tests demonstrated impairment to oysters exposed near plant outfalls; and in laboratory studies, baby clams and oysters experienced 50—percent mortality at chlorine residuals less than 5 parts per billion (ppb). Chlorine discharges above 1,000 ppb are frequently found in sewage discharges. “A 1974 progress report prepared by fisheries researchers at Oregon State University reported that coho salmon ex- posed to only 20 ppb of residual chlorine had signif i- cantly impaired growth. “Chlorine has been found to affect the environment in very subtle ways. Several studies, including four done by Michigan Department of Natural resources rearchers in 1971, reported long river reaches downstream rendered uninhabitable to many fish due to chlorine residuals in sewage effluents. Aquatic organisms in the food chain other than fish may be killed or harmed. Tests have shown that the highest total residual chlorine concentration having no measurable chronic adverse effect on an impor- tant fish food organism was 2 to 4 ppb. A level of 6 ppb is roughly equivalent to a quart of laundry bleach in 2 million gallons of water. Chlorine also interferes with the anaerobic conditions essential to the normal process- es in a tidal salt marsh, or swamp, and with the repro- duction of some aquatic animals.” The recommended water quality criteria to protect marine organisms, 10 pg/i of total residual chlorine (Water Quality Criteria,1976). In addition to toxicity effects, residual chlorine has been reported (Shumway, 1971) as impairing fish flavor. The addition of dechlorination with sulfur dioxide to the treatment process stream will tend to mitigate these impacts. Chlorination of wastewater also results in the for- mation of chlorinated organics (Rosen, etal,. 1972, Tolley, 1975) and the long term insidious effects of these, upon aquatic life and potentially people, is a major adverse im- pact of wastewater chlorination. Chlorinated organics re— moval which requires the application of carbon adsorption, is not practical. Alternative disinfection processes, as 5—12 ------- well as the no disinfection and de-chiorination options, may be utilized to mitigate these impacts. Chapter 6 discusses these options. Dredging operations for the required Harbor crossings will have a temporary negative impact upon water quality. Ex— cavation of bottom materials can cause increased water column turbidity and suspended solids levels. Chemical con- stituents, such as toxic metals, associated with the dredged materials may mobilize into the water column. Depending upon prevailing currents, these effects may not be localized in the vicinity of the dredge site. However, construction techniques are available to minimize these impacts and will be discussed in Chapter 6. Disposal of dredge material will also present problems. Increased suspended solids and turbidity will occur at the disposal site. Constituents absorbed to the dredged spoils may be mobilized into the water columns. Disposal of this material at any approved duxttpsite will not eliminate these impacts; however, the use of an approved dredge spoils dis- posal site will confine the impacts to an acceptable area. The “foularea” appears to be an environmentally acceptable disposal site due to the existing degradation of the area caused by previous dumping. Disposal of dredge spoils into the bay for backfilling the trench following construc- tion of the bay crossing will cause additional water quality impacts. Hence, only material which is substantially free of fines should be backfilled. Potential exists for long term adverse water quality impacts from landfilling of sludge and incineration ash. High concentrations of toxic metals will be present in both materials (see section 3.3-6). Leaching of these metals poses a potential threat to surface and ground- waters proximate to the disposal sites. Disposal of these materials by landfilling in a “secured landfill” (one from which all leachate and surface drainage is collected for treatment) can prevent these impacts. Interceptor relief programs will have a positive impact upon water quality by eliminating overflows to the rivers from hydraulically overloaded sewers during wet periods. In summary, the following water quality impacts are associated with the recommended wastewater managmentplan. Positive impacts resulting from the upgrading to secondary treatment and consolidation of all treatment on Deer Island include improved quality in southern harbor waters, re- duced mass discharge of pollutants to President Roads and the elimination of sludge discharges and interceptor over- 5—13 ------- flows. Dredging activities will cause temporary negative impacts; however, their magnitude is difficult to quantify. In addition, potential negative water quality impacts are associated with landfilling of incinerator ash and secondary sludge as well as wastewater chlorination. Negative impacts tuay be reduced and deemed acceptable through institution of proper mitigating procedures. Measures to mitigate the neg- ative impacts associated with the proposed project are presented in Chapter 6. 5—14 ------- 5.3 Water Quantity Impacts The Recommended Plan will result in the export of water to Boston Harbor from local watersheds*. Seventeen towns within the proposed, expanded MSD utilize surface and/or groundwater for water supply and discharge wastewater to the MSD sewerage system. Table 5.3-1 sununarizes this export. A total of 2,180,000 m 3 /d (57.5 mgd) of local water would be exported to Boston Harbor under the recommended option. This represents approximately 10 percent of the total projected flow to Deer Island. The export represents a negative impact of undefined magnitude upon these watersheds. I/I has been estimated at 681,300 m 3 /d (180 mgd), which is approximately 31 percent of the total projected wastewater flow. This water represents a significant potential loss of local water, especially from the Charles and Neponset rivers where interceptors run through sand and gravel deposits adjacent to the rivers. These potential impacts upon the watersheds draining to Boston Harbor may be mitigated through effective water conservation, a vigorous program to correct I/I, and limiting the size of the MSD. *Th term local watershed refers to those watersheds within the expanded MSD. Local water originates in one of these basins rather than coming from the MDC water supply system. 5—15 ------- TABLE 5.3 -1 WATER EXPORT TO BOSTON HARBOR YEAR 2000 Export Watershed Export Watershed Watershed Town Volume Total Watershed Town Volume Total Mystic Winchester 2.65 33.65 Neponset Canton 11.51 69.61 (0.70) (8.90) (3.04) (18.39) Woburn 31.0 Norwood 11.36 (8.20) (3.0) Sharon 4.50 Charles Dedham 6.93 55.10 (1.19) (1.83) (14.55) Walpole 28.46 Natick 23.66 (7.52) (6.25) Westwood 13.77 U, Needham 12.87 (3.64) (3.40) Wellesley 11.62 Weymouth Weymouth 17.10 47.6 (3.07) (4.51) (12.58) Hingham 7.1 Sudbury Ashland 8.7 11.9 (1.87) (2.31) (3.16) Holbrook 4.7 Hopkinton 3.2 (1.25) (0.85) Weymouth 18.7 (4.95) Entries: m 3 /d x 1000 (mgd) Export is the volume of water originating in basin discharged to MDC Sewerage System. Export = projected wastewater volume if local water supply > projected wastewater or Export = capacity of local water supply if projected wastewater > local water supply Wastewater = total of residential, commercial and industrial flows Total volume export from local water supplies = 21.8 x lO m 3 /d (57.5 mgd) ------- 5.4 AIR QUALITY The effects of the project on air quality will be primarily due to incineration of the northern service area sludge, with transportation related sources providing a secondary, and relatively minor, addition to pollutant emissions. A general discussion of air quality effects due to incineration was presented in Section (3.3.6). An air quality model was prepared (Appendix 3.5.4) in which the detailed effects of incineration on air quality were examined. To determine annual ground level concentrations the G/C Air Quality Model based upon the Modified Air Quality Display Model was used. For short term analyses, the EPA Single Source Program (CRSTER) and. Texas Episodic Model (TEM) were used, along with the EPA Point Maximum (PTMAX) program. It should be noted that the Deer Island alternative was examined in the air quality model considering the incineration of all the MDC sludge on site; however, under the Recommended Plan, only the secondary sludge from the northern service area and all primary sludge would be incinerated. Since the air model calculated ground level concentrations for incinerating all the sludge, a ratio of the sludge to be incinerated in the Recommended Plan to the total sludge generated was used to determine ground level concentrations. Table 5.4-1 gives the increments resulting from incinerating sludge at Deer Island along with the total concentration resulting from the background concentrations (l9 5) and those induced by the Recommended Plan. Annual and short term concentrations were determined for the Deer Island site. On an annual basis, maximum SO 2 levels were determined to be 4.1 . g/m 3 while particulate levels were 1.2 ilg/m 3 . The short term analysis (24 hour) showed that the sulfur dioxide and particulate concentrations were 34.2 and 10.2 pg/rn 3 , respectively. For a three hour averaging time for sulfur dioxide, the maximum concen- tration was found to be 137.8 pg/rn 3 . Nitrogen dioxide and hydrocarbon levels are anticipated to be 6.7 pg/rn 3 and 9.7 pg/rn 3 HC. 5—17 ------- TABLE 5.4-1 IMPACT OF RECOMMENDED PLAN ON AIR QUALITY ( .ig/m 3 ) 1985 1985 Federal Standard Total Suspended Increment Background Total Particu].ates Due to Incineration Concentration Concentration Primary Secondary Annual Geometric Mean 1.2 45 (Deer Island)’ 46.2 260 150 24 Hour Maximum 10.2 168 (Revere) 2 178.2 75 60 Sulfur Dioxide Annual Arithimetjc Mean 4.1 21 (Deer Island)’ 25.1 1,300 U, 24 Hour Maximum 34.2 189 (Revere) 2 223.2 365 — 3 Hour Maximum 137.8 648 (Revere) 2 785.0 80 1. Projections are based upon the Department of Environmental Quality Engineering Division of Air Quality Control. 