United States Environmental Protection Agency Environmental Monitoring Systems Laboratory Las Vegas, NV 89193-3478 Research and Development EPA/600/SR-93/107 September 1993 w EPA Project Summary Case Studies in Wellhead Protection Area Delineation and Monitoring Beth A. Moore Groundwater monitoring is one of many management options for Well- head Protection Program implementa- tion. Groundwater parameters are monitored (1) to assess source-control measures, (2) to monitor compliance with drinking water standards at sites other than the wellhead, and (3) to pro- vide advance warning of contaminants in ground water. Cooperative research was conducted with five municipalities to develop long-term monitoring pro- grams for their existing wellhead pro- tection areas. The product of this research is a technical assistance docu- ment which contains a methodology for planning and implementing a well- head protection monitoring program. The methodology emphasizes source assessment, correct wellhead protec- tion area delineation, and hydrogeo- logic characterization. Five case studies are included in the document to exem- plify the monitoring methodology for different hydrogeologic and contami- nant source settings. The five case study research sites include Stevens Point, Wl; Littleton, IMA; Sioux Falls, SD; Dover, NH; and Spring- field, MO. Three of these municipalities obtain their drinking water from uncon- fined aquifers; two aquifers receive sig- nificant recharge from a nearby pond and river. Two other case study sites are situated in fractured-bedrock and karst limestone aquifers. The document emphasizes a multi-disciplinary ap- proach for hydrogeologic characteriza- tion, wellhead protection area delineation, and flowpath assessment. Hydrogeologic characterization tech- niques include: well installation, water quality sampling and assessment, geo- logic and structural-control mapping, aquifer testing, dye tracing, borehole geophysics, analytical solutions, and groundwater flow modeling. Long-term monitoring programs for wellhead pro- tection include monitoring objectives, existing and new monitoring sites, guid- ance for monitoring site construction and installation, sampling protocol, op- timal monitoring parameters and fre- quencies, and quality assurance and quality control considerations. This Project Summary was developed by EPA's Environmental Monitoring Systems Laboratory, Las Vegas, NV, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction The increasing contaminant threat to public water supply wells has created a new political and technical awareness of groundwater protection programs. Recog- nizing the need for conjunctive manage- ment of contaminant sources and public water supplies to prevent, or minimize, groundwater quality degradation, Congress amended the Safe Drinking Water Act in 1986 to include Section 1428. This sec- tion mandated the development of the Wellhead Protection Program (WHPP), which established a legal framework to protect public water supply wells, wellfields, and springs from contamination. An im- portant technical element of WHPP imple- mentation is wellhead protection area Printed on Recycled Paper ------- Landfill Monitoring well WHPA Water well Water table Ground-water contamination plume Figure 1. Conceptual wellhead protection area and monitoring scenario. delineation. A wellhead protection area (WHPA) is defined as the surface and subsurface area surrounding a well, wellfield, or spring, through which con- taminants may pass and reach the ground water contributing to the supply source (Figure 1). Criteria and methods for WHPA delineation are given in several U.S. Envi- ronmental Protection Agency (EPA) guid- ance documents. Groundwater monitoring may enhance source characterization, WHPA delinea- tion, and new water supply evaluation. This technical assistance document pro- vides information to local, state, and tribal governments and the EPA Regions in their implementation of WHPPs. The primary goals of this document are to present a monitoring methodology for WHPAs and to exemplify this methodology in five unique case study settings. Wellhead Protection Area Monitoring In 1989, U.S. EPA's Environmental Monitoring Systems Laboratory (EMSL) at Las Vegas, NV, engaged in cooperative research with five carefully selected mu- nicipalities to develop proposed, long-term monitoring programs for their existing WHPAs. The product of the cooperative research contains two types of informa- tion: (1) A recommended methodology for planning and implementing a well- head protection monitoring pro- gram which emphasizes source assessment, correct WHPA de- lineation, and hydrogeologic char- acterization. (2) Five case" study narratives used to exemplify the monitoring meth- odology for different hydrogeo- logic and contaminant source settings (Table 1). The monitoring methodology is intended to serve as a guide for WHPP imp- lementors in establishing technically de- fensible, reliable, and effective groundwa- ter monitoring programs for wellhead pro- tection. This methodology emphasizes saturated zone monitoring. The first four case study narratives are presented in the document in order of increasing hydro- geologic complexity (aquifer heterogene- ity). The exception to this organization is the Springfield, MO, case