DRAFT
ENVIRONMENTAL IMPACT STATEMENT
WASTEWATER COLLECTION AND TREATMENT FACILITIES
NEW SHOREHAM, RHODE ISLAND
United States
Environmental
Protection Agency
Region I
JOHN F. KENNEDY FEDERAL BUILDING - GOVERNMENT CENTER - BOSTON, MASSACHUSETTS 02203
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15620
DRAFT
ENVIRONMENTAL IMPACT STATEMENT
WASTEWATER COLLECTION AND TREATMENT FACILITIES
HEW SKOREHAM, RHODE ISLAND
Prepared By
U.S. Environmental Protection Agency
New England Region I
John F. Kennedy Federal Building
Boston, Massachusetts 02203
ional Administrator
?J
1
^
Date/ /
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This Environmental Impact Statement (EIS) has been prepared pursuant
to P.L. 91-190, the National Environmental Policy Act (NEPA) of 1969, and
Executive Order 11514,"Protection and Enhancement of Environmental
Quality" dated March 5, 1970. Both NEPA and Executive Order 11514 require
that all Federal Agencies prepare such statements in connection with their
proposals for major Federal actions significantly affecting the quality of
the human environment.
This EIS has been prepared in accordance with the regulations and
guidance set forth in the President's Council on Environmental Quality
(CEQ) Guidelines dated August 1, 1973, and the U.S. Environmental Protec-
tion Agency's (EPA) Interim Regulation, CFR 40-Part 6, dated January 17,
1973; both concerning the preparation of Environmental Impact Statements.
Under the statutory authority of P.L. 92-500, the Federal Water Pollu-
tion Control Act Amendments of 1972, the EPA is charged with administering
Federal financial assistance for the construction of publicly-owned waste-
water treatment facilities and their appurtenances. In addition, the EPA
will issue permits to municipal governments to allow the discharge of
treated wastewater effluent into navigable waters in such a manner as to
protect the health and welfare of the public and the environment.
P.L. 92-500 further establishes a national goal of eliminating the dis-
charge of pollutants by 1985, and wherever attainable, an interim water
quality goal by July 1, 1983, which provides for the protection and propa-
gation of fish, shellfish, and wildlife, and provides for recreation in
and on the water.
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For the purposes of the Environmental Impact Statement, EPA, Region I,
Boston, Massachusetts is the "Responsible Federal Agency" as required by
the National Environmental Policy Act.
To insure that the public is kept fully informed regarding this action,
and that it participates to the fullest extent possible in the Agency's
decision-making process, this Draft EIS is being circulated for a 45-day
review as required by the CEQ, August 1, 1973 Guidelines. In addition, a
public hearing is scheduled to be held in the near future.
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TABLE OF CONTENTS
LIST OF TABLES
LIST OF MAPS viii
LIST OF APPENDICES lx
SUMMARY x
REPORT
1.0 INTRODUCTION 1
1.1 Background 1
1.2 Other Proposed Actions 2
2.0 EXISTING ENVIRONMENT 4
2.1 Historical Background 4
2.2 Physical Inventory 5
Climate 5
Topography 5
Geology 6
Groundwater g
Water Quality 9
Noise Levels 12
Air Quality 13
Fish and Wildlife 13
Environmentally Sensitive Areas 15
2.3 Utilities and Other Community Facilities 16
Water . 15
Sewer . 16
Gas 16
Electricity 16
Telephone 16
iii
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CONTENTS (Cont.)
Refuse Disposal 17
Other Facilities 17
2.4 Growth and Land Use Analysis 17
Populations and Socio-Economic Trends 17
Existing Land Use 19.
State and Local Land Use Plans 20
Existing Zoning 23
Analysis of Existing Plans, Policies
and Zoning 24
Growth Assumptions 24
3.0 ALTERNATIVES 27
3.1 Alternative Treatment Plant Locations 27
3.2 Multiple Facility Alternatives 28
3.3 Treatment Process Alternatives 28
Extended Aeration 29
Modified Activated Sludge 29
Aerated Lagoon 29
Stabilization Pond 31
Physical Chemical Treatment 31
Land Disposal 32
Summary of Treatment Methods 32
3.4 Outfall Location Alternatives 34
3.5 Sludge Disposal Alternatives 34
3.6 Flow Reducing Alternatives 35
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CONTENTS (Cont.)
4.0 IMPACT OF ALTERNATIVE ACTIONS 36
Alternative Wastewater Flows . 36
4.1 . No Action Alternative 37
Description 37
Primary Impacts 37
Secondary Impacts 38
4.2 Alternative A - Fenton Keyes Proposed Project 38
Description 38
Social Impact 39
Technical 40
Environmental Impacts 42
Economic Impacts 45
Political and Legal/Institutional Impacts 46
Secondary Impacts 47
4.3 Alternative B - Proposed Project Minus Stage II 50
Description 50
Primary Impacts . 50
Secondary Impacts • 51
4.4 Alternative C - Rehabilitation of Individual 53
Subsurface Disposal Systems
Description 53
Social Impacts 54
Technical 54
Environmental Impacts 54
Economic Impacts 55
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CONTENTS (Cont.)
Political and Legal/Institutional Impacts 56
Secondary Impacts 56
4.5 Alternative D - Sewer System for Old Harbor 57
Description 57
Social Impacts 57
Technical 57
Environmental Impacts 58
Economic Impacts 58
Political and Legal/Institutional Impact 58
Secondary Impacts 58
5.0 PREFERRED ALTERNATIVES 60
6.0 PROBABLE ADVERSE IMPACTS WHICH CANNOT BE AVOIDED 64
6.1 Primary Impacts 64
Alternative B 64'
Alternative D 64
6.2 Secondary Impacts 64
Alternative B 64
Alternative D 65
7.0 SHORT TERM VERSUS LONG TERM PRODUCTIVITY 66
8.0 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF RESOURCES 67
APPENDICES
vi
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LIST OF TABLES AND CHARTS
Table Page
1. Water Quality Standards for Sea Water ]]
2. Noise Levels on Block Island January 1975 12
3. 1970 Air Sampling Data, Block Island Airport 13
h. Comparison of National Primary and Secondary 14
Standards and Rhode Island Air Quality
Standards
5. Population 17
6. Labor Force . 18
7. Housing Characteristics 19
8. Existing and Proposed Land Use 22
9. Growth Assumptions 26
10. Average Costs for 300,000 Gal/Day Treatment 29
Facilities in Southern New England
11. Comparative Equivalent Service Area Population 35
and Wastewater Flows
12. Actual Numbers of Units and Persons to be 37
Served Under Alternative A
13. Annual Costs of Alternative A 45
lU. Comparison of Development Trends in Proposed 47
Sewer Service Area
15. Estimated Annual Costs of Alternative B 52
16. Estimated Annual Costs of Alternative C 55
17- Estimated Annual Costs of Alternative D 59
Chart
A Comparative Summary of Treatment Methods 33
3 Comparison of Preferred Alternatives 52
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LIST OF MAPS
Following
Map ' Page
1. Area of Influence 2
2. Proposed Sewer Service Area 2
3. History, Recreation, and Tourism 6
k. Topography 6
5. Soil Characteristics 8
6. Groundwater Availability 8
7. Water Quality Classification Closure Map 12
8. Environmentally Sensitive Areas 16
9. Water Service Areas 16
10. Community Facilities- 18
11. Existing Land Use 20
12. Proposed Land Use Plan 22
13- A Proposed Zoning Map 24
ik. Existing Zoning 24
15. Alternative A 36
16. Alternative D 58
viil
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APPENDICES
Appendix Page
A Existing Water Quality • A-l
3 Watercraft Waste Regulations B-l
C Proposed. Land Use Categories C-l
D Basis of Costs for Alternative Treatment D-l
Systems
E Flow Reduction Equipment E-l
F Design Flows F-l
G FHC Waste Treatment System G-l
H Ocean Current Studies, Pebbly Beach O.utfall H-l
Location
I Cost Basis for Alternative Actions I~l
J Impact of Sewers on Specific Sectors of the J-l
Island
K Letter from U.S. Soil Conservation Service K-l
L Letter from State Historical Commission L-l
M State of Rhode Island Minimum Standards . M-l
Relating to Location, Design, Construction
and Maintenance of Individual Sewage Disposal
Systems
a Environmental Effects of Subsurface Disposal N-l
on Groundwater Quality
Ix
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SUMMARY
1. Type of Action
(x) Administrative (x) Draft Environmental Impact Statement
( ) Legislative ( ) Final Environmental Impact Statement
2. Background of Project
In August 1973 the Town of New Shoreham (Block Island), Rhode Island
applied to Region I for financial assistance under Title II of the Federal Water
Pollution Control Act, as amended (PL 92-500). The community requested a grant
for construction and reimbursement for planning and design of a wastewater
treatment facility, including sewering and construction of pumping stations.
After preparing the environmental impact appraisal as part of the review
of the proposed project, EPA determined that the project would not significantly
affect the environment and issued a negative declaration on May 6, 1974.
Before final approval of the project, Block Island residents brought three
key issues to the attention of the Regional Administrator:
1. Possible accelerated growth induced by the project,
2. Possible adverse effects of the outfall pipe on adjacent beaches, and
3. Possible adverse effects from locating the wastewater treatment
plant within a designated national historical district.
After carefully considering the potential impacts of the proposed action
in light of these locally controversial issues, the Regional Administrator
reversed his initial decision and issued a notice of intent to prepare an
environmental impact statement on September 19, 1974.
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3. Preferred Actions
After completing the environmental study and draft impact statement to
find an environmentally sound, cost effective solution for Block Island's waste-
water treatment problem, EPA has selected two preferred alternative actions.
Both systems include a municipal collection system and an extended aeration
system at the Spring Street location.
Several recommendations are made to improve the treatment plant as it
is presently designed including extension of the outfall, noise attenuation,
effluent filtration and sludge aeration.
The difference between alternatives is the extent of the area to be served.
One plan extends the collection system only to the developed Old Harbor section
of New Shoreham. The second plan extends the collection farther to include the
New Harbor area.
EPA prefers sewering only the Old Harbor area. This would encourage the
improvement arid rehabilitation of the Old Harbor area and reduce the development
pressures around the New Harbor area. Increased development around New Harbor
would cause encroachment on wetland areas. This preferred plan is in general
conformance with the objectives of the Block Island Master Plan, which include
maintaining the rural character of the Island.
Also in support of EPA's preferred alternative is the fact that the
developed Old Harbor area does not have sufficient land available to support
subsurface disposal systems. On the other hand, New Harbor has enough land and
suitable soil for existing development to rely on subsurface disposal systems.
xi
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4. Summary of Impacts
The major direct Impacts of EPA's preferred alternative are related to
construction and operation of the wastewater treatment facility and include
the aesthetic impact of locating the plant at the Spring Street site, the
temporary disruption of various parts of Old Harbor by noise and other
construction related activities, the protection of Old Harbor's subsurface
drinking water supply, elimination of odor problems from malfunctioning septic
systems, and enhancement of water quality along the recreation beaches on Block
Island.
The major indirect impact of EPA's preferred alternative is the inducement to
rehabilitate and redevelop the Old Harbor area as a result of eliminating
the existing wastewater treatment problems and potential health hazard.
5. Other Alternatives Considered
Three other major alternatives are discussed in detail in the draft
environmental impact statement, including the alternative of taking no action.
The no action alternative was determined to be unfeasible because the
failing subsurface disposal systems in Old Harbor are a potential health hazard
and produce unpleasant odors.
The project proposed in June 1973 by the Firm of Fenton Keyes Associates
was considered undesirable because it extended the sewer service area beyond the Old
and New Harbor areas, especially in Phase II. In addition, Fenton Keyes1 pro-
posed action did not appear to be consistent with the goals of the Master Plan
adopted by Block Island.
xii
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The alternative of rehabilitating the septic systems in the densely
populated area around Old Harbor was considered impractical because
there is not enough suitable land to support these systems..
Sub-alternatives discussed include various outfall locations,
treatment plant sites, types of treatment and possibilities of flow
reduction devices.
6. Distribution
Copies of the draft following Federal and State agencies.
FEDERAL
Council on Environmental Quality
United States Department of the Interior
Bureau of Sports Fisheries and Wildlife
Bureau of Outdoor Recreation
Bureau of Land Management
Geological Survey
United States Department of Agriculture
Soil Conservation Service
United States Department of the Army
Corps of Engineers
United States Department of Commerce
National Oceanographic and Atmospheric Administration
Department of Housing and Urban Development
Department of Health, Education, and Welfare
Senator John 0. Pastore
Senator Claiborne Pell
Representative Fernand J. St. Germain
Representative Edward P. Beard
xiii
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State of Rhode Island
Department of Natural Resources
Department of Water Resources
Department of Health
Historical Preservation Commission
xiv
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REPORT
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1.0 INTRODUCTION
1.1 Background
The Town of New Shoreham -(Block Island) is located in the county
of Washington, Rhode Island, approximately 10 miles offshore from the
south coast of the mainland of Rhode Island and approximately 14 miles
east of Montauk Point, Long Island. The land area is approximately 11
square miles (see Map 1). The Island is a year-round residence to 500
people and a summer residence to an additional 1,200 people. During
the average day of the summer tourist season, the Island is a refuge
to approximately 1,000 overnight guests and an equal number of day visitors.
In the past few years, there has been an increase in summer visitors
and in construction of summer residences. This growth coupled with forced
abandonment of raw ocean discharges and the lack of a municipal treatment
system has caused Islanders to resort to subsurface disposal systems.
Because of improper construction due, in part, to insufficient land
area, these systems are not functioning properly. The concentration
of a number of failing systems in the commercial area of New Shoreham
has resulted in a situation which is aesthetically displeasing to residents
and visitors. In addition, failing subsurface disposal systems are a
potential health hazard.
Because of the seriousness of the situation, the people of New Shoreham
enlisted the services of the engineering consulting firm of Fenton G.
Keyes Associates to study the problem. In February, 1972, the firm submitted
a report to the Town entitled: Preliminary Engineering Survey and Report
on the Control of Water Pollution for the Town of New Shoreham, Rhode
Island, February 1972.
On June 6, 1972, the Town Council filed a notice of intent to apply
for Federal aid for a municipal collection and treatment system and on
April 2, 1973, contracted with Fenton G. Keyes Associates to design,
supervise construction, and start operation of the wastewater treatment
system recommended in their report.
On August 17, 1973, the Environmental Protection Agency (EPA) received
an application for Federal aid from the Town of New Shoreham. The application,
based on engineering estimates, was for a total project cost of $1.8
million.
Based on the application and the proposed design by Fenton Keyes,
EPA prepared an Environmental Impact Appraisal in accordance with the
National Environmental Policy Act (NEPA). The project appraisal was
for the construction of a secondary wastewater treatment plant, interceptor
sewers, two pumping stations, associated force mains, and an outfall
aewer off the breakwater near Old Harbor. The treatment facility proposed
consisted of an extended aeration-type treatment with a design capacity
of 0.28 million gallons per day (mgd). This system was to serve both
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the Old and New Harbor areas, including marinas, and was to be adequate
for the design year of 1997. The locations of the proposed treatment
plant and service area are shown in Map 2.
Reviewing the proposal, EPA made the preliminary determination that
the funding of this project was not a major action significantly affecting
the environment and circulated a negative declaration on May 6, 1974.
Hearing no significant comment or controversy in response to the negative
declaration, EPA, in accordance with Title II, Section 201 (g)(1) of
the Federal Water Pollution Control Act of 1972, made a grant offer to
the Town of New Shoreham on May 21, 1974. The offer was accepted on
June 7, 1974.
Final plans and specifications were approved June 14, 1974 and the
job was opened to bid. On August 14, 1974, the low bid was confirmed
at $4.4 million, approximately $2.6. million higher than the engineering
estimates made a year earlier.
The higher cost of the treatment system sparked a new citizen awareness,
causing considerable controversy about the project. Issues raised were:
(1) possible accelerated growth due to a municipal collection
and treatment system;
(2) possible effects of the outfall on adjacent beaches;
(3) possible infringement of plant site on historical landmarks.
Finally, on September 17, 1974, a meeting was held in the EPA Regional
Office so that proponents and opponents of the project could air their
views to the Agency. The next day, based on the issues brought to the
attention of EPA at this meeting, a decision was made to reverse the
initial determination and to proceed with an environmental impact statement
in accordance with the National Environmental Policy Act (Section 102(2)(c).
1.2 Other Proposed Actions
The proposed wastewater collection and treatment system is an independent
action; that is, it was not proposed because of another project. It
is not anticipated that the sewage system will be the cause of another
Federal project, other than possible Stage II extension of the proposed
sewer.
However, pending EPA approval of the project, the Farmers Home Adminis-
tration (FmHA) is prepared to grant additional Federal aid for the project.
On April 23, 1973, a loan for $1,015,000 was approved and later on October
21, 1974, funds were obligated for an additional loan of $85,000 and
a grant for $220,000. The FmHA as stipulated the preparation of the
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MAP I.
NEW SHOREHAM, BLOCK ISLAND
AREA OF INFLUENCE
MASSACHUSETTS
BAY
FERRY ROUTES
AIR SERVICE
URBAN LOCATIONS
PROVIDENCE
CAPE COD
BAY
NANTUCKET
SOUND
NEWLONDON
BLOCK ISLAND
LONG ISLAND SOUND
SOURCE: ARMY MAP SERVICE
CORPS OF ENGINEERS, U.S. ARMY
WASHINGTON, D.C.
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MAP 2.
NEW SHOREHAM. BLOCK ISLAND
PROPOSED SEWER SERVICE AREA
NORTH
ROAD CLASSIFICATION
LIOMT-DUTY UNIMPROVED DIRT
STAGE I
STAGE H
SOURCE: FENTON 6. KEYES ASSOCIATES, 1972
SLUDGE DISPOSAL AT
SANITARY LANDFILL
PROPOSED SEWAGE
TREATMENT PLANT
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environmental impact statement and subsequent decisions by EPA are a
condition of final approval of the grant.
The State of Rhode Island has also made a grant offer of $140,000
as a matching fund to the EPA grant.
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2.0 EXISTING ENVIRONMENT
The history and existing environment of Block Island are described
to provide a background against which the impacts of alternative actions
can be evaluated.
2.1 Historical Background
Originally, Block Island was called by its Indian inhabitants, "Monisses,"
the "Isle of the Little God." Adrien Block, in 1614, was the first white
man to land.on the Island, but it was not until 1661 that the first white
settlement consisting of sixteen families arrived on the Island. In
1672, it was incorporated as "New Shoreham, otherwise Block Island."*
During the next 100 years, the vulnerable island was repeatedly
beseiged by pirates. When the War of Independence broke out, there were
nearly eight hundred whites, 'fifty Indians, and forty negroes living
on the Island and the prosperous little community was considered quite
a temptation to the British fleet.
After the War and through much of the 19th century, the Islanders
supported themselves by fishing and piloting vessels through the hazardous
waters between the Island and the mainland. In 1870, the first of two
breakwaters was begun with Federal funds. It was the construction of
the harbors that signaled the growth of the Island as a vacation resort.
In 1879, New Shoreham's official name was changed to Block Island, yet
delighted visitors called it "The Bermuda of the North." By the turn
of the century, steamers arrived daily from New York, Boston, Providence,
Newport, New London and Montauk. Fashionable hotels and plush golf courses
covered the Island.
The First World War, however, abruptly ended this prosperous era.
The Depression and subsequent Second World War further curtailed the
Island's tourist trade and many hotels closed. Fortunately, the Island
was still self-supporting through this period by fishing and farming.
In the postwar decades, Block Island was rediscovered as a family resort.
Private yachting and flying grew more and more popular and a new generation
of tourists once again visited the Island. What they found was a lovely,
windswept place, with old fashioned inns and simple cottages. Many bought
abandoned farmlands overrun by shrubs and bayberry, but dotted with ponds.
They fixed up the old homes bit by bit, doing most of the work themselves.
Today, "New Shoreham, otherwise Block Island," is governed directly
by a five member Town Council. In 1970, its people defeated a bill to
establish legalized gambling on the Island. It is interesting that opposition
to this bill was so intense that even the possibility of secession from
the State was explored as an alternative to the Island becoming "The
Las Vegas of the East." It is now the concensus of those who visit or
reside on the Island that preservation of the existing rural character
and pristine environment is of utmost importance and they are determined
* Land Use Analysis, New Shoreham, Rhode Island
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to achieve a sensible balance between conservation and development before
it is too late.
Map 3 displays general points of interest on the Island.
2.2 Physical Inventory
Climate. Block Island's climate is typically maritime, but can
be affected by extreme conditions. For example, temperatures ranging
from 10° to 95° have been recorded. Summers are usually dry with maximum
temperatures averaging 74° during July and August. The Island is too
small to build up cumulonimbus clouds, therefore local thunderstorms
do not occur. Fog occurs on one out of four days in early summer when
the ocean temperatures are relatively cold.
Winters are distinguished for their comparative mildness with temper-
ature maxima averaging 4° to 10° above freezing and minima averaging
25° in February. The surface winds are usually from the east, when snow
begins it soon changes to rain or melts rapidly if it does pile up.
The ocean has a dampening effect on hot winds in the summer and
an accelerating effect on cold winds from the mainland in the winter.
Sea winds can reach 40 mph under certain conditions in the winter with
the .average for that season about 20 mph. Year round averages are also
relatively high at 17 mph. In the early fall, the Island is affected
by most of the tropical storms moving up the coast.
During these storms and other periods of high wind, flooding occurs
along the shores of the Island. The extent of this flooding, the hurricane
high water line is indicated in Map 4.
The efficiency of a wastewater treatment facility is directly related
to the ambient temperatures.
With relatively mild conditions prevailing throughout the year,
it is not expected that the operation of such a facility would be inhibited,
However, with the high winds experienced on the Island precautions must
be taken to reduce the possibility of flooding of structures built on
the shoreline or in the sea itself.
Topography. Block Island consists of two irregular, hilly areas
connected by a sandy lowland. It may be divided into three topographic
units which are illustrated on Map 4.
The first unit is a lowland covering about 3 square miles which
extends along the north and west sides of the northern half of the Island
and encloses Great Salt Pond on the east and west. A manmade breach
of the lowland on the pond's west shore forms a channel into a protected
harbor. The highest altitude in the lowland is 40 feet above mean sea
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level (msl) and relief is slight except in areas of sand dunes. Brackish
ponds and marshes are numerous.
The second unit is the plain, about 3/4 of a square mile in area,
in the extreme northeastern part of Block Island. Its altitude increases
northeastward to about 100 feet msl at the eastern sea cliffs, the altitude
of the highest point being 141 feet. About a dozen ponds, each covering
roughly an acre, occupy local depressions.
The third unit is the southern section of Block Island with an
area of about 5 square miles. Its altitude increases from Great Salt
Pond, reaching about 140 feet above msl at the southern sea cliffs.
The western portion of this section is very irregular; local relief
often exceeds 50 feet and the highest point has an altitude of
211 feet above msl. Much of the eastern portion of the southern
section of the Island is nearly flat; local relief is a few tens of feet.
Its highest point has an altitude of about 170 feet above msl. Of the
approximately 50 ponds in the area, about 12 are larger than an acre.
Many ponds and swamps in the higher parts of Block Island go dry during
the summer and most of the streams on the Island are intermittent.
The Island is principally covered by low to medium height shrubs
such as bayberry, rusugo rose, sumac and chokeberry. Presumably, early
settlers had used all available forests for fuel and lumber.
The area of development proposed to be sewered encompasses the eastern
halves of the first and third topographical units discussed above.
Geology. Block Island was affected by two or more periods of Pleistocene
glaciation. However, most of the superficial glacial deposits were left
by the most recent glaciation. Most of the glacial deposits on Block
Island are part of the terminal moraine, consisting of till and sorted
drift, that extends northeastward from the Bonkonkoma moraine of Long
Island to Nantucket.
Till generally has low porosity and permeability because all sizes
of rock debris were dumped together by the melting ice so that the smaller
particles fill the pore spaces between the larger rocks. Till particles
range in size from clay to boulders.
Although sorted drift has the same size range of rock particles
as till, the drift has been sorted and layered by glacial meltwater streams
so that individual layers generally have a narrow range of particle size.
Since the Pleistocene glaciation, wave erosion of the Cretaceous
and glacial deposits around the perimeter of the Island has formed sea
cliffs along large parts of the shoreline. Pebbles and coarser materials
have accumulated at the base of these cliffs while sand and finer particles
have been transported away by ocean currents. Some of the sand has been
redeposited as beaches on the lee side of the Island, along the western
shore of the northern part of the Island, and around Great Salt Pond.
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NEW SHOREHAM,BLOCK ISLAND
HISTORY- RECREATION -TOURISM
®AREAS OF EARLY SETTLEMENT A BOAT LANDING .--FERRY
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MAP 4.
NEW SHOREHAM.BLOCK ISLAND
TOPOGRAPHY
NORTH
"040 CL»SSIFICATlO
LIGHT-DUTY
UNIMPROVED DIRT
nn 0-5
ALTITUDE IN FEET
J 50-100 I I
•V- .«- MARSH or SWAMP
SOURCE LAND USE ANALYSIS, NEW SHOREHAM, R I , 1968
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Till, sorted drift, and beach deposits are the materials which would
be encountered throughout the trench depths required for sewer construction.
Severe excavation .techniques such as blasting are not expected to be
necessary.
The major portion of the Island is overlaid by two types of fairly
permeable soils, as shown on Map 5.
1. Narragansett Fine Sandy Loam, well drained non-stony
soil, which covers the northern and southeastern parts of
the Island, is formed on sorted drift and compact till. This
soil usually averages about 2 feet in thickness and occupies
gently rolling to rolling areas. The natural drainage is
good, but due to a relatively compact substratum, the down-
ward movement of water is retarded to some extent and the
soil has a fairly high water holding capacity.
2. Gloucester Stoney Fine Sandy Loam, well drained stony
soil, which covers the southwestern part of the Island,
is formed on sorted drift and relatively permeable loose
sandy till. This soil averages about 2 feet in thickness
and has developed in areas having steeply rolling
relief. Natural drainage is good to excessive.
A third type of soil, Whitman Silty Clay Loam, is poorly drained
and occurs only in a few small bodies which occupy small depressions
or pot holes and are practically stone free. Natural drainage is poor,
and water stands on the surface in wet seasons.
The Muck and Peat Areas are composed of deposits of organic matter
in varying degrees of decomposition. None of these areas are drained
and water stands on the surface of the ground most of the year.
The Coastal Sand Areas, including beach and dune sand, have value
only for recreational purposes.
Evaluation of the above soils would indicate that only the two well
drained types, Narragansett Fine Sandy and Gloucester Stoney Fine Sandy
Loams, are satisfactory for onsite septic tank disposal fields year round.
The Gloucester type in the steep phase is not satisfactory due to its
erosive characteristics, and a considerable area in the southwestern
section of the Island has slopes greater than 12 percent. However, this
is only a general analysis and individual onsite investigations are necessary
prior to approval of septic system locations.
An important factor of the geology of Block Island is the lack of
the proper type gravel and stone for septic tank leaching field construction.
Good "bank run gravel" for fill purposes and 1/2:-1 1/2 inch washed, crushed ;
stone for leaching field construction are not readily available.
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Ground water. The source of all fresh water on Block Island
is precipitation. Since the water vapor for this precipitation is derived
by evaporation from the ocean, the precipitation falling on Block Island
contains more salt than that falling on most mainland areas. Part of
the Island's precipitation runs off into the sea, part returns to the
atmosphere by evaporation and the remainder seeps into the ground. Map
6 displays general areas of ground water availability on Block Island.
Ground water on Block Island occurs principally within three types
of layers: The upper perched water bodies, the lower perched water zone
and the main zone of saturation, in order of increasing depth below land
surface.
The upper perched water bodies are not considered a dependable source
of supply. Many of the upper perched ponds and wells tapping the perched
water go dry during the summer. Only domestic water supply systems utilize
the upper perched water with yields averaging about 5 to 10 gallons per
minute (gpm).
The lower perched water zone is supported by aquicludes of clay
or compact till and underlies considerable areas of the northern and
southern sections of Block Island. Maximum well yields from the lower
perched zone may be as much as 80 gpm.
The main zone of saturation is continuous beneath all of Block Island.
The upper part of the main zone of saturation consists of fresh ground
water, the lower part is saline. The water table of the main zone of
saturation is only 1 or 2 feet above sea level in the lowland and shore
areas of Block Island. The mid-southern section of the water table ranges
from 3 to 18 feet above sea level.
The most important source of fresh ground water on Block Island
is the lower perched water zone in the southern section of the Island.
For several decades, it has been a reliable source of water for public
supply. Recharge to this perched water body is roughly estimated to
be 720 million gallons per year. The yield obtainable by normal development
methods is estimated to be on the order of 1 million gallons per day
(mgd). Most discharges from the lower perched water zone are natural,
only about 15 million gallons per year are discharged from wells on thr
Block Island Water Company.
The yield of fresh ground water from the main zone of saturation
depends primarily upon the height of the water table above sea level.
For each foot the water table stands above sea level, a maximum of about
2 gpm can be pumped without saltwater encroachment. Thus, the best potential
area for development in the main zone of saturation is the southern section
of the Island where the water table is highest.
Fresh and Sands Ponds in the southern section of Block Island, when
used together, would be a potential source of water supply. Sands Pond
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MAP 5
NEW SHOREHAM.BLOCK ISLAND
SOIL CHARACTERISTICS
NORTH
ROAD CLASSIFICATION
LIBHT-OUTY
J WELL-DRAINED NON-STONY
j WELL-DRAINED STONY
| POORLY DRAINED
UNIMPROVED DIN'
] SWAMP OR MARSH
BEACH OR DUNE SAND
SOURCE^ COMPREHENSIVE COMMUNITY PLAN,
NEW SHOREHAM, RHODE ISLAND 1968
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MAP 6.
NEW SHOREHAM,BLOCK ISLAND
GROUND WATER AVAILABILITY
NORTH
KOAD CLASSIFICATION
UWHT-DUTY
FAVORABLE GROUND WATER
DEVELOPMENT
MODERATE GROUND WATER
SOURCE^ COMPREHENSIVE COMMUNITY PLAN,
NEW SHOREHAM, RHODE ISLAND 1970
BLOCK ISLAND
WATER COMPANY WELLS
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is used seasonally by the Block Island Water Company. Both ponds are
a part of the lower perched water zone and have a surface area of about
0.05 square mile, direct recharge averages about 25,000 gpd.
Overland runoff and ground water discharge into the ponds also contribute
some recharge. Each pond is reported to average about 10 feet in depth.
About 10 million gallons of water is stored for each foot of their depth.
It is assumed that at least 5 feet of the 10 foot pond depth is perennially
available. Thus, about 150,000 gpd can be withdrawn safely from the
ponds. Treatment, in accordance with State requirements for adequate
sanitary protection, would be necessary.
Water Quality. The State of Rhode Island, Dept. of Health has classified
the relative quality of all the waters of the State by means of a letter
designation. The present and proposed classification for most of the
waters around Block Island is S(A), the highest marine water quality
designation. Two exceptions are closures around the docking areas in
Great Salt Bay and Old Harbor (shown on Map 7). Both closures were given
the second highest marine water classification S(B). The uses and standards
of quality of waters under each of these classifications are defined
by the State and shown on Table 1.
Although the existing classifications indicate a relatively clean
water environment, apparently there are localized conditions where the
quality of water is in violation of the standards set forth under each
classification. Little data is available on existing water quality levels
for Block Island except for a survey done in 1973 by the Rhode Island
Department of Health on Great Salt Bay (see Appendix A). However, officials
from the State Dept. of Health, Division of Food Protection and Sanitation
have attested to the severity of existing localized conditions.
The cause of local violations of water quality standards is directly
attributable to untreated or partially treated discharges of domestic
wastewater. No public sewers exist within the town. Waste disposal throughout
the town is handled entirely on an individual basis by means of septic
tanks, cesspools or by direct outfalls to ponds, harbors or the ocean.
In the Engineering Report developed by Fenton G. Keyes Associates, the
sources of pollution were identified as wastes from pleasure crafts,
overflowing and inadequately drained septic systems and direct outfalls.
A generalized indication of the location of these discharges is shown
on Map 7. Their existence has created a potential health hazard on the
Island.
Specifically, in the New Harbor area (north of Beach Avenue), there
are several structures whose combined septic effluent is collected in
a pit on the shore and subsequently seeps into the harbor. In addition
to many single direct discharges, there -is one discharge whose effluent
flows very close to a spring-fed water supply pumping station. Also,
there are several low-lying leaching fields whose operation is limited
by high water table conditions.
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TABLE 1 - Rhode Island Water Quality Standards for Sea Water
CLASS SA: Suitable for all sea water uses including shellfish harvesting
for direct human consumption (approved shellfish areas), bathing,
and other water contact sports.
Standards of Quality
Item
Water Quality Criteria
1. Dissolved oxygen
2. Sludge deposits—solid refuse
floating solids
oil
grease
scum
3. Color and turbidity
Coliform bacteria per 100 ml
Not less than 6.0 mg/1 at any time.
None allowable
None in such concentrations that
will impair any usages specifically
assigned to this Class *
Not to exceed a median MPN of TO and
not more than 10% of the samples
shall ordinarily exceed an MPN of
230 for a 5-tube decimal dilution or
330 for a 3-tube decimal dilution
5. Odor
6. PH
7. Allowable temperature increase
8. Chemical constituents
None allowable
6.8 - 8.5
None except where the increase will
not exceed the recommended limits
for the most sensitive water use.
None in concentrations or combinations
which would be harmful to human, animal,
or aquatic life or which would make the
waters unsafe or unsuitable for fish
or shellfish or their propagation,
impair the palatability of same, or
impair the waters for any other uses.
9- Radioactivity
10
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TABLE 1 - Rhode Island Water Quality Standards for Sea Water (Continued)
CLASS SB: Suitable for bathing, other recreational purposes, industrial
cooling and shellfish harvesting for human consumption after
depuration (restricted shellfish area); excellent fish and
wildlife habitat; good aesthetic value.
Standards of Quality
Item
_Water Quality Criteria
1. Dissolved oxygen
2. Sludge deposits
solid refuse
floating solids
oils
grease
scum
3. Color and turbidity
. Coliform bacteria per 100 ml
5. Taste and odor
6. pH
7. Allowable temperature increase
8. Chemical constituents
Not less than 5-0 mg/1 at any time
Not allowable
None in such concentrations that
would impair any usages specifically
assigned to this class.
Not to exceed a median value of
TOO and not more than 2,300. in more
than 10$ of the samples
None in such concentrations that would
impair any usages specifically assigned
to this class and none that would
cause taste and odor in edible fish
or shellfish
6:8 - 8.5
None except where the increase will
not exceed the recommended limits on
the most sensitive water use assigned
to this class
None in concentrations or combinations
which would be harmful to human,
animal or aquatic life or which would
make the waters unsafe or unsuitable
for fish or shellfish or their
propagation, or impair the water for
any other usage assigned to this class.
9. Radioactivity
11
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The Old Harbor Village is heavily developed with characteristically
small lots and large structures. This condition results in septic systems
with relatively small leaching fields (or none at all). These small
fields, which serve many of the hotels and commercial establishments,
appear sufficient for winter operation but are undersized for the great
demands put upon them by the large influx of summer population.
In both Harbor areas, pleasure craft dispose of their sanitary wastes
overboard, and until January 1975 there were no Federal or State regulations
controlling such disposal. (New Federal regulations aimed at correcting
this problem are described in Appendix B). In any event, no disposal
facilities such as pumpout stations are presently provided at marinas
to relieve the pleasure craft of these wastes. In addition, no public
toilet facilities are available on the Island to boaters, thus increasing
discharges from pleasure crafts.