2. Based upon Ecoisciences projected 1985 background data for the Revere monitoring site. ------- The quantities of pollutants emitted from incinerating the sludge at Deer Island were calculated. It is estimated the yearly maximum allowable emissions in kilograms (tons) for the Recommended Plan would be: particulates 117,936 kg (130) tons, sulfur dioxide 302,098 kg (333) tons, nitrogen dioxide 609,638 kg (672) tons and hydrocarbon 69,854 kg (77) tons. A comparison of emissions from the Recommended Plan and the all Deer Island Plan appear in Table 5.4-2. It is apparent that lower emissions will occur under the first option due to composting and landfilling of approximately half the secondary sludge. On the basis of the air quality model it may be seen thattheNationalAmbjentAjr Quality Standards (NA QS) and Prevention of Significant Deterioration Standards (PSD) are met except for the twenty-four hour secondary particulate standard. The 24 hour TSP standard may be exceeded due to background concentrations at Revere and possibly due to incineration increments. Using the 1985 annual projections for Deer Island and adding the maximum incinerator increments to the Deer Island levels satisfies the NAAQS. Short term 1985 projections for the Deer Island site are not available; however, air quality standards are expected to be met in the immediate vicinity of Deer Island. If the nearest monitoring site to Deer Island with short term projected concentrations (Revere) is used for predicting 1985 air quality concen- trations, it appears a violation of the secondary 24 hour particulate standard occurs. It must be emphasized that the projected 1985 Revere background data (which already exceeds the secondary standard) was used because no closer monitoring site for background data was available, and that it is not representative of Deer Island. The Deer Island site, where incineration is to occur, has been declared a “clean” zone (meets NAAQS) for particulates. In addition maximum incremental concentrations due to incineration will occur approximately 800 meters (2624 ft.) due east of Deer Island, not at Revere. Table 5.4-3 gives the percentage of the permitted PSD standards which would be used by the project. It may be seen that for each averaging time 28 percent or less of the allowable PSD increment is used under the Recommended Plan, except for the 24 hour maximum for sulfur dioxide which uses 38 percent of the allowable increment. 5—19 ------- TABLE 5.4-2 A COMPARISON OF MAXIMUM ALLOWABLE EMISSIONS AND POTENTIAL EMISSIONS FOR THE RECOMMENDED PLAN AND THE 100% SLUDGE INCINERATION ALTERNATIVE kg/yr (TONS/YR) Recommended Plan 100% Sludge Incineration Maximum Allowable 1 Potential 2 Maximum Allowable Potential 1. Maximum allowable emissions the emission rate calculated based upon the maximum rated capacity using new source performance standards and AP-42 controlled emission factors. 2. Potential emissions - the emissions based on maximum rated capacity in the absence of air pollution control equipment. NOTE: Emissions are based upon incineration of sludge and fuel oil. Total Suspended Particulates 117,936 (130) 8,512,257 (9383) Sulfur Dioxide 302,098 (333) 315,706 (348) Nitrogen Dioxide 609,638 (672) 675,864 (745) Hydrocarbons 141,523 399,168 793,800 88,906 69,854 (77) 103,421 (114) (156) (440) (875) (98) 10,191,485 416,405 878,170 130,637 (11234) (459) (968) (144) ------- Table 5.4—3 PERCENTAGE OF PREVENTION OF SIGMIFICANT DETERIORATION STANDARDS USED BY T} RECOMMENDED PLAN Maximum Concentration Percentage of Max Allowable From S udy Allowable Increment ( fm ) Increments Particulate Matter Annual Geometric Mean 19 3 2 24 Hour Maximum 37 10.2 28% Sulfur Dioxide Annual Arithmetic Mean 20 4.1 21% 24 Hour Maximum 91 34.2 38% 3 Hour Maximum 512 137.8 27% 5—21 ------- Air quality projections were prepared by the Common- wealth of Massachusetts, Department of Environmental Quality Engineering, Division of Air Quality Control. Figures 5.4-1 and 5.4—2 present annual sulfur dioxide projections for the years 1980 and 1985, while figures 5.4—3 and 5.4-4 present the annual total suspended particulate levels for the same years. Examination of the annual sulfur dioxide projections shows that the levels expected at Deer Island for the years 1980 and 1985 to be .006 ppm (16 pg/rn 3 ) and .008 ppm (21 pg/rn 3 ). These levels are well below the primary and secondary air standards (see Appendix 2.8-1). The addition of sulfur dioxide concentrations of 4.1 pg/rn 3 , as in- dicated by the air model, would not cause a violation of any standard. The concentrations added by the Recommended Plan to existing monitoring sites would be expected to be approximately 80 percent of the maximum levels found from the alternative where all the sludge is incinerated at Deer Island. Concentrations of sulfur dioxide added from incinerating all of the sludge at Deer Island would be less than .3 pg/rn 3 (Appendix 5.4, Figure A5.4-l) at both the Kenmore Square and Revere monitoring sites. Thus, it may be seen that on an annual basis, sulfur dioxide air quality standards would be met at the present and for the future, as evidenced by the air quality projections. Short term increments for sulfur dioxide were estimated to be 34.2 pg/rn 3 . The maximum concentration is expected to occur over water. Similar to the isopleth map in Figure A5.4—l for annual SO 2 concentrations, short term concentra- tions will decrease with increasing distance from Deer Island. Twenty-four hour sulfur dioxide levels are not projected to violate the NAAQS standards. In terms of the Prevention of Significant Deterioration regulations neither the annual nor short term concentrations will exceed those presented in Table 5.4-3 for sulfur dioxide. Examination of the estimated annual total suspended particulate levels projected for the year 1980 and 1985 at Deer Island shows 45 pg/rn 3 and 40 pg/rn 3 would be expected for those years. The maximum additional increment of particulates from incinerating the northern service area sludge is estimated to be 1.2 pg/rn 3 for the annual maximum. Adding this level to the background concentration would be in compliance with all existing air quality standards. At the surrounding monitoring sites the additional an- nual particulate pollutants added from the Recommended Plan would be insignificant. Figure A5.4-2 (in Appendix 5.4) shows that the levels added to the Revere and Kenmore Sauare 5—22 ------- 2 1 ; \ // Q Re ocV.. — CONTOUR LINES FIGURE 5.4-1 ANNUAL ESTIMATED SULFUR DIOXIDE (S02 ) LEVELS (ppb) IN 1980, BASED ON REGULATIONS EFFECTIVE 5/1/76 T r ( e ( 4 ---- - 4 l0 LEGEND AIR QUALITY CONTROL REGION MUNICIPAL BOUNDARY ‘P ip 5 0 5 MI LES K I LOMETERS SOURCE: Department of Environmental Quality Engineering Division of Air Quality Control ------- AIR QUALITY CONTROL REGION — ——- MUNICIPAL BOUNDARY CONTOUR LINES 5 0 S FIGURE 5.4-2 ANNUAL ESTIMATED SULFUR DIOXIDE (SO 2 ) LEVELS (ppb) IN 1985 BASED ON REGULATIONS EFFECTIVE 5/1/76 LEGEND 10 0 KILOMETERS ‘p MILES SOURCE: Department of Environmental Quality Engineering Division of Air Quality Control ------- eff 4 ( L — - - - / : To / / 40 P - CtTO.. 1’ r- I AIR QUALITY 5 0 5 FIGURE 5.4-3 ANNUAL ESTIMATED TOTAL SUSPENDED PARTICULATE (TSP) LEVELS (ug/M 3 ) IN 1980 BASED ON REGULATIONS EFFECTIVE 5/1/76 LE GE ND CONTROL REGION — ——- MUNICIPAL BOUNDARY L CONTOUR LINES 10 0 10 KILOMETERS MILES SOURCE: Department of Environmental Quality Engineering Division of Air Quality Control ------- AIR QUALITY CONTROL REGION — ——- MUNICIPAL BOUNDARY CONTOUR LINES 10 0 10 KILOMETERS S 0 S -I__J I MILES FIGURE 5.4-4 ANNUAL ESTIMATED TOTAL SUSPENDED PARTICULATE (TSP) LEVELS (ug’M 3 ) IN 1985 BASED ON REGULATIONS EFFECTIVE 5/1/76 SOURCE: Department of Environmental Quality Engineering D3visãon of Air Quality Control LEGEND ------- sites would be less than .07 pg/rn 3 (about 80 percent of this level for the Recommended Plan). Examining the 24 hour particulate increment shows a maximum 10.2 pg/rn 3 increase is projected to occur east of Deer Island. This increase is not expected to violate NAAQS or PSD standards at the inceneration site since Deer Island is a “clean” zone. Although air quality impacts from many sources fall of f rapidly to insignificant levels, the short term model was not carried out to neighboring non—attainment areas to show this fact. Thus as a “worst case” analysis, the maximum 24—hour increment was added to the nearest monitoring site, Revere. It should be noted that the maxima observed in these studies almost invariably occured over adjacent water bodies. These maxima, therefore, may not be additive to observed values for land based observation stations. If the 10.2 pg/rn 3 level for particulates is added to the short term concentration of 168 pg/rn 3 (already in violation) at Revere a continued violation of the secondary TSP standard is projected to occur. Other sites projected to exceed short term particulate levels may also receive some short term impact from incineration emissions. This is not a direct result of incremental incineration concentrations due to the Recommended Plan, rather it is a result of projected high background concentrations (Ecolscience, 1976) . Such an increase would exacerbate an existing violation of the NAAQS. Therefore, the Deer Island incinerator as a major source of particulates may also be subject to the “emission offset” policy. If a major source in an attainment area (Deer Island) exerts a significant affect on a non-attainment area (Revere) (Table 5.4—4) the emission offset policy is triggered. If the assumption is made that the 10.2 pg/rn 3 increment would occur in Revere, the 5 pg/rn 3 twenty—four hour significance level would be exceeded. Before construction is undertaken at Deer Island, a determination as to the actual potential for violation of the secondary NAAQS particulate standard due to the background concentration and the actual incinerator induced increment at Revere should be made. 5—27 ------- TABLE 5.4-4 MINIMUM AMBIENT CONCENTRATIONS CONSIDERED TO BE SIGNIFICANT LEVELS Pollutant Averaging Time Annual 24-Hour 8-Hour 3-Hour 1-Hour SO 1 ug/m 3 5 ug/m 3 25 ug/Tn 3 TSP 1 ug/m 3 5 ug/m 3 NO 2 1 ug/m 3 CO 0.5 mg/rn 3 2 mg/rn 3 5—28 ------- An examination of the