study, which is presented in abbreviated form in an ap- pendix. Basic hydrogeology concepts and equa- tions are reviewed including: groundwa- ter systems and flow, conceptual hydro- geologic models and flow nets, and accu- rate delineation and monitoring in differ- ent hydrogeologic settings. The spectrum of unconfined to confined aquifer condi- tions is discussed in relation to porous, granular aquifers; fractured-bedrock aqui- fers; and karst aquifers. Physical and chemical parameter moni- toring apply to wellhead protection. Three types of groundwater monitoring are use- ful in managing WHPAs: ambient trend, source assessment, and early-warning detection monitoring. Ambient trend moni- toring detects the temporal and spatial trends in physical and chemical quality of the groundwater system. Source assess- ment monitoring evaluates the existing or potential impacts on the physical or chemi- cal groundwater system from a proposed, active, or abandoned contaminant source. Early-warning detection monitoring is con- ducted upgradient from the wellhead, based on known travel times, to trigger a contingency response to prevent public exposure to contaminants. These types of monitoring are incorporated to measure or detect contaminants in aquifers, and should not be mistaken as preventative or remedial measures. ------- Table 1. Characteristics of the Case Study Research Sites. Municipality Hydrogeologic setting Characterization tasks Stevens Point, Wl Littleton, MA Sioux Falls, SD Dover, NH Springfield, MO Unconfined aquifer Unconfined aquifer, rehcarge from Spectacle Pond Undonfined aquifer; recharge from the Big Sioux River Fractured-bedrock aquifer, discrete flow system Mature karst (porous limestone) aquifer, conduit flow system Flowsystem modeledwith FLOWPATH (2-dimensional, steady state); point and nonpoint sources assessed Flow system modeled with FLOWPATH (2-dimensional, steady state); MODFLOW (3-dimensional, steady state); and FLOWCAD (2-dimensional, transient); Industrial and commercial point sources assessed Flow system modeled with FLOWPATH (2-dimensional, steady state); Big Sioux River assessed as a line source; point and nonpoint sources present Flow system characterized with lineament analysis, structural control mapping, aquifer testing, dye tracing, and borehole geophysics; a few commercial, point sources, and natural sources Flow system determined by watershed boundaries, dye tracing, and flow analysis; point and nonpoint sources assessed Source assessment is a critical first step in designing an effective monitoring pro- gram. Target monitoring parameters for early-warning detection and source as- sessment are selected from a compre- hensive list of known and suspected con- taminants associated with land-use activi- ties and practices. Optimal monitoring sites may be determined, reflecting prioritization of sources. An inventory of common sources of contamination within and in proximity to WHPAs is included. The monitoring methodology is divided into three phases: • Phase I: WHPP Elements and Scoping Tasks • Phase II: Research Monitoring Pro- gram • Phase III: Wellhead Protection Moni- toring Program Phase I WHPP elements and scoping tasks include: designating roles and a management framework, preliminary WHPA delineation, and source assess- ment. To support the research monitoring task, an initial information base of ancil- lary and monitoring data should be com- piled and reviewed to determine data limi- tations and gaps. The strategy is to maxi- mize information content; to define moni- toring objectives; and to conduct field stud- ies with the least, but still adequate num- ber of monitoring points. Existing monitor- ing sites identified in this phase can be incorporated in the long-term monitoring network. Phase I generally requires a 3- to 6-month period for completion. Phase II is aptly named the Research Monitoring Program, or the phase of ac- quiring information pertaining to how the subsurface system operates and of for- mulating interpretations. Research moni- toring is conducted to improve, or verify, elements of the hydrogeologic conceptual model. A technically defensible concep- tual flow model ensures a more protective and reliable monitoring program. Research monitoring for wellhead protection includes baseline water quality characterization, aquifer testing and characterization, re- fined or verified WHPA delineation, and groundwater flowpath determination to re- late sources to the water supply well or spring. The product of research monitor- ing is a proposed long-term monitoring program that may be partly implemented in Phase II. Phase II may require 1 to 1.5 years for completion, depending on the complexity of the site hydrogeology and the quality of the initial information base. The by-product of Phases I and II is a proposed wellhead protection monitoring program, Phase III. Generally, the pro- gram is submitted as a plan to be imple- mented in stages, as labor and financial resources become available. The plan should include an organization chart, a source assessment map and list, and a map depicting the WHPA and protective zones, as well as a description of the delineation criteria and method(s). Gen- eral and specific objectives for ambient trend, source assessment, and early-warn- ing