Noise Levels. Ambient noise level measurements were conducted by
EPA in the proposed study area and more specifically in the area adjacent
to the proposed treatment plant site. A summary of those results are
given in Table 2.
TABLE 2 Noise Levels on Block Island - January 1975
Location Time of Day L90 Leg .
Location on High St. 10:15 to 10:30 29 dBA 34 dBA
(approx. 100 ft. from plant) ,
12:12 to 12:27 27 34
14:50 to 15:05 26 47*
Ballard's Hotel 11:12 to 11:27 35 39
(approx. 250 ft. from plant)
14:11 to 14:26 33 38
Residence on Road "M" 10:48 to 11:03 34 50**
(approx 500 ft. from plant)
13:20 to 13:35 38 51**
Residence on Spring St. 16:04 to 16:19 25 44 '
(approx. 300 ft. from plant)
* aircraft overflights dominate Leq value
** high Leq due to vehicle traffic on Road "M"
Source: EPA Measurements
These levels are indicative of a very quiet noise climate in the
vicinity of the proposed treatment plant. On the basis of the above
data, a crude estimate of the day.time equivalent sound level (Leq) is
40 decibels (dBA) and it can be estimated that nighttime Leq would be
about 27 dBA. These values can be combined to obtain an estimated day-
night average sound level (Ldn) of 39 dBA.
12
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MAP 7.
NEW SHOREHAM.BLOCK ISLAND
WATER QUALITY CLASSIFICATION
CLOSURE MAP
NQRTH
ROAD CLASSIFICATION
LIGHT-DUTY UNIMPROVED DIRT _
O SEA WATER CLASSES
— CLOSURE AREA
GENERALIZE AREA OF FAILING SEPTIC SYSTEMS
SOURCE- STATE OF R.I..DEPT. OF HEALTH,
DIVISION OF WATER POLLUTION CONTROL,
"PROPOSED CLASSIFICATION OF WATER QUALITY MAP," 197:
•- STATE OF R.I..OEPT. OF HEALTH,
DIVISION OF FOOD PROTECTION ON SANITATION.
-------
This estimate is probably only valid during the winter season and
it can be expected that the noise levels will increase somewhat during
the summer months due to the seasonal increase in population.
Air Quality. No major sources of air pollution presently exist
on the Island. From 1969 through 1972, the State of Rhode Island Department
of Health maintained an air quality monitoring station at the New Shoreham
Airport on Block Island (approximately 1 mile west of the proposed wastewater
treatment plant). Data obtained from this station are shown in Table
3. It can be seen from Table 4 that none of the air quality data measured
during this period even approached violations of National Ambient Air
Quality Standards or Rhode Island Ambient Air Standards; and therefore,
the State discontinued the operation of the site.
TABLE 3 1970 Air Sampling Data
Block Island Airport*
Pollutants
Particulates Sulfur-Dioxide Nitrogen-Dioxide
Number of Readings 13 12 12
Maximum 24-hours 66.7 15.7 86.5
Minimum 24-hours 19.2 7.9 5.6
Arithmetic Mean 36.8 8.7 12.4
Geometric Mean 34.2
Standard Deviation 1.45 1.23 2.20
*latest complete data available
Source: State of Rhode Island Department of Health
Fish and Wildlife. The predominant fish species found in the
waters adjacent to Block Island are: yellow tail flounder, ocean pout,
little skate, winter flounder and spiny dog fish. Commercial fishing
on the Island is limited to the offseason as the primary occupation of
fishermen on the Island is shellfishing. Lobster harvesting is minimal
but clams and scallops are harvested in great quantities. Great Salt
Pond, which is protected from the ocean currents, contains at least five
species of shellfish commercially available to local fishermen. A marine
biologist from the Rhode Island State Department of Natural Resources
indicated that about 80% of the shellfish (hard and soft clams, mussels
and bay scallops) are located in beds outside of the closure (shown on
Map 6) in the open classification of this natural saltwater pond.*
* Memo from Edward Wong, Natural Resource Officer, Surveillance and
Analysis Division, EPA.
13
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TABLE 4 - Comparison of National Primary and Secondary
Standards and Rhode Island Air Quality Standards
Pollutant
National Primary
Standard
National Secondary
Standard
State of R.I.
1973 Goal
State of R.I.
1975 Goal
Particulates
Sulfur Dioxide
Nitrogen Dioxide
Carbon Monoxide
Total Oxidants
Hydrocarbons
75 ug/M3 (annual
geometric mean)
260 ug/M3 (24-hr
maximum)
80 ug/M3 (annual
arithmetic mean)
365 ug/M3 (24-hr
maximum)
100 ug/M3 (annual
arithmetic mean)
10 mg/M3 (8-hr
max. average)
40 mg/M3 (1-hr
max. average)
160 ug/M3 (1-hr
max. average)
160 ug/M3 (3-hr
max. average)
60 ug/M3 (annual
geometric mean)
150 ug/M3 (24-hr
maximum)
o
60 ug/MJ (annual
arithmetic mean)
1300 ug/M3 (3-hr
maximum)
260 ug/M3 (24-hr
maximum)
100 ug/M3 (annual
arithmetic mean)
10 mg/M3 (8-hr
max. average)
40 mg/M3 (1-hr
max. average)
160 ug/M3 (1-hr
max. average)
160 ug/M3 (3-hr
max. average)
60 ug/M3* (annual
geometric mean)
168 ug/M3* (24-hr
maximum)
72 ug/M3* (annual
geometric mean)
858 ug/M3* (1-hr
maximum)
358 ug/M3* (24-hr
maximum)
NONE
9.2 mg/M3* (8-hr
max. average
118 ug/M3* (1-hr
max. average)
118 ug/M3* (3-hr
max. average)
50 ug/M3* (annual
geometric mean)
130 ug/M3* (24-hr
maximum)
57 ug/M3* (annual
geometric mean)
687 ug/M3* (1-hr
maximum)
286 ug/M3* (24-hr
maximum)
NONE
NONE
NONE
NONE
*Standard conditions for measurements are established at 25°C, 1 atm pressure.
Source: State of Rhode Island, Department of Health
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The hard clams and ocean quahogs are distributed around the Island
with concentrations of surf clams growing in beds close to shore. The
quahogs and hard clams are in waters about one to two miles off-shore
predominantly on the western side of the Island. There are clams on the
eastern side; however, the density and yield is commercially less attractive
and because of wire cables extending out of Old Harbor, there are restrictions
on the dredging operations in that area. The fishing fleet is made up of
between four and six dredge boats operating simultaneously, although
not consistently, on a day-to-day basis.
The waters around Block Island have become increasingly valuable
during the past three years due to an increase in the production of the
ocean quahog and surf clams whose sources are traceable to this area.
In the listing of the Rhode Island Landings, Summary of 1971, dredge
boats harvested 1,650,000 pounds of clam mea'ts, having a landed value
of about $286,000. This is a conservative figure because the largest
operator reported a landed value on ocean quahogs to his firm alone for
1973 in the order of $306,000. All of these clams were collected from
areas west of Block Island and parts of Rhode Island Sound. Most of
the extensive harvesting is on the western side of the Island. After
processing by the food industry, the retail value of the shellfish is
several times the landed value.
Wildlife on Block Island includes birds and small mammals. The
Island serves as a migratory resting place for several varieties of birds,
many of which can be seen in the Wildlife Refugee at Sandy Point. None
of these birds are on the United States List of Endangered Fauna. One
mammal species of significance is the Block Island Meadow Vole. This
small rodent is found in areas of beach grass and uncut fields on about
600 acres of the Island. The vole has been decreasing in numbers due
to alteration or elimination of its habitat caused by the construction
of buildings and roads on Block Island.* However, it is not likely that
this small creature will be included on the United States List of Threatened
Species which is currently being prepared by the U.S. Fish and Wildlife
Service.
Another species which uses the Island as a temporary home during
migratory travels is the seal. Although neither State nor Federal Fish
and Wildlife agencies have recorded the seals' presence, many of the
Islanders have seen them. The seals are of special concern because their
resting area is on the eastern side of the Island, in the vicinity of the
proposed treatment plant outfall sewer.
Clough, C.G., and Fulk, G., Current Status of the Block Island Meadow
Vole, Rhode Island, 1971.
15
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Environmentally Sensitive Areas. Map 8 is an identification of
environmentally sensitive areas on Block Island. A fundamental definition
of an environmentally sensitive area is any area which is intolerant
to major changes by man. It is, therefore, implicit that exploitation
of such regions could result in irreparable and irretrievable damage.
Specific land types which fall under this category are; fresh and salt
water ponds, marshes and wetlands, coastal zones, areas with impermeable
soils, areas which have a slope greater than 15%, areas with high ground
water tables which generally includes any area on Block Island which
is below the 10 ft. elevation, areas favorable for ground water supply,
and dunes and bluffs.
2.3 Utilities and Other Community Facilities
Water. A small water supply system, owned by the Block Island Water
Company serves about 250 winter and 2000 summer customers in the Old Harbor
and surrounding areas (see Map 9). The water supply for this system
includes two wells with a reported capacity of 185 gpm and Sands Pond,
which is used about nine months of the year.
The remainder of the Island is serviced by private wells, springs
and in some cases, man-made impoundments. Recent proposals, however,
recommend the enlargement of this system to service the majority of the
southeastern portion of the Island, including the proposed sewer service
area. Such a system would require a capacity of 650 gpm or 0.6 mgp by
2022.*
Sewers. At present, there is no sanitary sewer system on the
Island. As was discussed earlier, all wastewater is treated on an
individual basis by means of either septic tanks, cesspools or direct
discharges. No public toilet facilities exist except for rest rooms
available in private establishments, and facilities to collect wastewater
from pleasure crafts are not available at marinas.
Septage which must be pumped from septic tanks, from time to time,
is disposed of at the recently relocated town landfill site.
Gas. Gas is provided by a private bottled gas company.
Electricity. Electricity is generated on the Island by the Island
Light and Power Company. Supply by overhead line is generally available.
Telephone. A radar link between Pt. Judith and the Island provides
telephone connection,to the mainland.
* Fenton G. Keyes Associates, Preliminary Engineering Survey and Report
on Water Supply and Distribution for the Town of New Shoreham, Rhode
Island, May 1972.
16
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MAP 8.
NEW SHOREHAM.BLOCK ISLAND
ENVIRONMENTALLY SENSITIVE
AREAS
NQRTH
ROAD CLASSIFICATION
LIGHT-DUTY UNIMPROVED DIRT _
GROUND WATER POORLY DRAINED SOIL
:-~;U'i-') MARSH AREA ___^ HIGH WATER LINE
SOURCE' EPA REGION X
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MAP 9.
NEW SHOREHAM,BLOCK ISLAND
WATER SERVICE AREA
NORTH
ROAO CLASSIFICATION
LIOMT-DUTT UNIMPROVED DIRT
EXISTING
PROPOSED-IMMEDIATE
PROPOSED-FUTURE
SOURCE^ FENTON G. KEYES, ASSOCIATES, 1972
-• RHODE ISLAND OEPT. OF COMMUNITY AFFAIRS, 1968
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Refuse Disposal. In 1974, the town began operation of a new 23
acre sanitary landfill. This new facility is located off West Side Road
near Swede Hill (see Map 10). The site has been approved by the State
for septage disposal and during the summer several truckloads are brought
to the site each week. This site appears to be adequate to serve the
town's solid waste disposal needs, including septage disposal, for the
foreseeable future.*
Other Facilities. The locations of other important public facilities
are shown on Map 10.
2.4 Growth and Land Use Analysis
Population and Socio-economic Trends. The Island's population and
economic activity reached its peak shortly after the turn of the century.
The Island supported a prosperous summer trade with flourishing summer
hotels, a fishing industry, and 1,400 year-round residents until the
1920's.
Subsequently, the 1938 hurricane destroyed the fishing fleet and,
given the distance from land markets, the fishing industry never recovered.
The summer hotel trade began declining here, as elsewhere with the increased
use of the auto in vacations. As shown in Table 5, the residential population
steadily declined to 486 by 1960, and has remained stable' since at between
450 to 500 year-round residents.
TABLE 5 - Population
Year Population
1915 1,414
1930 1,029
1960 486
1970 501
2000 500
Source: U.S. Census of Population 1960 & 1970, Rhode Island; Land
Use Analysis, Rhode Island Dept. of Community Affairs, 1968.
The population increases by approximately 1,200 summer residents,
1,000 overnight visitors to the hotels, and 1,000 day visitors on the
average day during the 100 day summer season. Estimates of peak holiday •
weekends have run as high as 3,000 visitors.
* EPA estimates of site capacity.
17
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With few employment opportunities, the proportion of the population
in the productive age brackets has declined sharply. The youth have been
leaving the Island to seek educational, employment, and cultural opportuntities.
Those who have come to live there have been mainly older retirees.
Since the first half of the century, the Island's resident labor
force has dwindled to approximately 180 persons. The majority are in
professional, managerial, craft and service occupations including construction
and maintenance, as shown in Table 6. Indicative of the highly seasonal
economy, 85 percent of the retail sales are made between May and October.
The 1969 median family income of $8,289 was substantially below the Rhode
Island median of $9,733.
TABLE 6 - Labor Force*
Labor Force
Occupation 1960 1970
Professional & Managerial
Craftsmen
Laborers
Operatives & Service Workers
Clerical
Sales
Not reported & Others
Total Employed
Unemployed
Total Labor Force
53
33
32
23
12
8
15
176
19
204
37
44
11
34
11
—
15
152
28
180
*Source: U.S. Census of Population, 1960, 1970.
Table 7 summarizes housing trends between 1960 and 1970.
Based on data from both the 1960 and 1970 census, it is estimated
that about forty-eight percent of the housing units (365) were constructed
prior to 1939. From 1940 to 1960, only 74 new housing units were constructed
on the Island, but between 1960 and 1970, there was a net increase of
314 new dwelling units. Of these, 301 were built by summer residents
as seasonal homes, an average of 30 units per year. From 1970 to 1974,
125 building permits have been issued for new dwelling units. There has
been very little multiple unit construction on the Island since 1960.
Thus, following several decades of overall decline, there is an upswing
in the construction of new summer homes, but not as yet in restoration
of the former hotel capacity and businesses serving the tourists.
The number of hotel and other overnight tourist accomodations has, in
fact, declined in the past decade, despite some rental cottage construction.
For example, three hotels totaling over 400 rooms closed. The existing over
night capacity of approximately 1500-1800 persons is not considered adequate
to sustain the Island's tourist economv.*
*Estimates by the Block Island Chamber of Commerce. See: The. Land Use Analysis.
18-
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MAP IP.
NEW SHOREHAM.BLOCK ISLAND
COMMUNITY FACILITIES
NORTH
MEDIUM-DUTY —
ROAD CLASSIFICATION
UOMT-OUTY UNIMPROVED DIRT
SOURCE- COMPREHENSIVE COMMUNITY PLAN,
NEW SHOREHAM, RHODE ISLAND, 1970.
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TABLE 7 - Housing Characteristics
Number of Units
Occupancy 1960 1967* 1970
Year-round 195 173 208
Owner-occupied 149 - 153
Renter-occupied 46 - 55
Seasonal (or vacant) 243 486 ' 544
Total - all units 438 659 752
*Year-round and seasonal single family homes, single family seasonal
units in cluster colonies, and 7 housing units in mixed use
structures, but not seasonal rooms.
Source:U.S. Census of Housing, 1960 and 1970, and 1967 Inventory
of Housing in Land Use Analysis, Rhode Island Department of Community
Affairs, 1968.
Existing Land Use. Development is concentrated in Old Harbor, as shown
on Map 11. Old hotels, inns, rooming houses, restaurants and shops cluster
along the harborfront. Homes and a few scattered inns line the five streets
radiating into the countryside, especially to the south and to the southwest
toward the airport.
Over the last twenty-five years, much smaller scale development has
been taking place in New Harbor, 1.5 miles to the northwest on Great Salt
Pond: a ferryslip three marinas and two hotels and restaurants. Along Ocean
Avenue, leading to New Harbor, are the Island's power plant, State highway
garage and fire-police building, as well as wetlands and open land.
Within a couple of blocks, of the old harborfront, the houses become
spaced farther and farther apart, with stonewalls enclosing bayberry heath
and abandoned pastureland. The remainder of the Island is largely open heath,
pasture, numerous ponds and inland and coastal wetlands. The scene conveys
a sense of openness, dotted with an occasional white building. The openness
is illustrated in Map 11 and Column 1 of Table 8, which summarizes existing
land uses statistically. Of the Island's nearly 7,000 acres, over 5,000
are in heath and open pasture (including some fields and scrub forest) and
another 1,000 acres are in water and wetlands.
19
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The newer homes are beginning, still almost imperceptibly, to close
in upon this sense of openness. This is becoming evident in the vicinity
of Old Harbor, especially on the uplands overlooking the Harbor.
State and Local Land Use Plans. Public and privately sponsored plans
for the Island all emphasize the need to preserve the Island's
unique natural environment and charm in the face of development pressures.
At the same time, they recognize the need to strengthen the economy.
These plans do not explicitly forecast population and economic activity,
nor do they present any optimum levels for designing future public facilities.
The Land Use Analysis (LUA) prepared for Block Island in 1968 by
the Rhode Island Department of Community Affairs, assumes 500 year-round
residents to be the minimum to sustain basic economic life, and projects
this minimum as the population through the year 2000.
The New Shoreham Comprehensive Community Plan (CCP) attempts to outline
community objectives; to plan for community facilities, recreation, conservation
and land use; and to recommend implementation action. The CCP was prepared
in consultation with the Town Council and Planning Board by the Rhode Island
Department of Community Affairs, and was adopted by the Town Council in
April, 1972.
A major stated goal of the CCP is "...to insure that development will
occur in an orderly fashion and will be in keeping with the present character
of the community...." To protect the Island's ecology and character, the
CCP states the following goals as the Town's official policy:
1. Development shall be avoided on land subject to periodic
flooding.
2. Development utilizing septic tanks shall be confined to
lands having good subsurface drainage.
3. Lands which are difficult and expensive to develop because
of steep slopes, poor soil or other factors shall be
utilized as recreational open space.
4. Waterfront development shall follow the natural undulations
of shoreline and shall avoid long, straight lines or
abrupt curves and angles.
5. Natural areas of special value shall be acquired and
preserved by.some public or quasi-public agency whenever
possible.
6. Freedom from air and water pollution is the right of the
citizens of the community. Any substance added to the
air or water to a degree which damages property, vegetation,
natural resources or commerce shall be considered
a pollutant and shall not be permitted.
20
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MAP II.
NEW SHOREHAM.BLOCK ISLAND
EXISTING LAND USE
NORTH
ROAD CLASSIFICATION
LIOHT-WJTY UNIMPROVED DINT
* YEAR ROUNp RESIDENT Q COMMERCIAL
SEASONAL RESIDENT f HOTEL
• PUBLIC AND SEMI-PUBLIC
SOURCE^ LAND USE ANALYSIS, NEW SHOREHAM, RHODE ISLAND, 1968
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7. Local flora and fauna are important to the natural
environment and are a part of our heritage. The town
shall support and encourage programs to protect wild-
life and to maintain and supplement vegetation.
8. The appearance of the town is recognized to be of high
importance to the town's economy, its future development,
and to the pride and pleasure of its residents. Improved
community appearance shall be encouraged whenever possible.
The town government shall cooperate with individuals and
groups which engage in constructive activities on behalf
of community appearance. A community's heritage should
be reflected'in its appearance; therefore, the policy of
New Shoreham shall be to preserve the rural New England
character. This goal involves preservation of buildings
of architectural importance, consideration of the design
relationship between new and existing structures, preserva-
tion of stone walls, maintenance of open space and so forth.
Recognizing the recent trends in construction of new homes through-
out the Island, the plan emphasizes that many types of development would
diminish the Island's "unspoiled, rural character," a strongly held value
of the year-round residents and a major attraction to tourists and seasonal
residents. "Therefore, (the CCP states) the major planning concern in
New Shoreham is to prevent indiscriminate, undesirable development."
At the same time, the CCP provides for additional development to strengthen
the hotel/tourist business base, lengthening the season and attracting more
visitors. Statements in the CCP about the development potential of the
Old and New Harbor areas and the contiguous, presently sparsely settled areas
assume moderate growth. Also, proposals for a sewer and water system, new
town hall and civic center presume moderate development.
Map 12 outlines future land uses proposed in the Comprehensive Community
Plan (CCP). These proposed uses take into account both environmental and
socioeconomic objectives, present land use patterns, soils, flood areas,
elevations, ground water, public utilities, development trends and community
goals. A detailed description of the proposed uses is indicated in Appendix C.
Table 8, Column 2 gives acreage distributions of these proposed uses.
The draft report, State Land Use Policies and Plan, sets forth the State,
environmental, social and economic goals; development and conservation policies;
and recommendations for State-local implementation. These are similar to
those which the CCP outlined somewhat more specifically for the Island.
The State Plan also outlines essentially similar future land uses in its
generalized sketch of proposed State land uses in 1990. These broad designations
are summarized in Table 8, Column 3.
21
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TABLE 8 - Existing & Proposed Land Uses
ACREAGE DISTRIBUTION
Land Uses*
Existing (1970)
Proposed (1990) Existing
(CCP) State Plan Zoning
Mixed — commercial, industrial,
high density residential
Commercial-industrial
High density residential
Urban public
Airport
Spoil areas
.Medium Density Residential — 1 acre lots
Medium residential
Light residential
Low Density Residential - 2 acre lots
Scattered residential
Heath
Pasture/abandoned field
Forest
Tilled
Developed Recreation
Open Space Recreation
(Should also include some of
heath/pasture W SE)
Conservation
Water & wet level marshes
ISLAND TOTAL
(Col.l)
157
34
4
43
57
19
108
54
54
(Col.2)
170
500
500 1,100
• "mixed"
& low
density"
3,400 3,400
"woodland
&
openland"
700
5,300
400
400
6,900
*Land Use categories combined to form a composite of existing and proposed land use
plans and zoning. Major categories follow the New Shoreham Comprehensive Plan (CCP),
subcategories follow William P. MacConnell, Univ. of Mass., mapping of 1970 land uses
for the Southeastern New England Study, New England River Basins Commission.
Subcategories are grouped into future land use categories in CCP.
Sources:
Col. 1: Compiled from Prof. William P. MacConnell, Univ. of Mass., Dept. of
Forestry and Wildlife Management., "Land Use and Vegetative Cover
Mapping for New England River Basins Commission, Southeastern New
England Study". Based on 1970 aerial photographs overlaid on U.S.
Geological Survey topographic quadrant of Block Island Quadrangle
Categories consolidated by EPA.
Col. 2: Acreage distributions estimated by EPA from Future Land Use Map,
New Shoreham Comprehensive Community Plan Rhode Island Dept. of
Community Affairs, 1970.
Col. 3: Summary of the Report on the -State Land Use Policies and Plan, Rhode
Island Statewide Planning Program, Providence, R.I., April 1973.
Col. 4: Acres estimated by EPA from Zoning, Chapter 33 of the Revised
Ordinances of the Town of New Shoreham, enacted June 5, 1967 through
November 5, 1973.
22
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MAP 12.
NEW SHOREHAM,BLOCK ISLAND
LAND USE PLAN
NORTH
MILE
ROAD CLASSIFICATION
UNIMPROVED DIM
1 LOW DENSITY
1 RESIDENTIAL
MEDIUM DENSITY
RESIDENTIAL
1 1 OP
[ | RE
CONSERVATION
EN SPACE
ECREATION
DEVELOPED
RECREATION
SOURCE^
COMPREHENSIVE COMMUNITY PLAN,
BLOCK ISLAND, RHODE ISLAND, 1970
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A major goal of the State Land Use Plan is to control urban sprawl.
Policies outlined in the Plan with specific regard to utilities include:
1. Policy #5: Locate public water and sewer facilities
so as to shape development in accordance with the
State Land Use Plan.
2. Policy #10: In developments which are of an intensity
to support public water and sewer facilities, coordinate
development with provision of facilities so as to assure
availability of these facilities at the time the area is
developed.
3. Policy #12: Minimize extensions of water and sewer systems,
consistent with goals to reduce existing pollution, in
order to discourage urban sprawl.
As a major private effort, the University of Rhode Island, School of
Design Study, evaluated the environmental constraints and demand for development
and prepared a study entitled the Block Island Report. This report has taken
the position that development pressures are fast upon the Island and attempts
to outline environmental constraints and a proposed zoning, design control, and
action program to guide this development. Again no estimates are made of
the future population, but the detailed suitability map provides a_guide
to the location, density and types of development, which can serve as a
planning tool. The most suitable development patterns are summarized in
a proposed zoning map (shown on Map 13).
Existing Zoning. New Shoreham's zoning ordinance and map, first enacted
on June 5, 1967 and subsequently amended as recently as November 5, 1973,
essentially projects existing land use and would permit extension of business
and residential development along and around the axis connecting Old and
New Harbor. The zoning classifications shown in Map 14 are as follows:
1. Business — commercial establishments and residences,
with special exceptions for hotels and inns.
2. Residence C — single-family dwellings on 1/2 acre lots
with exceptions for two-family dwellings, hotels, motels,
boatels, on 1 acre lots.
3. Residence B — single-family dwelling units on 1 acre lots,
with exceptions for marinas, hotels, motels, boatels on
3 acre lots.
4. Residence A — single-family dwelling units on 2 acre lots,
with exceptions for hotels on 10 acre lots.
23
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5. Beach — bathing, recreation or picnic areas, wildlife
refugees, with exceptions for beach clubs, bath houses
and marinas.
Table 8, Column 4 presents an estimated acreage distribution of the
zoning classifications.
The ordinance also includes the following provisions:
1. Development in residential clusters is permitted by the Planning
Board in Residential Zones A, B, & C, provided they blend in with the general
land use pattern established by the Zoning Ordinance and stay within the
overall maximum density set for the Residential Zone in which the development
would lie. The Planning Board must review and approve a development plan
for each cluster.
2. Subsurface sewage disposal facilities shall be located not less
than 100 feet from the edge of any pond or stream. In addition, the subdivision
code does not permit any subdivision in areas subject to periodic flooding;
further, existing stream channels and fresh water wetlands shall be preserved.
Analysis of Existing Plans, Policies and Zoning. No estimates of future
population or economic activity have been developed that systematically take
into account the Island's developmental limits necessary to preserve environmen-
tal quality and community character. The Land Use Analysis presents a maximum
estimate of 2,500 additional dwellings if the 3,960 acres of undeveloped
land deemed suitable for development were fully developed under the existing
zoning.* But, the Analysis hastens to emphasize that such maximum growth
would drastically alter the attractiveness of the Island as a resort.
The CCP cites the marked upturn in construction of new summer homes
as a warning to plan wisely to protect the Island's future environment and
charm. In balancing environmental and socioeconomic objectives, the CCP
and, by implication, the State Plan and Town zoning do not evaluate how much
development and what kinds of development the Island can take before development
infringes on the environmental and amenity values that residents and visitors
alike seek to preserve. Nor did the Islanders debate these issues when they adopted
adopted the CCP at town meetings—the basic issues of future growth, land
development and their impact on the Island's environmental goals and community
amentities. The unanswered question, then, becomes, "What social and economic
values would the Island have to give up and be willing to give up in order
to retain the high quality environment, and in particular, the rustic open
character of the Island as a whole, now present even in much of the Old Harbor
•area?"
Growth Assumptions. Three major alternate assumptions, about the Island's
future growth are summarized below. The three growth levels are quantified
in Table 9.
*These figures were based on the zoning map in effect in 1968. Since that
time, amendments have been made to the map which would result in a lesser
number of dwelling units at maximum development.
24
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MAP 13.
NEW SHOREHAM. BLOCK ISLAND
A ZONING MAP
NORTH
•OAO CL»SSIMC»T10N
NO USE OR CROSSING
URES
I NO STRUCT
UNI
J3 MEDIUM RESIDENTIAL
DENSE RESIDENTIAL
LOW RESIDENTIAL,OPEN
) SPACE, PRESERVATION
pjJSSiJa COMMERCIAL,
t::-:>::X-:vi DENSE RESIDENTIAL
SOURCE; THE BLOCK ISLAND REPORT, R.I. SCHOOL OF DESIGN
-------
MAP 14.
NEW SHOREHAM.BLOCK ISLAND
EXISTING ZONING
NORTH
MEDIUM-DUTY.
MOID CLASSIFICATION
LIOHT-OUTT UNIMMOVCO DIRT
BEACH AREA
] RESIDENCE B
1 RESIDENCE C
SOURCE'• CHAPTER 33 OF THE REVISED ORDINANCES OF THE
TOWN OF NEW SHOREHAM, 1972
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1. Present level - Restore existing tourist accommodations
to full capacity, less than 15 percent increase in summer
visitors.
2. Moderate growth - 15 to 25 percent in summer residents
and visitors.
3. Substantial growth - Nearly doubling of summer residents
and visitors.
The Moderate Growth assumption would appear to support goals
of the CCP. It would support major rehabilitation of the old hotels and
inns and allow a modest increase in visitor accommodations and residences.
At the same time, with effective planning and zoning, the valued character
of the Island would be maintained.
Fenton Keyes Associates design capacity (6,662 equivalent persons) is
in the order of magnitude of the Substantial Growth (doubling) assumption.
25
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TABLE 9 - Growth Assumptions
Population
Characteristics
Basic year-round
residents
Summer residents
Hotel visitors/
average summer day
Day visitors/average
summer day
Present - Little
Additional growth
island Study Area
500 400
1,200 500**
1,500* 1,400
1,000 1,000
TOTAL/Average Summer day 4,200 3,300
* Estimated capacity,
** Forty-five percent
*** Assume approximate
Moderate growth
Island Study Area
500 450
1,500 900**
2,000 1,900**
1,200 1,200
5,200 4,450
assuming rehabilitation of existing hotels and inns.
of summer residents are within Study Area.
doubling of summer residences, hotel visitors, and day
Substantial growth***
Island
600
2,500
3,000
2,000
8,100
visitors .
Study Area
550
1,500
3,000
2,000
7,050
Source: Estimates by EPA based on discussion with town and state officials.
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3.0 ALTERNATIVES
The following section deals with the description and evaluation
of possible alternatives that Block Island could pursue in its
attempts to improve existing wastewater treatment techniques. To
effectively evaluate possible avenues of action; and to do so in a
manner that will result in the most cost effective, environmentally sound
alternative: the analysis concentrates on what are considered
the four most practical alternatives. They are:
Alternative A. Construction of the project proposed by Fenton Keyes
Associates, which includes a treatment facility and collection system
to serve the Old and New Harbor sections of the Island (Stage I) with
provisions to serve the area south of Old Harbor in the future (Stage II)
Alternative B. Construction of the project (Stage I) without
provisions for sewering the area south of Old Harbor in the
future.
Alternative C. No sewer construction, but a comprehensive
program for the rehabilitation of individual septic systems.
Alternative D. Construction of a treatment facility and
collection system for the Old Harbor area only, with rehabilita-
tion of individual septic systems in the New Harbor area.
Also evaluated is the alternative of NO ACTION. Although the least
practical, it is presented to facilitate the reader's understanding of
the consequences of doing nothing.
Discussed below are common sub-alternatives which affect all or some
of the major alternatives to be addressed. An individual analysis of
each major alternative and its environmental impact is presented in
Chapter 4.
3.1 Alternative Treatment Plant Locations
For Alternatives A, B, and D above, a suitable site for a treatment
plant is required. In the proposed project (Alternative A), a site was
selected near Old Harbor on Spring St. Alternative sites were evaluated
one near the Island's Power Plant and another further south on Spring St.
Neither site displayed significant advantages over the proposed location
and were not recommended. It should be assumed throughout this Impact
Statement that any reference to a treatment facility location refers
to the Spring St. site.
27
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3.2 Multiple Facility Alternatives
For Alternatives A, B and D under discussion, the use of more
than one treatment plant was studied. No multiple facility arrange-
ment was found to be practicable. The major deterring factor was
the requirement by the Rhode Island State Department of Health,
Division of Water Supply and Pollution Control that there be only
one discharge into the waters of Block Island. Thus, any benefits
of a two plant system-would be negated by the additional cost of
pumping to one outfall location. Other factors such as operating
two facilities and utilizing two areas for treatment plants also made
the multiple facilities alternative unattractive.
3.3 Treatment Process Alternatives
A variety of treatment processes were evaluated by EPA in addition
to the process recommended in the proposed project (Alternative A).
In the analysis which follows, two points must be noted; first, the
analysis was based on a .30 mgd facility (Alternatives B and D
would not require a facility that large), and secondly, the cost
shown for each treatment type reflect average costs for New England
and are not specifically representative of costs on Block Island.
Certain treatment processes were eliminated immediately as a
preliminary analysis of the Block Island situation indicates that
they are not feasible. For instance, the conventional activated
sludge process and several of its modifications such as step aeration
and tapered aeration have been determined not feasible for a plant of
this small size. The trickling filter process was not considered
because of inadequate treatment and possible nuisance problems.
Primary treatment alone was not considered due to the fact that
secondary, treatment is required by law.*
The following treatment systems were considered feasible for a
project such as Block Island and are evaluated in more detail:
1. Extended Aeration
a. Aeration tanks (proposed project)
b. Oxidation ditch
2. Modified activated sludge (contact stabilization)
3. Aerated lagoons
4. Stabilization
5. Physical-chemical
*Federal Water Pollution Control Act, Public Law 92-500.
28
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6. Land disposal
A cost breakdown for each of the above systems is displayed
in Table 10.
Although the tabulation of basic average annual costs indicates
that certain alternatives appear more cost-effective than others,
evaluation of special considerations will tend to show that the
alternatives are really more equal than might appear.
Extended Aeration. The alternative chosen by Fenton Keyes
Associates, that of the extended aeration process with aeration tanks
has the highest initial construction cost and average operating
costs. It is, however, the system which is in greatest use for the
size project proposed and is probably the best overall method for
treating the large flow variation between winter and summer. A
minimum of operational manpower and skill are required to produce a
good effluent and will result in the production of a relatively small
volume of stabilized sludge which can be easily disposed of.
The use of oxidation ditches as a method of extended aeration treatment
is a very similar process to the above system and appears to be far
less costly to construct. However, the basic oxidation ditch system
is not able to handle the extreme variations in flow of the Block
Island system and would have to be modified by construction of an
additional small ditch to accommodate winter flows only. This may
increase the initial construction cost to an amount near the
amount estimated for an aeration tank system. The oxidation ditch
system would require only slightly more land area. However, this
would be sufficient to preclude use of the presently proposed site.
If a new site were found for this system, it may not be centrally
located and would result in adding to the cost of the collection
system and outfall sewer. The oxidation ditch is generally more
susceptible to adverse weather conditions which could cause operational
problems.
Modified Activated Sludge. The modified activated sludge process
known as a contact stabilization is slightly less costly to construct
than the proposed system; however, it has the major disadvantage in
being a costly and more complex system to operate. The major reason
for the increased operating cost is the larger volumes of sludge pro-
duced and the necessity to condition the sludge prior to disposal.
Aerated Lagoon. The basic aerated lagoon system is moderately
costly to construct and operate; however, it requires substantially
more land than the proposed system and a new site would be required.
This again would probably result in an increased cost for the collection
system and outfall sewer. It has been found that these systems generally
develop problems with formation of algae which could cause odor problems
and necessitate additional treatment to correct.