various standards and regulations which influence sludge incineration is listed in Table 5.4-5 . This involves the National Ambient Air Quality Standards (NAAQS), Prevention of Significant Deterioration Permits (PSD) including Best Available Control Technology (BACT) and the Emission Offset Policy (EOP). This table assumes all standards and regulations are met, except the N.AAQS secondary standard for particulates. A sewage sludge incinerator is not one of the 28 major stationary sources categories listed in the PSD regulations (June 19, 1978 Federal Register). Therefore a 250 ton/year potential emission level makes a sludge incinerator a major source. If a source exceeds the 250 ton limit, and has allowable emissions of more than 50 tons/year, a PSD review is required. This requires a close examination of many factors to ensure air quality is not degraded due to the new major source. For the Deer Island incinerator a PSD review will be required for particulates, nitrogen dioxide and sulfur dioxide. These three categories will also require Best Available Control Technology for their emissions. A major source is defined under the EOP as one with allowable emissions greater than or equal to 100 tons/year. If such a major source locates in a non-attainment area or exacerbates a violation in an adjoining non-attainment area for any individual criteria pollutant the EOP is triggered. Exacerbating a projected violation of the secondary NAAQS for particulates in an adjoining non-attainment area (Revere) triggers the offset policy for particulates. No other pollutant requires offsets. (However, this assumes the maximum 24 hour particulate increment will occur at the Revere monitoring site). Transportation related emissions compose a second source of air pollutants due to the proposed plan. The sources of these emissions are heavy duty vehicles, barge traffic and worker related automobile traffic. A compilation of the emissions from the various sources is presented in Table 5.4-6. The emission factors used to calculate the quantities of transportation related pollutants are represented in Appendix 5.4, Table A5.4-l. Emissions are separated into the construction and operation phases of the project. 5—29 ------- TABLE 5.4-5 STANDARDS AND REGULATIONS INFLUENCING SLUDGE INCINERATION POLLUTANT Sulfur Nitrogen Par ticulates Dioxide Dioxide Hydrocarbons A. Violation of National Ambient Air Quality Standard Annual no no no 24 Hr. yes no 3Hr. no no B. Requires Prevention Of Significant Deterioration Review yes yes yes no Requires Best Available Control Technology yes yes yes no C. Requires ission Offsets yes* rio no no * Offsets are required if a major source violates or exacerbates a NAAQS. May require Lowest Achieveable Emissions Rate (LAER) 5—30 ------- Table 5.4-6 TRANSPORTATION RELATED AIR POLLUTION EMISSIONS kg (tons)/year Construction Phase • Heavy Duty Vehicles 1,130 (1.2) 184 (0.2) 831 (0.9) 50 (0.1) 109 (0.1) A ztomobL1es 832,847 (918.0) 116,380 (128.3) 82,909 (91.4) 2,251 (2.5) 8,796 (9.7) Barge 61,021 167.3) 27,736 ( 30.6) 149,779 ( 165.1) 14 977 ( 16.5 ) ______ —— TOTAL 894,998 (986.5) 146,300 (159.1) 233,519 (257.4) 17,278 (19.1) 8,905 (9.8) perat ion and Maintenance Phase CO HC TSP Heavy Duty Vehicles 48,097 (49.7) 7,359 (8.1) 33,183 (36.6) 4,356 (4.8) 2,022 (2.2) Automobiles 168,531 (185.7) 23,550 (26.0) 16,777 (18.5) 4 5 (0.5) 1,780 (2.0) Barge 1 59l ( 1.8) 723 ( 0.8) 3,906 ( 4.3) 390 ( 0.4 ) —— TOTAL 215,219 (237.2) 31,632 (34.9) 53,866 (59.4) 5,201 (5.7) 3,802 (4.2) Percent of Total Emissions* ** 31 8 2 t in (J-) 1 0 & M Emissions *Percent Total Emissions — L 0 & M Emissions & Incinerating Emissions **Represente most of the CO emissions from the project since CO emissions from incineration are insignificant. ------- The annual number of miles traveled during construction for heavy duty diesel trucks was estimated to be 62,751 km (39,000 miles) (worst case condition). This figure was then multiplied by emission factors found in Supplement No. 5 for Compilation of Air Pollution Emission Factors (USEPA, 1975) for 1975 vehicles. The year 1975 was chosen as a worst case example, since it is assumed vehicle emissions will decrease in future years due to stricter emission controls. During the operation and maintenance (O&M) phase of the project the number of vehicle miles traveled increases greatly due to the landfilling of sludge and removal of compost. It is estimated over 2.4 million kin (1.5 million miles) of travel will occur annually. Emission estimates for 0 & M were qenerated based upon this figure. It should be noted that 1.2 million miles of this total are due to the removal of compost. There would be a substantial increase in barge traffic due to the Recommended Plan. Emissions were cal- culated for both the construction and 0 & M phases of the project for barge related emissions. The average fuel consumption rate of a diesel powered barge was estimated to be 8.74 gallons per mile (Ecoiscience 1976 ). Emissions were calculated based upon the number of miles traveled and the emission factor from Compilation of _ Air Pollutant Emission Factors, AP—42 ( USEPA 1975) . Automobile emissions were calculated based upon vehicle miles traveled by workers to and from work during the construction of 0 & M phases. It was assumed, as a worst case, that each worker would drive to work alone and have a 30 mile round trip. Emission factors were obtained from Supplement No. 5. The automobile emissions given in Table 5.4-2 represent the total emissions from all workers. These numbers, however, do not represent a totally new emissions source since the present 0 & M emissions from Deer Island personnel, amount to more than one—third of the projected automobile related 0 & M emissions. Transportation emissions were related to the total emissions from the project once incineration would begin. In Table 5.4-6 the percentage of transportation emissions in relation to the total emissions from the project were calculated. It is evident that transportation emissions add a small percentage of the overall emissions for parti- culates, sulfur dioxide and nitrogen dioxide, 3, 2, and 8 percent respectively. For hydrocarbons transportation sources would be a significant source (31 percent) of added emissions. Since the carbon monoxide emissions from 5—32 ------- incineration are considered negligible, transportation sources would contribute almost all of the Co emission. In summary, incineration may be seen to add small increments of the various pollutants to ambient concentra- tions as shown by the air quality model. Transportation related emissions should present an insignificant addition of pollutants to the ambient air concentrations. All air quality standards are projected to be met except the secondary 24 hour particulate standard which will exacerbate a projected violation. 5—33 ------- 5.5 NOISE Three sites will be examined for noise impacts; Deer Island, Nut Island and Squanturn. Noise impacts will be dis- cussed for expansion of the Deer Island facility, installa- tion of a lift station, headworks and demolition of the present treatment works at Nut Island, along with construc— tion of composting and ash landfill facilities at Squantum. The State of Massachusetts has no noise standards indicating specific noise levels, in decibels, which are acceptable or unacceptable. Therefore, the City of Boston’s Noise Control Regulations (Table 5.5—1) were used as a for acceptable noise levels for the study area. This was used in place of use of a subjective evaluation based on nuisance. The Deer Island facility would utilize almost the entire area on Deer Island, including the present site of the House of Corrections. Winthrop is the nearest community with residences that may be affected by noise. The nearest residence is 700 feet from the nearest portion of the proposed plant. Ambient noise levels were presented for the Deer Island site in the Stone and Webster Coincineration Report. The minimum sound level was found near the old pumphouse, a rather low 38 decibels. At Deer Island Point the ambient noise was recorded at 43 decibels. In the administration parking lot, 200 feet from the sewage treatment plant, a 56 decibel level was found. The highest level was found at a garage door opening to the pumping station building, 88 decibels. A projection of noise levels from the Deer Island facility may be made. Assuming that the highest noise level emanating from the completed plant is the measured 88 decibels originating at the main pumping station, a level of 50 DBA may be expected in the vicinity of the nearest residence. This level is acceptable for residential areas and therefore, it is not expected that noise levels during the operating phase would impact on local residences. Noise levels at the Squantum site, due to facility operations, should not impact any local residences. At present, the nearest property to be impacted would be commercial in nature. The use of equipment on site during operation is not expected to cause any detrimental noise impacts. On Nut Island a lift station and headworks are to be con- structed. Noise levels during operation should not impact upon adjacent residences. 5—34 ------- Table 5.5—i Boston Noise Control Regulations Maximum Allowable Noise Levels Residential 7:00 A.M. — 6 00 P.M.* 60 dEA All other times 50 dBA Residential/Industrial 7:00 A.M. — 6:00 P.M. 65 dBA All other times 55 dBA Business Any time 65 dBA Industrial Any time 70 dBA *Except Sundays Construction Noise Regulations Maximum Lot Use of Affected Property L 10 Level Noise Level Residential or Institutuonal 75 dBA 86 dBA Business or Recreational 80 dBA Industrial 85 dBA Note : L 10 defines the noise level that is exceeded 10 per cent of the time. SOURCE : Regulations for the Control of Noise, City of Boston. 