REPORT TO TOWN OF WALTHAM ON
DIAGNOSTIC/FEASIBILITY STUDY OF HARDYSPOND WALTHAM, MASSACHUSETTS January, 1986
- Metcalf&Eddyh^lc Engineers & Planners
10 Harvard Mill Square Wakefield. Massachusetts
Mailing Address: P.O. Box 4043 Woburn, MA 01888-4043
January 10, 1986
J-9822
Mr. Robert Mailloux Waltham Board of Health 119 School Street Waltham, Massachusetts 02154 Dear Mr. Mailloux: We are pleased to submit this final report on the Diagnostic/ Feasibility Study of HardysPond, Waltham, Massachusetts. The report presents analyses of the data collected and development of the recommendations for restoration of the pond. The staff of Metcalf & Eddy very much enjoyed working with you on this project, and we hope to continue our association with the City of Waltham. If we can be of any further assistance at this time, please do not hesitate to contact us. Very truly yours,
Richard L. Ball, Jr. Vice President
Telephone (617) 246-5200 - Telex 681 7067 (METED UW) - Cable METEDD-Boslon - TWX 710 321 6365 New Yo'k i Palo Alto / San Bernardino / Irvine. CA / Arlington Heights, IL / Chicago / Houston ' Atlanta / Somerville, NJ / Silver Spring. MD / Honolulu TABLE OF CONTENTS
Letter of Transmittal TABLE OF CONTENTS . i LIST OF TABLES iii LIST OF FIGURES V ACKNOWLEDGEMENTS v i i i CHAPTER 1 - INTRODUCTION 1-1 Chapter 628 Lakes Program 1-1 HardysPond Description and Problems 1-1 Eutrophication 1-4 Report Organization 1-5 CHAPTER 2 - ENVIRONMENTAL DESCRIPTION 2-1 Morphometric Description 2-1 Watershed Description 2-5 ( Recreational Uses 2-9 Historical Chemical Data 2-10 References 2-14 CHAPTER 3 - DIAGNOSTIC SURVEY 3-1 Description of Field Measurement Program 3-1 Pond Hydrology 3-10 Pond Water Quality 3-16 Pond Biology 3-39 Water Quality of Incoming Sources 3-53 References 3-64 CHAPTER 4 - ASSESSMENT OF EXISTING CONDITIONS 4-1 Assessment of Trophic State 4-1 Massachusetts Lake Classification 4-5 Hydrologic Model 4-7 Nutrient Model 4-10 References 4-18 CHAPTER 5 - ASSESSMENT OF ALTERNATIVES 5-1 Hardy Pond Problems and Objectives 5-1 Alternatives Development 5-6
METCALF a EDDY TABLE OF CONTENTS (Continued)
Pa^e
CHAPTER 6 - RECOMMENDED PLAN 6-1 Dredging . 6-1 Outlet Modifications 6-16 Shoreline Improvements 6-19 Swimming Area 6-20 Post-Implementation Monitoring Program 6*21 Public Education Program 6-23 Historical Commision Concerns 6-24 Restoration Plan Schedule 6-25 Cost Estimates and Funding Sources 6-25 APPENDIX - DIAGNOSTIC SURVEY DATA A-l - In-Situ Profile Data A-2 - In-Pond and Tributary Sampling Data A-3 - Stormwater Data r
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METCALF ft EDDY. LIST OF TABLES
Table 2-1 Summary of Previous Water Quality Measurements in HardysPond 2-11 2-2 Summary of Previous Pond Improvement Activities 2-13 3-1 Schedule of Surveys Conducted at HardysPond 3-3 3-2 Parameters Measured During Water Quality Surveys 3-5 3-3 Parameters Measured During Stormwater Runoff Surveys 3-9 3-4 Sediment Analysis 3-10 3-5 Summary of Hardy Pond Inflow, Outflow and Lake Elevation Measurements 3-13 3-6 Summary of Runoff Measurements Obtained During Rainfall Events 3-15 ( 3-7 Phytoplankton Taxa of Hardy Pond From June 1984 to June 1985 3-43 3-8 Pollution-Tolerant Genera of Algae 3-49 3-9 Summary of Flow Weighted Average Concentrations Measured During Stormwater Monitoring 3-61 3-10 Hardy Pond Sediment Sampling Results 3-63 4-1 Estimate of External Phosphorus Loading to Hardy Pond 4-4 4-2 State Classification System Applied to Hardy Pond 4-6 4-3 Input Parameters for Hydrologic Model 4-11 4-4 Input Parameters for Phosphorus Model 4-16 5-1 Hardy Pond Problems and Objectives 5-2 5-2 Summary of Storm Drainage for Hardy Pond 5-13 5-3 Hardy Pond Recommended Plan . 5-16 ( 6-1 Classification of Dredge or Fill Material 6-4
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METCALF « EDDY LIST OF TABLES (Continued)
6-2 Classification of Sludge for Land Application 6-4 6-3 _ .Great Lakes Sediment Rating. Criteria -_„ 6-_5 6-4 Classification of Dredge or Fill Material By Physical Characteristics 6-6 6-5 Potential Sediment Disposal Areas 6-12 6-6 Schedule of Activities for the Hardy Pond Restoration Program 6-26 6-7 Summary of Cost Estimates for Recommended Alternatives 6-28 6-8 Summary of Cost Estimates Projected Over the Project Period 6-28