29
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U)
o
TABLE 10- Average Costs for 300,000 Gal/day Treatment Facilities
Southern New England
.Type Treatment System
'Extended Aeration:
a) Aeration tanks
b) Oxidation ditch
Modified Act. Sludge
(Contact Stabilization)
Aerated Lagoons
Stabilization Ponds
Physical-chemical
Construction
Costs*
$ 750,000
525,000
640,000
635,000
585,000
450,000
Ave . Annual
Bond Payment**
$ 65,400
45,700
55,700
55,400
51,000
39,200
Annual Opera-
ting Costs
$ 22,500
13,000
35,000
22,500
8,500
40,000
Total Ave.
Annual Costs
$ 87,900
58,700
90,700
77,900
59,500
79,200
Land Disposal
*Based on a 20-year bond issue @ 6% with .08718
**ENR 2100
- Capital Recovery Factor
Source: See Appendix B
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Stabilization Pond. Stabilization ponds have a decided
advantage in construction costs and are quite simple to operate.
However, the extremely large amount of land.necessary for this
process could increase the initial cost well above that of other
alternatives, unless most of the land were available to the town
at little or no cost. The cost of the collection system would
be increased appreciably as there is no centrally located sites
of sufficient land area for this system. In addition, the cost to
construct an outfall from this system would be prohibitive as there
are no adequate sites in close proximity to any shore area.
Effluent would, therefore, have to be discharged through intermittent
sand filter beds in a form of land disposal. The possible environ-
mental effects of this method of treatment would probably preclude
this alternative. Land disposal is discussed in detail in a later
paragraph.
Physical-Chemical Treatment. The physical-chemical system has
the advantage of being the least costly to construct, requiring the
smallest area, being least susceptible to toxic wastes (such as
boat wastes), being able to handle flow fluctuation very well and being
able to be completely enclosed. However, this system is the most
costly to operate and requires skilled operation. Physical-chemical
treatment is generally used where a high degree of treatment and the
removal of phosphorus is necessary.
Although the use of the physical-chemical treatment alternative
appears to have several technological advantages as well as an
economic advantage over the proposed alternative, a note of caution
must be made. At present, there is no definitive cost data for
municipal physical-chemical treatment plants as there are few, if any,
which have been in operation for any length of time. The capital and
operating costs for physical-chemical treatment presented in Table 10
are based upon estimates from pilot plant and demonstration studies
upon manufacturers costs of equipment and upon experience with costs
of these processes in other industries. How the actual capital cost
will be affected by bidding of general contractors is relatively
unknown. Competition may be limited. In some areas, such as Block
Island, it is doubtful that contractors bidding on the work will be
familiar with this type of construction and the resulting bids are
likely to be higher than anticipated.
The annual operating costs presently being estimated for physical-
chemical treatment are even less reliable than the capital cost
estimates. There is little or no data on full-scale operations of
physical-chemical plants for wastewater treatment. The costs of
the chemicals and media used in the processes may increase rapidly
due to increasing demand. Associated with this increasing demand are
uncertainties concerning the long-term availability of these chemicals
31
-------
and media. For a small user, such as Block Island, the availability
and cost of such supplies could become critical in the future as
witnessed by recent experiences with shortages of chlorine. The
long-term maintenance requirements of physical-chemical wastewater
treatment facilities are unknown at this time and can only be
estimated from experience in other industries.
Land Disposal. Land application of the treated effluent and
sludge, at first glance, seemed attractive due to the abundant
presence of soils with characteristics favorable to land disposal
of treated wastewater and the high costs associated with a sub-
merged ocean outfall. In addition, there appeared to be sufficient
depth to groundwater beneath the acceptable soils even during
the wet season.
The U.S. Department of Agriculture, Soil Conservation Service
advised EPA that the sites tentatively proposed as land application
areas are generally well suited for the intended uses. One possible
conflict noted was the proximity of one area to the municipal
water supply wells at Sands Pond. (See Appendix K)
By combining the yearly base flow and the seasonal high waste-
water flow a determination of the amount of land necessary was
made. The application period was assumed to be limited to six
months per year due to climate. Using the adjusted flows, it was
determined that approximately 30 acres were required for spray
irrigation and approximately 5 acres were needed for rapid
infiltration.
Analysis of the areas with the best physical characteristics
revealed that without exception there are competing interests for
the sites. The soil type and topographical characteristics most
suitable for land application of wastes also are the best suited
for water supply development, construction purposes and agriculture.
It is not possible, within one to one-and-a-half miles of the
municipal center, to locate an adequately sized parcel of land a
sufficient distance from a public or private water supply well.
Summary of Treatment Methods. Chart A, which follows, summarizes
the relative merits of each of the treatment processes discussed
above.
While some of these methods may appear more attractive than
others, in the final analysis several .of them could be successfully
employed to treat Block Island's wastewater. Fenton Keyes Associates
chose the extended aeration process because of its cost effectiveness
and its reliability for small treatment plants. For the purposes of
this report, extended aeration has been assumed to be the method of
treatment to be employed for Alternatives A, B and D. The following
process modifications are recommended to be made to the plant as
presently designed:
32
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CHART A - Comparative Summary of Treatment Methods
Alternative
Technical
Environmental
Economic
1. Extended Aeration
A. Aeration Tanks
a. Biological system which may
be upset by watercraft wastes.
b. Has ability to operate under
variations in flow.
c. Requires minimum of skilled
operators.
d. Minimum amount of sludge to
be handled.
a. Will meet secondary
effluent requirements.
b. Minimal land requirements.
c. Minimum amounts of odors
and noise.
b. Less amenable to variations in
flow than Extended Aeration.
c. Sludge handling difficult.
b. Considerably more land
required than for
Extended Aeration.
a. Annual
cost -
$87,900
B. Oxidation Ditches
2. Modified Activated
Sludge
3. Aerated Lagoons
a. Same as above except efficiency
may be more susceptible to
variations in weather.
a . Same as for Extended Aeration,
Aeration Tanks, except will
require greater operational
controls and will produce more
sludge to be handled.
a. Biological system which may be
affected by watercraft wastes.
a. Same as above except
greater requirement for
land.
a. Same as for Extended
Aeration Tanks.
a. Will meet secondary
effluent requirements
but generally requires
additional treatment for
algae formation.
a. Annual
cost -
$58,700
a. Annual
cost -
$90,700
a. Annual
cost -
$77,900
d. Susceptible to adverse
weather conditions.
e. Minimum of skilled operators
required.
4. Stabilization Ponds
a. Although a biological system,
less susceptible to toxic wastes
from watercraft.
b. Amenable to flow variations.
c. Little or no sludge produced.
d. Least amount of operational
a. Generally will not meet
secondary effluent re-
quirements .
b. Minimal noises but re-
quires controls of odors.
c. Large amounts of land
necessary.
b. Best system to deal with
variations in flows.
c. Produces great amounts of
sludge.
d. Requires greatest amount of highly
skilled operators.
e. Requires greatest amount cf
importation of chemicals.
b'. Minimum amount of land
required.
Annual
cost -
$59,500
controls required.
5 . Physical-Chemical
a. Not a biological system. Not
susceptible to toxic wastes
from watercraft.
a. Will meet better than
secondary effluent
requirements .
a . Annual
cost
$79,200
6. Land Disposal.
a. Not susceptible to toxic wastes
from watercraft.
b. Amenable to flow variations.
c. No sludge produced.
d. Requires great amount of
operational controls.
e. Limited by weather conditions.
f. Requires constant monitoring of
groundwater supplies.
a. Essentially produces
no discharge.
b. Largest land requirements.
c. Aesthetics a major problem.
d. Possible contamination of
groundwater supplies.
33
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1. Provide a method for filtering the final effluent for
use during start up and peak periods in the summer to
ensure removal of excess solids.
2. Provide a method of supplying air to the sludge storage
tanks to insure complete aerobic stabilization of
sludge, thus preventing odor problems.
3. Provide a method for controlling odors at the treatment
plant such as introduction of an odor reducing chemical.
3.4 Outfall Location Alternatives
The outfall location chosen for the proposed project is off
Pebbly Beach. A detailed evaluation of that outfall site is presented
under Alternative A. Alternative locations were investigated but
none were considered better than the proposed site. Because of the
State requirement prohibiting a discharge into Class SA waters,
the only possible alternative sites are in the closures around
Old Harbor and Great Salt Pond (refer to Map 7). A discharge
in the Great Salt Pond closure is unacceptable due to the pond's
characteristic lack of sufficient flushing action. A discharge
into the Old Harbor closure, other than at the proposed site,
would be closer to Crescent Beach, the Island's only public
beach and prime tourist attraction. This also was unacceptable.
Thus, in each case, the location of the ocean outfall required for
Alternatives A, B and D is at the proposed site off Pebbly Beach.
3.5 Sludge Disposal Alternatives
For Alternatives A, B and D, the recommended sludge disposal
technique is by landfill at the Town landfill site. The ability of
that site to handle these residual wastes is discussed under
Alternative A. Alternative and more costly techniques, such as
incineration and dewatering or digestion, were not considered
practicable based upon the small amount of sludge produced by the
recommended extended aeration treatment process.
The disposal of septic tank pumpouts (septage) , is also by
application to the land at the Town landfill site. Because the
present site is more than adequate, alternative techniques or
sites were not investigated.
34
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3.6 Flow Reducing Alternatives
New technology has made available flow reducing equipment which
when installed in single or multiple unit homes, can reduce waste-
water flows by 15-20 percent. The types and costs of the various
equipment on the market are found in Appendix E). On the average,
an initial investment of $500 and an annual cost of $50 would be
required to achieve a 15% reduction per single home.
The use of this equipment is not recommended for homes or establish-
ments that will tie into a sewer system since it would have little impact
on a treatment plant operation. For homes that will remain on subsurface
systems, especially in the developed Old and New Harbor areas, installation
of this equipment could have significant benefits. Research has been
done which indicates that installation of these or similar systems will
increase the efficiency of septic systems and consequently mitigate
against their failure.
For Alternatives C or D which would require homes in the Old and
New Harbor areas of the town to remain on septic systems, installation
of the above equipment is recommended to reduce system failures. As
neither Federal or State authorities can require use of such equipment, it
would be the responsibility of the community to regulate and control its
installation and operation.
35
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4.0 IMPACT OF ALTERNATIVE ACTIONS
This Chapter presents a detailed description of the four major
alternatives outlined in Chapter 3, along with a discussion of the primary
and secondary environmental impacts of these alternatives and of the
NO ACTION Alternative.
Alternative Wastewater Flows
Wastewater flows are based on existing and future projected populations
for the area to be served. The three levels of population growth discussed
in Chapter 2 reflect the total Island and, therefore, must be modified to
reflect just the proposed sewered area. The general area under consideration
for a wastewater treatment system is shown on Map 2, and more specifically,
on Map 15 as the area encompassing Stages I and II. Table 11 presents
service area design populations and wastewater flow for the three alternatives
requiring a sewerage system. The figures for Alternative A were taken
directly from the engineering report for the proposed project. Figures
for Alternatives B and D were estimated from detailed data from the
engineering report. The wastewater flows were based on the total amount
of equivalent persons contributing to the system. The number of equivalent
persons at 100 gallons per capita per day (gpcd) were calculated combining
the estimated number of persons in single family dwellings at (100 gpcd)
with persons in multiple dwellings at 45 gpcd, and the number of persons
coming to the Island on boats at 25 gpcd*.
TABLE 11 - Comparative Equivalent Service Area
Population and Wastewater Flows
DESIGN YEAR
Alternative 1973 1998
Summer Winter Summer Winter
Population*
A
B
D
2032
1447
901
383
159
90
3000
2415
1271
538
258
150
Wastewater Flow**
A 203,200 38,300 300,000 53,800
B 144,700 15,900 241,500 25,800
D 90,100 9,000 127,100 15,000
* Equivalent persons
** Gallons per day
Source: Fenton G. Keyes and Associates and estimated by EPA based on
data from Fenton G. Keyes Associates.
* The estimate of 25 gpcd for boaters is based on the assumption that each
person visiting the Island by boat will spend a majority of time on land.
Therefore, the estimate represents 22.5 gpcd on land and 2.5 gpcd of 8,000 gal/day,
from the boat holding tanks*and implementation of Federal regulations concerning
holding tanks will have minimal impact on the capacity of the sewerage system.
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NEW SHOREHAM. BLOCK ISLAND
ALTERNATIVE A
/
•
.
-"... ill
-------
Actual population projections for the proposed project in terms of
single and multiple units and boats are presented in Table 12.
TABLE 12 - Actual Numbers of Units and Persons
to be Served for Alternative A
Description
of Units
1972
Single
Multiple
Boats
Totals
1997
Single
Multiple
Boats
Totals
2022
Single
Multiple
Boats
Totals
Units
162
345
800
350
700
900
392
845
900
Summer
Persons
567
690
3.200
4,457
1,225
1,400
3.600
6,225
1,372
1,690
3.600
6,662
Winter
Units Persons
114 400
400~
143 500
500
172 600
600
Source: Fenton G. Keyes Associates
A street by street breakdown of estimated present and future units
prepared by Fenton Keyes Associates is included in Appendix F.*
Estimation of units for Alternatives B and D are not shown but can
be assumed to be in general conformance to the above but at reduced scales.
Wastewater flows for Alternative C were not computed but estimations
of future septic system construction were based on present growth rates.
4.1 NO ACTION Alternative
Description. The alternative of NO ACTION implies a continuation of
existing conditions and practices of wastewater disposal on Block Island.
Primary Impacts. As was presented previously, existing water quality
conditions within the Old Harbor and New Harbor areas of the Island are tenuous.
*The design figures in Appendix F are not directly comparable to Table 12;
however, the resulting average flows are the same.
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Direct discharges and failing septic systems would continue, and associated
public health, aesthetic and environmental problems would persist. Pumping
and haulage of septage from overflowing septic systems would go on with
the regularity of the past. For many of the commercial establishments,
it is necessary to pump as often as once a week during the busy tourist season.
Fortunately, the disposal site for the final dumping of the septage is adequate
to handle such loads, (a further discussion of the septage disposal area
is included under Alternative A), but there are negative aesthetic affects
associated with the transportation of these wastes.
Since the major water supply is or will be taken from ground water
aquifers in the southern section of the Island, discharges from the Old
and New Harbor areas will not affect that supply. However, seepage from
direct outfalls and failing septic systems into Great Salt Bay, Old Harbor
and Crescent Beach could eventually affect the quality of fishing, shellfishing
and water contact recreation in those areas. The discharge of watercraft
wastes would also continue to contribute a great pollution load to Great Salt
Bay and the Harbor areas, at least until Federal regulations go into effect.
The State Department of Health has indicated that many warnings have
been issued to establishments on Block Island which are in violation of
the State sanitary code. However, sources from that Department say that
they have been hesitant to close establishments because the Town has exhibited,
in good faith, their intentions to improve conditions with proposals to
build waste water collection and treatment facilities. However, if no affirm-
ative action is taken, the State will have no course but to condemn these
establishments which continually violate sanitary regulations.
Secondary Impacts. Under the Alternative of NO ACTION, it is obvious
that growth rates will not increase (see present level trends in Chapter 2).
Yet, it is likely that there will be a significant change in present land
use. Inasmuch as growth within the established Island cores (Old Harbor
and New Harbor) cannot be assimilated because of inadequate land available
for subsurface disposal systems, it is conceivable the resultant effect
will be the eventual disintegration of the social, environmental, and economic
viability of those town centers. Further, future developments, if any, will
spread outward from these cores and possibly infringe upon the openness
of the southerly and northerly sections of the Island.
4.2 Alternative A - Fenton Keyes Proposed Project
Description. The alternative described and evaluated in this section
is the proposed project submitted by Block Island to the EPA for funding.
This project consists of pumping stations, interceptor sewers, lateral sewers
and a wastewater treatment plant. The total project is designed to be constructed
in two stages. The first and second stages are shown on Map 15. The dashed
lines ( ) indicate the extent of Stage 2. The design of the treatment
system was based on the projected waste flows displayed at the beginning of
this chapter, the design capacity is 0.3 MGD for expected flow through the
year 1998.
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The treatment plant is to be located on the high land south of
Old Harbor, east of Spring Street (refer to Map 15). The method of treatment
is the extended aeration modification of the conventional activated sludge
process. Properly operated, this system will remove at least 85% of the
suspended solids and 90% of the BOD contained in the incoming wastes. The
units in the treatment plant consist of grit removal, comminution, six aeration
tanks, two secondary sedimentation tanks, and dual chlorine contact chambers.
Power to operate the system will be generated at the plant site. This
self-sustaining feature was recommended by the engineers as a result of
a cost evaluation of alternative power supplies. Dual 1200 cubic inch diesel
generator pairs are proposed to supply every-day and emergency power. The
multiplicity of units in the treatment plant mitigates against total equipment
failure. Should such failure occur, however, the storage capacity of
the plant is sufficient to remove virtually all of the settleable and
floating solids.
The effluent from a plant of this type is essentially colorless and
low in suspended solids and turbidity. The suspended solids (10 to 15
percent remaining) are light and flocculent, will not form sludge banks>
and are relatively stable.
The effluent is to be discharged into the ocean off Pebbly Beach via
an outfall sewer (refer to Map 15). Due to the severe weather conditions
that are experienced in the area, it will be necessary to completely enclose
the submerged portion of the outfall in a concrete case.
Although the extended aeration process normally does not produce a sludge
by-product, at times an excess will buildup in the system. When this situation
occurs, excess sludge can be pumped from the system to a waste sludge holding
tank for ultimate disposal at the town landfill located in the southwestern
part of the Island. It is estimated that once every 30 days in the summer
and once every 60 days in the winter, the sludge must be hauled from the
treatment site to the landfill for final disposal.
Provisions to accept watercraft holding tank wastes at each marina
are included in the design.
Social Impact. The most significant social impact of this alternative
is that it will clean up the pollution problems in Old and New Harbors and
the resulting health and asthetic effects.
At present, the land on which the treatment plant will be constructed
is zoned for business. However, this site is located within the Old Harbor
area which was designated by the Rhode Island Historical Preservation Commission
as an historic district and was placed on the National Historic Register
in May 1974. The Commission indicated that it was unfortunate that the site
was to be located in an historical district, but further indicated that
in the future the whole Island may be designated as an historical area. In
that event, the relative effect of a treatment plant site in that area would
be minimal. (See Appendix 6).
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Of greater concern to the Commission was the close proximity of the
treatment facility to the Ocean View Hotel ruins, "The Shamrock Inn," which
is being restored, and the nearby church. Although the actual site will
be in a depression thus affording some natural cover, a sufficient buffer
zone does not exist between the three structures and the facility. Fences
and shrubbery will be required to screen the facility from the structures.
The Commission indicated it will assist in the design of fences and landscaping
that will effectively reduce any negative aesthetic impacts.
The route of the outfall sewer from the point it departs from the roadway
and continues through the beach area and eventually to the ocean, will have
aesthetic and psychological effects. The concrete encased outfall will
rise above mean sea level and will be in effect a groin or pier extending
from the shore out approximately 200 feet. From a visual sense, the groin
will undoubtedly change the natural setting of the area. From a psychological
sense, just the presence of a wastewater outfall may impart a negative attitude
or atmosphere to the area. Health aspects of this outfall are discussed
in the environmental section.
It can be seen from Map 15 that the sewer routes are in most cases
along existing roadways. It is not anticipated that these routes will be
affected negatively by the interceptor. However, the impact or short term
effects during construction of the sewers, as well as the treatment plant
and outfall sewer, depend on the time of year the construction takes place.
As was established earlier in this report, the Island's major asset is its
attractiveness as a recreational area. If construction occurs during the
tourist season, the associated disruptions will have an unfavorable effect
on the Island's tourist trade. For this reason, the condition that there
be no construction activities during the tourist season was included in
the design of the proposed system.
Technical. From a technical standpoint, there is no indication of
problems in construction of either the sewer system or the treatment facility.
The site of the treatment facility is high enough above sea level to be
protected against floods and the soil characteristics are amenable to construc-
tion of such a unit. Construction of that portion of the outfall that is
in the water, will be difficult, as is reflected in estimated costs; however,
no overwhelming constraints are foreseen.
Because many of the soils in the total project area are erosive and
the topography is steep and undulating, the Soil Conservation Service
indicated that a plan for control of erosion is required. Such a plan should
include provisions to reduce erosion from excavation areas, stock piled
soil material, construction sites and final revegetation after construction.
Practices that will probably be needed in the control plan include: temporary
and permanent seeding of critical areas, sediment basins, diversion interceptor
dikes, mulching, drainage log or bailed hay erosion checks, and tree planting
in heavy use areas. In addition, revegetation plans should include only
those plants that are tolerant and adapted to "salt spray" such as,
40
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Japanese Black Pine, Russian Olive, Tatarian Honeysuckle, and Scotch Broom.
The Soil Conservation Service is willing to assist in the development of
such a control plan.
Operation and maintenance of the proposed treatment facilities could
present some problems. Specifically, the drastic changes in flow due to
seasonal changes in population may upset the biological action in the treatment
plant. This will necessitate additional monitoring and operational activities
during the periods when flows change, at the beginning and end of the tourist
season and possibly on weekends.
Another problem may be the inclusion of salts and chemicals in the
system from the boat dumping facilities.
The magnitude of saline and chemically treated wastes emanating from
watercraft, that will affect a biological treatment plant has been deter-
mined by various research programs. A report developed by Ludzork & Noran
in the October, 1965 issue of the Journal of the Water Pollution Control
Federation indicated total concentrations of chlorides at the treatment
plant up to 8000 parts per million (ppm), assuming a reasonably constant
concentration, will not inhibit biological action. For the treatment system
described in this alternative, 2.5 gpcd for each of the 3600 boaters contrib-
uting, results in a chloride concentration of 645 ppm at the treatment plant.
It is not probable that levels of this nature will impair treatment efficiency,
but during periods of seasonal changes in flow, the shock loads of high
salinity wastewater may cause temporary disruptions in treatment efficiency.
Additional chemical ingredients which are found in watercraft wastes,
and' can be harmful to the treatment system are zinc and formaldehyde. A
research report prepared by FMC Corporation, San Jose, California for EPA
(1974) indicated zinc concentrations above 20 mg/1 or formaldehyde concentrations
greater than 120 mg/1 cause adverse effects in biological systems. Based
on the projected rate of 2.5 gpcd times 3600 persons and the reported concentra-
tions for zinc (4500 mg/1) and formaldehyde (4500 mg/1) in watercraft wastes,
the resultant concentrations at the treatment plant will be: 135 mg/1 zinc
and 135 mg/1 formaldehyde. Considering the reliability of these estimates
to be within 50%, it is probable that zinc concentrations, and to a lesser
extent, formaldehyde concentrations will upset the biological treatment
efficiency of the extended aeration facility.
The problem of salts and chemicals in the treatment system is directly
related to EPA, Coast Guard and State regulations concerning watercraft
wastes. The present EPA standard of no discharge by 1981 will require holding
facilities on boats and pumpout facilities at marinas in the future. Under
these requirements, pretreatment of chemically laded boat wastes will be
required for this alternative and Alternatives B and D, which also utilize
a biological treatment facility. It is possible that Federal or State authorities
will prohibit the use of these toxic chemicals in which case pretreatment
would not be necessary. However, such action does riot appear likely at
this time. It is also possible that the no discharge standard may be totally
41
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abandoned in favor of flow through devices, in which case no facilities
would be required at the marinas. (See Appendix B).
An example of the type of treatment systems necessary at each marina
under the present law is included in Appendix G. The exact type of system
to suit the situation on Block Island should be investigated and determined
by the design engineer. The disposal technique of the residual toxic wastes
from the pretreatment processes should also be investigated by the engineer.
Because of their expected toxicity, special landfilling procedures may be
required.
The materials to be used in the construction and operation of the
proposed project include concrete, fill material, piping and machinery,
which for the most part will have to be shipped from the mainland since
little or no supplies are available on the Island. Neither the consumption
nor the transportation of these materials is considered to have a signifi-
cant environmental impact.
As stated previously, power will be generated at the treatment plant.
Thus, there will be no consumption of the Island's municipal energy supply.
Although this type of treatment system, extended aeration, is known
for its reliability and simplicity of operation, under non-seasonal conditions,
the operational difficulties that will be experienced because of seasonal
flows will require skilled technicians. Finding personnel capable of operating
this facility may require relocating them from the mainland as the present
work force on the Island is limited. This in itself may be a problem.
Environmental Impact. Discharging over 300,000 gallons of treated
wastes in four feet of water only some 200 feet from shore presents
environmental questions that must be addressed in detail. For this purpose
a mathematical model, verified by on-site investigations was used by EPA
to simulate the conditions that can be expected if a discharge occurs.
The complete analysis is included in Appendix H, however, a summary
of the conclusions are as follows:
1. Drogue studies indicated it is highly improbable that the waste-
water effluent will encroach upon the nearest bathing area,
Ballard's Beach, and at no time will it reach Crescent Beach.
2. Dispersion models predicted the proposed outfall design
would meet water quality standards most of the time, but
that with an improved diffuser design, water quality stand-
ards could be met all of the time.
The above conclusions were based on secondary treatment wastewaters
with an effluent coliform count of 1000/100 ml. and the required water quality
standard (SB) of 700/100 ml. It was considered that the treatment plant
should at least chlorinate the wastewater at all times.
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Another important question concerning the outfall is its accessibility
to swimmers, strollers, or curious youngsters. Because the depth of water
at the end of the outfall is only four feet, it is conceivable that anyone
could walk out to that point. Furthermore, the concrete encasement for
the outfall, which will be above water, will afford an even more direct
route to the discharge point. For this reason, it is recommended that the
outfall be extended to a depth which would preclude easy accessibility (the
10 feet depth would require extending the outfall some 500 feet), or, some
arrangements to limit accessibility to the discharge point such as fences
or warning signs be employed.
EPA and the State will assist in the design of the improved diffuser,
and the extension of the outfall or the confinement of the discharge point.
As indicated in the project description, the sludge will be disposed
of no more than 20 times per year at the Town's landfill site shown on Map 10.
The United States Department of Agriculture Soil Conservation Service was
consulted and commented that the disposal site has well drained, deep, coarse
textured soils and a water table between 30 and 40 feet deep. Thus, the
site is suitable for the proposed use. Both the State Department of Health
and the local Conservation Commission have approved the site for sludge
disposal.
Since the majority of septic tanks now requiring frequent pumping would
be replaced by sewers, the septage load, under this alternative, coming
to the landfill would be greatly reduced.
The present treatment plant design does not contain provisions for
odor control and odors emanating from the treatment plant will be present.
With proper operating practices, these can be minimized; however, we recommend
that odor control provisions be made. Haulage of the sludge may present
some odor problems as the trucks must pass relatively near the populated
Old Harbor area. However, by collecting the sludge at times such as early
in the morning, when it will least affect the neighboring populace, the
potential problem can be minimized.
A preliminary inspection of the drawings of the treatment plant indicate
that the noise emitted from the plant may be considerably higher than the
measured ambient levels (indicated in Chapter 2), such that a significant
noise impact may be generated by the plant. The main source of emitted
noise can be identified as:
1. Radiator and radiator fan noise, 75 dBA at 50 ft. These
radiators are located on the outside of the proposed plant
and evidently will not be located behind acoustic barriers.
2. Exhaust noise, 75 dBA at 50 ft. The engine exhausts vent
directly to the exterior of the building. This assumes the
use of a standard exhaust muffler.
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3. Engine noise, 70 dBA at 50 ft. while the engines are
located inside the building in an acoustically treated
engine room, there is a 10 ft. by 5 ft. opening from the
room to the outside for engine inlet air and it is
reasonable to expect about 70 dBA at 50 feet emitted through
this opening.
All three sources are related to the two diesel generators (approxi-
mately 150 KW capacity each) and the dBA levels have been estimated based
on the data given for truck diesel engines in EPA-550/9-74-018, BACKGROUND
DOCUMENT FOR PROPOSED MEDIUM AND HEAVY TRUCK NOISE REGULATIONS, OCT. 1974.
All three sources are visible from the boundary line of proposed site
and all three sources are located on the inland side of the proposed building
and, therefore, visible to the adjacent receptors. All three sources together
give a single equivalent source of:
75 + 75 + 70 = 78.6 dBA at 50 ft.
Assuming 6 dB per doubling of the distance gives 72.6 dBA at 100 ft., 66.6
dBA at 200 ft., 60.6 dBA at 400 ft., and 54.6 dBA at 800 ft. Furthermore,
the emitted noise over a continuous 24-hour period will result in Ldn values
of 79 dBA at 100 ft., 73 dBA at 200 ft., 67 dBA at 400 ft., 61 dBA at 800 ft.,
and 55 dBA at 1600 ft. These LDN values should be compared to the Ldn of
39 dBA estimated for the existing winter level. During the winter period
the plant will be audible at distances up to about 1.2 miles with no additional
attenuation.
In view of the possible noise impact indicated above, EPA would require
that measures be taken to include noise attenuation features sufficient
to reduce the Ldn at all receptors to a maximum of 55 dBA. (An Ldn of 55 dBA
is identified in the EPA document, "Information on Levels of Environmental
Noise Requisite to Protect Public Health and Welfare With an Adequate Margin
of Safety" as adequate to protect against outdoor activity interference
and annoyance). As the noise impact would be the same for Alternatives
B and D, this requirement would apply to those alternatives as well.
In view of the low ambient levels, an Ldn of 45 dBA should be set as
a design goal to be achieved if economically feasible.
The following are possible solutions to the problem:
1. Use acoustically insulated louvers.
2. Construct an acoustical baffle between generators and
louver opening.
3. Construct acoustical barrier wall around radiator fan area.
4. Construct earth berm barrier between plant and receptors.
5. Use improved exhaust silencer.
6. Relocate generators to less sensitive area, if available.
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The preceeding are standard noise-control procedures. The effects
of such procedures on engine efficiency and plant working conditions must
be taken into account by the design engineer. The Region I Noise Program
will provide technical assistance to engineers to the extent possible.
The only effect of the treatment plant on the ambient air quality other
than the odors from the sewage itself will be emissions of -the diesel
generators. Operation of the two diesel engines, one at a time, will be
continuous, burning approximately 57,000 gallons of diesel fuel per year.
Using emissions factors in the EPA publication, "Compilation of Air Pollutant
Emission Factors", Second Edition, AP-42, p.3.1.5-2 (emission factors for
heavy-duty, diesel-powered vehicles), the following annual emissions are
predicted from the diesel engines:
Particulates 741 ///year
SOx (as S02) 1540 ///year
(Based on ave. sulfur content of 0.2%)
CO 12820 ///year
HC 2120 ///year
NOx (as N02) 21200 ///year
Aldehydes 171 ///year
(as ECHO)
Organic Acids 171 ///year
No background CO levels are estimated due to the absence of CO monitoring
on Block Island. However, as stated in the section on air quality, no major
sources of air pollution (including CO) exist on Block Island.
Due to the relatively low background levels of SO .and particulates and
the relatively insignificant amounts of air- pollutants estimated for this
facility, the emissions from the diesel engine will not cause a violation
of any applicable ambient air standards.
To determine the effect of the treatment system on the Island's
wildlife, various authorities were consulted. According to the Department
of the Interior, U.S. Fish and Wildlife Service, neither the wildlife refuge
area in Sandy Point nor the "Block Island Vole" will be disturbed by the
proposed system. In addition, Dr. Howard Winn, a marine mammalia expert
from the University of Rhode Island who has been studying the seals indicated
it was unlikely that the effluent from the proposed treatment plant would
adversely affect the reported seals.
The environmentally sensitive areas indicated in Map 8 were evaluated
with respect to the physical system proposed by this alternative. There
do not appear to be any major conflicts.
Economic Impact. The costs associated with Alternative A are shown
on Table 13. The costs for Stage I are based on bid prices of August 1974.
All other costs are based on best estimates.
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TABLE 13 - Annual Costs of Alternative A
Construction Average Annual Annual Oper- Total Average
Cost* Bond Payment ating Cost Annual Cost
Phase I
Phase II**
$ 4,383,000
500,000
382,000
44,000
27,000
0
409,000
44,000
Individual
House
Connections 150.000 13.000 0 13.000
TOTAL $ 5,033,000 439,000 27,000 466,000
* A detailed cost breakdown is included in Appendix I.
** When constructed.
Source: Construction Bids - August 1974 and Estimates by EPA
The Town's share of the construction cost will be borne by a minor
increase in the total tax rate and by betterment assessments on the properties
within the service area. The operating costs will be covered by service
charges based on extent of user facilities.
In addition to the annual costs of this.alternative there are other
ramifications to the economic base of the Island. It is a fact that many
of the Town's commercial establishments are suffering economically from
a lack of sanitary systems. For instance, some establishments are limited
in the number of people they can serve, and in some cases establishments
have been closed. Since the Island's economy is based on the ability of
its commercial industries to provide services to tourists, the improvements
provided by this alternative will significantly benefit the economy of the
established Town center.
Political and Legal/Institutional Impact. Many of the legal and institu-
tional arrangements required to maintain and regulate a sewer system have
already been established by the Town in anticipation of the construction
of this system, including the Block Island Sewer Commission and subsequent
sewer cost assessments. Some strengthening of these arrangements may be
necessary to better reflect the needs and desires of the townspeople since
the preparation of this impact statement would indicate that the dialogue
between local regulatory authorities and the general public is less than
complete.
In addition, the arrangements recommended by the designing engineer
concerning subsurface disposal systems for areas outside the sewer system
are excellent and should be implemented.*
*Preliminary Engineering Survey and Report on Control of Water Pollution
for the Town of New Shoreham, R.I., Fenton G. Keyes Associates,
Providence, R.I., Feb. 1972, pp.20-26.
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Secondary Impacts. Based on the development pressures on the Island's
coastline serving the Northeast's recreation demand centers, construction
of sewer lines and waste treatment capacity could be expected to stimulate
and accelerate growth on Block Island.
The design capacity of the proposed project is based on the assumption
that both single and multiple housing units will double in the study area
by 1997. (See Table 12).
The significance of this fact is dependent to a great extent on two
factors: (1) How much development could occur without the sewer systems,
and (2) How that new development is distributed within the study area.
Based on existing zoning allowances and recent demand for building
permits, doubling of the single housing units will likely occur within the
study area whether or not the area is sewered. Sewering this area could
cause an acceleration of single family development (See Table 14). However,
there has been almost no recent demand for building permits for multiple
units, probably due primarily to the lack of adequate sewage disposal.
Thus, without the new sewers, it is probable that few multiple unit structures
would be built.
It is possible that as a result of sewering this area the emphasis
will be placed on multiple unit development. A portion of this multiple
development will probably include hotels and possibly condominiums along
with commercial establishments. These will generally be located in either
New or Old Harbor. As Old Harbor is presently the most densely developed
area on the Island, additional development would likely have the effect
of enlarging the core of the Old Harbor area, possible causing more intensive
land use without substantial change to its character. If, on the other
hand, the greater portion of the multiple unit and commercial development
occurs in New Harbor, there will be a noticeable change in the character
of New Harbor, simply because present development in this area is minimal.
TABLE 14 - Comparison of Development Trends
in Proposed Sewer Service Area
NEW UNITS UNITS/YEAR
Total Single Multiple Total Single Multiple
Estimated
1960-1970 175 125 50 17 13 5
Projected
for Design
1972-1997
1997-2022
543
187
188
42
350
145
22
10
8
2
14
7
Source: 1) Estimates from U.S. Census and U.S.G.S. maps.
2) Fenton G. Keyes Associates.
3) This estimate includes 36 units in Ballards.