5—35 ------- Construction noise may be more intrusive than the noises associated with the normal operation and maintenance of the various sites. Although construction noise is not permanent, it can be disturbing. Construction equipment may be categorized into equipment utilizing internal combustion engines to provide motive and operating power (the more prevalent source) and impact tools and machinery. Table 5.5-2 provides noise levels associated with con- struction equipment. The noise levels generated by construction equipment would not have any significant impact at the Squantuin site. On Deer Island, noise levels should meet the construction noise regulations (see Table 5.5-1) at the Winthrop boundary. Noise levels may reach as high as 82 dba at the nearest property line (approximately 152.4xn, 500 feet) on the Nut Island construction site. These levels should be infre- quent. during construction. During the demolition of the old facilities at Nut Island, impact noise may more frequently reach, or occasionally exceed, the 82 DEA level at the nearest property line. Noise levels on site would be much higher than those at the surrounding site boundaries. The attenuation of sound may be primarily attributed to the distance between the source and receptor. Typical noise levels may be expected to range between 85-95 DBA near operating con- struction equipment. If and when pile driving equipment is necessary noise levels may reach 101 DBA on site. While construction noise may affect the area adjacent to the construction site, transportation related noise may affect the surrounding community. Transportation related noise levels may be raised significantly. Noise levels of up to 88 DBA (50 feet from road) may occur intermittently along truck routes. Average noise levels due to transpor- tation induced noise will be lower. The transportation re- lated noise levels due to operational truck traffic would, however, be limited to the Squantum site. At Squantum, approximately 125 vehicle round trips per day would be made, removing compost and digested sludge and bringing in treat- ment plant supplies for use at the Deer Island treatment plant. The impact on surrounding areas should be minimal at Squantuin due to the existing commercial nature of the area and the proximity to major transportation arteries. However, with the proposed residential use of the adjacent parcel, the potential for nuisance effects may increase. 5—36 ------- Table 5.5-2 TYPICAL CONSTRUCTION SITE EQUIPMENT SOUND LEVELS (in dBA) Typical Sound Level Construction Equipment at 50 Feet 1. Dump truck 88 2 Portable air compressors 81 3. Concrete mixer (Truck) 85 4. Paving Breaker 88 5. Scraper 88 6. Dozer 87 7. Paver 89 8. Generator 76 9. Pile driver 101 10. Rock drill 98 11. Pump 76 12. Pneumatic tools 85 13. Bac1thoe 85 SOURCE: EPA 1975 5—37 ------- Automobile traffic would cause transportation related noise levels to rise in Winthrop. Noise levels could reach between 68-75 DBA and possibly higher, during hours of peak traffic flow during the construction period. Assuming all the workers were to drive to the Deer Island site, the road- ways through Winthrop would become extremely congested since the carrying capacity of the roads would be exceeded. Mini- mal truck traffic would go to Deer Island since materials and equipment are to be barged to the site. Thus, increased noise levels through the community would be primarily due to construction worker traffic. The Nut Island site could have a maximum of 150 vehicles traveling through Houghs Neck per day during the construc- tion of the lift station and headworks. Sea Avenue would provide the only route with direct access for the workers to travel. Noise levels would increase near Quincy Great Hill (Sea Avenue) due to the increase in traffic. The carry- ing capacity of the road may be exceeded during rush hours, causing congestion and further increases in noise levels. Noise levels within 50 feet of the road should intermittent- ly reach between 65-70 DBA. However, this should occur only during periods of peak traffic flow. Sea Street should not experience any noticeable increase in traffic or noise levels due to the Nut Island construction since it would produce a minimal increase relative to the existing traffic volume. Raised noise levels should occur at Deer Island and Nut Island only during the construction phase of the pro- posed project. Squantuin would experience raised noise levels during the operation phase of the project since only then would digested sludge and compost need to be moved. In summary, the raised noise levels at Deer and Nut Island due to construction would be temporary in nature and would not pose a significant noise impact. Transpor- tation noise may be perceived as a nuisance during con- struction at the two island facilities. However, this noise would also be temporary. Squanturn truck traffic would produce a long term addition to noise levels. None- theless, the impact on the surrounding area would be minimal due to the easy access to major roads and the relative isolation of the site as it now exists. 5—38 ------- 5.6 BIOTA The proposed project will impact upon existing biotic communities in several ways. First, upgrading the existing primary discharges into Boston Harbor and eliminating the sludge discharge will significantly improve water quality conditions and thereby positively affect estuarine biota. Existing discharges affect adjacent benthic communities by causing a build-up of organic solids resulting in anaerobic mud deposits. These deposits support only a limited benthic community. The elimination of a Quincy Bay effluent dis- charge and the sludge discharge, will positively affect the Bay by an immediate improvement in water quality. The reversion of degraded benthic communities to their former condition will occur slowly and only to a limited extent. This is due to the very slow decomposition of organic mat- erial within the bottom muds. The localized water quality improvements which are realized may eventually open areas which are presently closed to shellfish harvest. In general, water quality improvements should improve the diversity of species found within the harbor. The total abundance (biomass) of organisms should not be greatly affected. Similarly, aquatic biota should be benefited to some degree by the relief of inland interceptors, thereby minimizing polluting overflows within the river systems. Another impact of the Recommended Plan is the displace- ment (and loss) of biota due to the construction and place- ment of sewerage facilities. Within the harbor area, sig- nificant impacts on terrestrial biota will occur on Deer Island, Long Island and Squantum. Biotic communities on Deer Island and Squantum site will be displaced by the construction of treatment, compostirig and ash landfill facilities. Approximately 4 ha (10 acres) of land on Long Island may be needed as a staging area in connection with the Bay crossing. These effects are discussed below: Deer Island - The entirety of Deer Island will be used for the development of treatment plant facilities. In addi- tion to the areas nowoccupiedby the prison and the treat- ment plant, Deer Island contains a grassy drumlin and the highly disturbed Fort Dawes area at the southern tip of the island. Some sections of the Fort Dawes area are bare and rocky. A low, marshy area exists adjacent to the rocky area. Common freshwater forbs are present. Many species of grass abound here, as well as on other parts of the island. In addition, barn swallows, red winged blackirds, kilideer and black—backed gulls are very common. 5—39 ------- The land adjacent to the existing treatment plant is equally unimportant. Large grassy expanses roll over the area with small forbs appearing occasionally. Young stands of trees exist, but they are young and not attractive or important ecologically. Development on Deer Island will not destroy any valu- able biota. Though attractive, the island exclusively con- tains secondary growth ecosystems. The littoral wash contains a predominance of Lamaria sp., chondrus crispus and Rhodymenia sp. The low diversitty of these rnacroalgae does not seem to indicate locally, healthy benthic conditions. As such, any siltation or dis- turbance to the bottom benthos could cause further degradation. Squantum - Approximately 28.3 ha (70 acres) of land at Squantum Point will be affected by the proposed project. The vegetation on the site is composed of a mixture of grasses with a variety of other annuals, shrubs and trees being found scattered throughout. Meadow areas, both wet and dry, are present. The wet areas are dominated by a virtually monotypic expansc of ra s. Large patches of bayberry shrubs are also found in this area. A small Spartina alterniflora salt marsh exists around the perimeter of the site (water boundaries). While the complete loss of this marsh would probably be insignificant surficially, too many acres of marshland have already been lost. By careful planning during construction and operation phases of the project, this marsh can be protected from loss. Overall, development of the Squanturn site will have a minimal effect upon terrestrial biotic communities. Provid- ed that an effective barrier is used to contain leachates from the ash landfill, adjacent aquatic biota will be unaffected. Long Island — Approximately 4 ha (10 acres) of land on Long Island will be needed as a staging area during the con- struction phase only. While areas south of the state mental hospital are available, they are not suitable due to the steep slopes which parallel the water/land interface. The area north of the state hospital is topographically more suitable. Biotic impacts will not be significant and will be short-term (the area will be restored following staging operations). However, land Ownership problems may be restrictive because the land is under the jurisdiction of the hospital. If access to a site north of the hospital cannot be gained, then staging operations will have be 5—40 ------- restricted to the other construction areas (Deer Island and Nut Island). Another component of the project which will cause sig- nificant biotic impacts is the dredging of the harbor asso— ciated with the construction of two bay crossings and one outfall pipeline. In terms of displacing the benthic biotic community, approximately 32.4 ha (80 acres) of bay bottom (hence benthic organisms) lie in the direct path of the pipe- lines and would be lost along with the dredge spoils. An even greater area of bay bottom would be affected by sedi- mentation. Many forms would be smothered while other (more motile forms) will adjust to the level of the sediment. While the short-term effects would be significant, berithic recovery would occur over several seasons. The placement of clean backfill over the pipes may result in an ultimate improvement over existing conditions. Other biotic impacts would result from the construction of relief sewers and a landfill for digested sludge. While the location and magnitude of these effects cannot be accu- rately determined at this point, they are expected to repre- sent significant displacement. In the case of relief sewers, construction rights-of-way will be restored following con- struction. While some losses of nature vegetation will probably occur, these impacts are primarily short—term in nature. Again, see Section 3.5-3 for a first approximation analysis. 