detection monitoring should be de- tailed. Each objective should justify the selection of monitoring sites, parameters, and frequencies. The locations of existing and recom- mended monitoring sites in the proposed network should be shown on a map. A formal identification system with a mini- mum set of data elements should be used to label each site. The integrity of the design and construction of each existing site should be considered prior to inclu- sion in the monitoring network to ensure data quality. New sites that require instal- lation should be described in detail, con- cerning completion depth, open or screened interval, schematic design, and construction materials, as well as the meth- ods of installation, development, and test- ing. Physical and chemical parameters to be monitored at select frequencies should be listed and technically justified. Monitor- ing site information should be stored in an automated data base for convenient and safe storage, update, and retrieval. Each monitoring program should formulate a minimum set of quality assurance and con- trol objectives to match the objectives of the wellhead protection monitoring pro- gram. A 15-step approach for the design of a wellhead protection monitoring program is depicted as a flowchart in Figure 2. The monitoring program should be reviewed and improved in an iterative process over the life span of the WHPP. The organiza- tion of the case studies research follows the logical outline of Phases I, II, and III. ------- Stevens Point, Wl: Case Study The city of Stevens Point is located in central Wisconsin and has a population of approximately 23,000. The source of the city water supply is from the Airport and Iverson wellfields. These wellfields pump an average of 5 million gallons of water per day from a shallow, unconfined aqui- fer. The aquifer is composed of coarse, unconsolidated sediments deposited by meltwater during the Wisconsin glaciation. The preliminary wellhead protection zones for the combined wellfields were based on estimates of the zone of influence, the 5- year time-of-travel (TOT) zone (analyti- cally determined), and the recharge area. In the review process, the validity of the 5-year TOT calculation was questioned, and the WHPA was never promulgated. An extensive, historical source assess- ment was conducted within the B Zone of the preliminary WHPA using aerial photo- graphic interpretation techniques combined with conventional methods such as sur- veys of directories, local and state records, visual inspections, and monitoring data. Point and nonpoint sources were identi- fied, ranked, and prioritized for manage- ment and regulation. Existing contaminant sources were given highest priority. Po- tential sources were then prioritized based on source type, quantity, hazard, and lo- cation. A network of 55 monitoring sites (single monitoring wells, well nests, and a multi- level well) were used to measure water levels, to sample ground water, and to conduct aquifer tests in the unconfined aquifer. Of the total network, three single wells and four well nests represent new monitoring points installed for this research. Aquifer parameter results from slug, con- stant-discharge, and recovery tests indi- cate a range of hydraulic conductivity val- ues for three distinct geologic settings: 820 to 1,700 ft per day (ft/d) for the buried valley, 220 to 240 ft/d for outwash plains, and 2 to 3 ft/d for bedrock highs. Hydrochemical data indicate that nitro- gen concentrations, a key indicator of con- tamination, have increased over time. Currently, nitrogen concentrations in the monitoring network range from less than 0.2 to 26.0 mg/L Other indicators of groundwater degradation include iron and manganese from organic-rich soils located along the Plover River, chloride in proxim- ity to roads where de-icing occurs, and previous volatile organic compound con- tamination at the Airport and several un- derground storage tanks. A two-dimensional, groundwater flow model (FLOWPATH) was used to delin- eate the 5- and 10-year TOT zones for the Airport and Iverson wellfields. In corn- Monitoring program design Conduct source assessment within WHPA Determine sampling frequencies for monitoring parameters Compile & organize existing information base Assess need for new monitoring sites Identify deficiencies of information base Establish new monitoring sites Determine data & processing needs for system characterization Implement monitoring program Establish monitoring objectives Review & interpret monitoring results Determine monitoring objectives Incorporate interpretations in characterization assessments Identify existing monitoring sites based on objectives Update monitoring objectives, network design, & program f Iterate monitoring N V process J Figure 2. Flowchart of the 15-step monitoring methodology for wellhead protection areas parison, the previous, analytically derived B Zone is larger; however, the 5-year TOT zone from FLOWPATH extends farther to the east due to the effects of pumping at the Iverson wellfield and the presence of bedrock highs. A long-term groundwater monitoring net- work is proposed for the Airport and Iverson wellfields consisting of 34 existing and proposed wells. Nine new well loca- tions are proposed to fill data gaps in the existing network, primarily