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In either case, there will be an eventual demand for an extension of
other public utilities and services such as water supply, electricity and
solid waste disposal.*
A large portion of the area proposed to be sewered by Phase II is wetlands,
and cannot be developed using subsurface disposal methods. If sewers were
made available there is a strong possibility that development would encroach
upon these areas. Intensive commercial resort development would be especially
likely in the extensive undeveloped areas in the vicinity of New Harbor,
accessible to Great Salt Pond, marinas and a ferry-slip. New summer home
developments would likely occur both in the vicinity of New Harbor and in
the heights to the south of Old Harbor. There is even a possibility that,
with the extension sewers and other utility services, a pattern of new condomin-
iums, motels and summer home developments in presently undeveloped areas
could take place at the expense of revitalization of the old hotels, homes,
and businesses of Old Harbor.
A substantial impact on the character of the residential areas outside
of Old and New Harbors would result from the sewers only if there were sufficient
demand for development to cause either zoning changes to smaller lot sizes
with in the sewered area or zoning variances to the same end. Such development
is theoretically limited by the design capacity of the sewer system, but
once the system reaches capacity, demand for additional development could
result in pressure for expansion of the system and the costly expansion
of treatment facilities. Then the cycle could begin again, resulting in
denser development of outlying areas.
Substantial changes in character of these types would be in direct
contrast to one of the Town's prime goals: maintaining its rural New England
character.
In further consideration of the character of the Island, present zoning
does not restrict building heights in the business zone or hotel heights in
other zones where they are allowed by special permit. Since residential
density for individual buildings will no longer be limited by on-lot sewage
disposal capabilities, it is possible that there will be some building to
heights greater than those now present on the Island. Such development
could create a substantial visual impact anywhere within the sewer service
area, unless the zoning bylaw is changed to include a height restriction
on these types of development.
It must be recognized that although the design capacity is based on
certain development assumptions, once the capacity is provided development
may proceed in many different ways and at differing rates, unless the town
*In 1972, Fenton G. Keyes Associates prepared a "Preliminary Engineering
Survey & Report On Water Supply & Distribution for the Town of New Shoreham."
48
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makes a conscious effort to control such development through zoning or other
planning techniques.*
On other northeast resort islands, the demand for recreation facilities
and summer homes has resulted in intensive development and proliferation
of resort complexes, condominiums, motels, shopping centers and well-equipped
modern summer residences. With sewers and other improvements, such development
would be made possible in the vicinity of proposed sewer lines on Block Island.
It is not probable that an extreme growth situation will occur on Block
Island either directly or simultaneously as a result of the proposed project.
But such growth will occur little by little if the sewer system is permitted
to expand with complementary changes in the zoning densities either by variance
and special permit or bylaw amendment. Based on the experience of these
other places and depending on the strength of development demand to force
zoning changes and further expansion of sewer and treatment capacity, an
extreme growth situation could result in the following impacts:
1. Impose resort complexes and residences on wetland and
shoreland ecosystems and on flood hazard areas.
Especially adverse would be encroachment upon the salt
water marshes of the Great Salt Pond embayments as well
as fresh water marshes abutting the Ocean Avenue and
Beach Avenue sewer lines; also, the south shoreline of
Great Salt Pond accessible to the West Side Road sewer
line and extensive areas in the south central sector
tentatively proposed for "conservation" or "open space
recreation" in the CCP and for "low residential, open
space preservation", "no structures", or wetlands in
the Block Island Report prepared by the University of
Rhode Island.
2. Facilitate condominium and medium density residential
development in the extensive open moors, dotted with
small lakes, to the southwest of New Harbor. Intrude
upon open space character, marsh and upland vegetation
and general sense of openness of the Great Salt Pond
area and view of Great Salt Pond and Block Island Sound.
3. Stimulate medium density residential development (1 acre
lots) on the extensive "low density residential" and
"conservation" areas southeast and south of Old Harbor
proposed in the CCP. These areas embrace perched fresh
water marshes, ponds, water supply recharge areas, and
the picturesque pasture-bayberry moor vistas of Old
Harbor and the ocean from the upland plateau. Proposed
for "low density residential" (2 acre lots) and some
*0ne such mechanism which could be used to check unwanted growth attributable
to sewer construction is through the National Pollutant Discharge Elimination
System permit. Effluent quantity limitations at different points
in the design life of the treatment facility, over development of the sewered
area could be controlled.
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"open space recreation" in the CCP and "low density,
open space preservation" in the URI report (zoning
in conflict with both).
4. Facilitate resort and beach house development northward
along Corn Neck Road toward North Neck, through the
potential for sewer connections. Thus closing in upon
the beaches, salt water marshes and open vistas of the
ocean, Great Salt Pond and North Neck Highlands. Much
of this area presents flood hazards and lies below the
hurricane highwater line.
5. A higher level of development, public services,
commercial activity, tax assessments and overall
publicity about the Island would encourage land sales
and greater numbers of people to build summer homes on
the Island even in areas beyond the influence of the
sewers and treatment plant, thus impairing surface and
ground water and further encroaching upon the open
countryside of the Island hinterland.
6. Greater numbers, densities, and range of activities on
the Island would have an overall adverse impact on the
high quality environment:
- on water quality through runoff from additional paved
and impervious surfaces, through some erosion and
sedimentation of fragile ponds and wetlands associated
with construction and continuing earth disturbance,
and through additional solid waste-septage disposal
and septic system operation - all associated with a
higher level of development;
- on noise levels through additional vehicles, lawnmowers,
and human activities;
- on air quality through additional motor vehicles and
powered boats;
- on visual appeal of sweeping vistas of sea, sand, and
sky; of rolling moors, pastures, ponds, and vegetation.
- on fragile ecosystems; salt and fresh water marsh
associations, dunes associations, and upland plant and
animal associations.
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7. Greater numbers, densities, range of activities, and standard-
ized outside architectural styles could overwhelm or clash
with the character of the Island countryside, with the
relative open scale of the Old Harbor community itself,
with the indigenous architecture, and with historic
preservation.
On the other hand, a sewer system would help to maintain
the historic hotels, shops, and houses of Old Harbor as
-a community cluster.
8. Greater numbers of residents and visitors and diversity
of outside interests could weaken the cohesiveness and
close personal relationships of a small tightly-knit Island
community. Yet, at the same time, some additional
residents economic activities, and services would sustain,
enrich, and round out the social fabric of the community.
9. Additional numbers, economic activity, and services would
provide a base for a sustained year-round economy and
raise the monetary level-of-living. At the same time,
this could lend to greater dependence on values associated
with a cash economy as opposed to a way-of-life that
features a quality environment, indigenous community
charm, arid opportunities for solitude.
A section by section analysis of the town under extreme conditions ,
of induced growth is included in Appendix J.
4.3 Alternative B Proposed Project minus Stage II
Description. It is apparent from an examination of the Septic System
Failure, Map 7 and the Soil Characteristics, Map 5 that septic systems are,
at present, working properly in the Stage II area (refer to Map 15), and
by all indications could continue to work with a reasonable degree of reliability
for the future. Therefore, Alternative B includes a wastewater system similar
to the proposed project which would include Stage I sewers but not future
Stage II sewers. The treatment facility design under Alternative A includes
an additional capacity of 58,500 gallons per day for Stage II. That capacity
would not be required under this Alternative. No other changes from the
system described in Alternative A are suggested.
Primary Impacts. Because of the similarity between Alternative B and
Alternative A, the primary Social, Technical, Political and Legal/ Institutional
Impacts will be the same. The environmental impacts differ only in that
the expected discharge under this alternative will be less than under Alterna-
tive A by 58,500 gpd at design conditions. This amount, however, is not
significant enough to consider a redesign of the outfall system or the treatment
process itself. This decrease in capacity should be handled by a simple
restriction on the NPDES permit.
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Table 15 lists the estimated costs for Alternative B and reveals a slight
savings over Alternative A. The economic advantages, however, may be deceiving.
While Alternative B would not require an expenditure of $500,000 for Stage II
sewer construction, growth within the Stage II area will require construction
of new septic systems. Based on moderate growth projections, individual expend-
itures for septic system construction in the Stage II area could total up to
$225,000 in the next 25 years. Further, while the sewer system costs are partially
funded by State and Federal grants, the cost for the construction of individual
septic systems must be entirely borne by the individual.
Secondary Impacts. Secondary impacts of this alternative would be similar
to those of the proposed project (Alternative A), except that there would
be no real pressure for smaller zoning lot sizes or for multiple unit structures
in the Stage II area. This would eliminate the potential adverse effects
of such development on the open space and ground water availability areas
to the south of Old Harbor. Elimination of Stage II could result in directing
development to sewered areas in New Harbor. Such development might eventually
encroach on environmentally sensitive areas adjacent to Great Salt Pond.
TABLE 15 - Estimate Costs for Alternative B
Average Operation & Total
Item Capital Annual Maintenance Annual
Treatment Plant
& Sewer System $ 4,083,000 355,000 25,000 380,000
House Connection 100,000 9,000 0 9,000
Future Stage II
Septic System
Construction 225,000 20,000 500 20,500
TOTAL $ 4,408,000 384,000 25,500 409,500
Source: See Detailed Cost Breakdown in Appendix I.
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4.4 Alternative C -Rehabilitation of Individual Subsurface Disposal Systems
Description. This alternative for dealing with the water pollution problems
of Block Island is based on the continued utilization of individual subsurface >
disposal systems. Subsurface disposal or septic tanks have been demonstrated
to be an effective, reliable, economic and environmentally satisfactory method
for the disposal of wastewater for individual homes at low development densities
and with appropriate soil conditions. Subsurface disposal systems have served
all of the commercial and residential dwellings on Block Island with many
dwellings using the subsurface systems originally constructed with the building.
However, in the more densely developed commercial areas of Old Harbor and
'New Harbor subsurface systems have failed because of either poor construction,
inadequate soil conditions or insufficient area for drainage fields. As was
stated previously, the proper backfill (Bank Run Gravel) and trench material
(1/2 to 1 1/2 crushed stone) are not readily available on the Island and were
probably not used in many cases.
As was discussed under Alternative B, septic systems in the Stage II
area are working properly and by all indications will continue to work
adequately for the future. Existing systems which have failed would be recon-
structed in accordance with the .State of Rhode Island's standards for construction
and maintenance of individual sewage disposal systems included in Appendix M.
A major assumption of this alternative is that all subsurface systems in the
areas, defined by Stage I of Alternatives A & B, would need to be rebuilt
within the next five years. The life of a reconstructed system is assumed
to be twenty years with annual inspections and pumpout of the septic tank
solids as necessary perhaps once every three years. In situations where sufficient
land is not available to construct systems to meet State regulations, such
land would have to be acquired. Future developments would also require more
stringent construction practices. Septage from septic tanks would be trucked
and disposed of at the existing landfill site.
The Federal requirements for disposal of watercraft wastes as discussed
in Appendix B may necessitate holding tank pumpout facilities at each marina
similar to those provided in Alternatives A and B. Under this alternative,
wastes pumped out of the boats will have to be trucked to the Town landfill
site for disposal along with the septage wastes. Although there is ample room
at the landfill site to accept these wastes, recent research has indicated
that the highly toxic chemicals added to holding tank wastes as a conditioner
could eventually seep into ground water supplies. Consequently, costly pre-
fireatment to eliminate such chemicals will be required prior to disposal in
a sanitary landfill.
In order for Alternative C to be considered viable, State regulations
on subsurface disposal must be rigidly enforced in the future to minimize
the possibility of additional water pollution problems resulting from failing
systems. It should be recognized that design and construction of subsurface
disposal systems is not an exact science, but that careful design and construc-
tion coupled with favorable soil conditions minimize possible septic tank
failure. Seasonal use of these systems further enhances the prospects for
their successful use. An additional mitigating factor would be the utilization
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of in-house flow reducing equipment discussed in Chapter 3 for the critical
New Harbor and Old Harbor areas.
Under this alternative, development would be constrained to present
levels and would be limited, prohibited, or uneconomical in the low lying
areas, generally below elevation of 10 feet. Environmentally sensitive
areas below elevation 10 feet were presented on Map 15.
Social Impacts. A primary social impact will be general disrup-
tion of services from construction activity during rehabilitation of the septic
systems. Construction impacts can be minimized, however, by scheduling such
activities during nontourism months. Additional social impacts may result
from public health and aesthetic problems of systems which may fail in the
future.
The aesthetic impacts of odors associated with transport and land disposal
of septage and watercraft wastes are expected to be minimal.
Technical. The continued use of individual subsurface disposal systems
provides a number of technical advantages in that such systems are simple,
relatively inexpensive, reliable and effective if designed, constructed, operated
and maintained properly. However, this alternative poses significant problems
particularly with regard to existing buildings which have failing systems.
The failure of these systems may generally be attributed to high ground water
conditions, inadequately sized or constructed leaching fields, or inappropriate
soil conditions. In the more densely developed areas of the Island, lot sizes
and geographical locations may physically preclude the construction of satisfactory
subsurface disposal systems. In those cases, reconstruction of the systems
may only provide an adequate functioning system for several months or less
and pumping of the septic tank on a regular daily or weekly basis may be neces-
sary. The only possible solution for these failing systems is to convey the
wastes to adjoining properties or other locations where satisfactory systems
could be built.
Use of properly constructed subsurface disposal systems will require
the continuation of pumping, hauling and landfilling septage, but on a less
frequent basis than at present.
Environmental Impacts. An advantage of subsurface disposal is that it
serves to recharge the ground water and thereby serves to sustain the fresh
water supply. The longterm effects on water quality of continued discharge
to the ground water are uncertain. However, experience with subsurface disposal
systems at the densities proposed on the Island indicate that the effects
would be minimal. In areas served by the community water system these impacts
would be further reduced (See Appendix N).
The possibility of continuing failure of subsurface disposal systems
always exists. Odors and public health problems which might arise from sewage
seepage would pose a significant environmental problem.
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The magnitude of septage to be disposed of will probably be less under
this alternative than under present conditions. ' The possibility of odors
and ground water contaminants at the disposal site are considered to be minimal.
Economic Impacts. The costs of continued use of subsurface disposal
systems are based on reconstruction of the existing systems and construction
of new systems in accordance with State of Rhode Island regulations. Recon-
struction of existing systems within the proposed sewered area and new con-
struction of systems to accomodate new development through 1998 is estimated
at $2,000,000.
As previously noted, several of the existing systems cannot be adequately
reconstructed because of physical site limitations. The cost of conveying
this wastewater to adjoining properties where adequate subsurface disposal
systems could be constructed is not included.
Total Capital and Annual Costs for Alternative C, including costs for
handling watercraft wastes are shown in Table 16.
TABLE 16 - Estimated Costs of Alternative C
Average Operation & Total
Item Capital Annual Maintenance Annual
Rehabilitation on
future construction
of Septic Systems
in Phase I areas $1,801,000 157,000 4,500 101,500
Future construction
of Septic Systems
in Phase II areas 225,000 19,000 500 19,500
TOTAL $2,026,000 $176,000 5,000 121,000
Source: See Detailed Cost Breakdown in Appendix I.
The continued use of subsurface disposal systems would require that the
costs of necessary system reconstruction and annual maintenance be financed
by private owners. Where additional land area is required for the construction
of existing systems, private land owners would have to acquire or make arrange-
ments for the use of adjoining land. Because of the high cost of septic system
construction on Block Island, the total costs to be borne by an individual
property owner in the proposed sewer service area would generally be higher
under Alternative C than the total assessments to be made on his property
over the design life of the sewer system. On the other hand, the cost of
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this alternative to property owners outside the proposed service area would
be zero as compared with the sewer assessment in the general tax rate under
Alternatives A, B and D.
Political and Legal/Institutional Impacts. The continued use of subsurface
disposal systems on Block Island poses special legal and institutional consid-
erations.
In order for individual systems to be considered a realistic possibility
for dealing with current and future wastewater management, existing laws and
regulations must be rigidly enforced including the use of stone for leaching
fields. While this may increase the costs of system construction, these actions
are necessary to reasonably ensure system reliability. Also, the minimum
distance to ground water from the leaching field should probably be maintained
at 4 feet for all new development on the Island.
All percolation tests and leaching field construction should be observed
and inspected by regulatory agency personnel, preferably by a well qualified
engineer.
In some instances, these requirements may place the Town and State
regulatory agencies in a politically difficult enforcement role, particularly
relative to existing systems. However, the adequacy of rehabilitated subsurface
disposal systems rests heavily on the achievement of this regulatory capability.
Secondary Impacts. Similar to the secondary impacts of the NO ACTION
Alternative, this alternative could perpetuate the deterioriation of the Old
Harbor town center. Extremely high costs for the construction or reconstruction
of septic systems in that area could channel development to other areas, instead
of channeling investment in the restoration and clustering development of
the Old Harbor core. .
Growth resulting from this alternative would be at or near "present levels"
such that the magnitude of the influx of people and associated development
would not infringe upon the environmental amenities of the Island. However,
the existing development patterns could be affected with a possible adverse
change in the Island's unique character and its ability to attract tourists.
A solution would be the adoption and strict enforcement of a refined
zoning plan, with emphasis on environmental suitability, land capability and
community goals. This solution is always subject to development pressures,
but such pressures should be less intense than those likely to result from
construction of a sewer system.
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4.5 Alternative D—Sewer System for Old Harbor
Description. Under Alternative D, only the immediate Old Harbor area
would be served by a sewer system and treatment facility. Map 16 indicates
the extent of this system. In New Harbor, or the portion of Stage I not served
by this system, inadequate subsurface disposal systems would be ameliorated
through rehabiliation as was discussed in Alternative C. For the area south
of Old Harbor, Stage II, existing individual septic systems can generally
continue to be used without rehabilitation.
The justification for consideration of this alternative is premised on
the general availability of amenable soils and sufficient land in New Harbor
to facilitate subsurface disposal techniques. Septic System Failures Map 7
indicates many systems, at present, are failing in the New Harbor area, rehabil-
itation of these systems and coupled with the utilization of in-house flow
reducing apparatus, would make individual subsurface systems an acceptable
disposal technique for that area.
The treatment facility for the Old Harbor sewer system under this alter-
native would be reduced in capacity to approximately 130,000 gallons per day.
This would require a major redesign of the plant and sewer system possibly
involving changes in the treatment process or sewer routes. For purposes
of discussion of this alternative, it is generally assumed that these things
will not change. Watercraft wastes from marinas in the New Harbor area would
have to be hauled to the Town landfill site. Pretreatment may be required
as discussed in the Technical section of Alternative A.
Social Impacts. The major social impact of this alternative is that
it will provide a municipal service to clean up the pollution problems in
Old Harbor. However, the remainder of the Island and particularly the New
Harbor area will not have the advantage of municipal responsibility for sewage
collection and treatment. Those areas outside of Old Harbor will have to
rely upon the effectiveness of code enforcement to insure that there will
be no repetition of current problems. While the chance of failure of proper
septic systems is minimal, such failure could result in adverse public health
and aesthetic conditions.
Technical. In order to reduce the capacity of the proposed treatment
plant to 130,000 gal/day, a major redesign would be required by the engineer.
Although the extended aeration treatment process would be viable under this
alternative, during the redesign process some other treatment method might
be found to be more suitable or more cost effective. In addition, during
the design process, sewer pipes may have to be re-sized and possibly relocated.
This whole process would take a few months, thus further delaying solution
to Old Harbor's problems.
Reconstruction of subsurface disposal systems in the New Harbor area
could begin immediately. Septic tanks will still have to be pumped out
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although on a less frequent basis than at present. Septage from these pumpings
and boat wastes from the New Harbor marinas will have to'be trucked to the
landfill.
Reduction of the plant capacity would not necessarily preclude expansion
of the plant and system to service New Harbor at some future time.
Environmental Impacts. The discharge from the treatment facility in
this alternative will be significantly reduced from that expected in
Alternative A. The resultant effect on the receiving water will consequently
be reduced. However, the reduction in flow is not so great that the outfall
sewer dimensions should be decreased or that the recommendations made for
the outfall sewer in Alternative A be disregarded.
Again, the possibility of septic system failure in the New Harbor area
remains. However, proper code enforcement action should prevent multiple
failures, thus preventing serious environmental problems in that area.
Economic Impacts. The costs associated with Alternative D are considerably
reduced from those estimated for Alternatives A and B, as shown in Table 16.
Again, however, expenditures for reconstruction of individual septic systems
are not fundable by either State or Federal grants and must be borne by the
landowner. Therefore, the costs shown on Table 17 represents overall reduction
in costs to the Island and cannot be interpreted to indicate a concomitant
reduction to the costs of each individual.
Further, the costs to New Harbor properties will likely be slightly greater
under this alternative than under Alternatives A and B because of the general
tax increase necessary to build the municipal facilities.
Political and Legal/Institutional Impact. The reduction in the size
and extent of the wastewater system in this alternative will reduce, somewhat,
the necessary administrative arrangements that would be required for a larger
system. However, the demand for regulatory and enforcement controls to oversee
construction or rehabilitation of septic systems will be nearly as significant
as those discussed under Alternative C.
Secondary Impact. The secondary impacts of this alternative will be
a concentration of growth in the Old Harbor area. Overall growth and particularly
development of multiple unit structures will be much less than predicted for
the proposed system without the stimulus of an extensive sewer system. Therefore,
the New Harbor and Stage II areas will essentially continue to develop at
a rate equal to or less than past trends. Thus, the potential for associated
adverse environmental effects to the wetlands and shoreline adjacent to Great
Salt Pond and the open space and scenic vistas to the south of Old and New
Harbors will be practically eliminated.
It is also clear that without a sewer system, expansion of the economic
base of the New Harbor area may be restricted. That is, large structures
such as condominiums or hotels may be prevented from building there due to
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NEW SHOREHAM. BLOCK ISLAND
ALTERNATIVE D
. •.
i
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the extremely high costs to construct large septic systems. Similarly, the
large land requirements for these systems would prohibit dense development.
On the other hand, the economic base in Old Harbor would benefit, both
in terms of rehabilitation of old properties which have been closed or have
reduced operations due to failing septic systems and from the potential for
new economic development.
Such development, if not too extensive, would be in keeping with the
development goals of the Island.
TABLE 17 - Estimated Costs of Alternative D
COSTS
Average Operation & Total
Item Capital Annual Maintenance Annual
Treatment Plant &
sewer system $2,820,000 225,000 20,000 245,000
House Connections 75,000 6,000 0 6,000
Present & future
Septic System con-
struction, Stage I 700,000 61,000 2,500 63,500
Future Septic System
Construction,
Stage II
TOTAL
225,000
$3,820,000
20,000
312,000
500
23,000
20,500
335,000
Source: See Detailed Cost Breakdown in Appendix I.
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5.0 PREFERRED ALTERNATIVES
Of the five alternatives evaluated in the previous Chapter, it is
the opinion of EPA that the following two represent the most environmentally
acceptable solutions to the existing wastewater disposal problems on
Block Island:
1. Alternative D - Construction of a sewer system and treatment
facility for Old Harbor only.
2. Alternative B - Construction of the proposed project without
including Stage II.
The rationale for rejecting the remaining alternatives is summarized
below:
1. NO ACTION Alternative - Due to the potential health hazard that is
present and the reliance of the Island's
economy on tourism, it would not be in
Block Island's best interest to allow the
existing situation to continue.
2. Alternative A
3. Alternative C
(Proposed Project) The basic assumptions of this
alternative are not invalid; however, it does not
appear that sewer service will be required in the
Stage II area in the forseeable future. Primary
impacts can be minimized with implementation of
the recommendations noted in the appropriate sections.
Yet, possible adverse secondary impacts, particularly
encroachment on wetlands, make this alternative
undesirable.
(Rehabilitation of Septic Systems) Rehabilitation
of septic systems in New Harbor and continuation
of present septic systems in the Stage II area are
viable solution; however, due to the lack of available
space in the densely populated Old Harbor area,
rehabilitation of existing systems appears impractical.
In addition, the secondary impacts of this alternative
are unattractive.
Of the two environmentally acceptable alternatives, the primary impacts
are essentiallly equal since both require a treatment facility and a
sewer system. (Alternative B provides sewer services to a greater
area, while Alternative D relies more on rehabilitation of septic systems
but is less costly.) The major differences lie in the secondary impacts of
each.
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As Alternative D will provide sewers for Old Harbor only, it will con-
fine the pressures for major development to that area. This will result in the
least amount of secondary growth on the Island as a whole, thus enabling
the Town to keep development in general conformance with the objectives
of its Master Plan, i.e., to maintain the Island's rural character.
Alternative B will provide relief in the Old Harbor area and also
provide sewer services in the New Harbor area. Multiple unit development
could result in a transformation of the open character of New Harbor.
The question of development in New Harbor, however, is not really
a decision to be made by EPA, but a decision for the Town. In EPA's opinion,
Alternative D, has the least adverse environmental impact. On the other
hand, the people of Block Island may feel that their Town's existence
is predicated on the stimulus for development that will be provided by
sewers in New Harbor. And if this is the case, Alternative B is acceptable
with the recommendations made in Chapter 4.
Chart B displays, for purposes of comparison, the primary and secondary
impacts of Alternatives B & D.
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CHART B - Comparison of Preferred Alternatives
Alternative B
Alternative D
Primary Impacts
Social
Technical
1. Treatment facility location in historical area.
2. Outfall sewer aesthetically unpleasing. May
change natural setting of area.
3. Short-term disruptions during construction will
not affect tourist season.
1». Construction of system will enhance the Island's
recreational assets.
Construction will be difficult but not over-
whelming .
Minimizing erosion during construction and
revegetation measures will be necessary and
difficult tasks. (See Alternative A)
Operating and maintaining the facility at
required levels of efficiency during periods
when flows drastically change will be difficult.
Operation under stable conditions will be no
problem.
Pretreatment of chemically laden watercraft
wastes will be required. (See Alternative A)
1. Treatment facility location in historical area.
2. Outfall sewer aesthetically unpleasing. May
change natural setting of area.
3. Short-term disruptions during construction will
not affect tourist season.
1». Construction of system will allow improvement to
Island's recreational ability.
5. Adverse public health and aesthetic impacts may
result from septic systems which may fail in the
future.
1. Construction will be difficult but not over-
whelming .
2. Minimizing erosion during construction and
revegetation measures will be necessary and
difficult tasks. (See Alternative A)
3. Operating and maintaining the facility at
required levels of efficiency during periods
when flows drastically change will be difficult.
Operation under stable conditions will be no
problem.
1*. Pretreatment of watercraft wastes will be required
along with transportation of these wastes to the
landfill.
5. Proper leaching field material must be shipped in
from the mainland.
6. Construction and reconstruction of septic systems
must comply with new State Regulation (R23-1-SD)
amended 30 August, 1971*- (Refer to Appendix K)
Environmental
1. Short-term effects due to construction although
present will be minimal.
2. Effluent will have little effect on receiving
waters with implementation of recommendations
noted. (See Alternative A)
3. Wildlife and environmentally sensitive areas
will be affected minimally.
h. Treatment system will have negligible affect
on air quality.
5. Noise impacts of treatment system can be
minimized by employing recommendations made.
(See Alternative A)
6. Land disposal of sludge not a problem.
T. Treatment system will collect wastes being
discharged directly or indirectly into
Island's water bodies. Such action will
eliminate health hazard potential and improve
Island's overall water related abilities, i.e.,
water contact sports, fishing and shellfishing.
8. Odors', from septage during haulage to the
disposal site will be minimal.
1. Short-term effects due to construction although
present will be minimal
2. Effluent will have little effect on receiving
waters with implementation of recommendations
noted. (See Alternative A)
3. Wildlife and environmentally sensitive areas
will be affected minimally.
h. Treatment system will have negligible affect
on air quality.
5. Noise impacts of treatment system can be
minimized by employing recommendations made.
(See Alternative A)
6. Land disposal of sludge not a problem.
7« Treatment system and rehabilitated septic
systems will collect wastes being discharged
directly or indirectly into Island's water
bodies. Such action will eliminate health
hazard potential and improve Island's over-
all water related abilities, i.e., water
contact sports, fishing and shellfishing.
8. Long term adverse effects on ground water from
septic systems in New Harbor are not expected.
9. Use of inhouse flow reduction apparatus should
be employed to reduce the potential for failing
septic systems.
10. Odors from septage and treatment plant sludge
haulage to the disposal site will be present
but minimal.
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Primary Impacts
Economic
Political
CHART B - Comparison of Preferred Alternatives, Cont'd.
Alternative B Alternative D
1. Estimated total cost $U,It08,000; estimated
annual cost $U09,500.
Construction of system will improve ability
of Town's commercial industries to provide
services to tourists.
Funds for this alternative will be raised by
a general increase in the tax rate and better-
ment charges to those to be served by the
system.
1. Total capital cost $2,820,000; total annual
cost $335,000, including costs for reconstruction
and new construction of all systems in New Harbor
area and new construction in the Stage II area.
2. Individual costs for inhouse wastewater flow
reducing equipment: initial = $500 per home;
annual O&M = $50 per home.
3. Construction of system will improve ability of
Town's commercial industries to provide services
to tourists.
U. Funds for the sewer system portion of this
alternative will be raised by a general increase
in the tax rate with betterment charges to those
to be served by the system.
5. The investment necessary to implement the New
Harbor portion of this alternative must be fin-
anced by private owners.
1. Strong enforcement of laws concerning design,
construction and maintenance of septic systems
is mandatory.
Legal/Institutional
Present legal and institutional arrangements
to maintain and regulate a treatment system
should be strengthened.
Strict enforcement of revised zoning plan,
and sewer connection will be necessary to
control growth and development.
NPDES permit limitations should be imposed.
Regulatory authority over septic system
construction outside of sewered area should
be implemented.
1. Strengthened regulatory action required to make
this alternative work
2. Sewer connections and NPDES permit limitations
are still necessary to control development.
Secondary Impact
Social
Environmental
Economic
Political
Legal/Institutional
Alternative B
1. Growth rates induced by this system will be 1.
moderate to substantial.
2. Construction of multiple unit development will 2.
be much greater than in recent years.
3. Greater densities will require increased public
services.
h. Future development could endanger Island's over-
all attractiveness.
5- Increased activity could provide a stable year-
round economy, raising the level of living on the
Island.
6. Growth would most likely take place in several
Old and Hew Harbor areas, strengthening established
city cores.
1. Uncontrolled growth could lead to densities of 1.
people which could adversely affect: water quality,
air quality, noise levels, and aesthetics.
2. Without Phase II, the possibility of encroachment
of the environmentally sensitive areas to the
south of the Island would be reduced. However,
for adverse impacts on Great Salt Pond would be
decreased.
1. Additional commercial activity could supplement 1.
existing economic base in Old and New Harbor areas.
1. New or expanded public facilities associated would
be required to serve the additional development,
possibly including public water supply and police
and fire protection.
1. Addition regulatory functions including zoning 1.
revisions may be required to control development
and serve a larger population
Alternative D
Growth rates will remain nearer present levels.
Most multiple unit and commercial development will
be directed to Old Harbor area.
Adverse affects to Great Salt Pond and southern
sections of the Island due to increased develop-
ment density will be averted.
The economy of Old Harbor will be boosted but at
expense of Hew Harbor.
Zoning revisions although desirable, will not be
as critical to control development.
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6.0 PROBABLE ADVERSE IMPACTS WHICH CANNOT BE AVOIDED
In this Chapter, the impacts which cannot be avoided for the
two preferred alternatives are discussed.
6.1 Primary Impacts
Alternative B. Unavoidable impacts will probably be greatest
for this alternative since it involves the most construction
activities. Erosion will be minimized through following an erosion
control plan (described in Chapter 4) to be developed with
assistance from the Department of Agriculture, Soil Conservation
Service. A revegetation plan, also developed in coordination with
the SCS, will aid in restoring construction areas as closely as
possible to original conditions.
Noises and odors emanating from the treatment plant are unavoid-
able but will be minimized as much as possible. Visual impacts of
the above-ground facilities, such as the treatment plant and pumping
stations, can be minimized with proper design and screening. The
Rhode Island Historical Society will assist in the design of fences
and shrubbery around these facilities. The visual impact of the
concrete outfall, however, cannot be reduced.
Alternative D. Unavoidable primary impacts for this alternative
will be similar to , but in many cases, less extensive than those
stated for Alternative B, above.
Disruption of traffic and noise during construction will be
confined to the smaller Old Harbor area. Impacts due to the treat-
ment plant will be similar to those for Alternative B, particularly
the impact of the sewer outfall.
Another possibly unavoidable consequence of confining the sewer
system to Old Harbor is that boat wastes will have to be hauled by
truck to the landfill site, if the present Federal law is put into
effect.
6.2 Secondary Impacts
Alternative B. Moderate growth rates, coupled with significant
multi-unit development, particularly in the New Harbor area, can be
expected with the implementation of this alternative. Commensurate
with this growth will be unavoidable adverse impacts on water quality,
air quality, and public services through encroachment into environ-
mentally sensitive areas, increased use of recreational facilities,
greater number of cars, and, in general, increased activities on the
Island. However, with revised zoning and strict enforcement of such
64
-------
regulations, the above affects can be minimized. In addition, through
the National Pollutant Discharge Elimination System, Waste Discharge
Permits, effluent quantity limitations can be included for different
points in the design life of the facility. This is a mechanism that
may be available to insure that the capacity of the treatment facility
is not reached in the early stages of its design life, and therefore,
can control growth in the service area.
Alternative D. The area to be sewered for this alternative is
considerably smaller than for the preceeding alternative, consequently
development pressures will be less intense. However, enforcement of
zoning and sewer connection ordinances, in addition to limitations
in the NPDES permits may still be necessary to keep growth under
control.
65
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7.0 LOCAL SHORT-TERM VERSUS LONG-TERM PRODUCTIVITY
This Chapter will consider the tradeoffs between the immediate
local benefits of each of the preferred alternatives and their
effects on future options available to the Island. For example, both
of the preferred alternatives have the short-term benefit of abating
existing pollutional sources. However, each alternative will have
different affects on the long-term productivity or future courses of
action the Island can take.
Alternative B can commit the Island to a pattern or course of
action that may be acceptable now but not acceptable and unchangeable
in the future. For instance, permanent municipal structures can limit
road changes, development patterns, or other community goals that may
require change in the future. In addition, growth rates can be
stimulated which will result in population and development densities
beyond optimum capacities for the Island, and once the development is
there, it will stay whether the population does or not.
The future of the Island is not to be determined by a sewer
system alone. The availability of other public services such as
water supplies and fire protection also play a significant role in
a town's future development. However, an initial step is necessary
before any action can be taken and construction of a sewer system
and treatment facility can provide, that step.
Alternative D, by its smaller physical nature, is less limiting
on the future options of the Island. It will serve an area which
is already developed and is likely to be upgraded because of the
sewer system. At the same time, however, sewering Old Harbor will not
be the major cause of new development in presently sparsely developed
portions of the Island. If additional public facilities, such as
an expanded sewer system are required in the future, that option will
still be available, although at an increased cost.
66
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8.0 IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES
Under each of the two alternatives considered in this statement,
the materials and energy used in construction will be an irretriev-
able commitment of resources. Where the alternatives require land
that cannot be used for purposes other than intended, such commitment
of land is considered irretrievable, at least for the design life of
the structure on it. Loss in property values due to the nature of
the project, such as the treatment plant and visable outfall sewer,
are also likely to be irretrievable and irreversible for the life
of the structures.
Necessary changes in the natural topography and unavoidable loss
of vegetation through construction are considered irretrievable.
Further, to the extent that both alternatives, in differing degrees,
will induce growth resulting in a loss of open space, such a loss
is irreversible.
On one hand, the State and Federal funds committed to this project
will be an irreversible and irretrievable commitment of financial
resources in that such funds will be unavailable for other projects or
needs. On the other hand, such a substantial investment is not
irretrievable since it will be manifested in an improvement in the
quality of life on Block Island.