5—41 ------- 5.7 SOCIO-ECONOMIC EFFECTS Implementation of the Recommended Plan can be expected to have significant socio-economic impacts, both positive and negative. The positive impacts will be primarily associated with construction employment and increased commercial activity in the vicinity of the staging areas. Construction of the recommended project will require approximately 4,400 man years of construction labor. At an average wage rate of $25,000 per man year, this amounts to approximately $110 million in wages that would be dispersed over a two to four year period. Substantial portions of this money would be spent locally, thereby increasing employ- ment in other sectors of the economy. In addition, sustained employment of 385 persons for operation and maintenance of the facilities, at an average salary of $14,500 annually, would account for $5.6 million in regional income per year. Other positive impacts of the proposed project result from the availability of Nut Island for recreational pur- poses. This, plus the elimination of a Quincy Bay discharge will greatly increase the attractiveness of the Quincy Bay area for revenue-generating recreational uses. Negative impacts associated with the Recommended Plan include the removal of land from municipal tax rolls and possible devaluation of the property value (or usefulness) of the areas adjacent to the Squantum site. Specifically, implementation of the Recommended Plan would result in the removal of 28.3 ha (70 acres) of land from the tax rolls of the City of Quincy. Since this land is now assessed at a rate of $.l0 per square foot and taxed at the rate of $187.20 per thousand dollars of assessed value (personal communica- tion with Jim Papile, Tax Assessor, City of Quincy, on May 19, 1978), the actual tax loss to the City of Quincy would be about $57,000 annually. The actual loss of future taxes could be even greater, not only because the Plan pre- cludes future residential development on the site, but also because the location of facilities at Squantum could diminish the attractiveness of adjacent land for residential develop- ment. This adjacent land is now zoned for Planned Unit De- velopment. It is not possible to quantify these potential losses accurately at this time, but they could be signifi- cant. The specific reasons for this impact relate to the 5—42 ------- operation of the site as a landfill (visual impact); the increased vehicle traffic which will be involved in trans— porting chemicals, sludge and compost; and the possible nuisance conditions (chiefly odors) from the composting activity. Chapter 6 discusses mitigating measures which can greatly reduce these adverse effects. The proposed pro- ject, by the inclusion of a 5.2 meter (17 foot) berm in its design, will minimize visual impacts. However, the place- ment of high rise residential structures on the adjacent par- cel would negate the shielding effect of a berm for upper story residents. Another potential negative impact in the localized effect of street closure on local businesses in the vicinity of sewer line construction. For the areas surrounding Boston Harbor, this does not seem to be a problem since very little construction will occur in or near streets. However, for inland interceptor relief projects, the potential for impact is significantly greater. The construction of sewerage facilities in many parts of the country is often associated with secondary (on in- duced) impacts. Typically, the installation of needed sewer capacity where it was formerly a limiting factor serves as a catalyst for significant population growth. This growth often results in negative environmental impacts to a far greater degree than those associated with sewer construction itself. Therefore, the potential for secondary impacts was evaluating for the recommended project. This was done by evaluating the expected rate of growth for all MDC communi- ties from 1975 to 2000 (Appendix 5.7). Communities with an annual growth rate exceeding 3 percent may be suspected of showing induced growth. An annual growth rate of less than 3 percent would indicate a growth rate not stimulated by sewerage facilities. This analysis indicated that all MDC communities, except one, show growth rates less than 3 per- cent annually. This one exception is Dover, whose population is expected to increase 4 percent annually from 1975 to 2000 (using 1975 as the base year for calculation, i.e. total growth is projected to be 25x4 percent = 100 percent). How- ever, Dover is not expected to contribute flow to the sewer- age system until after 2000. Hence, the high growth rate of the Town of Dover must be ascribed to other factors. Overall, it does not appear that the proposed project will cause second- ary, induced-growth impacts to any significant degree. 5—43 ------- 5.8 CULTUBAL RESOURCES In order to determine if documented cultural resources are present in the proposed construction areas in Deer Island and Squantum, a preliminary analysis of State records and files was performed. For historical properties, this includ— ed examination of the site location maps and files of the Massachusetts Historical Commission. This material locates and describes sites on the National/State Register of His— toric Places, as well as properties documented by local his- torical commissions. For aboriginal sites, the site location maps and files of the Massachusetts Historical Commission’s staff archae- ologist were reviewed. Additionally, the site maps of the State archaeologist (Bronson Museum), were also checked and correlated with the above data. Finally, the Massachusetts Landscape and Natural Areas Survey, prepared by the Massachusetts D.E.M. Office of Plan- ning, was examined for possible identification of Historical/ Aboriginal properties. None of these sources nor field visits to the sites indicated the presence of any cultural resources in the proposed Deer Island and Squantum construction areas. It is recommended that a more intensive field survey of these sites, as well as the interceptor relief alignments and landfill site, be conducted during facility planning. 5—44 ------- 5.9 RECREATIONAL AND SCENIC SITES The Recommended Plan will have both positive and nega- tive effects on recreational sites and recreation in the study area. Negative effects can be attributed to the total loss of Deer Island for recreational use. The Boston Harbor Islands Comprehensive Plan (MAPCI 1972) proposed recreation- al uses for those portions of the Island not used by the Er4MA-recornmended expansion. Specifically, the drurnlins were suggested as a vantage point from which the harbor can be viewed. The Fort Dawes area was recommended for use as a passive recreational area. However, the presence of a large treatment facility at the northern end of the Island is con- sidered to diminish somewhat the value of an immediately adjacent recreational area. It should also be noted that the MAPC, in formulating its recommendations, acceded to the plans for expansion of the two presently existing uses (the prison and treatment plant) on the Island. Perhaps the trade—offs which are inherent in the Recommended Plan will also be acceptable to the MAPC and other Boston Harbor Island Plan supporters. Positive recreational impacts will result from the demolition of most of the Nut Island treatment facilities and the availability of this area for recreational use. Also, in the future, the Squantum site will be available for reversion to recreational use when the design capacity of the ash landfill has been reached (about 20 years). In a general sense, the recreational use of the harbor and the inland rivers will be enhanced by the improvements in the wastewater effluent quality, reduction in pollutant loads, elimination of sludge discharge and the reduction in wastewater overflows and bypasses. On balance, the construction of the Recommended Plan would appear to positively affect the status of recreational sites and recreation in the study area. Although the future construction of relief sewers may cause specific local ad- verse effects, these can be mitigated through careful facil- ities planning. 5—45 ------- 5.10 SITES OF SPECIAL SIGNIFICANCE Included under sites of special significance are designated historic preservation areas, pre-historic aborig- inal sites and significant natural areas. The construction of harbor-based facilities (treatment facilities, bay crossings, outfalls) will not affect any documented or recorded historic sites. Similarly, no known aboriginal sites are recorded on either Deer Island or Squantum. However, a detailed field survey of thse sites, especially Deer Island, should be conducted during facilities planning to determine if any unrecorded aboriginal sites are present. While this is unlikely due to the extremely dis- turbed nature of both sites, the discovery of such a site would require proper mitigation (removal of artifacts or recording of data). With respect to singificant natural areas, no sites on the National Registry of Natural Landmarks will be impacted by the proposed action. One site (Deer Island) on the Massachusetts Landscape and Natural Areas Survey will be impacted as discussed previously. 