along the boundaries of the 5- and 10-year TOT zones. Wells in the long-term monitoring network should be sampled twice a year in April and September for indicator pa- rameters. Water levels should be recorded each time a well is sampled. Compliance monitoring networks are recommended for point sources of highest priority. The wellhead protection contingency plan consists of three components: (1) reaction to the early-warning detection sys- tem based on preventive action and state drinking water limits, (2) spill response, and (3) new water-supply development and implementation. Littleton, MA: Case Study The town of Littleton is located approxi- mately 35 miles northwest of Boston in northeastern Massachusetts. The daily water demand for the town's population of 7,300 is from 800,000 to 1,500,000 gal- lons per day from four production wells. Techniques for refined delineation and long-term monitoring of the WHPA sur- rounding Production Well Number 5 (PW- 5) are discussed. Production Well Num- ber 5 is completed at a depth of 167 ft 4 ------- within saturated, stratified valley-fill depos- its. The aquifer is unconfined and receives significant surface-water recharge (20 to 25%) from nearby Spectacle Pond and Bennetts Brook. Land-use activities within the .WHPA cover a range of commercial, industrial, and to a lesser degree, agricultural opera- tions. Collectively, these land-use activi- ties pose potential contamination threats to the aquifer, including heavy metals, vola- tile organic compounds, pesticides, and nutrients. Baseline monitoring results indi- cate that groundwater quality within the capture zone of PW-5 is currently unaf- fected by source operations. Sodium is the only exception. Slightly elevated lev- els of sodium in surface water and the shallow aquifer are attributed to roadway de-icing. Manganese and iron concentra- tions are elevated throughout the recharge area of PW-5, primarily because of their occurrence in wetland sediments and gla- cial deposits. The levels of these param- eters have increased at PW-5 for several years and may warrant treatment in the future. The PW-5 WHPA consists of three pro- tection zones delineated using a combi- nation of numerical groundwater flow mod- els (FLOWPATH, FLOWCAD, and MODFLOW) and hydrogeologic mapping. Zone I is the 400-foot sanitary protective radius mandated by the State of Massa- chusetts. Zone II is the most critical man- agement area and was delineated con- servatively as the union of three numeri- cal capture zone solutions. These numeri- cal solutions incorporate two- and three- dimensional flow, as well as steady-state and transient flow conditions. Local and regional groundwater flow simulations are based on the results of short- and long- term aquifer testing. Zone II generally represents the steady- state capture zone for PW-5 that corre- sponds approximately to the 400-day travel-time contour. Flowpath simulations indicate that Zone II extends to the bot- tom of the aquifer and is constrained by bedrock and glacial till. Within Zone II, three existing wells and two new wells are proposed for inclusion in the monitoring network for early-warning detection and source assessment purposes. These wells lie along either the 150-day or the 300- day travel-time contours. Screened inter- vals for the new monitoring wells were chosen based on results from MODPATH computer flow simulations. Monitoring pa- rameter groups for these wells include general water quality, site-specific, and physical parameters. Recommended moni- toring frequencies for these parameter groups vary from quarterly to annually, depending on the travel-time distance from the monitoring well to PW-5 and the moni- toring well depth. Zone III is defined as the upgradient area of the aquifer that contributes to Zone II and extends to the watershed bound- ary. Zone III is monitored at two surface- water locations, one at the inflow and one at the outflow of Spectacle Pond. In addi- tion, Zone III is monitored biannually at existing compliance networks around waste management and industrial sites. Monitoring parameters for the compliance wells include general water quality, site- specific, and physical parameter groups. The Littleton WHPP incorporates con- tingency planning. Catastrophic releases initiate a spill-response plan that involves many departments and agencies. In the event of contamination of PW-5 or an- ' other production well, Littleton has sited a new production well. The proposed well site is approved by the State, and protec- tion Zones I, II, and III are delineated. The adjacent town of Boxborough shares the recharge area to the proposed well. Boxborough has adopted complementary strategies with Littleton to ensure its water quality protection. Sioux Falls, SD: Case Study The city of Sioux Falls is located in the southeast corner of South Dakota. The Big Sioux aquifer is the primary source of water for about 125,000 persons in the Sioux Falls metropolitan area. One of the municipal wells in the Big Sioux aquifer, the airport wellfield, is underlain by surficial, glacial outwash deposits. The Big Sioux River is located directly west of the airport wellfield and flows south over and through the outwash, draining approximately 4,000 square miles of upstream land. The city's wells pump