67
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APPENDICES
-------
APPENDIX A - EXISTING WATER QUALITY
. BLOCK ISLAND SURVEY
August 26, 1971
A. Water Quality
Station*
1
2
3
4
5
6
7
8
High Tide 12:05 pm (EDT)
Coliform MPN/100 ml
Total Fecal
3-
4
230
93
9
3-
4
3-
3-
4
11
21
4
3-
4
3-
*See chart
Source: Rhode Island Department of Health, Division of Water Supply
and Pollution Control.
A-l
-------
f2>|»»LLS
*" till "X"
\
.:__ a.
t- W..K PM - '* V^x55
'; WEST BI«CH «a- r^^^r^
-------
APPENDIX B - REGULATIONS GOVERNING WASTE DISCHARGES FROM WATERCRAFT
The State of Rhode Island has no existing law regarding the dis-
charge of sanitary waste from watercraft. Vessel pollution control
will be covered, however, under Section 312 of the Federal Water
Pollution Control Act Amendment of 1972. Under the Act, EPA is
authorized to promulgate effluent standards for marine sanitation
devices, and the Coast Guard is authorized to promulgate criteria
on the design, construction and certification. Furthermore, the
Federal law will preempt any State laws regarding the design,
manufacture, installation or use of any marine sanitation devices.
Such preemption will not take place, however, until the effective
date which is 2 years and 5 years from the date of final promulgations
for the new and existing vessels, respectively. Section 312 also
provides two waivers for the States to apply for no discharge zones,
one based on water quality protection and the other based on the
availability of pump-out facilities, but no guidelines have yet
promulgated for the application of no discharge zones.
The Coast Guard promulgated its design criteria and certifi-
cation procedures on January 30, 1975 and EPA has promulgated its
standards on June 23, 1972. Therefore, Section 312 'of the Act will
come into effect on January 30, 1977 for new vessels and on January 30,
1980 for existing vessels. In brief, the EPA standards requires zero
discharge after the effective date. However, as an incentive for
existing boaters to install marine sanitation devices before the
effective date, the following provisions are included: (1) any
existing vessel, equipped with a Coast Guard certified flow-through
device that will reduce fecal coliform bacteria to no more than
1000/100 ml, with no floating solid and is installed with .3 years
after the time of promulgation, the vessel shall be deemed in
compliance. (2) If the above device is installed after 3 years from
the time of promulgation but before the effective date, the vessel
shall be deemed in compliance for only 3 more years following the
effective date. In addition, the Coast Guard promulation further
allows one year incentive period (ending January 30, 1976) for new
vessels to install certified flow through devices and still be
deemed in compliance.
Reference:
1. Section 312, Public Law 92-500, Federal Water Pollution
Control Act Amendment of 1972.
2. Federal Register, Volume 37, Number 122. Title 40 -
Protection of Environment, Chapter 1, Part 140.
B-l
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APPENDIX C - COMPREHENSIVE COMMUNITY PLAN PROPOSED LAND USE CATEGORIES
Mixed Uses. Commercial and intensive residential development.
Suitable areas are Old Harbor, the center of the present hotels and
commercial establishments, and New Harbor, the location of the three
marinas on Great Salt Pond. Ferries from the mainland serve both areas.
The Comprehensive Community Plan notes that further development could
take place on vacant land in the Old Harbor area, and that the vacant
land along West Road in New Harbor is suitable for the same kind of
mixed commercial and residential development that characterizes
Old Harbor.
Medium Density Residential. Tourist cottages, boarding houses,
summer homes and year-round residence, averaging one dwelling unit per
acre. These areas border the two mixed use areas, contiguous to
proposed sewer and water systems, and the Comprehensive Community Plan
envisions tying into these proposed systems in the future.
Low Density Residential. Year-round and summer homes, averaging
one dwelling unit per 2-acres. These are the areas now rural in
character embracing much of the remainder of the Island beyond the
development centers. Here, according to the Comprehensive Community
Plan, low density will conserve ground water supplies and the open
space character. The soils are generally well-drained and suitable
for properly installed and operated septic systems.
Developed Recreation. Areas designated for facilities to
support intensive recreation such as marinas, restaurants, and movie
theatres. Mixed use areas are suitable for such development, but in
addition, such development could occur in the shoreline areas at the
piers at Old and New Harbor, with buildings on stilts to avoid the
flood water (potential conflict, with conservation objectives).
Open Space Recreation. Areas maintained in open space free of
intensive recreation facilities and homes to maintain the Island's scenic
qualities and ecological balance. Areas include the erodable and highly
scenic southwestern cliffs, the ground water recharge zone in the south
portion and the low-lying beach land separating Great Salt Pond from
the ocean.
Conservation. Relatively undisturbed shoreline ecology to be
preserved in its natural state. These areas include the salt marshes
around Great Salt Pond, fish spawning grounds; western coastline north
of Great Salt Pond, lying below the hurricane high water line and in-
cluding a bird sanctuary; narrow strips along the northwestern and
southwestern shores, where the cliffs are subject to erosions, not
suitable for development yet highly scenic; and also Rodman Hollow in
the southwest, an unusual land form linking the southwest sector to
the ocean.
C-l
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APPENDIX D - BASIS OF COSTS ALTERNATIVE TREATMENT SYSTEMS
The cost data for this report was compiled in the following manner:
a) Construction Costs - EPA, Region I prepared graphs of con-
struction costs vs. design capacity for various treatment plants located
in Southern New England (Conn., Mass., and R.I.) in the Summer of 1973.
The costs for these graphs were taken from the low bid quotes for the
recent construction of Municipal Wastewater Treatment in those states.
A least mean regression computer analysis was made which resulted in
equations for a log/log plot in the form:
Iogl0 (cost) = a Iog10
a = slope of line of best fit
b = y intercept
Q = design average flow
For this Report, these costs have been updated to present conditions
based on an ENR Construction Cost Index of 2100. These costs represent
the complete treatment facilities including preliminary treatment, if
any; effluent disposal and sludge handling. As they are a composite of
many diverse projects, they should be used as a guide .with consideration
for any special conditions which may affect the individual project.
b) Operation & Maintenance Costs - The records of the Operation
and Maintenance Section of EPA, Region I were analyzed to compute
average yearly costs of operations and maintenance of wastewater
treatment facilities. These are based on actual reported costs by a
large number of municipalities throughout New England over the last
several years. It should be noted that these costs generally represent
treatment of a more or less constant flow throughout the year. Projects,
such as Block Island, which will treat a greatly varying seasonal flow
must be analyzed with this fact in mind.
c) Exception - The capital and operating costs for physical-
chemical treatment alternative are based upon pilot-plant and demon-
stration studies, upon manufacturers costs of equipment and upon
experience with the cost of those processes in other industries.
There are no functioning physical-chemical treatment facilities in
New England (or in the U.S.) at present. Therefore, there is no
actual capital and operating cost data to be presented.
d) Land Costs - The cost of land has been estimated as $10,000/
acre based on correspondence with local officials in New Shoreham.
D-l
-------
e) Summary - The use of the above cost data is Intended to
show the relative costs of alternative treatment systems and the
costs presented are not meant to imply the actual cost to construct
any of the systems on Block Island. The cost data reflects capital
and operating cost for a treatment facility with a design average
flow of 300,000 gal/day, unless indicated otherwise.
D-2
-------
TABLE A - Average Costs for 300,000 Gallon_,Per Day Treatment Facilities
Southern New England
Type Treatment System
Extended Aeration:
a) Aeration Tanks
b) Oxidation Ditch
j Modified Act. Sludge (Contact
Stabilization)
Aerated Lagoons
Stabilization Ponds
' Physical -Chemical
Construction
Cost
$ 750,000
525,000
640,000
635,000
585,000
450,000
Avg. Annual
Bond Payment*
$ 65,400
45,700
55,700
55,400
51,000
39,200
Annual
Operating
Cost
$ 22,500
13,000
35,000
22,500
8,500
40,000
Total Avg.
Annual
Cost
$ 87,900
58,700
90,700
77,900
59,500
79,200
Package Treatment Plants
(60,000 MGD)
100,000
8,700
6,000
14,700
* Assuming 20-year bond issue @ 6%.
.08718 - Capital Recovery Factor
-------
TABLE B - Land Area Required for Various Treatment Alternatives
Type Treatment System
Extended Aeration:
a) Aeration Tanks
b) Oxidation Ditch
Modified Activated Sludge
(Contact Stabilization)
Aerated Lagoons
Stabilization Ponds
Physical -Chemical
Land Area
(Acres)
2.0
3.0
2.0
6.0
30.0**
0.25
Cost of
Land *
20,000
30,000
20,000
60,000
300,000
2,500
* Assuming $10,000/acre.
**Including land for intermittent sand filters.
-------
EVALUATION OF ALTERNATIVE TREATMENT SYSTEMS.
References:
1. Preliminary Engineering Survey & Report for the
Town of New Shoreham - Fenton G. Keyes Associates,
Feburary, 1972.
2. Environmental Impact Appraisal - EPA, Region, May, 1974.
3. "Wastewater Treatment for Small Communities" -
George Tchobanoglous, University of California,
September 28, 1973.
4. Construction Cost Curves, EPA,Region I, January, 1974.
5. Personal communications.
D-5
-------
APPENDIX E - FLOW REDUCTION EQUIPMENT
The following In-house flow reduction equipment has been tested
by EPA and are available or will shortly be available on the open
market. The information shown below was adopted from the EPA
publication, "Demonstration of Waste Flow Reduction from Households",
EPA-670/2-74-071, Sept., 1974.
Description of Units Tested
Wash Water Recycle System = Laundry and bath water are collected in
a suitably sized vented storage tank, provided with an overflow pipe, side
bottom outlet, and a low-level control system for supplemental feed water.
The stored wash water is either continuously or intermittently (when the
pressurization pump operated) disinfected prior to filtration. The treated
water is pressurized by a 1/3 HP shallow well jet pump mounted on either a
45 or 115 liter pressure tank, controlled by a pressure switch over the
range of 105 to 210 cm HG. When the pump is activated, wash water is
pulled through a cartridge or diatomite filter and pressurized. The
treated water is then carried through copper tube lines to the flush
toilet and lawn sprinkler.
Shallow Trap Toilet = One of the approaches involved the use of a
water saving toilet designed to use approximately one-third less water
than ordinary toilets. The specific model selected for testing was the
American Standard Water Saving Elongated Cadet. It is similar in
appearance and cost to the standard model except for a noticeably smaller
tank. Less water is required for flushing, due to the special design of
the bowl (shallower trap).
Dual Flush Toilet Devices = The second approach utilized devices which
converted a conventional water closet to dual cycle operation, i.e., a
short flush for liquids and a normal flush for solids. Two different
devices were examined during the program.
1) Econo-Flush = This toilet device consists of two interconnected
plastic tanks open at the bottom which are positioned inside the toilet
tank, and a handle/lever assembly incorporating a unique valve arrangement.
The Econo-flush operates in the following manner:
(a) Light flush - this is activated by pushing the handle
up. The handle assembly, through a unique linkage arrange-
ment, simultaneously opens the toilet flush valve,and
closes a plastic valve which seals both plastic tanks from
the atmosphere. The contents of both tanks (approximately
one gallon) are thereby trapped by the vacuum created and
a reduced flush results.
-------
(b) Normal flush - this is activated by pushing the
handle down in the usual manner. The plastic valve now
opens in conjunction with the toilet flush valve, breaks
the vacuum seal and thereby allows a full flush to occur.
A label is included for posting on or near the toilet
in order to remind the household occupant of the new
flushing procedure.
2) Sink-Bob = This dual flush device consists of a polystyrene
float and lead sinker connected to the float stem by a split brass
ring. As with the Econo-flush device, most standard toilet models
will accomodate the Sink-Bob. The Sink-Bob attaches to both rod and
flapper-type seals at a point just above the flush valve. The device
operates in the following manner:
(a) Light flush - the Toilet handle is tripped in the normal
manner, opening the flush valve and allowing the water in
the closet tank to drain into the bowl. When the level
inside the tank has decreased by approximately 50%, the Sink-
Bob attains sufficient negative buoyancy to prematurely
seat the flush valve.
(b) Normal flush - for full flush, the handle must be held
down during the entire flushing operation to prevent premature
closing of the flush valve.
Flow Limiting Shower Heads = Shower heads with built-in flow limiting
orifices are available which can reduce water consumption rates from the
typical 19 to 38 liter per minute (1pm) (5 to 10 gpm) to 9.5 or 13.3 1pm
(2.5 to 3.5 gpm). The actual amount of water saved will depend primarily
on the system water pressure and the personal habits of the bather. Two
different Speakman flow limiting shower heads were selected for testing.
The first of these, "Auto-flo" flow is equipped with a 13.3 1pm integral
limiting orifice. This shower head has a fully-adjustable spray, integral
ball joint and a 5 cm face. The second shower head is equipped with a
9.5 1pm integral "Auto-flo" limiting orifice. It is also of the adjustable
spray, ball joint type but has a much narrower shape. Both shower heads
have standard 1.27 cm (1/2") I.P.S. female inlets which are compatible with
standard shower arms.
The following Tables summarize waste flow reduction from households:
E-2
-------
TABLE A - Water Savings Summary
w
1
u>
Water % Reduction
Unit Savings of water
Tested lpcda usage
Wash water 44.0 (11.6)b
recylce
system
Shallow 14.8 (3.9) 25.6
Trap water
closet
Dual Flush
Devices:
Sink-Bob 20.5 (5.4) 28.6
Econo-Flush 12.4 (3.3) 16.6
Flow limiting
shower head 2.7 (.7) 7.1
% Reduction
in total • Benefit to Homeowner - Adverse Effects
water usage
26.0 The recylce system minimize the surge Temporary stains in toilet
in outflow to the septic system. bowls.
It reduced total waste flow & allowed
the septic tank and soil absorption Tie-up of essential metals
system to operate more effectively. needed for plant growth due to
Little maintenance required. . high phosphate detergents.
Possible reduction in soil
moisture content.
6.9 Achieve good reduction in water use. None
8.6 Achieve good reduction in water use. None
3.3 Achieve adequate reduction in water use. None
1.0 Significant savings in hot water. The flow None
a - Ipcd = liters per capita-day.
° - gallons per capita-day.
limiting shower heads have good reduction
for high frequency users.
-------
TABLE B - Cost Summary - Bathroon Water Saving Devices
Water
saving
device
Shallow -trap
flush toilet
Dual flush
devices
Sink -Dob
Econo-Flush
Savelt
Plow limiting
shower heads
13.3 1pm
9.5 1pm
a - The Total
cost over
Material
Cost-$
60
4
14
6
6
8
Annual Cost
the expected
Labor Installed
Coat-$ Cost-$
15
Ob
Ob
Ob
ob
was based
life of
1 1 « .. -J j_
75
4
14
6
6
8
Operating
Cost-4
0
0
0
0
0
0
on amortization of
Expected
Life.yrs.
20
10
10
10
15
15
Totald
Annual
Coot-$/yr.
3.75
0.40
1.40
0.60
0.40
0.53
the installed
the device.
U -J _ 1 C
-------
TABLE C - Cost Summary - Wash Water Recycle Systems
Prototype
Recycle Sy sterns^
Diatomite Cartridge
filter filter
Projection for
mass produced
recycle system
(Diatomite filter)
A. Initial cost
Storage sys,--*-^
Filter sys.
Pressurlza-
tion sys.
Disinfectant
Valves, pipe,
•fM 4-4-1 VKTr- _______
Total Mat'l
Cost —
Labor Cost
^175
135
115
- 20
s4o
JT*J
100
$175
60
115,
20
QO
ou
4^0
*t^v
90
A _, ..
$70
100
85
20
^SO
3j*->
Total Installed
Cost $640
$540
$400
B. Annual .opera-
coat
.
Filter media --- $3.50
Electric power — 12.00
Disinfectant — 5.50
$21.00
$33.80
1.20
5.50
$45.50
$3.50
7.00
5.50
$16.00
c» Total annual cost2
Expected life
years 15
Total cost per
yr $63.50
15
$81.50
15
$43.00
l
2
- Fram filter selected for cost analysis.
- The Total Annual Costs were determined by amortizing the initial
costs over the expected life and adding the respective operating
costs.
E-5
-------
TABLE D - Cost Comparison
1 '
Flov reduction device
Shallow trap water closet
Dual
flush
devices
Flow
limiting
shower
heads
Wash
water
recycle
system
Sinkbob
Econoflush
Save it
13.3 1pm
9.5 1pm
Prototype
Mass-produced
Cost per unit
vol. of flow
reduction
$/1000 liters
0.15
0.02
0.07
O.OU
0.08
0.22
0.57
0.39
Typical c
water rates
4/1000 liters
0.16 - O.U2
0.16 - O.U2
0.16 - O.H2
0.16 - O.U2
0.16 - O.U2
0.16 - O.U2
0.16 - O.U2
0.16 - 0.1+2
Typicald
sever rates
.'k/1000 liters
0 - 0.13
0 - 0.13
0 - 0.13
0-0.13
0 - 0.13
0 - 0.13
0 - 0.13
0 - 0.13
Septic tank
system -
poor soil
$/1000 liters
...
o.Uo
o.Uo
Net
Savings
$/year
$.25 to
9.80
$U.10 to
15.60
$1.72 to
9.20
$2.1*0 to
10.20
$1.10 to
5.32
$.52 to
3.53
$-U5.70
to -2.30£
$-1.30
to 27.60
$-25.20
to 18.208
$19.20
to U8.10
a
b
c
d
Net savings per year based on water and sewer rates.
Net savings per year based on water rate and septic system cost.
Domestic water rates throughout the State of Connecticut.
Typical sewerage use rates in the Connecticut area.
-------
F - jESIGi-i FLOV3
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F-l
-------
FENTON G. KEYES ASSOCIATES
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-------
APPENDIX G - FMC WASTE TREATMENT SYSTEM*. AN EXAMPLE OF A PHYSICAL/CHEMICAL
TREATMENT SYSTEM FOR MARINAS.
The FMC Waste Treatment System employs a physical/chemical process to
treat sanitary sewage and other wastes. Chemicals are added to con-
dition the sewage, which is then filtered to remove suspended solids.
The system operates automatically on demand, with instantaneous on-
off treatment capability. Influent sewage flow may be constant or
variable, with no loss in degree of treatment.
During the process, chemicals are added automatically in proportion to
the influent sewage flow rate. The type and function of each chemical
is as follows:
1. Bactericidal Agent. A bactericidal agent, chlorine, is used
to destroy bacteria and inactivate viruses present in sewage so
that the effluent water and solid filter cake are free of live
pathogenic organisms.
2. Activated Carbon. Powdered activated carbon is used to adsorb
certain soluble organic compounds in sewage that could not be
removed by filtration. Once adsorbed, they are readily re-
moved by filtering out the spent carbon particles.
3. Flocculating Agent. A flocculating agent, aluminum sulfate,
is used to destabilize the colloidal particles of sewage. The
result is the coagulation of many small colloidal particles
into large floes, which are removed by filtration.
4. Filter Aid. A filter aid, diatomaceous earth, is used to
assist the filtration process. Diatomaceous earth is a finely
divided, insoluble, rigid material that will not compact or
channel when forming a mat during filtration. This maintains
the filtration rate by preventing fine gelatinous solids from
blinding the filter surface.
The basic process, shown schematically in Figure 10, involves four
operations: (1) comminution, (2) disinfection, (3) flocculation, and
(4) vacuum filtration.
* "Development of On-Shore Treatment System for Sewage from Watercraft
Waste Retention System", EPA-670/2-74-056, July, 1974.
G-l
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SA9HTARY
HATER
DISCHARGE
DRY
CHEMICALS
ooHOPPERooo
ooooooooooo
oooooooooo
ooooooooo
O9OOOCOO
ooooooc
000000
00000
0000
oco
ooo
PROCESS
PUMP
Figure 10. Schematic drawing of FMC waste treatment system
Influent wastes are coarsely screened and comminuted to reduce solid
particle size. A bactericidal agent (aqueous chlorine) is added auto-
matically with a metering pump. This treated mixture flows to an
agitated surge tank designed to handle anticipated load fluctuations.
A dry chemical mixture of activated carbon and filter aid is added
automatically to the surge tank by a vibrating feed mechanism supplied
from a hopper above the tank. At a set level, sewage in the surge
tank is moved by a low-volume pump into a reactor coil wound around
the surge tank. Before entering the coil, chemical flocculant is
added automatically to the sewage/chemical mixture by a metering pump.
The coagulated sewage mixture then flows to a rotary vacuum filter,
which separates solids from the liquid. Sewage solids, filter aid,
and carbon retained on the drum filter fabric are removed with a "wire
doctor blade." The clear effluent passes through an air separator
tank before being discharged. The solid filter cake is accumulated
and disposed as sanitary landfill.
Complete automatic operation is accomplished with a magnetic flow meter,
electrical timers, relays, and liquid-level sensors. Fail-safe in-
telligence systems prevent the unit from operating if any component
fails. An alarm system sounds a warning of low chemical level and, if
not replenished, the system automatically shuts off.
G-2
-------
.7? DRY CHEMICAL HOPPER
DRY CHEMICAL FEEDER
SURGE TANK
FLOCCULENT TANK
""Vr^ll
BACTCR1CIDE
TANK
VACUUM f/'....J
PUMP f "'""'J'|
., —.JJ
REACTION COIL
% ...,- .,, ; • t . w •- •- '4 '• - ••<• .-.:--
r »*w*^
COM I X PROCESS PUMP
./. S3
Figure 11. Photograph identifying major components of the FMC
waste treatment system, model 50-2000
Figure 11 is a photograph of the FMC Waste Treatment System Model 50
2000, with major components identified. An aluminum frame houses
copper-nickel plumbing and shielded electric motors. Overall dimen-
sions are 239 cm long, 122 cm high, and 203 cm wide, with a total
empty weight of 1135 kg (2500 pounds) . Maximum electrical demand is
12 kva, using three-phase 220- or 440-volt current. The design
flow capacity for processing domestic sewage is 1.5 kl/day (4000 gal/
day) at an average flow rate of 9.5 1/min (2.5 gal/rain).
Operating costs for wastes having approximately 2000/mg/l ss and
were //602/KI ($23.5/1000 gal). Auxiliary treatment cost for zinc
removal and postchlorination was $1.5/KI ($5.7/1000 gal.).
Capital costs for unit not given.
G-3
-------
APPENDIX H - OCEAN CURRENT STUDIES - PEBBLY BEACH' OUTFALL LOCATION AND BLOCK
ISLAND OUTFALL ANALYSIS
(see following pages)
H-l
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
SUBJECT: Proposed Ocean Outfall, New Shoreham, Rhode Island DATE: january 7, 1975
FROM: • IAS
TO: Wallace E. Stickney, Chief
Environmental Impact Statment Office
Enclosed is our final report prepared for the ocean current studies
conducted near Pebbly Beach, New Shoreham, Rhode Island, during
October 22 - 24, 1974. Most of the report presents the conditions
which existed and occurred during the study. The discussion portion
presents our interpretation of the data collected.
This report is presented as part of our support effort to the
environmental impact statement being prepared for the proposed
wastewater treatment system at New Shoreham.and, at the discretion
of the editor, may be used in its entirety or without the discussion
portion included.
Myron 0. Knudson, Chief
Surveillance Branch
'Attachment
1975
H-2
EPA Form 1320-6 (Rev. 6-72)
-------
OCEAN CURRENT STUDIES
PEBBLY BEACH OUTFALL LOCATION
NEW SHOREHAM (BLOCK ISLAND), RHODE ISLAND
OCTOBER, 1974
H-3
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TABLE OF CONTENTS
PAGE NUMBER
INTRODUCTION 1
STUDY DESIGN 2
STUDY OBSERVATIONS 4
Monday, October 21 4
Tuesday, October 22 5
Wednesday, October 23 7
I
Thursday, October 24 '8
I
DISCUSSION 1
ii-U
-------
LIST OF TABLES
TABLE NUMBER TITLE PAGE NUMBER
1 WIND DIRECTIONS AND VELOCITIES 6
H-5
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List of Appended Figures
Ocean Current Studies
Pebbly Beach Outfall Location
New Shoreham (Block Island), Rhode Island
October, 1974
Figure No. Title
1 Location Map
2 Drogue Detail
3 Station Displacement
4-8 Current Studies
Proposed Outfall at Pebbly Beach
New Shoreham, Rhode Island
October 22, 1974
9-16 Current Studies
Proposed Outfall at Pebbly Beach
New Shoreham, Rhode Island
October 23, 1974
16 - 21 Current Studies
Proposed Outfall at Pebbly Beach
New Shoreham, Rhode Island
October 24, 1974
H-6
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OCEAN CURRENT STUDIES
PEBBLY BEACH OUTFALL LOCATION
NEW SHOREHAM (BLOCK ISLAND).RHODE ISLAND
INTRODUCTION
During October 21 - 25, the Environmental Protection Agency,
Region I'3 Surveillance & Analysis Division engaged in near shore current
studies off the east shore of Block Island (see Figure 1). The studies
vere precipitated as part of a data collection program prior to preparing
an environmental impact statement for a proposed municipal wastewater
treatment plant at New Shoreham, Rhode Island.
The Environmental Protection Agency mathematically modeled the
drift and dispersion of the sewage plume from a proposed sewer outfall
at Pebbly Beach, New Shoreham, Rhode Island. The preliminary model
used available modeling techniques.
Two data sources were immediately available with which to compare
current .velocity assumptions used in developing the model. These were
a report prepared for Fenton Keyes Associates and Department of Commerce
Tidal Current Charts for Block Island Sound. The Fenton Keyes current
study had used drogues deposited 60 meters (200 feet) east of the end
of the Old Harbor breakwater. This point is some 1070 meters (3500
feet) north of the currently proposed outfall which will be submerged
In 1.3 meters (4.3 feet) of water*- approximately 70 meters (230 feet)
from Pebbly Beach.
mean low tide
H-7
-------
The currents shown in the Department of Commerce Tidal Current
Charts are based upon data collected approximately 1600 meters (one
mile) offshore and did not necessarily represent local current patterns.
The charts showed that offshore from the proposed outfall the near shore
current patterns are southeast on ebb tide, but on flood tide the current
splits. North of the Old Harbor breakwater the current drift Is north-
vest while at Southeast Point the drift is southwest. The proposed
outfall lay in the nebulous area where the current splits.
The Environmental Protection Agency needed to collect local current
data which would demonstrate the reasonableness of the assumptions used
In developing the model. In addition, currents at locations more distant
from shore needed examination in case the proposed outfall terminus is
unsuitable.
STUDY DESIGN
Since the mathematical model used critical time-displacement vector
assumptions, the Environmental Protection Agency conducted shallow
water drogue and surface float studies to determine the tide and wind
induced current patterns in the vicinity of the proposed outfall. The
drogue details are shown in Figure 2. The floats were constructed of
15.2 cm X 15.2 cm X 1.3 cm (6" X 6" X 1/2") squares of plywood and
painted orange.
The field crew deposited drogues approximately 75 meters (250 feet),
150 meters (500 feet), and 230 meters (750 feet) from shore. Because
of concerns about a current split, two stations were selected which
were 750 meters (250 feet) perpendicular to the proposed outfall pipe
H-8
-------
extended. See Figure 3 for the displacement pattern. Because of the
shallow depth at the outfall location, the validity of the drogue data
from this location might be doubtful. Therefore, the crew used floats
at the 75 meters and 150 meters locations to plot surface currents.
On bluffs overlooking the outfall location, the field crew operated.1.
two transits for triangulating the drogue and float drift positions.
Critical .observations were made at two minute intervals for the first ten
minutes on floats. If the drogues were moving laterally along the shore-
line, sightings were recorded at fifteen minute intervals. If the drogues
were moving out from shore, they were withdrawn. In the event that the
drogues and/or floats reach shore, the contact time and locations were
noted and that test series terminated.
The Environmental Protection Agency felt that flood tide -and north
to east winds would create the critical transport currents. Three days
were allotted to tracking current patterns. Because of time constraints
for completing the study, October 22 - 26 was the only time envelope
which was favorable (i.e. when light would be available) for tracking
the drogues. This time frame allowed for sightings through the entire
flood tide and a major portion of ebb tide. If inclement weather had
prevented conducting the study on one or two days, tides and light still
would have been favorable for observing most of the flood tide.
In conversations with personnel at the National Oceanic and
Atmospheric Administration's weather station at the Block Island State
Airport, it was learned that winds during the late spring and summer
are usually from the-south - southwest quadrant. As fall progresses,
the winds shift toward the northwest and in December and January are
H-9
-------
prevallent from the north - northeast. The wind then begins its counter-
clockwise movement toward becoming a south - southwesterly wind in the
late spring.
STUDY OBSERVATIONS
Monday, October 21
Weather: Overcast Winds: North
Tides: low - 0545 hours1 high - 1230 hours
On Monday, October 21, the winds were from the north and arriving
on the island at 1100 hours the crew had its first encounter with the
type of surf north or east winds create. A steady line of white capped
waves were rolling in on Crescent Beach. The waves were 1.2 to 1.8
meters (4 to 6 feet) in height and began breaking approximately 240
meters (800 feet) from the shoreline. In the Pebbly Beach area, the
vicinity of the proposed outfall, ground swells were rolling in at
approximately the same height and crashing into the rocks. The waves
in this area were breaking 60 to 150 meters (200 to 500 feet) from
shore.
On Monday, the crew established stations for setting up transit.
One station was located at the northeast end of Spring Street, overlooking
Pebbly Beach; the other was located 134 meters (438 feet) northeast of
the first point on the edge of the bluff overlooking Pebbly Beach. On
the next day the crew had to abandon this point because of sun reflections
in the early morning. It was replaced with a new transit point at the
times in this report are Eastern Daylight Time.
H-10
-------
edge of Spring Street 117 meters (383 feet) southeast of the first
transit point.
Tuesday, October, 22
Weather: Clear Winds: West —southwest 10-14 knots1
Tides: low - 0635 hours high - 1328 hours
In the vicinity of the outfall rocks 0.3 to 0.6 meters (1 to 2 feet)
in diameter littered the beach, and boulders 1 to 2 meters (4 to 6 feet)
in diameter are visible in the water or lying slightly submerged up^to
60 meters (200 feet) from shore. The winds were blowing directly off-
shore, and the seas were lapping gently against the shoreline. Wave
heights were less than 0.5 meters (1 1/2 feet) high.
At approximately 0800 hours the first drogue was installed at
Station 4 and shortly thereafter at Stations 2 and 3. Surface floats
were installed at Station 1. It was not long until the crew determined
that the north transit location was unsuitable. At approximately 1000
hours, the transit was moved to the southerly location on Spring Street.
Later, when drogues were released at Station 1, their paths were erratic
seeming to indicate that the drogues would get hung up on rocks and
bounce among them. The velocities of the drogues Installed at Station 1
are suspect. Drogues installed at Stations 2, 3, and 4 moved south-
easterly on a flood tide. This same general drift continued throughout
the day and into ebb tide. (See Figures 4-8.)
Surface currents rapidly moved floats placed at Station 1 from
shore in an east - northeast direction. (See Figures 6 and 8.)
^Hourly wind readings are available in Table 1.
H-ll
-------
TABLE
WIND DIRECTIONS1 AND
VELOCITIES2
OCEAN CURRENT STUDIES
PEBBLY BEACH OUTFALL LOCATION
NEW SHOREHAM (BLOCK ISLAND), RHODE ISLAND
DATE
10/22/74
10/23/74
10/24/74
Time
C-Iours)
(EDT)
0600
0700
0800
^00
1000
1100
1200
1300
1400
1500
1600
1700
1800
Direction
270
300
240
260
240
240
220
220
220
210
240
230
230
Knots
10
11
10
11
12
13
13
12
13
14
14
12
14
Direction
280
260
280
310
300
330
300
310
290
290
250
230
320
Knots
10
11
11
10
12
19
15
15
16
15
14
11
12
Direction
350
360
350
340
020
010
040
070
070
160
170
170
180
Knots
07
133
143
143
103
103
06
06
06
08
09
07
07
NOTE: .Wind directions and velocities were supplied by the National Oceanic and
Aeronautic Administration's Weather Station at the Block Island State
Airport.
^Direction indicates the azimuth from which the wind blows. The azimuth is read
clockwise with zero and 360° denoting north.
«*
*Five knot correction factor has been added to reported readings.
3Station was manned; no correction factor applied.
H-12
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Surface velocities were 0,97 knots at 1145 hours and 0.31 knots at 1440
hours. Other floats were not recorded because the slight wave action
coupled with the narrow field-of—view of the transits prevented
observers from locating and tracking the floats. Using binoculars, the
floats were observed moving out from shore.
The drogues, although all moved southeastward, gradually shifted
to a more easterly direction as high tide approached and on into ebb
tide. Drogues released from 0800 - 0900 hours travelled from 0.05 to
0.09 knots with those farther from shore having greater velocities.
During the next two hours, the velocities in the vicinity .of 230 meter
stations remained relatively constant. However, when the drogues were
northeast of the near point (see Figure 1), velocities increased to
more than 0.12 knots. Throughout the tidal cycle little velocity change
vas noted in the cove.area, but the velocities of the offshore drogues
and those which passed the near point increased markedly at the approach
of high tide and into ebb tide. The farther the drogue was from shore
the more rapid its movement. One and one-half hours after high tide,
velocities greater than 0.30 knots were recorded.
Wednesday, October 23
Weather: Clear Wind: West - northwest 10-19 knots
Tides: low - 0736 hours high - 1427 hours
Wednesday the sea .and weather conditions were similar to those on
Tuesday., The wind, however, had shifted northward. This shift had an
apparent effect upon the current patterns in the cove area. The drogue drift
was more to the south with a gentle sweep eastward as they approached
the near and far points of land. (See Figures 9 — 16.) As had occurred
H-13
-------
8
on the previous day, the drift moved more eastward near the time of high
tide and into ebb tide. The drogues on this day tended to run aground
among submerged rocks lying off the points.
Because the drift continued to be in one direction with no indication
of a current split northward, Stations 2 and 3 were abandoned as drogue
release points. A Station 5 lying midway between Stations 1 and,4 was
established.
Drogue velocities were similar to those encountered on 10/22/74e
Those placed at Station 4 moved more rapidly than those deposited at
Station 5. Velocities of the Station 5 drogues sometimes doubled as
the drogues passed the near point. Velocities in the cove area (Station
5 drogue) ranged from 0.06 to 0.16 knots with most being 0.07 to 0.08
knots. Off the near point, these drogue velocities ranged from 0.07
to 0.18 knots but generally held about 0.11 knots. At Station 4 drogue
velocities ranged from 0.08 to 0.24 knots with most being near 0.12 knots.
Floats placed at Staion 1 moved parallel to the shoreline at
velocities ranging from 0.20 to 0.27 knots. All were washed onto the
north shore of the near point,
Thursday, October 24
Weather: Overcast changing to broken clouds
Wind: North - northwest changing to east 6-14 knots with
gusts to 25 knots
Tide: low - 0855 hours high - 1520 hours
Thursday morning the weather was blustery, similar to that encountered
upon the crew's arrival on the island. North winds existed from 0600
to 1100 hours. White capped swells 1.5 to 2.5 meters (5 to 8 feet) high
-------
were rumbling into shore from the northeast. The waves were rolling,
cresting, and breaking nearly 150 meters (500 feet) from shore. Those
thundering against the Old Harbor breakwater would toss water high above
and at times over the breakwater. The waters within Old Harbor were
more violent than the boat crew had encountered at the outfall location
on Tuesday and Wednesday. Throughout the day seas continued to run from
the east-northeast quadrant, but their intensity diminished in the late
morning to rythmic ground swells 1.2 to 1.8 meters (4 to 6 feet) high.