5—46 ------- 5.11 SIGNIFICANT ENVIRONMENTALLY SENSITIVE AREAS Significant and/or sensitive components of the environ- ment are described in Chapter 2, Environmental Inventory. A summary of impacts on these features is summarized below: Geology — Over one hundred drumlins have been identi- fied as distinctive geologic features in the Boston area. The Recommended Plan impacts the two drumlins present on Deer Island. The Boston Harbor Islands Plan will serve to protect the remaining drumlins which form most of the Harbor’s Islands. Surface Waters — Water quality will be positively impacted by the Recommended Plan. In addition to water quality improvements, no water areas will be lost by fill- ing any harbor areas. Recharge Areas The proposed project will not involve the permanent construction of any facilities on recharge areas. Wetlands - Construction at Deer Island and Squantum will not result in the displacement of any salt marsh areas. These wetlands are found on the perimeter of both sites but should be minimally affected by facilities construction. A small wetland area exists within the Squantum site but is not flushed by the tide. Hence, it makes no detrital constribution to the bay ecosystem. During relief sewer construction, some inland freshwater wetlands may be temporarily distrubed. However, proper facilities planning should minimize these disturbances and mitigate any long term effects. Steeply Sloped Areas - It is not anticipated that any facilities (except for minor segments of relief sewers) will be constructed on steeply sloped areas. Forests and Woodlands - Harbor facilities will not affect forests and woodlands. Relief sewers will traverse wooded areas to a significant degree and will impose sig- nificant effects. 5—47 ------- Air Quality - Since Boston is designated as a non- attainment area, every effort has been made to reduce air emissions from the recommended project. This has been done by maximizing the amount of sludge to be disposed of by composting and landfilling. However, incineration still represents the major method of sludge disposal. The result- ant increased emissions will remain within permissible limits and standards,except for the secondary TSP standard. Habitat of Rare or Endangered Species - The Recommended Plan will not result in the loss of any significant habitat for rare or endangered species. Again, caution during facilities planning can minimize this effect resulting from relief sewer construction. Public Use/Cultural Resource Sites - Cultural resource sites will not be affected by the construction of harbor facilities. Public use sites will be both negatively affected (Deer Island) and positively affected (nut Island). 5—48 ------- CHAPTER 6 MEASURES TO MITIGATE ADVERSE IMPACTS As discussed in Chapter 5, the Recommended Plan is ex— pected to result in a number of adverse environmental effects. It is the function of this Chapter of the ElS to present feas— ible recommendations which can significantly minimize these impacts. These are listed below: 1. The possible adverse effects of wastewater chlorina- tion are presented in Chapter 5. Several alternatives exist which can serve to both disinfect the effluent and minimize the adverse effects of chlorine. The simplest option is to eliminate the chlorination step during that period of the year when the harbor is little used for water-contact recrea- tion, Labor Day to Memorial Day. During the summer season, effluent could be both chlorinated and then dechlorinated (using sulfur dioxide). The additional cost of dechlorina- tion would be more than offset by the savings realized from the elimination of chlorine addition for nine months each year. The rationale behind the seasonal chlorination concept is that, in addition to killing bacteria in the wastewater, chlorine residuals also kill “normal” harbor microorganisms which would otherwise prey upon and deplete the sewage bac- teria. Because seawater has been demonstrated to be a hostile environment for sewage bacteria, the practice of chlorination only when human contact with the diluted effluent may occur quickly has received ever-increasing support. The recently discovered harmful effects of chlorine and chlorinated hydro- carbons has strengthened this position. Other options include year round chlorination and de- chlorination; the use of an alternative disinfectant during summer months (such as permanganate or ozone); and the use of a low-level chlorine dose (which could be quickly diffused to a sub-toxic level). This study recommends that these alternatives be exam- ined with respect to cost and feasibility during facilities planning. Environmental considerations would seem to favor the first approach (chlorination and dechlorination during the summer season only). In addition to the water quality and biotic benefits, a savings in resources (chemicals) and transport requirements will be realized. This should be coupled with a coliform monitoring program to test the effi- cacy of this approach and to safeguard the public health. 6—1 ------- 2. The Recommended Plan will continue the present prac- tice of exporting water from inland river basins to the har- bor. The analysis of water losses shows that losses due to inflow and infiltration (I/I) greatly exceed net water export values. Hence, efforts which will reduce I/I will tend to significantly mitigate the effect of water export. It is recommended that, wherever possible, the cost of developing additional water supplies should be figured into the cost/ benefit analysis for I/I removal. Furthermore, water conservation programs (both voluntary and involuntary) should be promoted. The MDC, acting as both a sewer and water authority, is in an ideal position to ad- vance this concept. For example, the MDC should seek the enact- ment of new plumbing codes which specify the installation of water saving devices in new homes. The MDC should also actively campaign toward the education of the public concerning the need for water conservation and what steps can be economically and easily taken to save water. Further details can be found in Chapters 3 and 4. 3. Another way in which groundwaters are often lost is by lateral movement along the outside sewer pipes. That is, sewer pipes are often installed by placing them in a bed of coarse porous gravel. Since the pipes are often placed to allow water to flow by gravity, the gravel beds can act as large subsurface drains and result in the loss of water from aquifers and recharge areas (the water travels down the gravel bed until it can reach a surface stream in which it is soon transported to the harbor). In order to avoid this situation, a plug of impermeable material (such as clay) should be placed around the sewer pipe (in lieu of the gravel bed) for 1.5 m (5 ft) of pipe length on every third pipe section. 4. This project attempts to mitigate air quality impacts by maximizing the disposal of sludge by marketing or giving away a composted product. Therefore, the success of the corn- posting operation is important in ultimately keeping air emis- sions as low as possible. In order to enhance the feasibility of this program, the MDC should actively publicize the avail- ability and virtues of composted sludge. This includes pro- viding leaflets instructing the public in its proper use and contacting other institutions, agencies, and commercial organi- zations concerning the use of composted sludge. Since the use of composted sludge is a relatively new idea on this scale, the program must be actively promoted. In order to enhance the quality (hence, the usefulness) and market potential) of the composted sludge, the MDC should investigate additional methods of reducing its metal content. 5. To ensure that the National Ambient Air Quality Standards and any other applicable regulations are maintained, an air monitoring station should be placed in the vicinity 6—2 ------- of Deer Island. This station would ensure constant surveil- lance of air quality in order to prevent air quality violations due to incineration. 6. In order to mitigate the effects of dredgingin the Harbor, the use of a specially designed dredging barge should be investigated. The barge would be equipped with legs which are lowered to stabilize the barge once it is properly posi- tioned. Steel sheeting is then driven around the front and sides of the barge and the trench section below is excavated. Utilization of sheeting will reduce the volume of material excavated, decreasing the number of barge trips necessary for disposal and the cost of the harbor crossing. The volume of backfill required also is reduced, as well as the cost of this operation. In addition localized sedimentation and siltation impacts are limited to the area within the sheets. Under actual operating conditions elsewhere, the cost of this method, has been shown to be competitive with other, more conventional approaches. 7. In addition to providing cornposted sludge for public pick-up at Squantum, the MDC should truck compost to dispersed distribution sheds located through the study area. These sheds could be located on MDC parkiand or other public land. This will greatly reduce traffic into Squantum; will reduce total travel and air emissions; and will increase the market for compost. 8. To further mitigate impacts on the adjacent PUD zone at Squantuin, coniposting operations should be conducted on that part of the site farthest from the PUD zone. Also, the berm nearest the PUD zone should be well screened with vege- tation to shield the site to a maximum extent possible. Ash placed in the landfill shouldbewetted and covered with soil as needed to prevent dust and wind erosion. Compost piles should not be broken down for movement to curing areas when the prevailing wind is in the direction of the PUD zone. 9. In order to minimize the effect of increased traffic through Winthrop to Deer Island, the maximum use of water transportation to move materials and machinery is recommended. The feasibility of bringing construction workers to the site via shuttle bus should also be investigated. If workers can be brought in from outlying parking areas, traffic could potentially be reduced from 2000 vehicle round trips to 50 vehicle round trips (at 40 workers per bus). 