most of their wa- ter directly from the aquifer and a small quantity from the Big Sioux River. How- ever, the river is hydraulically connected to the aquifer, and recharge from the river in the airport wellfield area is significant. In 1988, approximately 79% of the re- charge to the airport wellfield aquifer was induced from the river due to wells pump- ing. Induced flow from the river to the aquifer is demonstrated by decreased flow in the river during low recharge periods. This research was conducted to evalu- ate (1) the hydraulic connection between the Big Sioux River and the adjacent aqui- fer, and (2) the potential impact of the river on aquifer water quality. In the broader perspective, additional goals in- cluded refined delineation of the wellfield protection area and design of a long-term water quality monitoring program. Drilling logs indicate that the thickness of the aquifer in the wellfield area ranges from 20 to 50 ft. Aquifer testing results yield an average hydraulic conductivity value of 800 ft/d and a transmissivity value of approximately 21,000 ft2/d for the aqui- fer. Many potential point sources of con- tamination exist in the study area. These include: industrial and commercial areas, the South Dakota Air National Guard facil- ity, a petroleum pipeline, the Sioux Falls Regional Airport, and a decommissioned municipal landfill. The threat of contami- nation from these sources is underscored by the recent history of contaminant re- leases in the area. To estimate groundwater travel times in the study area, aquifer testing, dye trac- ing, and groundwater modeling were em- ployed. During aquifer testing, two dye injections were made. The first dye was injected in a well approximately 40 ft north of the pumping well. Detectable dye con- centrations first arrived at the pumped well after about 12 hours. The second dye was injected in a well near the edge of the river, approximately 140 ft north of the pumping well. Detectable dye concentra- tions from the second injection site first arrived at the pumped well in 7 to 9 days. Aquifer testing and dye-tracing results in- dicate that a contaminant could travel from the river to the wellfield in less than 9 days. A two-dimensional, steady-state model (FLOWPATH) was used to generate time- related capture zones for the municipal wells and to simulate contaminant travel times. One-, two-, and five-year capture zones were calculated for each of the municipal wells in the airport wellfield. Modeling of simulated spill sites from sev- eral of the potential point-source contami- nation areas indicates that contaminants entering the aquifer at areas to the north and south of the well field could reach the municipal wells in 1 to 2 years. The City of Sioux Falls and Minnehaha County have delineated wellhead protec- tion areas by using the hydrogeologic- mapping method. Wellhead protection or- dinances are designed to impose guide- lines and restrictions on new land uses, or proposed changes in existing use, in or- der to protect the aquifer water quality. A wellhead protection monitoring pro- gram at the airport wellfield is proposed to document ambient water quality conditions and to serve as an early-warning detec- tion system. Line-source monitoring is pro- posed to monitor the Big Sioux aquifer and the diversion canal for contaminants that could potentially enter the aquifer. Point-source and nonpoint-source moni- ------- toring are proposed to monitor water qual- ity between the airport wellfield and po- tential sources. The categories of param- eters for monitoring are general water qual- ity, volatile organic compounds, trace met- als, pesticides, and nutrients. Sampling frequencies for each of the categories were selected as a function of the type of source to be monitored. Contingency planning is warranted to establish emergency responses to con- taminant releases at the surface of the aquifer and in the river. Alternative water supply development must also be contin- ued as part of the contingency planning effort. Dover, NH: Case Study Dover is a city of 26,000 people located in the seacoast region of New Hampshire. To meet the increasing water supply de- mands of the future, the city embarked on a water exploration effort in a fractured- bedrock aquifer at the Blackwater Brook site. A test well was installed to a depth of 400 ft in the bedrock aquifer as part of the groundwater exploration program. A well- head protection area and groundwater monitoring strategy were established for the test well. This study describes how the conceptual hydrogeologic model for the site was developed and refined. The bedrock aquifer consists primarily of quartz monzonite and metasedimentary rocks that interfinger along a fractured, faulted contact zone trending north 60 de- grees east (N60°E). A N5-10°W trending lineament and fracture zone intersects the N60°E zone at the site. The bedrock aqui- fer Is directly overlain by Pleistocene-age sands and gravels. These sediments are overlain by low-permeability marine clay and lodgement till. It is estimated that 20% of the water produced from the bed- rock aquifer is derived from overburden sediments in the watershed area. Four overburden and bedrock well pairs constitute the present monitoring network for the test well. Two well pairs lie along