By early afternoon the surf line had moved to within 60 meters (200 feet)
offshore. Residents on the island disclosed that during stronger wind
conditions or storms at sea the surf line could extend more than 300
meters (1000 feet) out from shore.
Because of the turbulent conditions, the boat crew could not approach
Station 1 so they released no drogues there. In addition, a Station 6
was established to determine current velocity and direction farther from
shore. Station 6 lay on a line with Stations 1, 4, and 5 approximately
300 meters (1000 feet) from shore.
From 0830 - 1000 hours the drogues moved as on the other days—
southeastward. From 0830 - 0915 the current drift was approximately
0.20 knots. During the next hour, the drogue velocities decreased rapidly
and at 1030 hours current reversal was detected. During this same period
winds had shifted from north-northwest to north-northeast. Continued
drogue releases showed that the offshore current movement was southward,
but a clockwise eddy was being generated. Drogues released at Station 6
moved south but gradually turned westward as they approached the near
point. Once entering the cove area the drogues moved northward parallel
H-15
-------
10
to the shoreline. Drogues placed at Station 5 moved northwest and
•n '
(^
started to parallel the shoreline. At 1400 hours, winds were shifting
rapidly from east — northeast to south - southeast, and currents were
moving onshore (southwest) but the velocity decreased rapidly near
shore. Drogues placed at Station 6 moved approximately 140 meters
(450 feet) din twenty-one minutes while the drogue near Station 5 moved
about 35 meters (120 feet) in nineteen minutes. From 1430 hours to
1520 hours (high tide), the drogue movements were relatively stagnant,
and the? the drogues began moving off to the southeast at 0.03 knots
although the winds had shifted to south -southeast at 8 knots. (See
Figure 21.)
Groups of floats were placed at Station 5. Floats deposited
at 0900 hours were on shore within nine minutes. Those dropped at
1020 hours were at Station 1 in six minutes and on shore two minutes
later. Others placed at 1200 hours were on shore in nine minutes.
At 1500 hours floats were tossed from shore in the vicinity of
Station 1. The floats that landed just beyond the surf line drifted
southeastward. Those which landed within the surf line were on Pebbly
Beach within one minute.
.11-16
-------
11
DISCUSSION
Pebbly Beach Is aptly named. Rocks and boulders litter the proposed
outfall area. Drogues released at Station 1 appear to ground or get
hung up on rocks. Their paths were erratic and drogue velocities in
this area were not reliable indicators of current movements.
The near shore ocean currents in the vicinity of Pebbly Beach appear
to be wind influenced. The predominent drift on both flood and ebb
tides was southeast. A north - northeast wind can induce clockwise
currents near Old Harbor Landing and Pebbly Beach. While the wind effect
seems to have counteracted the southeast movement during flood tide,
it did not overcome the southeast flow during ebb tide. On Thursday,
October 24, 1974, the wind had shifted to south - southeast but had not
been from that quadrant long enough to determine the effect of a sustained
southeast wind.
The surf is of major concern. While the wind direction is critical
for surf development, the surf produced the most rapid on shore move-
ment. On Thursday the crews recorded on shore float velocities of 1
to 2 knots in the surf. Residents said that Thursday's surf was not
unusual with the northeast wind. Since the surf line remained at, or
beyond, the proposed outfall location, one can expect that anything
discharged at that location under such conditions would be on the beach
in 1 to 2 minutes. Residents * comments that the surf line can occur
more than 300 meters from shore means that an extended outfall will be
at times subject to the same phenomenon. However, since winds are
reportedly from the south and west during the late spring, summer, and
H-17
-------
12
early fall months, sewage wash, may be an infrequent problem during the
months of high recreation use.
The nearest recognized bathing area is Ballard's Beach, located
on the south side of the Old Harbor breakwater (see Figure 1). This
beach is approximately 550 meters (1800 feet) north - northeast of
the proposed outfall. At no time did a float or drogue get within
300 meters (1000 feet) of Ballard's Beach.
H-18
-------
^. WjS^-^/m V*
) liQJP Jv \
i. pretf Meartiii: Hill\- '• TT J-V-V X • • ,
|T~ .», Su-amp 4- .. .'.y. "'v \\ X.T//
v
-------
e
to
-------
Station Displacement
Ocean Current Studies
Pebbly Beach Outfall Location
New Shoreham (Block Island), Rhode Island
FIGURE 3
H-21
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
•-• Floats
DATE: October 22,1974 TIDES: Low 0635 hrs. High 1328hrs.
WIND DIRECTION: 240°-260° VELOCITY: 10 - 12 knots
'0816
3831
3809
is
13
23
FIGURE 4
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
'Hours) (Hours)
• • Drogues •
•-• Floats
DATE: October 22,1974 TIDES: Low 0635 hrs. High 1328 hrs.
WIND DIRECTION: 260Q-220° VELOCITY: 11-13 knots
23
17
.0910
29
(0919
15
13
FIGURE 5
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours)
(Hours)
Drogues •--
•-• Floats
DATE: October 22,1974 TIDES: Low 0635 hrs. High 1328hrs.
WIND DIRECTION: 220° VELOCITY: 13 knots
1326
1310
13
23
FIGURE 6
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
Floats
DATE: October 22,1974 TIDES: Low 0635 hrs. High 1328 hrs.
WIND DIRECTION: 210°-240° VELOCITY: 13-14 knots
23
17
1328
29
1348
16
1410
FIGURE 7
-------
LOCATION MAP.
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
(Hours)
•—
1 inch = 250 feet
(Hours)
• Drogues •
Floats
DATE: October 22,1974 TIDES: Low 0635 hrs. High 1328 hrs.
WIND DIRECTION: 2io°-220° VELOCITY: 13-14knots
14
17
1439
1426
J448
13
FIGURE 8
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
(Hours)
LEGEND
1 inch = 250 feet
(Hours)
• Drogues •
•-• Floats
DATE: October 23, 1974 TIDES: Low 0736 hrs. High 1427 hrs.
WIND DIRECTION: 280°-3io° VELOCITY: 10-12 knots
14
17
.0801
16
15
FIGURE 9
-------
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
1 inch = 250 feet
(Hours)
• Drogues •-
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs
WIND DIRECTION: 300°-3IO° VELOCITY: 10-12 knots
\
--*ll*Wi^Sss;?S&*S;*\
'"^^^^A •• • •
••'•<*!&K'A-.S\ '
Old Harbor Pt.
FIGURE 10
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
•-• Floats
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs.
WIND DIRECTION: 300°- 330° VELOCITY: 15 -19 knots
23
17
J045
IO45
1110
is
13
FIGURE II
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LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
'.Hours)
1 inch = 250 feet
(Hours)
• Drogues •
Floats
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs.
WIND DIRECTION; 290°-310° VELOCITY: is-ie knots
23
14
17
16
1230
.1250
IS
13
FIGURE 12
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LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
•-* Floats
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs.
WIND DIRECTION: 250°-3IO° VELOCITY: 14-16 knots
17
23
1331
1351
1330
1350
19
13
1554
•"•^408 \I4I6
Old Harbor Pt.
m
FIGURE 13
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LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
(Hours)
1 inch = 250 feet
(Hours)
• Drogues •
•-• Floats
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs
WIND DIRECTION: 250«-290° VELOCITY : 14 -15 knots
14
16
1444
1446
13
1627
FIGURE 14
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
(Hours)
1 inch = 250 feet
(Hours)
• Drogues •
Floats
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs.
WIND DIRECTION: 230°-250° VELOCITY: 11-14 knots
23
23
1530
13
FIGURE 15
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
•-• Floats
DATE: October 23,1974 TIDES: Low 0736 hrs. High 1427 hrs.
WIND DIRECTION: 230°-250° VELOCITY: II-14 knots
17
16
': I605-.1-60:
7
.1636
J70I
1636
'1620
13
FIGURE 16
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
! Hours) (Hours)
• • Drogues •
•-• Floats
DATE: October 24,1974 TIDES: Low 0855 hrs. High 1520 hrs.
WIND DIRECTION: OIO»-350° VELOCITY: 10-14 knots
14
0857
16
0826
is
13
FIGURE 17
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
•-• Floats
DATE: October 24,1974 TIDES: Low 0855 hrs. High 1520 hrs.
WIND DIRECTION; 010°-020° VELOCITY: 10 knots
JOI9
14
.1017
17
23
IS
13
. *
. *.
FIGURE 18
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
Floats
DATE: October 24, 1974 TIDES:Low 0855 hrs. High 1520 hrs.
WIND DIRECTION: 010°-070° VELOCITY: 06 knots
14
16
.1139
FIGURE 19
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
(Hours) (Hours)
• • Drogues •
•-* Floats
DATE: October 24,1974 TIDES: Low 0855 hrs. High 1520 hrs.
WIND DIRECTION: 040°-160° VELOCITY :oe-08 knots
1443
17
.1210
16
IS
23
FIGURE 20
-------
LOCATION MAP
CURRENT STUDIES
PROPOSED OUTFALL AT PEBBLY BEACH
NEW SHOREHAM, RHODE ISLAND
LEGEND
1 inch = 250 feet
'Hours) (Hours)
• • Drogues •---
•-• Floats
DATE: October 24,1974 TIDES: Low 0855 hrs. High 1520 hrs.
WIND DIRECTION: 070°-i7o° VELOCITY: oe-os knots
23
14
17
23
I5I8
1407
16
1604 (
1619 V\71428 l603
^1450 1618
1639
19
10
13
FIGURE 21
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INTRODUCTION:
We have conducted analyses of two aspects of dilution of wastewater
from the proposed New Shoreham Wastewater treatment facility. These
are dilution due to diffuser design and depth of water over the
diffuser; and dilution due to dispersion of surface plume of waste-
water under two conditions;constrained by a seawall parallel to the
path of flow and unconstrained in the horizontal plane.
RESULTS:
We found that it would be desirable to relocate the outfall in
deeper water to increase dilution. Certain specific modifications of
the diffuser design would also increase dilution.
The following sections detail the analyses of the diffuser problem
and allow for the investigation of a large number of design options
by means of generalized tables and charts.
-------
-2-
BLOCK ISLAND OUTFALL ANALYSIS
A. Diffuser analysis
The dilution of sewage effluent by means of a diffuser system is a
function of jet velocity, jet diameter, discharge angle, sewage density,
and water depth. Work by Fan & Brooks (1), as presented by Norman Brooks
at Manhattan College, May, 1973, analyzes sewage dispersion by use of the
densimetrie Froude Number, and the depth/diameter ratio of the diffuser,
for peak flows of 0.3 MGD (0.45 cfs) each port of the 8 port present -
design would have a Froude Number of 2.3 and would,, if acting independently,
- , ~- U
f-vou cJC.
o-| dcwiv^es. 4-o
vAt fAC/'ifl^
. . f.
^ rUfvAu^ t( *
(1) Van, Loh-Nien and Brooks, N.H., "Numerical Solutions of Turbulent
Bouyant Jet Problems" W. M. Keck Laboratory of Hydraulics and
Water Resources Report No. KH-R-18, California Institute of
Technology, Pasadena, January, 1969, 54 pp.
-------
produce dilution ratios somewhere between 6 and 9. However, the close proximity
of the eight individual ports, as shown below, make the likelihood of plume
interaction very high, although impossible to determine (because of the very
low velocity, and very shallow, changing depth).
v-v
o
G-
o
0'
oe
A
o
c>
G
^ Q -
0*
i
Interaction of G & F and B & C to a high degree is certain because low jet
velocities mean there will be very little horizontal movement before density-
differences cause vertical rise. Interaction between jets E & H and A & D
are also very likely, although the resulting loss of dilution would
probably not be as great as in the case of G & H and B & C. There is
also a likelihood of plume interaction between adjacent ports in the
horizontal plane, such that ports F & E, E & D, H & A, G & H, A & B,
and C & D would not be likely to have sufficient spacing to allow
unrestrained dilution.
Besides the problem of actual plume interaction, there could be a problem
of restraint of dilution water flow. Plume analysis theory requires
sufficient access to the plume by clean dilution water. With this scheme,
H-U2
-------
-4-
as the individual plumes expand, the availability of clean dilution water
could be severely limited, thereby decreasing dilution.
Additionally, dilution expected during periods of considerably lower
flow (lower than 0.45 cfs), would be drastically lower still, because of
decreased velocity and therefore a lower Froude Number, so that the
sewage field would not be likely to act as a jet, but as a weakly buoyant
flow, with little mixing likelihood. As a result of the above analytical
difficulties, no dilution of the sewage could be ascribed to the present
design.
Several other possible diffuser arrangements were analyzed for their
possible environmental effects. Three designs were analyzed for six
one-inch diameter ports at plant flows of 0.45 cfs, 0.225 cfs, and
0.112 cfs, along with three designs for six two-inch ports at the same
flows. In each case, ports were assumed to be spaced such that they
would not interact (spacings of several feet, discharging horizontally).
Froude Numbers of: 9.3, 4.6, and 2.3 resulted from the two-inch ports
at the specified flows, while the one-inch ports at these flows resulted
in Froude Numbers of: 54.7, 27.8, and 13.9, respectively.
The following chart shows the dilutions that could be expected from
a given depth and Froude Number.
H-l*3
-------
Uj
60- vf
50
3 40
^ 30
§ 20
*|Q
10
8
*S-
l*s
VL*
^
vQ,
X
N
\
\
^
IS
—o
£
— 5>-
^3og
N25
Vs
20
456 8 10
F * FROUDE No. *
20
30 4O
FIG. 7.-DI1..UT1ON AS A FUNCTION OF v/D AND F FOR HORIZONTAL DISCIIAnCE
DIFFUSERS FOR DISPOSAL OF SEWAGE IN SEA WATER
By A.M. Rawn, F.R. Bowerman, and Norman H. Brooks
-------
BLOCK ISLAND OUTFALL ANALYSIS
B. Surface Plume Analysis
Once the bouyant jet from the diffuser reaches the surface, the sewage
field Is carried In local ocean currents, and undergoes further reductions
in concentration of pollutants by far field dispersion and by decay of
non-conservative substances such as coliforms and biochemical oxygen
demand, (BOD). The following equation is used to describe the changes in
concentration due to lateral dispersion, advection and decay:
£. - diffusion coefficient
C = Concentration
U - Velocity in "x" direction
K - decay rate
c spatial coordinate system
q
The equation was solved numerically by the Systems Analysis Branch, EPA,
Region I, (3) for two cases, herein referred to as .the unconstrained case
and the constrained case. The unconstrained case is open to dispersion in
(2) Brooks, N.H. "Waste Water Disposal in the Marine Environment" Pearson,
U. California, Berkely, 1959, Pergamon
(3) Internal Memos, October - November, 1974, Systems Analysis Branch, EPA, Region
-------
-6-
both directions perpendicular to the center-line velocity. The constrained
case has a berm or seawall along one side, preventing dispersion in that
direction. Figure 1 below illustrates the two cases studied.
s d o f c
I I I I II I I I I I
u = current velocity
FIGURE 1
The plume analysis computed lateral dispersion perpendicular to the
center-line of the sewage plume. The plume need not be heading toward shore
to be valid, although this would seem to pose the most environmentally
important case, as other paths require additional lengths of travel, and
result in higher dilutions. Figures 2 through 10 summarize the computer
runs of the plume model. All sewage concentrations refer to the ratio C/Co
or the fraction of the original surface concentration remaining.
Figure 2 shows a schematic drawing of the system being analyzed, with
the peak concentration declining as the plume spreads, i.e. as the plume
width increases. Figure 2 shows only half of the plume for the symmetric
unconstrained case, and shows the whole plume for the constrained case
because there is no dispersion through the seawall.
H-U6
-------
2
O
S '•«
u
2-
O
u
Co
Ay
M
ORIGINAL /
PLUME WIDTH
PLUME
CENTERLINE^- X
|- PLUME WIDTH
-------
tr-
CO
Ay
b
u
D
X
.25'
Plume Width (2.5*)
Velocity (0.3 fpsT
.00339 ft.2/sec.
Distance along center line (ft.) from source
1/2 OF UNCONSTRAINED SYMETRICAL PLUME
20
30 40 50 60
DISTANCE PERPENDICULAR TO CENTER LINE (ft.)
70
80
''9-
-------
K
I
£r
VO
Co
UNCONSTRAINED
Ay = 0.25'
b « 2.5*
0 = 0.00339 ft.2/sec.
X = Distance along center line
u = 0.5
u = 0.3 fps
u = O.I fps
700
800
CENTER LINE CONCENTRATIONS
-------
1.0-,
0.8-
0.6-
C_
Co
V/l
o
0.4-
0.2-
V
UNCONSTRAINED
u = 0.3 fps
b = 1.5
100
200
300 400 500 600
DISTANCE FROM SOURCE (ft.)
700
800
EFFECT OF SOURCE WIDTH ON CENTER LINE CONCENTRATION
-------
C
Co
M-,
VI
c/
UNCONSTRAINED
X - 200* Along center line
u = 0.3 fps
10
30 40 50
DISTANCE FROM CENTER LINE (ft.)
60
70
80
EFFECT OF SOURCE WIDTH ON CONCENTRATION PROFILE PERPENDICULAR TO CENTER LINE
-------
CONSTRAINED
Ay = 0.25'
b =2.5'
D = 0.00339 ft2/sec.
X - Distance from source
u = 0.5 f ps
700
800
LINE OF HIGHEST CONCENTRATION (ALONG SEAWALL)
-------
I.O-,
0.8-
0.6-
Co
VI
0.4-
0.2
CONSTRAINED
X = 100'
u = 0.3 fps
10
20
30 40 50 60
y (DISTANCE FROM BARRIER-ft.)
70
80
EFFECT OF SOURCE WIDTH ON CONCENTRATIONS PERPENDICULAR TO CENTER LINE
-------
1.0
0.8-
0.6-
Co
w.
v/i .
* 0.4 -I
0.2
A7'
CONSTRAINED
X = 200* (Distance from source)
u - 0.3 fps
10
20
30 40 50
y ( DISTANCE FROM BARRIER -ft.)
60
70
80
EFFECT OF SOURCE WIDTH ON CONCENTRATION PERPENDICULAR TO CENTER LINE
-------
c/
CONSTRAINED
0.8-
X = 500* (Distance from source)
u = 0.3 fps
0.6-
.C
Co
0.4-
0.2-
10
20
30 40 50
y (Distance from barrier -ft.)
60
70
80
EFFECT OF SOURCE WIDTH ON CONCENTRATION PERPENDICULAR TO CENTER LINE
-------
Figure 3 shows the concentrations perpendicular to the plume center-line
at various distances from the sewage source, for the unconstrained case.
These curves show the peak decreasing, and the plume width increasing
with distance from the source.
Figure 4 shows the effect of various current velocities on the dispersion
of the sewage. It can be seen that higher velocities result in lower dilution
of the sewage.
The reasons for this become apparent when the solution of the differential
equation (2) is examined in finite difference form for the case where there
is no decay:
_
Where: C.Ci-.v'N r Concentration at i, j
r Concentration at i + 1, j
L. \ r Are grid coordinates in the x and y
directions respectively
£ - Diffusion Coeficients
U r Velocity in the x direction
b - Original source width
A/ - Grid spacing in x direction
<4M - Grid spacing in y direction
The whole first term on the right side shows the change in concentration from
one grid point to the next in the x direction. This is seen to become smaller with
increasing velocity u.
H-56
-------
-8-
Figure 5 shows the effect of source width on plume centerline
concentrations for a constant velocity, and the unconstrained case.
This is important because various diffuser alternatives would result in
different dilutions and different surface boil sizes.
Figure 6 shows the effect of source width on plume profile concentrations
at a distance of 200 feet from the source.
Figures 7, 8, 9, and 10 show similar analyses for the case of a
constrained plume.
Using the above generalized curves, almost any expected current
strength or outfall location can be evaluated.
C. Special Surf Conditions
If an outfall is subject to surf conditions, the results of any diffuser and
surface plume analysis must be evaluated in a different light. Breaking
surf usually occurs when sea depths become shallow. A diffuser system
that is located inside the surf line is subject to widely varying hydro-
dynamic forces, most of which are adverse. Swell action causes significant
depth changes when compared to total depth, and local velocities near the
diffusers could interfere with jet dispersion. The surface plume, when
caught in a surf would experience high velocity which would be guaranteed
to be shoreward in direction, and dilution would be significantly reduced.
The curves for plume dilution as found in Section B would be invalid. The
following is quoted from Brooks (2) pp. 262:
H-57
-------
-9-
"The prediction of the coliform count in the surf
zone presents an added difficulty because of the
littoral drift, upwelling of bottom water, and
the less rapid flushing in the shallow region
very close to shore. Because of these effects-
the shore count of a given magnitude may be as
much as two or three times as frequent as
predicted by the above analysis. The experience
of the Los Angeles County District indicates
that the frequency of counts greater than 10 per
ml is greater at the shore than it is offshore."
Therefore, a diffuser located in only 3 to 4 feet of water, at only two
hundred feet offshore, and known to be within the surf line in some current
conditions, would not be likely to produce significant sewage dilution
with a high degree of confidence. Any site for an outfall which falls
within the surf line should be considered a poor site.
D. Diffuser/Plume Analysis Applied to Survey Results
The EPA study of October, 1974, utilized floats and drogues in the
vicinity of the proposed outfall, 225 offshore of Pebbly Beach. The study
was designed to test the reasonableness of computations and assumptions
made in the plume analysis. Current studies were conducted on three days.
Two days during the study found almost no surf, with one day showing a
predominantly south west wind (9 - 13 knots) and the other day with a
north west wind (9-18 knots). The third day showed heavy surf
H-58
-------
-10-
200 to 400 feet offshore in the morning with a North to North-East wind
(6 - 14 knots gusting to 25 knots). The wind dropped to 5 - 8 knots from
a southerly direction in the afternoon.
Drogues and floats were released periodically starting one hour
after low tide, and their velocities and paths were recorded. On the
second day, with a southwest wind, all drogues moved in a southeasterly
direction with a velocity range of .07 fps to .4 fps with a large grouping
at about .15 to .20 fps. These are within the range of velocities used
to develop the curves in Section B.
The third day's work encountered winds roughly parallel to shore
to almost directly on shore, NNE to SE. Heavy surf prevailed about 200 feet
to 400 feet off the beach. Floats released in the surf line came up on the
shore, and had an approximate velocity of 6 fps. The analysis of Sections A and B
would not be valid for this condition. However, drogues released beyond the
surf exhibited a definite shoreward motion soon after flood tide began, with
velocities ranging from .1 fps to .6 fps. The curves derived from the analysis
in Section B are valid for this situation up to the point the plume enters
the surf line. The diffuser analysis of Section A applies for locations beyond
the surf.
E. Example Dispersion Analysis
1. An outfall is located 225 feet offshore, with wind from the North-
west 9-13 knots.
The effluent coliform count is 2300/lOOml.
The present outfall design, with seawall depth =3.5 feet at low water
produces a source width of 2.5 feet.
Dilution due to diffuser is unknown (=1).
The path of plume is 565 feet towards Old Harbor Point.
H-59
-------
-11-
The average current velocity is 0.13 fps in that direction.
The centerline dilution is 5.8 to 1 (from Figure 4).
The centerline concentration at Old Harbor Point is 2300/5.8 = 396/100 ml
2. Same conditions as Example 1, except a diffuser with 3" ports and
a Froude Number of 4.67 is used.
The dilution due to the diffuser is 7:1 (Table 1).
The dilution due to the surface plume is 5.8:1 (Figure 4).
The total dilution at Old Harbor Point is 7 x 5.8 = 40.6:1
The coliform concentration at Old Harbor Point is 2300/40.6 = 56/100ml
3. Northeast wind 6-14 knots.
Present outfall location and design.
The surf line is at 225 feet and the outfall dilution due to the diffuser
is 1:1.
The dilution due to dispersion in the surface plume (velocity = 6 fps).is
1.33:1 (likely to be lower).
The coliform concentration on Pebbly Beach is 2300/1.33 = 1725/100 ml.
4. Outfall 600' offshore, northeast wind surf at 400' offshore.
The diffuser is composed of 2" ports.
The plume source width is 2.5 feet.
The depth is about 10*.
The current velocity is 0.2 fps to surf line.
The densimetrie Froude Number is 13.9.
The dilution due to diffuser is found to be 30:1 (Table 1).
The dilution due to a 200 foot plume traveling to the surf line is
H-60
-------
-12-
The total dilution is 2.5 x 30.1:1 =75:1 at the surf line.
The coliform concentration at surf line = 2300/75 = 30./100 ml.
Any combination of possible situations can be analyzed in this manner, and
the above 4 examples only illustrate possible situations.
H-6l
-------
APPENDIX I - COST BASIS FOR ALTERNATIVE ACTIONS
Alternative A: Collection and Treatment.
Cost basis: The costs for the treatment plant and sewer system are taken
from the bid prices of the selected contractor.
Costs for Phase II sewers which were not included in original
bid are based on Block Island estimated costs per foot of
sewer installed.
House connections costs were estimated by EPA, Region I,
at $500/unit.
Total Costs:
Treatment Plant
Sewer System
Tech. Services
Legal
Administrative
Contingency
Inspection
Site
Subtotal
Phase IT sewers
House Connections
Total
Capital
$ 2, 21 ^, 000
1,505,000
338,000
16,000
16,000
Ave. Annual
0 & M
Total Annual
100,000
10.000
$ 1*, 383, 000
500,000
150.000
$ 5,033,000
$ 382,000
1*1*,000
13.000
$ 1*39,000
$ 27,000
$ 27,000
$ U09.000
1*1* ,000
13.000
$ 1*66,000
1-1
-------
Alternative B: Collection and Treatment minus Phase II sewers.
Cost basis: Future sewer constructions costs for Phase II eliminated.
Existing septic systems in Phase II areas adequate. Future
septic tank construction estimated at $225,000.
Design of treatment facility reduced by amount of flow
estimated for Phase II or approximately 60,000 gpd.
Reduction in cost of treatment facility interpolated from
EPA, Region I cost curves. Therefore, a 2^0,000 gpd
treatment facility would cost $2,000,000 (this does not
include any redesign costs).
Total Costs:
Treatment Plant
Sewer System
Tech. Services
Legal
Admini strative
Contingency
Inspection
Site
Subtotal
Future Phase II
septic system
construction
House Connections
Total
Capital
$ 2,000,000
1,505,000
300,000
lit, 000
lU.OOO
11*0,000
100,000
10,000
$ it,083,000
225,000
100,000
$ U, 1*08,000
Ave. Annual 0 & M
Total Annual
$ 25,000
— 1,000
$ 38it,000 $ 26,000
$ 1*10,000
1-2
-------
Alternative c: Rehabilitation of Individual Subsurface Disposal Systems.
Cost basis*: Construction or reconstruction of single
home septic system = $ it,000.
Construction or reconstruction of multiple
unit S.S. with average daily flow less
than 2,000 gallons = 10,000.
Construction or reconstruction of multiple
unit S.S. with average daily flow
between 2,000-5,000 gallons = 25,000.
Construction or reconstruction of multiple
unit S.S. with average daily flow over
5,000 gallons = 50,000.
Annual Cost Basis:
Assumed each septic tank must be pumped
once every three years @ = $60/pumping
Therefore, 207 units (Phase I only) at a
design life of 20 years will require
1,1*00 pumpings § $60/per = $8^,000 4 20 years
= H,200 or $U,5'00/yr.
Estimated units from Fenton G. Keyes Associates projections
Appendix F, less Phase II.
Total Costs;
Capital Ave. Annual 0 & M Total Annual
Construction of
Septic Systems in
Phase I areas $ 1,801,000 $ 157,000 $ U,500 $ 161,500
Wew Construction
of septic systems
in Phase II areas 225.000 19,000 500 19.500
$ 2,026,000 $ 176,000 $ 5,000 $ 181,000
*SOURCE: Tony Lafasio, Rhode Island Department of Health
1-3
-------
Alternative D: Collection and treatment of Old Harbor only. Rehabilitation
of individual septic systems for remainder of Phase I area.
Cost basis: Sewer construction of Phase'II eliminated.
Sewer construction for "Old Harbor Only" taken from bid
costs - $1,505,000 - U05,000 = $1,100,000.
Treatment plant design average flow reduced by 50,000 gpd
(Phase II) and lllj,l*00 gpd (Hew Harbor area). Reduction
in cost of treatment facility interpolated from EPA
curves. Therefore,
300,000 - (60,000 + llU.OOO)
= 126,000 gpd or $1,300,000
Reconstruction or new construction of septic systems in
New Harbor estimated at $700,000. Future construction of
septic systems in Phase II areas estimated at $225,500.
Total Costs
Capital Ave. Annual 0 & M Total Annual
Treatment Plant $ 1,300,000
Sewer System 1,100,000
Tech. Services 21+0,000
Legal 10,000 — ~
Administrative 10,000
Contingency 100,000
Inspection 50,000
Site 10,000 — — . _ . —
Subtotal $ 2,820,000 $ 20,000
House Connections 75»000 — — —
Individual Septic
systems in Phase I 700,000 — 2,500
Future septic systems
in Phase II 225.000 — — —
Total $ 3,820,000 $ 312,000 $ 22,500 $ 335,000
I-k
-------
APPENDIX J - IMPACT'OF SEWERS ON SPECIFIC SECTORS OF THE ISLAND
Following is an analysis of the growth and environmental impact of Phase I
and Phase II sewer lines, or the potential for connecting to these sewer lines,
in the various sectors of the Island. Refer to Maps, Alternative A superimposed
on environmental sensitive areas and cultural features.
New Harbor
A sewer to the New Harbor marinas would extend from Old Harbor for 1.5 miles
along Ocean Ave and West Side Road, plus a Beach Ave loop, through extensive
vacant land, highly attractive for development, yet largely environmental-
critical marshland, shoreland, and scenic uplands. This line, and the potential
for connections, would, based on all experience elsewhere, open up for resort
and summer house development the mid portion of the Island, adversely altering
the environment of Great Salt Pond, its shoreline, marshes, and moor-pasture
uplands rising to the south.
Specifieally, the West Side Road sewer to Champlins marina could encourage
condominium and resort development along West Side Road and, in addition, the
opportunities for connections to this sewer could spur condominiums and medium
density, residential subdivisions to the west along West Side Road and Center
Road and to the south toward Beach Hill Road. This would press upon salt water
marshes, fresh water marshes, ponds and shorelands and bring strong pressures
for intensive resort development within the storm inundation areas adjacent to
Great Salt Pond and the extensive lowlands below the hurricane high waterline.
If such developments were to occur and suffer flood and hurricane damage,
pressures could, in turn, mount for flood protection projects, which would be
costly and damaging to the wetland ecosystems and scenery. These' development
pressures could defeat CCP proposals to preserve as a conservation area Cormorant
Point and Cove Northwest to Champlins marina and the Charlestown Beach Peninsula.
Southwest to West End Road, it would crowd open bayberry heath, up land pasture,
vegetative cover, and scenic vistas of the Great Salt Pond.
Northern Section
With a basic sewer system in Old Harbor, the potential for extension
northward along Corn Neck Road would stimulate beach condominiums and houses
between the road and the southeast embayments of Great Salt Pond (especially
Harbor Pond). Unless this development were carefully confined to the higher
ground (as proposed in Bradford), it would encroach upon the salt marshes.
Some of the area is subject to storm inundation and lies within the hurricane
high water line. Dense development would diminish views of Old Harbor, the
ocean, Great Salt Pond and the North Neck uplands.
Old Harbor
Development associated with the basic sewer system might bring pressures
to fill in a portion of the marshy area at "the foot of High St. - near the
commercial center. More intense development would fill in the "vacant" open
J-i
-------
spaces and vegetation and might stimulate construction that would diminish the
area's essential openness and charm. Construction of new architectural styles
might clash with the older styles and historic character. Development of the
open spaces surrounding the Old Harbor care would further diminish this appeal.
On the other hand, construction of a sewer system would permit concentrations
of people and buildings and encourage restoration and additions to strengthen
a compact town center, without the density limits set by individual subsurface
disposal systems. But proliferation of the system into the hinterland, particularly
to New Harbor, might actually turn additional investment and development away
from restoration of Old Harbor.
Southeast Sewer Extensions - Phase 1 and II
Pressures for summer home development have already been demonstrated in
the construction of approximately 60 new homes in this section since 1957-
The Pilot Hill Road sewer extension southward and upward from the school
would support growth in the lower perched ground water zone, on which much of
the Island's population depends for water supply. The area embraces Sands Pond
and a number of other ponds. Lacking outlets and small in size, these ponds
have little capacity for self-cleansing: they are extremely sensitive to
pollutants from construction activity and'from runoff from build up areas.
The area embraces approximately 20 percent of the Island's taller, heavier
coastal shrub cover and approximately 20 percent of its agricultural land.
The entire area is recommended for "low residential, open space preservation"
in Bradford. That portion west of Pilot Road embraces a proposed park for
extensive recreation - water supply - conservation uses, and that portion east
of Pilot Road for "low density residential" in CCP.
The Southeast Road extension, together with lateral interceptors, would
cumulatively crowd the breathtaking open vistas of, moor, farmland, stone-walled
pastures and ocean. There would be a lesser impact on water supply. The area
west of the road, as Bradford suggests, is generally best suited to "low
residential, open space preservation", but the area east of the'road may
accommodate, if desired, a ring of "medium" to "dense residential" development.
The Conn. Ave. extension could encourage connections of development
impinging upon Great Swamp. On the other hand, the high ground immediately to
the east of the Connecticut Ave. terminus appears suitable for development and
offers vistas of Old Harbor. It is proposed for "commercial" and "dense
residential" in Bradford, and for "medium" and "low" residential in CCP.
Dense development here would enclose some of Old Harbor's open, vegetative
backdrop. This closing in upon open space would become more pronounced as
development were extended as a belt along the hillsides to the south of
Old Harbor.
South-Southwest
The Old Town Road-Center Road extension would also traverse upland moor and
wooded areas southwesterly from Old Harbor. Large sections would traverse a
strip deemed suitable for "dense residential" in Bradford and for "medium density
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residential" in CCP. But, this extension could also induce development of
intermingled wetlands to the south of Old Town Road. In addition, the
associated development would diminish the backdrop to Old Harbor of 'some of
the Island's taller coastal shrub and moors. Sedimentation and other pollutants
associated with the increased land runoff from construction and denser settlement
would wash into the fragile wetlands and ponds, which have little flushing
action.
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APPIiiiOIX K
UNITED STATES DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
222 Quaker Lane, West Warwick, Rhode Island 02893
November 12, 1974
Mr. Mark Possidento
Sanitary Engineer
US Environmental Protection Agency
Region I
J. F. Kennedy Building
Boston, Mass. 02203
Re: New Shoreham, Rhode Island
Impact Statement
Dear Mr. Possidento:
As requested, our Agency has completed a review of the "Preliminary
Engineering Survey and Report on Control of Water Pollution for the
Town of New Shoreham". This review has been separated into two
sections: The first being of erosion and sediment control during
construction and the second section dealing with an evaluation of the
soils of the land disposal and sludge disposal sites.
SECTION #7 - GEOLOGY:
The majority of the soils on New Shoreham are underlain either
by stratified sands and gravels or coarse textured glacial till.
This fact is going to make it important that provisions are made
to control erosion and sediments of this erosive soil material
during excavation and construction. There is also growing concern
that these permeable soils may lead to contamination of ground waters
because effluent may pass through them to rapidly to be adequately
filtered if ground waters are relatively close to the surface.
SECTION #11 - DESIGN .OF SEWAGE SYSTEM:
Because many of the soils found on the Island are erosive and the
topography of the "Area of Study Concentration" is steep and
undulating, it is our opinion that a plan for the control of erosion
and sediment needs to be included in the design of the sewage
system. Such a plan should include provisions to reduce erosion
from excavation areas, stock-piled soil material, construction sites
and final revegetation after construction.