6—3 ------- 10. To mitigate impacts upon the seasonal recreational use of the harbor, construction activities should be sched- uled to avoid intensively used recreational areas during the peak—use season. 11. To minimize the loss of terrestrial biota during the construction of relief sewers, a minimum right-of-way width should be employed. A maximum width of 15 to 23 m (50 to 75 ft) is recoiimiended in vegetated areas. 12. To insure the sludge landfill does not contaminate underlying groundwaters, a series of monitoring wells should be installed around the landfill site. A water quality sampling program should be maintained to guard against the degradation of groundwater. 6—4 ------- CHAPTER 7 ADVERSE EFFECTS WHICH CANNOT BE AVOIDED This chapter of the EIS recognizes that the Recommended Plan will result in some adverse impacts on the environment which cannot be mitigated or avoided. These are summarized below in qualitative terms. While water quality conditions are expected to generally improve, the proposed effluent discharge will still introduce organic and inorganic pollutants to the harbor. Specifically, the total loading of cadmium, mercury and nickel into Presi- dent Roads from the effluent discharge will increase margin- ally over present conditions. (This ignores the present sludge discharge). However, these metals should be quickly diluted to acceptable levels. Other unavoidable water quality effects include the intro- duction of silt, organics and metals to the harbor from the bottom muds during dredging operations. The increased export of water from inland river basins to the harbor can be viewed as an adverse effect. Strictly speaking, this effect is avoidable through water conservation measures and through the reduction of inflow and infiltration. However, it is not likely that this effect will be completely mitigated by these measures. Hence, net water export will probably represent an adverse effect. This impact should be manageable and, if sincere efforts are made by the MDC and the public, it should be minimal. In any event, severe impacts on local water supplies and river flows are not fore- seen. The Recommended Plan attempts to minimize air quality impacts through the use of alternate sludge disposal methods, thereby relying on sludge incineration to the least degree possible. However, air emissions from sludge incineration will be significant and will represent an unavoidable adverse effect. Similarly, air emissions resulting from additional barge, truck and automobile traffic are unavoidable. Noise impacts during construction (especially along interceptor sewers) are unavoidable. However, during facili- ties operation, noise impacts should be minimal. Unavoidable adverse impacts on the area’s biota will result from the permanent displacement of existing biotic communities at Deer Island, Squantum and at the recommended 7—1 ------- sludge landfill. Unavoidable short-term impacts will result from dredging the harbor and the construction of relief sewers through vegetated areas. Additional short-term effects may result from the use of a Long Island site for staging opera- tions and the storage of backfill material in the bay. With respect to socio—economic effects, the negative f is- cal impact of taking the Squantuxn site for a tax exempt use is unavoidable. Also, the recommended use of the Squantuin site may hamper a developer in marketing units in the adjacent PUD zone. At such time when residents occupy the PUD zone, high-rise residents may be affected by the visual impact of the ash landfill and compost operation. In terms of recreational and scenic areas, the loss of Deer Island (particularly the drwnlins) for recreational pur- poses will represent an unavoidable adverse impact. 7—2 ------- CHAPTER 8 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF RESOURCES The construction, operation and maintenance of the Recommended Plan is expected to result in the irreversible and irretrievable commitments of resources. These major resources include land, energy, chemicals, dollars and labor. In addition to these items, other resources which are diff i- cult to quantify will also be committed. These include such things as cement, aggregate, backfill, etc. They are, how- ever, reflected as costs. Labor — Labor is considered a resource whose commitment to this project is irreversible. That is, once labor (which could be spent in other ways), is committed to this project, it isa resource that has been expended in an irretrievable manner. This project will require approximately 4,400 person years for the construction of the proposed facilities (this does not include inland relief sewers). For operation and maintenance, a permanent staff of 384 persons will be needed. Energy - The energy requirement of the proposed facili- ties during the operational phase is approximately 224 million kilowatt hours per year. In addition, about 3,520 m 3 (930,000 gallons) of fuel oil will be needed annually. No estimate of energy requirements during the construction phase has been made. Land - Approximately 85.6 ha (210 acres) of land at Deer Island will be permanently committed to wastewater treatment use. Twenty-eight and five tenths ha (70 acres) at Squantum will be reversibly committed. That is, when the ash landfill reaches its design capacity, it will be restored and can revert to an alternate use. The construction of relief sewers will require permanent easements which can restrict the use of land through which the rights-of--way pass. Chemical Resources — For operational purposes, chemicals are required, in bulk, for disinfection and treatment. These commitments are quantified below. The estimate for chlorine is not adjusted in accordance with a seasonal chlorination program. 8—1 ------- Chlorine kg/year (tons/year) Lime kg/year (tons/year) Ferric Chloride kg/year (tons/year) Polymer kg/year (tons/year) Dollars - Dollars are included here in the sense that once money is appropriated, it can be considered a resource with alterative uses. Dollars also represent a common basis with which other resources can be quantified. In this sense, the cost of a project represents the sum total of all resources corr rtitted to a project. The total capital cost of the RecoIn- mended Plan is estimated at 771 million, with annual operations and maintenance costs estimated at $24.8 million. 6.5x10 6 l.3x10 7 3. 2x10 6 1.0x10 5 (7,135) (14,600) (3,500) (113) 8— 2 ------- The Metrolxlitafl District CcxrmissiOn ath the Executive Office of Envixox enta1 Affairs revie d a preliminary draft of this document. Their ca ents are nc1t iei . It should be riotel, however, that a number of changes re made to the “preliminary draft” eis before it was printeL These changes re made in response to caiirtents frau the State of Massachusetts arxi the Boston Harbor Citizens ? visory Carmittee. 8—3 ------- c97Ti 12 ii 2 ii / J lie 1o12m mcn, jj eattlz tai acIu eU4 c€d e o/ &vôonrnenI’a/ 2Ø u 100 amL p 9 Le J acA et/ 02202 :vELYN F. MURPHY August 1, 1978 Ms. Rebecca Hanjner Deputy Regional Administrator U.S.Environmental Protection Agency J.F.Keimedy Federal Building Boston, Massachusetts 02203 Dear Ms. Hanmer: This letter presents some initial comments by both the Executive Office of Environmental Affairs and the Metropolitan District Commission on the Preliminary Draft Environmental Impact Statement (EIS) on MDC’S Mk Plan for Upgrading of Facilities of the Metropolitan Sewerage District. We appreciate the opportunity to review this document and to have our comments included as part of the Draft EIS (DEIS). As time for this review has been rather short, this letter presents only a tentative response to the Preliminary Draft. The Executive Office of Environmental Affairs and its various Departments and Divisions, including the Metropolitan District Commission, will utilize the sixty-day federal review period for a more thorough analysis of the data in the DEIS and the recommendations based upon them. We recognize that the magnitude of the proposed upgrading of the Metropolitan Sewerage Systems and the complexity of the environmental impacts associated with the alternatives considered makes a more thorough and complete evaluation imperative. As the implementation of any one of these alternatives may come within the purview of a number of EOFA agencies, it is essential to assess potential impacts upon agency programs and, where necessary, to weigh trade-offs between conflicting goals. Thus, while we must defer acceptance of any specific plan for the Metropolitan Sewerage System, the Executive Office of Environmental Affairs and the Metropolitan District Commission offer the following comments on the Preliminary Draft ETS: I. General Comments 1. The EOEA and the MDC appreciate the difficulty of finding a treatment plant site or sites in the metropolitan area suitable for the expansion SECRETARY 8—4 ------- -2- of the system as required by the Federal Clean Water Act. The EPA has generated and evaluated a sizable array of additional sites for primary and secondary treatment of the flows from the Metropolitan Sewerage District EMSD). However, we believe that the assessment of the sites and the screening of alternatives still requires further analysis. When the E?4 1A Plan was completed, a number of wastewater treatment issues were identified that remained to be resolved. Foremost among these were: the locations and impacts of the satellite treatment plants and related interceptor relief sewers, the need for secondary treatment at the harbor plants in terms of costs and environmental impacts rather than legislated requirements, and means for expanding the Deer Island and Nut Island plants considering the impacts of filling in the Harbor and the intended recreational use of the Harbor Islands. The environmental impacts associated with these issues have not been thoroughly evaluated in the Preliminary Draft EIS. 2. The EIS represents a departure from the usual procedure of preparing an EIS on a treatment plant after completion of Step 1 facilities planning. The sequence followed in this ETS approximates the process of hItiering! recently proposed by the Council of Environmental Quality which provides for a progranmatic EIS with more detailed analysis of site specific impacts during or after the Step I Facilities Planning. We feel that such an approach is appropriate for a regional system such as the MSD. However, further determinations are still necessary to identify which system components and/or alternatives may result in unacceptable negative impacts upon the environment. 