the N60°E faulted contact zone, and two well pairs lie along the perpendicular N30°W trend. The test well and four of five bedrock wells airlift in excess of 150 gal/min. Few contaminant threats exist near the site. Baseline sampling indicates that minor, elevated levels of iron, manga- nese, and radon pose the only water qual- ity problems at present. Test drilling and borehole surveys (cali- per, video camera, acoustic televiewer, thermal-pulse flowmeter, and hydro- physical logging) indicate that fracturing and groundwater flow are highly discrete. Flow occurs at isolated, definable depths rather than uniformly along the length of the borehole. Hydrophysical logging indi- cates that the borehole water is distinctly layered with respect to the fluid electrical conductivity parameter. Most borehole water is produced by moderately to steeply dipping fractures and fracture zones that intersect the wells. Aquifer testing and dye-trace results in- dicate that the N30°W and N60°E direc- tions have higher aquifer transmissivities relative to the surrounding bedrock matrix. Drawdown contours are elongate about the N30°W well alignment, suggesting pre- ferred flow in this direction. Dye-trace re- sults indicate more rapid travel of injected dye along the N30°W direction than the N60°E direction. Dye traveled 152 ft in 130 minutes (the time of first arrival of the dye) from injection in a bedrock monitor- ing well along the N30°W trend to the test well, which was pumped at 200 gal/min. This represents a velocity of 1,680 ft/d. Dye injected in a bedrock monitoring well located 596 ft from the test well arrived there in 148Siours, indicating a velocity of 96 ft/d along the N60°E direction. Flowmeter and acoustic televiewer sur- veys indicate that a moderately west-dipping fracture zone provides inter- connection between the test well and bed- rock well R2 along the N30°W trend. Lack- ing discrete flow information beyond the test well and well R2, statistical fracture descriptions become good approximations of flowpaths at increasing distances from the site. Therefore, prominent fracture peaks along the N5-10°W and N60°E trends represent the most probable flow directions within the bedrock fracture sys- tem at Blackwater Brook. The N60°E trend is substantiated by the existence of the faulted, fractured contact zone along this strike. Evidence to suggest preferred flow along the N5-10°W direction is structural and hydrogeologic. Structural control is inferred by strong expression of the linea- ment on several platforms of photography and in outcrop fracture trends. Enhanced transmissivity along the N30°W direction is attributed to the proximity and similar orientation of the N5-10°W fracture zone. A quadratic equation is derived from accepted hydrogeologic relationships (Darcy's Law and the Thiem equation). In this equation, groundwater travel time (de- termined using the time of first arrival of dye at the test well) is directly proportional to the square root of distance from the test well. Constants of proportionality for the quadratic relationship are calculated for the N30°W and the N60°E directions based on dye-trace velocities. Distances for the 200-day and 1,000-day TOT thresh- olds are then calculated for the two frac- ture zone directions: N5-10°W and N60°E. Three wellhead protection zones are delineated within the recharge area for the test well using a variety of criteria and methods. Zone I is the state-mandated 400-foot sanitary radius. Zone IIA con- sists of two 1,000-foot-wide "arms" along the N5-10°W and N60°E directions, ex- tending to the 200-day TOT distances. Zone IIB is the area within a smooth curve connecting the outer boundaries of Zone IIA, producing an oval shape. Zone III is the upgradient area contributing to the 1,000-day TOT distance modified by hy- drogeologic features. Recommended regu- lation of the wellhead protection zones varies from complete control and restric- tion of activities in Zone I to public educa- tion in Zone III. A major component of wellhead protec- tion program management is long-term groundwater monitoring. Under present conditions, monitoring of the test well and existing monitoring wells will focus on a moderate effort to assess ambient water quality and physical parameters. After the production well is developed, the monitor- ing frequency and list of monitoring pa- rameters increases. Proposed frequencies, parameters, and new sites for monitoring derive from technical and management goals. Action levels are proposed to trig- ger contingency responses. -&U.S. GOVERNMENT PRINTING OFFICE: 1993 - 7504711/80082 ------- ------- Bath A. Moore iswith Lockheed Environmental Systems & Technologies Company, Las Vegas, NV 89119. Steven P. Gardner Is the EPA Project Officer (see below). The complete report, entitled "Case Studies in Wellhead Protection Area Delineation and Monitoring," (Order No. PB93-213510AS; Cost: $61.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Environmental Monitoring Systems Laboratory U.S. Environmental Protection Agency Las Vegas, NV 89193-3478 United States Environmental Protection Agency Centerfor Environmental Researchlnformation Cincinnati, OH 45268 Official Business Penalty for Private Use $300 BULK RATE POSTAGES FEES PAID EPA PERMIT NO. G-35 EPA/600/SR-93/107 ------- |