Probable practices that may be required in an erosion and sediment
control plan include: temporary and permanent seeding of critical
areas, sediment basins, diversions, interceptor dikes, mulching,
drainage, log or baled hay erosion checks, heavy use area protection
and tree planting.
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2.
11/12/74
Mr. Mark Possidento
Our Agency is willing to cooperate with the firm awarded the
design contract for this project to develop an erosion and
sediment control plan once this proposal has reached that stage.
SECTION #13 - SEWAGE TREATMENT PLANT SITE:
The last paragraph in this section discusses the "landscaping
of the plant site in a pleasing fashion". We would like to caution
that this landscape plan include only those plant materials that
are tolerant and adapted to "salt spray" such as: Japanese Black
Pine, Russian Olive, Tatarian Honeysuckle and Scotch Broom. We
would recommend Dr. Robert Wakefield, Professor - Plant and Soil
Science, College of Resource Development, University of Rhode Island,
in regards to salt tolerant plant materials.
SECTION #15 - COST ESTIMATES:
Cost estimates should be developed to include necessary expenditures
for erosion and sediment control measures.
The second part of this report deals with an evaluation of the soils of
the land disposal and sludge disposal sites. To complete this part of
the report we had our soil scientist update and re-map the soil survey of
those sites that you had indicated on the topo map. The results of the
soil survey is enclosed on the attached photo copies. The areas we were
asked to investigate are shaded in "red".
The following is a list of the soils found on these properties and a brief
description of them:
16A BRIDGEHAMPTON SILT LOAM: This is a deep silty soil on 0-3%
slopes underlain by stratified sands and gravels. Depth to bedrock
is generally greater than 10 feet and depth to seasonal high water
table is greater than 4 feet. Surface drainage is slow to rapid
depending on the slope and soil cover. Internal drainage and
permeability are moderate in the upper sequim. The lower sequim may
be water-logged in winter, early spring and after heavy rains
because of the strongly contrasting textures in the lower solum and
the substratum. The permeability range of this soil is between 0.6
and 2.0 inches per hour. The available water holding capacity of this
soil is 0.18 to 0.30 inches per inches of soil.
16B BRIDGEHAMPTON SILT LOAM: This is the same soil as 16A except
that the slopes will range from 3-8%'.
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3.
11/12/74
Mr. Ma-k Possidento
27A HINCKLEY GRAVELLY SANDY LOAM: This is an excessively
drained sandy soil underlain by stratified sands and gravels
on 0-3% slopes. Depth to bedrock is generally greater than
10 feet and depth to seasonal high water table is greater than
4 feet. This soil has been developed from deep outwash deposits
of sand and gravel. The permeability range of this soil will be
something greater than 6.0 inches per hour and the available water
holding capacity of this soil is between 0.06 and 0.14 inches per inch
of soil.
27C HINCKLEY GRAVELLY SANDY LOAM: This is the same as 27A except
that the slopes will range from 3-15%.
27D HINCKLEY GRAVELLY SANDY LOAM: This is the same soil as 27A
except that the slopes will range from 15-25%.'
28C HINCKLEY-ENFIELD COMPLEX: The soils in this unit occur in
such an intricate and complex pattern that it is not practical to
separate them with the scale used. This complex includes both well
drained sandy and silty soils underlain by stratified sands and
gravels on slopes ranging from 0-15%. The permeability range of this
soil is between 0.60 and 6.0 inches per hour. The available water
holding capacity of this soil is between 0.06 and 0.30 inches per inch
of soil.
50A - - ENFIELD SILT LOAM: This is a well drained silty soil on 0-3%
slopes underlain by stratified sands and gravels. These soils are
on terraces and outwash plains formed by glacial melt waters. Depth to
bedrock is generally greater than 10 feet and depth to seasonal high
water table is greater than 4 feet. The upper 2 feet of this soil
has a permeability range from 0.60 to 2.0 inches per hour. The
permeability range in the substratum will be greater than 6.0 inches
per hour. The available water holding capacity in the upper 2 feet
will be between 0.16 and 0.30 inches per inch, below 2 feet it will
be between 0.01 and 0.08 inches per inch.
51B WINDSOR LOAMY SAND: This is an excessively drained sandy soil
on 3-8% slopes underlain by sands. Depth to bedrock is generally
greater than 10 feet and depth' to seasonal high water table is greater
than 4 feet. The permeability of this soil will be something greater
than 6.0 inches per hour. The available water holding capacity of this
soil is between 0.01 and 0.12 inches per inch of soil.
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4.
11/12/74
Mr. Mark Possidento
53 RAYNHAM SILT LOAM: This is a poorly drained silty soil on
slopes of 0-3% underlain by stratified sands and gravels. Depth
to bedrock is generally greater than 10 feet and depth to seasonal
high water table is commonly between 0.5 and 1.5 feet of the surface.
Internal drainage is slow because of the high water table that occurs
in the winter and spring. The permeability of this soil will range
from 0.60 to 2.0 when the water table is down and the available
water holding capacity of this soil is between 0.17 and 0.30 inches
per inch of soil. The high water table condition of this soil
restricts its uses.
54 BELGRADE SILT LOAM: This is a moderately well drained deep
silty soil on 0-3% slopes underlain with stratified sands and gravels.
Depth to bedrock in this soil is generally greater than 10 feet and
the water table is usually within 2 feet of the surface from late fall
to early spring. During the summer and early fall the water table
recedes to below 4 feet. The permeability range of this soil is
between 0.60 and 2.0 inches per hour when not being restricted by the
high water table. The available water holding capacity of this
soil ranges between 0.17 and 0.24 inches per inch of soil.
61 TISBURY SILT LOAM: This is a moderately well drained soil on
0-3% slopes underlain with stratified sands and gravels. Depth to
bedrock in this soil is generally greater than 10 feet and the water
table is usually within 2 feet of the surface from late fall to early
spring. During the summer and early fall the water table recedes to
below 4 feet. The permeability range of this soil in the upper two
feet is between 0.60 and 2.0 inches per hour; when not restricted by
high water tables, the substratum in this soil will have a permeability
rate greater than 6 inches per hour. The available water holding
capacity of this soil ranges between 0.01 and 0.30 inches per inch of
soil.
68B BROADBROOK SILT LOAM: This is a well drained soil on 3-8%
slopes underlain by glacial till. In Rhode Island these soils have
an impervious fragipan at a depth of 30 inches or more. Depth to
bedrock in this soil is generally greater than 10 feet and depth to
seasonal high water table is greater than 4 feet. The permeability
range in the upper 3 feet of this soil will be between 0.60 to 2.0 inches
per hour; below this depth the fragipan will restrict to permeability
to less than 0.20 inches per hour. The available water holding capacity
of the upper 3 feet of this soil is between 0.15 to 0.30 inches per
inch; below 3 feet the range will be between 0.08 to 0.16 inches per
inch.
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5.
11/12/74
Mr. Mark Possidento
117B AGAWAM FINE SANDY LOAM: This is a deep well drained
soil on 3-8% slopes underlain by coarse textured outwash materials.
Depth to bedrock in this soil is generally greater than 10 feet and
depth to seasonal high water table is generally greater than 4 feet.
The permeability range in this soil will be between 2.0 to greater than
6.0 inches per hour. The available water holding capacity of this
soil in the upper 2 feet will range from 0.11 to 0.25 inches per
inch, below 2 feet the range will be from 0.01 to 0.09 inches per
inch.
The above brief descriptions of the soils found on the lands tentatively
proposed as possible land disposal sites (irrigation of liquid effluent)
and sludge disposal sites leads to the conclusion that the sites picked are
generally well suited for the intended uses. The exception to this general
statement would be Raynham, Belgrade and Tisbury Silt Loam which have a
high seasonal water table condition that may restrict their use during periods
of the year.
Both the existing sludge disposal site and the proposed sludge disposal
site are suited for land fill and disposal areas because they are well
drained, deep coarse textured soils that we estimate from topographic
maps that the water table will be between 30 to 40 feet deep.
Another important consideration is that the Towns' wells are located on
the property indicated just north of Sands Pond as a possible land
disposal area. Detailed investigation would be recommended to determine
that the ground water supply would not become contaminated.
In this review we have attempted to point out some items we feel need
further consideration in the areas in which our Agency has expertise. It
is hoped that our suggestions and recommendations will be useful in
strengthening this already fine "Preliminary Engineering Survey and Report".
If we can be of further assistance please contact our office.
Austin L. Patrick, Jr.
State Conservationist
Attachments
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APPENDIX L
STATE OF RHODE ISLAND AND PROVIDENCE PLANTATIONS
HISTORICAL PRESERVATION COMMISSION
John Brown House
52 Power Street
Providence, R. I'. 02906
(401)277-2678 September 16,
Mr. John McGlennon, Regional Administrator
Environmental Protection Agency
John F. Kennedy Federal Bldg.
Boston,'Mass. 02203
Dear Mr. McGlennon: ,
At the request of your office, we have reviewed the plans for
the proposed sewage treatment facility at Block Island. We under-
stand that considerable discussion of alternative sites has already
taken place.
The fact that the location chosen falls within the National
Register Historic District is unfortunate. However, preliminary
survey by our Commission indicates that several other districts
could be identified as eligible for the Register, and possibly the
whole island could be considered as a district, as has been done at
Nantucket. This means that any location could possibly affect historic
sites, and therefore an attempt to minimize impact should be the goal.
In its presently planned location, we are concerned with the
sewage facility's proximity to the Shamrock Inn, recently purchased
and slated for restoration. We feel it is essential that improvements
be made in the design of the fence surrounding the aerating tanks,
and provision made for plantings which could provide a more effective
screen between the facility, the hotel, and the nearby church.
We feel that the construction of the sewage treatment facility
at Block Island is in the best interests of historic preservation
there. We would be happy to advise^lhe design of a suitable fence
and landscape planning which could effectively accomplish the screening
which we propose. We certainly want to review final plans for improve-
ments in this area, but see no reason why this could not be done as
construction progresses.
Richard Alan Dow
•Executive Director
RAD/dn
cr. Mr. Horhnrt S. Whitman L^-l
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APPENDIX M - STATE OF RHODE ISLAND MINIMUM STANDARDS RELATING TO LOCATION,
DESIGN, CONSTRUCTION, AND MAINTENANCE OF INDIVIDUAL SF/JAGE
DISPOSAL SYSTEMS
(see following pages)
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R23-1-SD
RULES AND REGULATIONS ESTABLISHING MINIMUM STANDARDS
RELATING TO LOCATION, DESIGN, CONSTRUCTION AND
MAINTENANCE OF INDIVIDUAL SEWAGE DISPOSAL SYSTEMS
AS AMENDED JULY 1973
STATE OF RHODE ISLAND AND PROVIDENCE PLANTATIONS
DEPARTMENT OF HEALTH
AUTHORITY: Chapter 23-1-17 and 23-1-18 (6)
of the General Lous of 1956, as
amended
NEW AMENDMENTS EFFECTIVE 30 AUGUST 1974
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TABLE OF CONTENTS
Page
PART A - DEFINITION OF TERMS
R23-I-SD 1.00 Definitions
SD 1.01 through SO 1.28 1-3
PART B-l APPLICATION AND .CONDITIONS FOR APPROVAL
R23-I-SD 2.00 Disposai of Sewage
SO 2.01 Approval of an Individual Sewage
Disposal System 4
SD 2.02 Application for Approval of a New
Sewage Disposal System 4
SD 2.03 Repair and Alteration 5
SD 2.04 Use 5
SD 2.05 Certification of Conformance . . 5
SD 2.06 Inspection 5
SB 2.07 Discharge to a Watercourse 5
SD 2.08 Discharge on or to the Surface of Ground . . 5
SD 2.09 Dwelling or Building 5
SD 2.10 Connection to a Public Sanitary Sewer .... 5
SD 2. I I Maintenance ; . 6
SD 2.12 -" PrBSia^BSJ2^8Sgiaa«BgUSBgS^g . . 6
Use of Acid in Septic Tanks
PART B-2 CONDITIONS FOR APPROVAL IN RELATION TO WELLS
SD 2.14 Construction in Areas Served by
Private Wei Is 6
SD 2.15 Location of Wells 6
SD 2.16 Protection of Wells on Adjoining Property . . 6
PART C. STANDARDS FOR CONSTRUCTION AND DESIGN
R23-I-SD 3.00 Standards of Flow and Minimum Distances
SD 3.01 Determination of Sewage Flow 7-8
SD 3.02 Separate Systems 9
SD 3.03 Type of System Required .' 9
SD 3.04 Surface Water Drainage 9
SD 3.05 Location .... 9-10
SD 3.06 Subsurface Drains • 10
SD 3.07 Subsurface Drain Discharges 10
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R23-I-SD 4.00 Building Sewers
SO 4.01 Size II
SD 4.02 Material II
SD 4.03 Joints II
SD 4.04 Slope or Grade II
SD 4.05 Alignment II
SD 4.06 Manholes II
SD 4.07 Ventilation II
SD 4.08 Grease Traps II
R23-I-SD 5.00 Septic Tanks
SD 5.01 Capacity . . 12
SD 5.02 Length i ....... 12
SD 5.03 Diameter of Circular Tanks 12
SD 5.04 Depth 12
SD 5.05 Multiple Compartments 12
SD 5.06 Construction 12
SD 5.07 Inlet and Outlet 12
SD 5.08 Inlet and Outlet Elevations 13
SD 5.09 Foundation 13
SD 5. 10 Materials 13
SD 5.11 Access Manholes 13
SD 5.12 Accessibi lity 13
SD 5. 13 Backfill 13
SD 5.14 Holding tanks 13
SD 5.15 Pumping to Septic Tanks Prohibited ..... 13
R23-I-SD 6.00 Dosing Tank
SD 6.01 General 14
SD 6.02 Capacity ..... 14
SD 6.03 Construction 14
SD 6.04 Foundation 14
SD-6.05 Ventilation 14
SD 6.06 Inlet • 14
SD 6.07 Access 14
R23-I-SD 7.00 Distribution Box
SD 7.01 General 15
SD 7.02 Inlet 15
SD 7.03 Outlet Elevations 15
SD 7.04 Distribution Pipes '..... 15
SD 7.05 Construction 15
SD 7.06 Number of Outlets 15
SD 7.07 Foundation 15
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R23-I-SD 8.00 Sewage Seepage Systems - General
SD 8.01 Minimum Leaching Area 16
SD 8.02 Ground Water 16
SD 8.03 Impervious Material 16
SD 8.04 Excavation 16
SD 8.05 Location . '. 16
SD 8.06 Minimum Leaching Area for an
Individual Dwelling ... 16-17
SD 8.07 Minimum Leaching Area for Places Other
Than Individual Dwellings 17
R23-I-SD 9.00 Specifications for Disposal Trenches and Disposal Beds
SD 9.01 Effective Leaching Area 18
SD 9.02 Construction of Disposal Trenches
and Beds . . 18
SD 9.03 Distribution Lines 18
SD 9.04 Stone 19
SD 9.05 Construction in Fill 19
SD 9,06 Backf i II 19
SD 9.07 Parking Area Location 19
SD 9.08 Finished Grade 19
R23-I-SD 10.00 Seepage Pits
SD 10.01 Acceptability 20
SD 10.02 Leaching Area 20
SD 10.03 Spacing 20
SD 10.04 Access 20
SD 10.05 Construction 20
R23-I-SD 11.00 Cesspools
SD 11.01 Acceptability 21
SD 11.02 Leaching Area 21
SD 11.03 Construction 21
SD 11.04 Access 21
R23-I-SD 12.00 Privies, Chemical Toilets and Incinerator Type
SD 12.01 Acceptability 22
SD 12.02 Location 22
SD 12.03 Construction 22
SD 12.04 Maintenance 22
PART D. SOIL STUDIES AND PERCOLATION TESTING
R23-I-SD 13.00 Subsoil Exploration
SD 13.01 General 23
SD 13.02 Site Suitability 23
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SD 13.03 Percolation Test 23
SD 13.04 Exploration holes 23
SD 13.05 Persons Qualified to Test 23-24
SD 13.06 Recording Results 24
R23-I-SD 14.00 Percolation Test Procedure
SD 14.01 and 14.02 25
R23-I-SD 15.00 Procedures For Ground Water Table Elevation Determinations
SD 15.01 and 15.02 26
PART E. SUBDIVISIONS
SD 16.01 Subdivisions - Individual Sewage
Disposal Systems 27
SD 16.02 Topographic Map 27
SD 16.03 Location Map 27
SD 16.04 Percolation Tests 27
SD 16.05 Ground Water Table 28
SD 16.06 Certification 28
SD 16.07 28
APPENDIX
Minimum Design Criteria and Typical Layouf I I Iustrjtlons
I. Lot Layout 29
II. _ Septic Tank 30
III. Dosing Tank 31
IV. Distribution Box 32
V. Trench Type Field 33
VI. Bed Type Field 34
.-VII. Soil Percolation Hole 35
page
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I
I STATE OF RHODE ISLAND AND PROVIDENCE PLANTATIONS
2 DEPARTMENT OF HEALTH
3 RULES AND REGULATIONS ESTABLISHING MINIMUM STANDARDS
4 RELATING TO LOCATION, DESIGN, CONSTRUCTION, AND
5 MAINTENANCE OF INDIVIDUAL SEWAGE DISPOSAL SYSTEMS
6 PART A. DEFINITION OF TERMS
7 R23-1-SD 1.00 Definitions
8- As used in these rules and regulations, the following terms
9 shall, where the context permits, be construed as follows:
10 SO 1.01 Alteration - Alteration shall be held to mean any change in
II size or type of system or installation of a replacement system.
12 SO 1.02 Bui I ding Sewer - The building sewer shall be held to mean
.13 the pipe which begins three feet outside the building wall and extends to
14 a public sewer, septic tank, or other place of sewage disposal.
15 . SD 1.03 Cesspool - The term cesspool shall be held to mean a covered
(6 pit with open-jointed sidewall lining and an earth bottom into which raw
17 sewage is discharged.
18 SD 1.04 Director - The term director shall mean the director of
19 health of the state of Rhode Island or his duly authorized agent.
20 ' SD 1.05 Disposal Bed - A disposal bed for sewage shall be held to
21 mean a shallow excavation in the ground, backfilled with stone in which
22 open-jointed or perforated distribution lines are laid-and over which a
23 cover of earth is placed.
24 SD 1.06 Disposal Trench - A disposal trench shall be held to mean
25 a shaltow ditch with vertical sides, filled with stone. In which a single
26 distribution line is laid and over which a cover of earth is placed.
27 SD 1.07 Distribution Box - A distribution box shall be held to mean
28 a water-tight structure which receives septic tank effluent and distributes
29 it In substantially equal portions to two or more pipe lines leading to
30 some type of seepage system.
31 SD 1.08 Distribution Line - A distribution line shall be held to
32 - mean an open-jointed or perforated pipe used to disperse septic tank
33 effluent.
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I SD 1.09 Dosing Tank - A dosing tank shall be held to mean a
2 watertight structure placed between a settling or septic tank and a
3 distribution box and equipped with one or more siphons or pumps designed
4 to discharge sewage Intermittently into a seepage system.
*3 SD 1.10 Impervious - For the purposes of these regulations, any soil
6 with a percolation rate in excess of 40 minutes per inch, or any ledge or
7 shale are considered Impervious and unsuitable for individual sewage
8 disposal systems.
9 SD l.tl Individual Sewage Disposal System - An Individual sewage
10 disposal system shall be held to mean one installed to provide sanitary
II sewage disposal by leaching Into the ground where no public sewer system
12 Is available or accessible.
13 SD 1.12 Invert - The Invert shall be held to mean the lowest portion
14 of the Interior of a pipe or fitting placed horizontally.
.15 SD 1.13 Leaching Area - The leaching area, when applied to a disposal
16 trench or disposal bed shall be held to mean the bottom area of the trench
.17 or bed; when applied to a seepage pit, the combined bottom area and sidewall
16 area below the inlet pipe; when applied to a cesspool, the sidewall area
19 below the Inlet pipe, only.
20 SD 1.14 Maximum Ground Water Table Elevation - The maximum ground
21 water table elevation shall be held to mean that observed when the ground
.22 water is at Its highest level during the year or the highest level observed
23 in past years when such Inforamtlon is available.
24 SD 1.15 Owner - Owner shall be held to mean any person .who alone, or
25 Jointly, or severally with others (a) has a legal title to any premises, or
26 (b) has control of any premises as agent, executor, executrix, administrator,
27 administratrix, trustee, lessee, or guardian of the estate of a hoJder of a
28 legal title. Each such person is bound to comply with the provisions of
29 these rules and regulations.
30 SD 1.16 Person - The term person shall Include any individual, group
31 of Individuals, firm, corporation, association, partnership or private
32 entity, Including a district, county, city, town, or other governmental unit
33 or agent thereof, and in the case of a corporation, any Individual having
34 active and general supervision of the properties of such corporation.
35 SD 1.17 Privy - A privy shall be held to mean a structure used for a
36 toilet lacking the flushing aid of water. It consists of a shelter built
37 above a pit or vault, In the ground into which the waste matter falls.
38 SD 1.18 Repair - Repair shall be held to mean replacement of septic
39 tank, distribution box, leach field, or pipes connecting same with no
40 change In type of material, location, or area of system.
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I SO 1.19 Sanitary Sewage - Sanitary sewage shall be held to mean any
2 human or animal excremental liquid or substance, any putrescible animal or
3 vegetable matter, garbage and filth, including the discharge of water
4 closets, laundry tubs, washing machines, sinks, dishwashers, and the contents
5 of septic tanks, cesspools, or privies.
6 "*' SO 1.20 Seepage Pit - A seepage pit shall be held to mean a covered
7 pit with open jointed sidewalls and bottom, from which septic tank effluent
8 Is leached into the soil.
' 9 SO 1.21 Septic Tank - A septic tank shall be held to mean a water-tight
10 receptacle which receives the discharge of sewage from a building sewer,
II and Is designed and constructed to permit the deposition of settled solids,
12 the digestion of the matter deposited, and the discharge of the liquid portion
13 Into a leaching system.
14 SO 1.22 Siphon - A sIphon shall be he Id to mean a hydrau11c devIce
15 designed to discharge the contents of a dosing tank rapidly when a predeter-
16 mined level is reached.
17 SO 1.23 Slope or Grade - Slope or grade shalI be held to mean the rate
18 of fall or drop of a pipe line or of the ground surface in reference to a
19' horizontal plane. It is commonly expressed as fall or drop in inches per 100
20 feet, inches per foot, or feet per 100 feet.
21 SO 1.24 Subdividing - Subdividing for the purposes of these regulations
22 shall be held to mean the division of a lot, tract or parcel of land into
23 three (3) or more lots, sites or other division of land for the purpose,
24 whether Immediate or future, of building development.
25 SO 1.25 Subsurface Drains - A subsurface drain shall be held to mean
26 a deep trench intended to lower the water table of an area where an
27 Individual sewage disposal system is to be located. It shall consist of not
28 less than 6 inches of washed stone j inch to 2 inches in diameter, over which
29 Is laid a perforated or open jointed pipe. The stone shall extend above the
30 pipe to within 2 feet of the ground surface, and then be covered with at
31 least a 2 inch layer of washed pea stone or a 2 inch layer of straw or hay,
32 or by a layer of untreated building paper. The size of the pipe used shall
33 be at least 4 inches in diameter when less than 3 lots are being drained;
34 otherwise the pipe must be at least 8 inches in diameter.
35 SDI.26 Test Pit - A test pit shall be held to mean an open pit dug to
36 permit an examination of the soil profile, and a determination of the elevation
37 of the ground water table.
38 SD 1.27 Watercourse - The t«rm watercourse shall be held to mean any
39 tidewater, or any river, stream, brook, pond, lake, swamp, or any other
40 standing or flowing body of water.
41 SD 1.28 We I I - A well shall be held to mean an opening Into the ground
42 or bedrock located safely in respect to sources of pollution, encased,
43 covered and equipped In a sanitary manner, and yielding supply of potable
44 water safe for human consumption sufficient to meet the needs of the
45 property on which it is located and ordinari ly used as a drinking water supply.
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4
| PART B-l APPLICATION AND CONDITIONS FOR APPROVAL
2 R23-1-SD 2.00 Disposal of Sewage
3 SO 2.01 Approval of an Individual Sewage Disposal System - No person
4 shall install, construct, alter, or repair or cause to be installed,
•* 5 constructed, altered, or repaired any individual sewage disposal system,
6 nor shalI he begin construction of any improvement to his property from
7 which sewage will have to be disposed of by means of an individual sewage
8 disposal system until he has obtained the written approval of the director
9 of the plans and specifications for such work. Repairs or alterations
10 shall, insofar as possible, comply in every respect with the standards set
II forth in these regulations.
12 Note: A municipality may only grant a building permit according to
13 the provisions of Chapter 2S-27-S of the General Lous of the State of
14 Rhode Island as amended.
15 ' SD 2.02 Application for Approval of a New Sewage Disposal System -
16 (a) The application for approval of plans and specifications for a new
17 sewage disposal system shall be made on forms provided by the director.
18 (b) It shall be accompanied by basic design data, and a plan, to scale,
19 of the property or pertinent portion thereof showing the size and
20 location of the sewage disposal system, also monholes, cleanout plugs,
21 essential invert elevations, and a fixed bench mark that can be readily
22 referenced and that will not be disturbed during construction.
23 (c) Other information to be provided includes: I. present, and-proposed
24 finished grades. 2. the location of test pits. 3. the results of
25 percolation tests. 4. a description of the type of soil. 5. the
26 max i mum •& I evat i on of the ground water table in the location of the
27 proposed seepage system, and 6. size and location of building(s).
28 (d) The location of any drinking water line within 25 feet, and any well,
29 watercourse or drain within 200 feet of the proposed disposal system
30 must be shown.
31 (e) Approval granted an applicant shall expire two years from the date of
32 Its Issuance ifv£iCtrifc^i^?i'".hay TO^begum JpjfhaJ.gj^r.Lod. It may be
33 renewed if the oa I a "pro.v rdea »wf ^mfe ufpp/"\(fi|i*ficjnj litj Vrr^l^'^B^^ • ^ ^
34 required-design criteria shall be included.
35 (f) The location of existing individual sewage disposal systems within 100
36 feet of any well to be installed on subject property must also be shown.
37 (g) Nothing in the foregoing shall prevent the director from requiring any
38 additional information he deems necessary to carry out his obligations
39 for approving an application.
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I SD 2.03 Repair and Alteration - Application must be made for repair
2 or alteration of a system. Requirements for repair or alteration under
3 these regulations may be waived at the discretion of the director.
4 SD 2.04 Use - The use of an individual sewage disposal system shall
5 conform to the terms of the approval; its designed capacity must not be
6 exceeded. .
7 SD 2.05 Certification of Conformance - A newly constructed, altered
8 or rebuilt individual sewage disposal system, shall not be covered with
9 earth until the director shall have inspected it and certified in writing
10 that it conforms with the terms of'the approval granted under the provisions
II of these regulations. Said system shall be covered within 48 hours after
12 inspection and approval. No dwellings, buildings, or additions thereto, to
13 be served by such a system, shall be sold or occupied until the entire system •
14 Is completed, including the covering of the system and the necessary grading
15 to divert surface water from the area of the leaching field.
16 SD 2.06 Inspection - The director may inspect the installation of an
17 Individual sewage disposal system at any stage of its construction, and may
18 require its modification if unanticipated conditions are disclosed which make
1$ It necessary. If changes from the approved plans and specifications are
20 found necessary, revised plans must be submitted for review and approval.
21 SD 2.07 Discharge to a Watercourse - No person shall discharge or
22 ' permit the entrance of sanitary sewage, treated or untreated,/into any
23 watercourse, nor shall he discharge or permit the entrance of such sewage
24 into any open or covered drain tributary to such waters, without having
25 obtained an order from the director approving the same.
26 SD 2.08 Discharge on or to the Surface of Ground - No person shall
27 discharge or permit the overflow or spillage of any sanitary sewage on or to
28 the surface of the ground, provided, however, this shall not interfere with
29 the spreading of animal manure on the surface of the ground in an amount not
30 In excess of that essential to meet agricultural requirements, and that will
31 not cause water pollution.
32 SD 2.09 Dwelling or Building - Each dwelling or other building having
33 plumbing fixtures, or on which sanitary sewage is produced, in a location where
34 no public sanitary sewage system is available or accessible, shall be provided
35 with art individual sewage disposal system of type and design approved by
36 the director.
37 SD 2.10 Connection to a Public Sanitary Sewer - An individual sewage
38 disposal system shall not be approved for use on any premises if a public
39 sanitary sewer is accessible to such premises, and permission to enter it can
40 be obtained from the authority having jurisdiction. When problems are encoun-
41 tered in the operation of an individual sewage disposal system and public sewage
42 service Is accessible and available to the property on which it is located
43 and where permission to enter such a sewer can be obtained from the authority
44 having jurisdiction over it, the director may require the owner or occupant of
45 an existing building or buildings to be connected thereto within a period of
46 time as specified by him.
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7
8
9
10
1 1
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
SD 2. 1 1 Maintenance - All building sewers and individual sewage
disposal systems shall.be maintained in good repair by the owner. The
director may order the owner to clean or repair such sewers or systems within
a reasonable time if he finds them to be in need of the same.
SD 2.12 Septic Tank Cleaners — No person shall engage In the removal or
transportation of the contents of privies, cesspools, or septic tanks without
first having obtained the approval of the. director for the site, and the means
of disposal of such contents that he proposes to use.
Such approval may be withdrawn by the director if he finds, that with
use, the site or means of disposal has become insanitary or offensive.
Note: See Chapter 23-49 Rhode Island General Lous 1956 as amended
Entitled: Cesspool and Sanitary Tank Cleaners
SD 2. 13 Prohibi tion
system may be constructed
other area where water
grtain Filled Areas - No sewage disposal
f i jQl i iTTj&Q5xjf pj^-ifl swamp. m^*~sh, bog, or
\J3eTcf:"lo'ici'~in^ep&ic Tanks
PART B-2 CONDITIONS FOR APPROVAL IN RELATION TO WELLS
SD 2.14 Construction in Areas Served by Private Wells - Before an
approval can be granted to construct a building being served by a private
well, sufficient additional area must be available for the replacement
of the disposal field, in case of failure. This area must be on the property
of the individual seeking approval and meet all the minimum distance
requirements set forth in these regulations.
SD 2.15 Locat i on of We I Is - No person shalI locate or cause to be
located, any werl within 100 feet of an individual sewage disposal leaching
area. The director may grant an exception for the replacement of a well on
property with an existing, owner occupied, private single family dwelling
when no other water supply is avallable.
SD 2.16 Protection of Wells on Adjoining Property - An applicatlon
for the installation of. a sewage disposal system shall not be denied on
the grounds that the system cannot meet the required minimum distance from
a well if the well is on adjoining property and a public water supply is
readily available to such property.
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7
PART C. STANDARDS FOR CONSTRUCT ION.AND DESIGN
R23-1-SD 3.00 Standards of Flow and Minimum Distances
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I TYPE OF ESTABLISHMENT GALLONS PER PERSON PER DAY
2 Restaurant, toilet and kitchen wastes (per patron) 10
3 Restaurant, throughway service area (per table seat or
4 counter seat) 350
5 Factory or industrial plant without cafeteria - (per person) 15
6 Factory or industrial plant with cafeteria - (per person) 20
7 Office BuiIding 15
8 Drive-in-theater- (per stall) 5
9 Theater - (per person) 3
10 Auditorium or hall - (per person) 3
II Gymnasium - (per spectator) 3
12 Gymnasium - (per participant) 15
13 Service, station (minimum) 500
14 CocktaiI lounge, bar (per seat) _ 20
15 Bowling alley - (per alley) 200
16 Hospital - (per bed) 200
17 Country club - (per person at maximum usage)
18 (Exclusive of Food Service and Bar) 25
19 Fellowship Hall (per seat) 6
20 Barber shop (per chair) 100
21 Beauty Parlor (per booth) 200
22 . Dental ..Office (minimum 3 persons per chair) 500
23 Mobile Home (exceeding 8 feet wide and 32 feet long) 75
24 (using individual toilets) (minimum 450)
25 Trailers (not exceeding 8 feet wide and 32 feet long) 200
26 land recreational vehicles using individual toilets) (per day per space)
27 Central Service BuiIding (Toilet-Shower-Lavatories) 140
28 Serving recreational vehicles/trailers (per day per space-)
29 Dumping Station (for recreational vehicle/trailer park 50
30 without individual water and sewer connections) (per day per space)
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I SD 3.02 Separate Systems - Where separate treatment systems are to
2 be Installed, the following proportions should be used unless there is
3 definite data available as to the exact distribution of flow. Toilet and
4 bath facilities - 60% of total flow, kitchen wastes - 40? of total flow,
5 laundry wastes - 40? of total flow.
•s
6 SD 3.03 Type of System Required - Except as provided in Sections II
7 and 12, an individual sewage disposal system shall consist of a' septic
8 tank followed by a subsurface seepage system or other sewage disposal method
9 approved by the director.
10 SD 3.04 Surface Water Drainage - Provision shall be made to prevent the
II flow of surface water from the surrounding area onto the area of the seepage
12 system.
13 SD 3.05 Location - The horizontal distances between the parts of an
14 Individual sewage disposal system and .the items listed in the following table
15 shall not be less than those shown.
16 MINIMUM DISTANCES
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
Septic
Tank
Disposal Seepage
Trench or Pit or
Disposal Cesspool
Bed
(ft)
(ft)
(ft)
Bui I ding
Sewer
(ft)
Privy
(ft)
I. Wei I or suction
line (f)
2. Water supply
Iine (pressure)
3. Property line
4. Owe I I ing
5. Surface drinking
water supplies or
tributaries in-
cluding open and
subsurface drains,
thereto
6. Watercourses
7. Subsurface drains
8. Edge of any bank
sloping to a level
lower than the invert
of the distribution line
50 100
10 (b) 25 (b)
10 10
5 15 (d)
(c) 50 (a)
25 (b) 10 (b)
20
20
50
25 (b)
30
30
50 100
25 50
25 25
10 (e) 25 (e)
150
50
25
25 (e)
50
50
25
25
10 (e)
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10
I (a) Distance may be reduced if extra heavy cast Iron pipe or equal
2 with tight joints is installed.
3 (b) Disposal facilities shall be installed as far away as possible
4 from water supply lines. Where sewer lines must cross water supply lines,
5 they should be constructed of durable, corrosion-resistant material with
6 water-tight joints. Whenever possible, however, sewer lines should be
7 laid below water supply lines at crossings.
•^
8 (c) Installation of a seepage pit or cesspool is unacceptable If
9 drinking water is obtained from wells within 200 feet.
10 (d) Distance may be reduced to 8 feet with no cellar.
II (e) Where fill is required and where it is necessary to fill beyond
12 the boundary of the subject property to meet the requirements of these
13 regulations, no approval will be granted unless the adjoining property
14 owner(s) have given a permanent legal release (easement, etc.) granting
15 such right to the owner of the applicant property. A copy of such right
16 of access and use shall be attached to the application.
17 (f) See Section SD2.H
18 SO 3.06 Subsurface Drains - The effectiveness of subsurface drains
19 used to lower the water table to meet the limitations of these regulations
20 must be demonstrated through one complete wet season, January I, through
21 April 30, before consideration can be given to an application for an
22 individual sewage disposal permit.