3. The EOEA recognizes, therefore, that this document represent a preliminary evaluation of environmental impacts of particular combinations of coastal and of inland treatment plant alternatives. Although a great deal of work has gone into such elements as the modelling of water-quality impacts of satellite treatment plant discharges, we expect the plan recommended in the Draft EIS to be modified as a result of the comments received during the formal review period from EOEA, other state agencies, local officials, and from the public. The analysis conducted during the Step I planning which will begin soon is expected to resolve the outstanding issues, provide additional environmental analyses and produce an acceptable plan for the improvement of MSD wastewater treatment facilities. At this time we have a number of more specific coan ents to make based on review of the Preliminary Draft EIS. II. Specific Comments 1. While the Recommended Plan appears to be an all Deer Island solution, it necessitates the operation of two separate plants at Deer Island as well as several scattered sites for conveyance, treatment and disposal. 8—5 ------- -3- The segregation of flows from the northern and southern parts of the MSD are proposed in order to dispose of the sludge in various ways. The duplication of facilities and the added costs required by the two plants at Deer Island have not been identified. The operation of several sites, widely-separated processes, and various transpor- tation modes are likely to create severe managerial problems. Little or no information is given on the amount and availability of land, the energy requirements, and the legal arrangements for implementation of the Recouuiiended Plan. Some of the other major elements of the Reconmended Plan, require evaluation of their environmental impacts. These include relieving the High Level Interceptor and other interceptors, construction of a pipeline from Long Island to Nut Island, a single discharge location, leveling of the drumlin, elimination of recreational use at Deer Island, and site determinations for composting sludge. 2. While it is important to retain composting as an option for the disposal of sludge, the method devised in the Preliminary Draft seems cumbersome and costly. Other alternatives for developing a composting facility should be identified and evaluated. In this regard, the experience of USDA indicates that composted sludge requires a bulking agent, such as wood chips. The compost alternative should include the availability of wood chips, their cost, and the resulting increased volume of compost. 3. In the analysis of Harbor treatment plant sites, a number of problems are evident. In the Preliminary Draft, certain sites were eliminated primarily because of a conflict with the Conmionwealth’s Boston Harbor Islands Plan. However, the Recomended Plan does not conform with the Harbor Islands Plan. In fact, the Preliminary Draft overlooks the importance of Deer Island as the only island in Boston Harbor with a shoreline to open ocean waters that is accessible by land and available for recreational development. The potential recreational and open space use- of all sites should be considered in compliance with EPA requirements. 4. The discussion in the Preliminary Draft of the potential impacts of effluent discharge from inland treatment plants does not seem compelling enough to eliminate satellite plants from consideration as components of the MSD. The impacts of the discharges from the satellite plants into the rivers are discussed in terms of a single parameter, dissolved oxygen, as determined by mathematical simulations. The specific ecological effects of failing to meet the dissolved oxygen criteria are not described nor are methods examined for compensating for this projected deficiency. The adverse and beneficial impacts of dissolved oxygen and other water quality parameters as well as the impacts on potential sites should be delineated. 8—6 ------- The beneficial environmental impacts of satellite plants, such as retaining wastewater in the basin of origin, decentralization of treatment plants, and options for sludge disposal (land application, cotreatment,composting) have not been evaluated. Most importantly, opportunities for reuse, which satellite plants will provide and an all-harbor solution will preclude, have not been considered. The EOEA will devote a great deal of attention during the review period to assessing the potential impacts of these systems on water quality of the Charles and of the Neponset Rivers. 5. The Preliminary Draft in several instances reflects a misunderstanding of the EM LA Plan. The ENMA Plan does not promote expansion of DC’s service area or the building of capacity for future growth. The basis of the plan is the provision of adequate treatment capabilities and interceptor capacities for present member communities. The D1 ’L-\ Plan could accommodate flows from additional peripheral communities, should these communities decide to develop sewerage systems, without significant increase in the size of treatment plants. For example, Lincoln, Lyrmfield, and Weston, if sewered, would contribute only slightly more than one percent of the projected 400 mgd average flow at an improved Deer Island Plant. Similarly, low flow augmentation was not one of the main objectives for recommending satellite plants. Low flow augmentation was an environmental benefit derived from this recommendation. In conclusion, we regard the Recommended Plan as another alternative for the treatment and disposal of wastewater, which warrants careful study by EO , MDC, other governmental agencies and the general public. We fully expect this alternative along with other alternatives to be carefully evaluated during Step 1 Facilities Planning conducted by the MDC. We are confident that that the Step 1 process, which includes ample public participation, can serve as the framework for, reaching a decision on an environmentally sound, cost-effective, publicly supported plan for improving the MDC wastewater treatment plants. Both EOEA and MDC look forward to a productive formal review period and are ready to assist in encouraging public comment on the DEIS. Sincere lv yours, ‘ Eve lvr F Executive Office of Environmental Affairs cc: W.Adams, EPA 8—7 R.Thompson, EPA W.Stickney, EPA Joim P. Snedeker Commissioner ------- BIBLIOGRAPHY Anderson — Nichols and Company, Inc., Neponset River Basin Flood Plain and Wetland Encroachxneiit Study . Boston, Massachusetts, 1971. “A Seasonal Survey of the Fishes in the Mystic River, a Polluted Estuary in Downtown Boston, Mass.” Estuarine and Coastal Marine Science , Vol. 2, pp. 59-73, 1974 Brackley, R.A., W.B. Fleck and W.R. Meyer, “Hydrology and Water Resources of the Neponset and Weyinouth River Basins.” Hydrologic Investigations Atlas MA-487 . U.S. Geological Survey, Washington, D.C., 1976. Beauregard, D.C., Mystic River, 1973 Water Quality Analysis: Part C , Water Quality Section, Division of Water Pollu- tion Control, Mass. Water Resources Commission, West- borough, Mass., May, 1975. Benesh, F.H., K.W. Wiltsee and R.D. 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EMMA Study Technical Data Volume 3 Industrial Process Wastewater Analysis and Regulation for the Metro- politan District Commission, Commonwealth of Massachusetts, Boston, Massachusetts, October 1975c. 9—9 ------- BIBLIOGRAPHY (Continued) Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor — Eastern Massachusetts Metropoli- tan Area. EMMA Study Technical Data Volume 3A Study of Certain Industrial Wastes for the Metropolitan flis- trict Commission, Commonwealth of Massacriusetts, Boston, Massachusetts, October l975d. Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor — _ Eastern Massachusetts Metropoli- tan Area. EMMA Stu4y _ Technical Data Volume 3B Study of Wastes . from Large Industries for the Metropolitan District Commission Commonwealth of Massachusetts, Boston, Massa- chusetts, October 1975e. 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Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor - Eastern Massachusetts Metropoli- tan Area. EMMA Study Technical Data Volume 9 MDC Inter- ceptor and Pumping Station Analysis and Improvements , for the Metropolitan District Commission, Commonwealth of Massachusetts, Boston, Massachusetts, October 1975i. Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor - Eastern Massachusetts Metropoli- tan Area. EMMA Study Technical Data Volume 10 Deer Island Wastewater Treatment Plant Analysis Improvements for the Metropolitan District Commission, Commonwealth of Massa- chusetts, Boston, Massachusetts, October 1975j. 9—10 ------- BIBLIOGRAPHY (Continued) Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor — Eastern Massachusetts Metropoli- tan Area. EMMA Study Technical Data Volume 11 Nut Island Wasteater Treatment Plant Ana1 (sis and Improvements for the Metropolitan District Counnission Commonwealth of Massachusetts, Boston, Massachusetts, October 1975k. Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor — Eastern Massachusetts Metropoli- tan Area. EMMA Study Technical Data Volume 15 Recommended Plan and Implementation Program for the Metropolitan Dis- trict Commission, Commonwealth of Massachusetts, Boston, Massachusetts, October 19751. Metcalf and Eddy, Inc., Wastewater Engineering and Management Plan for Boston Harbor - Eastern Massachusetts Metropoli- tan Area. EMMA Study Technical Data Volume 16 Agency Reviews for the Metropolitan District Commission, Common- wealth of Massachusetts, Boston, Massachusetts, October 197 Sm. Metropolitan Area Planning Council, Open Space and Recreational Plan and Program for Metropolitan Boston . 4 Volumes, 1969. 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