23 SO 3.07 Subsurface P6giftJl5£h£rJC!e-? ~ Subsurface drains which discharge
24 ground water to a waterco|r^€jf sh| \\ Srieeflth^ c|R?|-p»^e requirements in
25 Section SD 3,05 pertaini
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II
I R23-1-SD 4.00 BUILDING SEWERS
2 SO 4.01 Size - The building sewer shall be designed with a capacity,
3 when running full, of not less than twice the peak rate of flow from the
4 connected fixtures. In no case shall the building sewer be less than four
5 inches in diameter.
6 SO 4.02 Material - The building sewer shall be constructed of cast
7 Iron, vitrified ti le, concrete, asbestos cement, or other material acceptable
8 to the director, provided, however, cast iron or equal shall be used where
9 the building sewer may be subjected to heavy loads.
10 SD 4.03 Joints - All pipe joints for the building sewer shall be made
II water-tight and protected against damage by roots. Poured type joints
12 shall be properly wiped on the Inside to prevent obstruction of flow.
13 SD 4.04 Slope or Grade - The grade of the bui I ding sewer should be
14 at least \%, I foot fall per 100 feet, or 1/8 inch per foot.
15 SD 4.05 AIionment - The buiIding sewer should be laid as nearly as
16 possible in a straight line. Horizontal bends, where unavoidable, shall
17 not be greated than 45 degrees. Any greater bend requires a manhole at the
'18 change in alignment.
19 SD 4.06 Manholes - A manhole with a removable cover of concrete, cast
20 Iron, or other durable material shall be provided at the junction of two or
21 more pipes, at all sharp changes in direction or grade of pipes, and at
22 Intervals not greater than 300 feet.
23 SD 4.07 Vent!I at ion - The buiIding sewer shal I be vented through the
24 stack or main vent of the building it serves. No trap shall be installed
25 in the building sewer.
26 SD 4.08 Grease Traps - A grease trap may be required at premises from
27 which large quantities of grease can be expected to be discharged and where
28 there Is reasonable assurance that it wiI I be cleaned frequently. A separate
29 line shall be installed to serve the fixture from which the grease is discharged
30 and the grease trap inserted in this line. The trap shall be so located
31 and constructed that the temperature of the sewage will be reduced to promote
32 congealing or separation of grease. It shall be located and constructed in a
33 manner'that wiI I permit easy access for cleaning.
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12
I R23-1-SD 5.00 SEPTIC TANKS
2 SD 5.01 Capacity - For Individual dwellings, the required capacity
3 of a septic tank, below the flow line, shall be at least that shown in
4 the following table:
5 Number of bedrooms Capacity below flow line in gallons
6 2 750
7 3 900
8 4 (I) 1,000
9 (I) For each additional bedroom, add 250 gallons.
10 For other than individual dwellings, the
II capacity of the septic tank for sewage flows
12 up to 500 gallons per day shall be at least
13 750 gallons. For flows between 500 and 1,500
14 gallons per day, the capacity of the tank shall
15 be equal to at least one and one-half of a days'
16 flow. For flows greater than 1,500 gallons per
17 day, the capacity of the tank shall equal 1,125
18 gallons plus 75? of the daily flow.
19 SD 5.02 Length - In rectangular tanks, the distance between the inlet
20 and outlet should be at least equal to the liquid deptli of the tank and at
21 least one and one-half times the width.
22 SD 5.03 Diameter of Circular Tanks - Circular tanks shalI have a
23 diameter of. at least 52 inches.
24 SD 5.04 Depth - The depth of the tank below the flow line should be
25 not less than 4 feet or more than 8 feet.
26 SD 5.05 Multiple Compartments - Multiple compartment tanks, including
27 two individual septic tanks placed in series, will be approved, provided
28 the total capacity (below the flow line) is not less than 5,000 gallons and
29 the capacity of the first compartment or tank is at least one-half of the
30 capacity required.
31 SD 5.06 Construction - Septic tanks shall be water-tight. They Shall
32 be constructed of sound and durable materials not subject to excessive
33 corrosion, decay, or frost damage, or to cracking or buckling due to settlement
34 or soil pressures. Tanks and covers shall be constructed so as to withstand
35 any load that may be expected to be placed upon them.
36 SD 5.07 Inlet and Outlet - The tops of inlet and outlet tees or the tops
37 of the baffles shall extend a minimum of 6 inches above the flow line. Tops
38 of the inlet and outlet tees or baffles shall be left open to provide ventilation.
39 There shall be an air space of at least 3 inches between the tops of the tees or
40 baffles and the top of the tank. The outlet tee or baffle should extend downward
41 one-third of the depth below the flow line. The inlet tee or baffle should
42 extend downward at least I foot below the flow line but not below the outlet
43 tee or baffle. Multiple outlets shall be provided on tanks wider than 7 feet.
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13
I SD 5.08 Inlet and Outlet Elevations - The invert elevation of the
2 outlet shall be at least 2 inches below the invert elevation of the inlet.
3 SD 5.09 Foundation - The septic tank shalI be installed on a level
4 base that will not settle.
5 SD 5.10 Materials - Septic tanks may be constructed of poured in
6 pl.ace reinforced concrete, pre-cast reinforced concrete, coated'steel,
7 or other material approved by the director. Steel tanks designed in
8 accordance with the provisions of these regulations shall meet Commercial
9 Standard 177 of the U. S. Department of Commerce.
10 SD 5.11 Access Manholes - At least one manhole with a removable
II cover of concrete, iron, or other durable material shall be provided
12 each septic tank compartment. Inlets and outlets shall be made accessible
13 'for cleaning by placing manholes or clean-out plugs over the tees or
14 baffles. Manholes on tanks of under 2,000 gallons capacity should be
15 brought up to within 12 inches of finished grade; and properly marked for
16 location. Manholes on tanks of 2,000 gallons capacity or over shall be
17 brought up to finished grade.
18 SD 5.12 AccessibiIity - Septic tanks shalI be so located on the lot
19 as to be accessible for servicing and cleaning. They should be placed
20 between^the building and the street wherever practicable, to facilitate
21 connection to a public sanitary sewer when it becomes available.
22 SD 5.13 BackfiI I - Backfi11'ShalI be placed around the septic tank
23 In such a manner as to avoid damage to it. All backfill placed around
24 the septic tank shall be free of large stones, stumps, waste construction
25 material and rubbish.
26 SD 5.14 Holding tanks - Holding tanks are not acceptable as a means
27 of an Individual Sewage Disposal System for new installations.
28 SD 5. 15 Pumping to Septic Tanks Prohibited - Sewage shal I. not be
29 pumped Into septic tanks unless approved by the director.
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14
' I R23-I-SD 6.00 DOSING TANK
2 SD 6.01 General - A dosing tank equipped with a siption or two
3 pumps shall be provided where the total length of the distribution
4 lines exceeds 500 feet. The dosing tank shall be provided with at least
5 two alternating siphons or two pumps delivering to separate fields or beds,
6 If the total length o.f the distribution lines exceeds 1,000 feet. When
7 pumps are installed, the pump discharge lines shall be inter-connected and
8 properly valved or gated so as to permit dosage to both fields or beds with
9 one pump when the other is being repaired. The pumps installed must be
10 capable of passing 2.5 inch diameter solids. System head curves must be
II submitted for each installation.
12 SD 6.02 Capacity - Dosing tanks shall discharge a volume of sewage
13 which is between 60 and 75? of the interior capacity of the distribution
14 lines of the disposal trenches to be dosed, and not more than the full
15 capacity of the distribution lines in the case of a disposal bed.
16 SD 6.03 Construction - Dosing tanks shall be water-tight. They
17 shall be constructed of sound, durable materials not subject to excessive
18 corrosion or decay and be able to withstand any load which may be placed
19 upon them.
20 SO 6;04 Foundation - Dosing tanks shal I be constructed on a level
21 base that will not settle.
22 SD 6.05 VentiI at ion - Dosing tanks and similar appurtenances shall
23 be adequately venti lated.
24 SD 6.06 Inlet - The invert elevation of the inlet pipe to the
25 dosing tank shall be located above the maximum water elevation in the dosing
26 tank, and a* least one foot above the maximum elevation of the ground
27 water table.
28 SD 6.07 Access - Each dosing tank or compartment thereof shall be
29 provided with an access located so as to facilitate repair or adjustment
30 of the siphons or pumps.
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15
I R23-I-SD 7.00 DISTRIBUTION BOX
. 2 SD 7.01 Genera I - A distribution box shall be Installed between
3 the septic tank and the seepage system.
4 SD 7.02 Inlet - The distribution box shall be provided with an
5 Inlet tee or a suitable baffle. The invert of the. inlet pipe shall be .
6 not less than 2 inches above the invert of the outlet pipe.
7 SD 7.03 Outlet Elevations - The invert of alI the outlet pipes
8 shall be a minimum of 4 inches above the floor of the distribution
9 box. All outlet inverts shall be at the same elevation.
10 ' SD 7.04 Distribution Pipes - All distribution pipes for minimum
II of 2 feet from the distribution box to the first section in the laterals
12 shall be level and unperforated and shall be laid with tight joints. Any
13 sections of such pipe laid with tight joints shall not be considered in
14 determining the leaching area.
15 SD 7.05 Construction - The distribution box shall be constructed
16 water-tight of concrete or other durable material; it shall be designed
17 to accommodate the necessary distribution lines.
18 SD 7.06 Number o' Outlets - If there is no dosing tank, there shall
19 be a separate outlet for each distribution line. Where a dosing tank or
20 pump chamber is installed, there should be either a separate outlet for
21 each distribution line, or a separate outlet of at least six (6) inches
22 In diameter for every two distribution lines. In all cases following a .
23 dosing tank or pump chamber, the outlet shall be of sufficient size to
24 accept the sewage flow at the rate sewage Is delivered to the distribution
25 box.
26 SD 7.07 Foundation - The distribution box shalI be installed between
27 the septic tank and seepage system on a solid and level base that will
28 not settle.
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16
I R23-I-SD 8.00 SEWAGE SEEPAGE SYSTEMS - GENERAL
2 SD 8.01 Minimum Leaching Area - The minimum leaching area of a disposal
3 system will be dictated by the number of bedrooms in the case of individual
4 dwellings, or the maximum daily sewage flow for places other than
5 individual dwellings, and the results of percolation tests performed in
6 accordance with Sect-ion SD 14.00.
7 SD 8.02 Ground Water. - The bottom of the-seepage system shall be at
8 least 3 feet above the maximum elevation of the ground water table.
9 SD 8.03 Impervious Material - The bottom of the seepage system shall
10 be at least 5 feet above impervious formations. Excavating into impervious
II material is prohibited unless otherwise approved by the director.
12 SD 8.04 Excavation - The excavation for the seepage system may be made
13 by mechanical means, however, if such means are used, care must be taken
14 to assure that the soiI at the bottom of the excavation is not compacted or
15 smeared. The bottom of the excavation shall be level and scarified.
16 SD 8.05 Location - The minimum distance the sewage seepage system
17 must be from items it might effect is found in Section SD 3.05.
18 SD 8.06 Minimum Beaching Area for an Individual Dwelling - The minimum
19 leaching area required per bedroom shallbe determined from the following
20 table:
21 Percolation Rate Disposal Trenches Disposal Beds, Seepage
22 (minutes per inch) (leaching area, Pits, Cesspools, (leach-
23 sq. ft. per bedroom) ing area, sq. feet per
24 — (I) (3) bedroom (2) (3)
25
26
27
28
29
30
31
32
33
34
2
3
4
5
10
15
20
25
30
40
85
100
115
125
165
190
220
240
250
290
125
145
165
180
235
270
315
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17
1
2
3
4
5
6
7
8
9
10
II
12
13
14
15
16
17
18'
19
20
21
22
23
24
25
26
27
28
29
30
31
32
(1) Soil with a percolation rate of over 40 minutes per inch Is
unsuitable for disposal of sewage by any means of sub-surface leaching.
(2) Soil with a percolation rate of over 20 minutes per inch Is
unsuitable for these means of subsurface leaching.
(3) To determine effective leaching area, see Section SD 9.00, 10.00,
and 11.00.
SD 8.07 Minimum Leaching Area for Places Other
The minimum leaching area
table us ing -the estimated
Section .SD 3. 01.
Percolation Rate
(minutes per inch)
2
3
4
5
10
15
20
25
30
40
Than Individual Dwellings
required shall be determined from the following
daily sewage flow as determined by means given in
Disposal Trenches
(maximum rate of
sewage application
gal Ions per sq. ft.
per day ) (1) (3)
3.5
2.9
2.5
2.2
1.6
1.3
I.I
1.0
0.9
0.8
Disposal Beds, Seepage
Pits, Cesspools (maxi-
mum rate of sewage
application) - (gals.
Per sq. ft. per day)
(2) (3)
2.5
2.0
1.8
1.6
I.I
0.9
0.8
(1) Soil with a percolation rate of over 40 minutes per inch is
unsuitable forfiji-saosal of sewage by any means of subsurface leaching.
(2) Soi 1 with
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18
I R23-I-SD 9.00 SPECIFICATIONS FOR DISPOSAL TRENCHES AND DISPOSAL BEDS
2 SD 9.01 Effective Leaching Area - The effective leaching area shall be
3 held to mean the total bottom area of the disposal trenches or the entire
4 bottom area of the disposal bed. The leaching area required shall be
5 determined in accordance with the provisions of Section SD 8.00. In no event
6 shall the "total effective leaching area be less than 170 square feet in the
7 case of disposal trenches or 250 square feet in the case of disposal beds.
8 SD 9.02 Construction of Disposal Trenches and Beds - Disposal trenches
9 and beds shall follow the construction details listed in the table below:
10 Minimum lines per field or bed 2
II Maximum length per line 100 feet
12 Minimum diameter of distribution lines 4 Inches
13 Grade of distribution lines 2 to 4 inches per 100 feet
14 (No gradient needed if dosed by siphon or pumps)
15 Maximum width of disposal trench bottom 3 feet
16 Minimum distance between walls of adjacent trenches 5 feet
17 Minimum cover over distribution lines 12 inches
18 Maximum distance between distribution lines 6 feet
19 in disposal beds
20 Maximum dep'th of invert of distribution pipe 2.5 feet
21 below finished grade
22 Minimum distance between adjacent beds 10 feet
23 Length of bell and spigot clay pipe lines 2 feet
24 Openings at joints of bell and spigot 0.5 inches
25 clay pipe Iines
26 Distance between distribution lines and 2 feet
27 edge of bed shall not be less than
28 Termination of distribution lines 2 feet
29 from end of trench
30 SD 9.03 Distribution Lines - The distribution Iines may consist of clay
31 or tile,bell and spigot pipes, perforated asbestos cement pipe, or other
32 suitable pipe approved by the director. The ends of all distribution lines
33 shall be interconnected, unless otherwise approved by the director.
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19
I SD 9.04 Stone - The stone used in the leaching system to surround the
2 distribution lines shall consist of washed stone ranging from not less than
3 1/2 inch to not more than 2 inches in size and free from iron, fines and
4 dust. It shall cover the full width of the trench or bed and shall be
5 placed to a depth not less than 6 inches below the bottom of the distribution
6 "* lines in a disposal trench and not less than 12 inches below the
7 bottom of the distribution lines in a disposal bed. The stone shall extend
8 at least 2 inches above the top of the distribution pipes. The- stone shall
9 be covered with at least a 2 inch layer of washed pea stone or a 2 inch layer
10 of straw or hay, or by a layer of untreated building paper.
II SO 9.05 Construction in Fill - When a sewage leaching system can be
12 approved in filled land, the leaching area, extending at least 10 feet on
13 all sides, must be stripped of trees, brush, stumps, topsoi I, and soil
14 containing fines and the bottom of the excavation scarified and backfilled
15 with a coarse grained soil containing little or no fines. The leaching
16 system shall not be constructed when the original soil was stripped to, or
17 into, the ground water table unless approved by the director. Distribution
18 lines shall be supported by grade boards attached to stakes driven into
19 undisturbed soil whenever required.
20 SD 9.06 Backf iI I - AlI backfiI I placed over a seepage system shalI
21 be free of large stones, frozen clumps of earth, rubbish, masonry, stumps
22 or waste construction materials. Backfill shall be placed carefully in
23 disposal trenches or beds so as to avoid displacement and damage to piping.
24 Heavy machinery shall not be permitted to pass over the leaching area.
25 SD 9.07 Parking Area Location - The area of the seepage system shalI
26 not be paved or used for vehicular parking or vehicular traffic. Systems
27 serving other than individual dwellings shall be adequately curbed or
28 fenced so as to exclXide all vehicular traffic. Parking areas adjacent to
29 seepage systems shall be graded or curbed to divert runoff from the seepage
30 area.
31 SD 9.08 Finished Grade - The surface area over Hie sub-surface
32 disposal field shall be grassed.
M-25
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20
I R23-I-SD 10.00 SEEPAGE PITS
2 SD 10.01 Acceptab!Iity - A seepage pit may be constructed In lieu of
3 a disposal field only where a special condition justifies its use. It
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21
I R23-I-SD 11.00 CESSPOOLS
2 SD I 1.01 AcceptablIity - The Installatlon of a cesspool wiI I be
3 approved only In those situations in which the soil has excellent seepage
4 properties, the need is of short term, or the use is infrequent, or in other
5 special situations which warrant their approval. Cesspools will not be
6 "* approved in areas where water is obtained from wells within 200 feet.
7 SD 11.02 Leaching Area - The leaching area of a cesspool shall be
8 determined in accordance with the provisions of Section SD 8.00. Only the
9 sidewall area below the Invert of the inlet shall be considered to be
10 leaching area. The size shall be determined by the director.
II SD 11.03 .Construction - The lining of a cesspool shall be of stone,
12 brick, or cement block laid with dry open joints. The space between
13 the excavation and the lining shall be backfilled with stone 1/2 inch to
14 2 inches In size, for a distance of at least 6 inches from the lining.
15 SD 11.04 Access - The top of the cesspool shall be provided with an
16 access manhole with a removable cover of concrete, iron, or other durable
17 material. The top of the manhole should be brought up to within 12 inches
18 of the finished grade, and properly marked.
M-2?
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22
I R23-I-SD 12.00 PRIVIES, CHEMICAL TOILETS AND INCINERATOR TYPE
2 SD 12.01 Acceptab!IIty - The installatton of a privy, chemical or
3 Incinerator type toi let wi I I be approved only where a water-carriage
4 system is not practicable.
5 SD 12.02 Location - The Location of a privy shall meet the requirements
6, of Section SD 3. OS.
1 SD 12.03 Construction - A privy shall have a self-closing seat cover,
8 and a fly-tight vault and superstructures. A screened vent shall extend
9 from the vault to the atmosphere.
10 SD 12.04 Maintenance - When a privy vault becomes fiI led to within two
II feet of the surface of the ground, it shall be cleaned and the contents
12 disposed of in a sanitary manner, or it shall be covered with clean
13 compacted earth to a depth not less than two feet.
M-28
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23
I PART D. SOIL STUDIES AND PERCOLATION TESTING
2 R23-I-SD 13.00 SUBSOIL EXPLORATION
3 SD 13.01 General - The suitability of the soil for disposal of
4 sewage by leaching shall be determined through the consideration of the
5 type of soil, the results of percolation tests, the maximum ground water
6 table elevation, the occurrence of impervious formations, and any other
7 relevant data. The director may require percolation tests and ground
8 • water table determinations on individual lots in subdivisions or parts
9 thereof which have been reviewed and the soil found suitable for the
10 Installation of individual sewage disposal systems. In areas where
II available information makes such tests unnecessary the director may waive
12 or modify the requirements for soil studies and percolation tests.
13 SD 13.02 fil±e_Suitability - The installation of an individual
14 sewage dlsposaL^ySem/i 4 ir&H\'\i\Hr5
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24
I (c) I. Home Owner - If the property owner Is Installing,
2 constructing or altering an individual sewage disposal system
3 to serve a building he occupies or will occupy as his intended
4 permanent domicile, he or his representative may prepare the
5 .necessary holes and carry out the tests as prescribed in these
6 regulations.
7 (c) 2. Whenever in the opinion of the director the requirements
8 of these regulations protecting the public health and environment
9 can be met, a home owner as defined in Section SD 13.05 (C-'l) may
10 prepare the plans and layout of his proposed system. For this
II purpose any requirements of these regulations may be waived at the
12 discretion of the director. The director reserves the right to
13 require any data he deems necessary to fulfill his obligations
14 under these regulations.
15 (d) The director may require that all soil examinations be
16 performed in the presence of one of his agents.
17 SD 13.06 Recordin'q ResuIts - The complete record of percolation tests,
18 ground water table determinations, type of soil, and the location of
19 Imperyious formations in the area shall be recorded on forms provided by,
20 or approved by, the director. Any person making and/or witnessing the
21 determinations shall certify to the accuracy of the •'echnical data recorded.
M-30
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25
I R23-I-SD 14.00 PERCOLATION TEST PROCEDURE
2 SD 14.01 (a) Dig two or more test holes within the area of the
3 proposed seepage system, not less than 10 feet apart. One of the holes
4 should be at the depth of the bottom elevation of the proposed seepage
.5 system, and the second hole should be at a depth of about 18 inches below
6 the bottom elevation of the proposed seepage system. This is to evaluate
7 the consistency with depth of the seepage qualities of the soil. The size
8 of the seepage system must be based on the highest percolation rate obtained.
9 The holes shall be not less than 6 inches in diameter or 6 inches square, nor
10 should they be greater than 8 inches in diameter or 8 inches square.
II (b) Scarify the bottom and sides of the test holes and remove ail
12 loose material. Place about 2 inches of coarse sand or fine gravel in the
13 holes to prevent bottom scouring.
14 (c) Fill the holes with clear water to a minimum depth of 12 Inches
15 above the coarse sand or fine gravel. Keep water in each hole for at
16 least four hours and preferably overnight by refilling. If necessary to
17 maintain water in each hole for this period, provide a reservoir of water
18 and an automatic siphon to deliver it to the holes intermittently, or the
19 percolation test holes should be soaked and maintained full for not less
20 than four hours before the percolation test is made. In uncompacted sandy
21 soils containing no clay or silt, the above saturation procedure is not
22 necessary; the test can be made as soon as the water from one filling
23 has seeped away.
24 (d) The percolation test should be made following the saturation
25 process. . When the saturation process is complete, the water depth should
26 be adjusted to 6 inches over the coarse sand or fine gravel before the test
27 Is begun. The drop in water level should be measured from a fixed reference
28 place, such as a board laid across the hole, over 30 minute intervals,
29 refilling the holes to a depth of 6 inches as necessary.
30 (e) When three consecutive readings at 30 minute intervals read the
31 same rate, the test may be considered complete. If no stability is reached
32 between three 30 minute readings, not less than four hours of readings must
33 be followed. The drop in water level which occurs during the final 30
.34 minute period is used to calculate the percolation rate. This rate is expressed
35 In minutes per inch.
36 . (f) Soil's in which the first 6 inches of water seeps away in less than
37 ' 30 minutes, after the saturation period, the time interval between
38 measurements should be reduced to 10 minutes and the test run over a period
39 of one hour. The drop in water level which occurs during the final 10-minute
40 period is used to calculate the percolation rate. This rate is expressed in
41 minutes per inch.
42 SD 14.02 If an unanticipated cut is made, the results of any percolation
43 test made prior to the cut is invalid. A new percolation test shall be made
44 under the changed conditions.
M-3-1
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26
I R23-I-SD 15.00 PROCEDURES FOR GROUND WATER TABLE ELEVATION DETERMINATIONS
2 SO 15.01 The ground, water table elevation determination shall be
3 made when the water table is highest; this occurs usually during the
4 months of January through April. (Specific dates nay be determined on a
5 yearly basis by the director). In making this determination it is necessary
6 to bore or dig an adequate number of holes of convenient size in the
7 proposed leaching area to a depth of at least five (5) feet below the lowest
8 point of the proposed sub-surface seepage
9 ^aeaMate9tt4>***««N» An open perforated pipe at least 4 inches in diameter
10 shall be installed. Such pipe should be installed at +he beginning of the
II wet season and remain in place until a permit has been issued by the
12 director. This pipe shall be capped at the top and mounded to prevent the
13 collection of surface water. All water table test holes shall be witnessed
14 by an agent of the director unless otherwise waived.
15 SD 15.02 Ground water table determinations made other than during the
16 months of January "WjQJ April will be accepted provided the material in the
17 test pit consists Qpiftcomt acted sand or gravel containing little or no
18 fines, and the percoTSticyTJrra^e/lifitinat. greater than (5) min. per inch in the
19 original soil; and the hole'is'Siig/fdCyjdepitjj of at least 15 feet below the
20 lowest part of the proposed sub-surfac^s^effygff^y^faf and no water is
21 encountered.
M-32
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27
I PART E. SUBDIVISIONS
2 SD 16.01 Subdivisions - Individual Sewage Disposal Systems - No
3 person shall construct in any subdivision located in areas where sewage
4 will have to be disposed of by means of individual sewage disposal
5 systems until he has obtained certification from the director that the
6 subsoil Is suitable for disposal of sewage by individual sewage disposal
7 systems. Application for such certification shall be made on forms
8 orovlded by the director and accompanied by data described In
9 SD 16.02 through SD 16.06.
10 SD 16.02 Topographic Map - A.topographic map of the entire area
II under consideration shall be prepared to an appropriate engineering scale
12 and submitted with the application. It should show existing conditions on
13 the entire site including existing (a) houses, foundations and excavations
14 for basements; (b) existing individual water supplies and sewage disposal
15 systems; (c) right of ways or easements; (d) natural waters or water
16 courses, swamps and marshes; (e) rock out-crops and wooden areas; (f) stone
17 walls. There shall also be shown, designated, or reported for lands
18 Immediately adjacent—(a) natural waters or water courses within 200 feet
19 from the property; (b) wells within. 150 feet from the parcel being considered.
20 The topographic map shall show ground elevations on the tract as
21 follows^- (a) for land that slopes less than approximately 2% show spot
22 elevations at all breaks in grade, along all drainage channels, or swales,
23 and at selected points not more than 100 feet apart in a I I directions;
24 (b) for land that slopes-more than approximately 2% show broken line
25 contours with an Interval of not more than 5 feet where ground slope is
26 regular and Intervals of not more than 2 feet where the ground slope is
27 Irregular. The datum on which the elevations or contours are based should
28 be reported.
29 Where cut and/or fill of more than I foot can be anticipated and
30 estimated, It should be indicated by solid line contours showing
.31 approximate finished grade. Plan and profile showing existing and proposed
32- finished grades of proposed roads must be provided.
33 SD 16.03 Location Map - A location map or sketch showing existing
34 highways, streets and/or other identifiable landmarks or distances thereto,
35 shall be furnished to facilitate an inspection of the site. This may be
36 Incorporated on the topographic map.
37 SD 16.04 Percolation Tests - An adequate number of percolation tests
38 not less than one to an acre, with a minimum of two tests in smalI areas
39 shall be made by the developer, to indicate clearly the soil conditions through-
40 out the property. These tests shall be made in accordance with the procedure
41 outlined l,n Sections SD 13.00 and SD 14.00. Unfavorable soil conditions
42 will require more tests, up to one per lot at the proposed site of each
43 subsurface absorption unit. The results of each percolation test and pertinent
44 Information shall be recorded in the tabulation provided on the application and
45 the location of the percolation tests shall be marked on the topographical map
46 and Indexed by the corresponding number used in the tabulation of results.
M-33
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28
I SD 16.05 Ground Water Table - An adequate number of borings,
2 excavations or observations shall be made by the developer to clearly
3 establish the elevation of the ground water table in accordance with the
4 procedure outlined in Sections SD 13.00 and SD 15.00. The ground water
">5 table determinations should be made when the ground water table is at its
6 highest level. The results of each observation and pertinent information
7 shall be recorded in the tabulation of the application. The location of the
8 ground water table observations shall be indicated on the topographical
9 map together with the index letter used in the tabulation of the results.
10 SD 16.06 Certification - The engineer, surveyor, soil scientist,
II or sanitarian shall execute the certificate relating to the accuracy of
12 the technical data on each sheet on which such technical data is recorded.
13 SO 16.07 Nothing in Sections SD 16.01 through SD 16.06 shall prevent
14 the director from requesting any or all of the procedures established in
15 these regulations for a single lot if in his opinion the protection of the
16 public health and environment so requires.
^_
Page 28 (See Amendments)
The foregoing rules and regulations, after due notice and hearing,
are hereby adopted and filed with the Secretary of State this 6th
day of July 1973, to become effective tuenty (20) days thereafter, in
accordance with the provisions of Chapter 23-1 and 42-35 of the General
Laws of Rhode Island, 1956, as amended.
/Joseph B. Cannon, M.D., M.P.H.
Director of Health
notice given on 5 January 1973
Hearing held on 25 January 1973
(
: b
Piled: _b__July
Secretary of'State
NEW ATOEMDMZNT3 EFFECTIVE 30 AUGUST 1974
M-31*
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29
Voter
Service —
Line
""l 1
r ]
1 Existing \
• Leaching ,
1 Field 1 '
1
1
1
i .
r
H 26- r.
| minimum \
1
1
I
\
\
x^
S
/
10 feet minimum
_ _ ' ' to property lines
•fa
Property Line
iff
T^inphinrr Bed \ >••<
IK' *. Septic
~~ " Tank
^ _ mwnmum_j^ ^
^
^
House
~^^
\
\
100 feet Minimum
to leaching fields
50 feet Minimum
to septic
Top edge of any bank,
for a ZS foot perimeter,
must not drop below
field invert elevation
Well
Property Line
100 feet minimum to leaching fields
SO feet minimum to septic tanks
Alternate Area for
future expansion
of leaching field
TYPICAL LOT LAYOUT
(tto Scale)
Reference: See Sections SD 2.00 and 3.00
M-35
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30
r
Ground Surface
Manhole Covers 1 . foot
ff$L W -» «=^ 4*
Tee
•.o
'.'It)
j'.C •
$
,
$
;i'-'
?J;
:.r.
°u
•i-
'"tl U' (T8 4 'II IT1"
__._._ j., _l
C" '> Jnuert ojf Inlet Z incht
Jie=H H above Invert of Outlet*
^ \\ \ 1
1 | — I Liquid Level \
-: -.- -HjnrT t -,r=. TV=i.- -
'^ r'rTs^f ~
\ iMinirmon
\_Baffles may be used
Instead of Sanitary
fees
I
(4 to
\
'i^X~*'.<''b'* "» 'r~: « W- rf .j-.l.-^'.'.-f:
r p.:
>
«/t;
'(Cv-v:
, ^*--
S 1 r
^
«==\
i_!a
/J-
"— -
Vanht
C~
1
1
j
-4-
1
1
1
1
1
1
1
i
•'^•. — •'
SECTION VIEW
•)le Cover
•"="- ="~X Outlet
^Sanitary
Tee
Manhole
Covers
Inlet fiTI
TOP VIEW
TYPICAL SEPTIC TANK
Reference: See Section SD 5.00
Outlet
' M-36
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""Inlet
Inlet
31
A.
Manhole
*-•
V
TOP VIEW
Manhole
=N 7
Section View
UPICAL DOSING TANK
(Jto Scale)
Reference: See Section .'O e.
Outlet
Overflew
Outlet
M-3T
-------
Inlet
3 Alternate
inch^inlets
i
i
- Knockouts for
inch outlets
TOP VIEW
• Cover •
Outlets^
~N\ //•'•
ijjc
-ST-; X V^J-X
SECTION VIEW
Outlet
Tfiinimut
r'
:1I
~-ii
M
h-T^
ir
-ll.
It.
END VIEW
TYPICAL DISTRIBUTION BOX
(No Scale)
Reference: See Section SD 7.00
M-38
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33
Perforated 4 inch Pipe
TYPICAL PLAN LEACHING TRENCHES
•^ h ^3Wf>-
A,'/ -Earth Covef'^nim
Stone
fJ/2 *c 2 Inches diameter)
TYPICAL TRENCHES
CROSS SECTION.
TYPICAL TRENCH TYPE FIELD
(Ato ScaZ«;
Reference: See Section SD fi.00 onj 9.00
M-39
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Building
Sewer
1 SeP
la.
Sol
Pip
Si
tic _
nk [«
Distribution Box
id 4 inch .i/vmlts of
3 \ _ ... r „ leachina Bed.
±1 •^-L—-,
1 • Perforated 4 inch /
' pipe ~~\
]_j. -
_i .......
Length
—1
1
]
i
i
1
. j
TYPICAL PLAN LEACHING BED
I*— 2 /"eet—N« 6 jfeet maximum w«-6 /eet maximum-
-2 /eet-
^S^r O
^ V?
2
__ minimum
foot
ifnufn
Stone
1/2 - 2 inches diame
4 inch perforated
— pipe'
<^>^^ovp/
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35
'Reference
Board \^
Ground Surface
6 Inches
to
8 Inches
TYPICAL SOIL PERCOLATION HOLE
(So Scale)
Reference: See Section SD 14.00
M-Ul
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APPENDIX M - iiJVIROrlMENTAL EFFECTS OF SUBSURFACE DISPOSAL OK GROUND WATER
QUALITY
An important consideration in the evaluation of alternative wastewater
management schems for Block Island, is the impact on ground water quality.
This is particularly significant since the ground water is also the sole
source of supply of water for commercial and domestic use on the Island.
A general assessment of the effects of subsurface disposal on ground
water quality can be developed from the past experience of communities and
individuals as well as scientific studies. A recent comprehensive evaluation
of this question is a report titled The LongIsland Sound Ground Water
Pollution Study prepared by the New York State Department of Public Health
and published in 1972. Another important study is the Report on the Investi-
gation of Travel of. Pollution prepared by the California Water Pollution
Control ,Board in 195^. The information presented here is based in part on
infornatipn obtained from these studies.
It can be confidently stated that the disposal of domestic wastes into
the ground using subsurface disposal systems such as septic tanks and
leaching fields will result in some degradation of the ground water quality.
The important question is whether the changes in quality are significant
relative to the usefulness of the water as a water supply.
A complex combination of physical, chemical and biological phenomena occur
from the entrance of wastes into a subsurface .disposal system and through the
system, the unsaturated soil and saturated soil. Sorption, dilution, diffusion,
chemical reaction, precipitation, filtration and biodegradation processes take
place, reducing the pollution concentration of the wastewater. Nevertheless.
some fraction of the pollutants reach the groundwater. Based upon the
information presented in the previously mentioned studies and accepted standards
for drinking water quality, continued use of subsurface disposal systems on
Block Island would not appear to constitute a significant threat to the
ground water quality.
Many rural and suburban communities have utilized and continue to utilize
subsurface waste disposal systems in combination with private individual
water systems,or community water systems without effecting significant changes
in the quality of the ground water supply. In many instances this preservation
is sustained by requiring a physical separation of water supply wells from
subsurface disposal systems. Distances ranging from i+00 ft. to 1,000 ft.
separation are general guidelines applied for community wells. For individual
water supply systems distances of 50 ft. to 100 ft. are practiced.
Significant ground water quality problems have occurred, .such as on
Long Island, where the density of development and soil conditions have stressed
environmental systems beyond their capability to respond. The contamination
of individual water supply, systems can usually be attributed to inadequate
physical separation from the subsurface disposal system.
N-l
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Based, upon the information available, subsurface disposal systems now-
used, on Block Island, have not significantly impacted the quality of the ground
water used for water supply. Previous scientific studies and investigations
and past experience, indicate that continued use of subsurface disposal systems
will not significantly impact the water quality of the island particularly in
view of the currently proposed densities of development and the seasonal nature
cf the present population. In order to ensure the preservation of the ground
water quality, it is recommended that presently proposed developmental densities
be maintained or reduced. It is further recommended that community water systems
from protected sources be provided, in the more densely developed areas of the
island.
i'i-P
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