XV
METCALF A EDDY, , LIST OF FIGURES
Figure Page 1-1 Hardy Pond Location 1-3 2-1 Bathymetric Map of Hardy Pond 2-3 2-2 Hardy Pond Depth - Volume Relationship 2-4 2-3. Hardy Pond Drainage Area 2-6 2-4 Hardy Pond Storm Drainage Outlets 2-7 3-1 Hardy Pond Monitoring Stations 3-2 3-2 Hardy Pond Stormwater Runoff Basins 3-7 3-3 Hardy Pond Temperature and Dissolved Oxygen Profiles, June 8, 1984 3-19 3-4 Hardy Pond Temperature and Dissolved Oxygen Profiles, June 21, 1984 3-21 3-5 Suspended Solids Measurements, Near Water ( Surface - Station 2 3-22 3-6 Suspended Solids Measurements, Surface and Bottom - Station 2 3-23
3-7 Turbidity Measurementsr Surface and Bottom - Station 2 3-24 3-8 Total Phosphorus Measurements, Surface and Bottom - Station 2 3-27 3-9 Ammonia Nitrogen Measurements, Surface and Bottom - Station 2 3-30 3-10 TKN Measurements, Surface and Bottom - Station 2 3-31 3-11 Nitrate Nitrogen Measurements, Surface and Bottom - Station 2 3-32 3-12 Alkalinity Measurements, Surface and Bottom - Station 2 3-33 3-13 pH Measurements Near Water Surface - Station 2 3-35
METCALF ft EDDY f LIST OF FIGURES (Continued)
Figure Page
3-14 Fecal Coliform Measurements, Water Surface - Station 2 3-36 3-15 Iron Measurements, Surface and Bottom - Station 2 3-37 3-16 Chlorophyll-a Measurements, Water Surface - Station 2 3-42 3-17 Phytoplankton Density Near Water Surface - Station 2 3-46 3-18 Seasonal Variation of Phytoplankton Taxonomic Composition in Hardy Pond - Station 2 3-47 3-19 Hardy Pond Macrophyte Survey 3-51 3-20 Total Phosphorus Measurements at Inlet - Station 3 3-55 3-21 Ammonia Nitrogen Measurements at Inlet - Station 3 3-56 3-22 Nitrate Nitrogen Measurements at Inlet - Station 3 3-57. 3-23 Suspended Solids Measurements at Inlet - Station 3 3-58 3-24 Fecal Coliform Measurements at Inlet - Station 3 3-60 4-1 Trophic State of Hardy Pond 4-3 4-2 Phosphorus Model Simulation Without Sediment Load 4-15 4-3 Phosphorus Model Simulation Including Sediment Load 4-17 5-1 Comparison of Various Phosphorus Load Reductions 5-8 5-2 Hardy Pond Stormwater Runoff Basins 5-12 c 6-1 Hardy Pond Sediment Depth 6-3
VI
METCALF ft EDDV LIST OF FIGURES (Continued)
Figure Page
6-2 Conceptual Layout - Hardy Pond Dredge Material Containment Area 6-9 6-3 Location of Potential Sediment Disposal Sites 6-13 6-4 Recommended Outlet Structure Modifications 6-18 6-5 Hardy Pond Restoration Program Schedule 6-27
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VII
METCALF A EDDY ACKNOWLEDGMENTS
We sincerely achnowlege the assistance and cooperation of the City of Waltham , especially Mr. Robert Mailloux. We also appreciate the assistance and review provided by the Massachusetts Division of Water Pollution Control, including Mr, Michael Ackerman, Mr. Alex Duran, and Mr. Gary Bogue. We finally acknowledge the comments and assistance given by residents of Hardy Pond and the City of Waltham who attended the public meetings. This study was conducted by Mr. David Bingham, Mr. John Cardoni, and Peter Boucher, under the direction of Mr. Richard Ball.
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METCALF A EDDY f CHAPTER 1 INTRODUCTION
In accordance with the State of Massachusetts Clean Lakes Program, this report contains the findings of a Phase I Diagnostic/Feasibility study for the restoration of Hardy Pond in Waltham, Massachusetts. Chapter 628 Lakes Program The Chapter 628 Massachusetts Clean Lakes and Great Ponds Program provides funds for the restoration, preservation and maintenance of the publicly owned lakes and ponds of the Commonwealth for public recreation and enjoyment. A Chapter 628 restoration program is carried out in two phases. Phase I includes a diagnostic survey to gather information and data to identify existing or potential sources of pollution and to determine the limnological, morphological, and other pertinent characteristics of the pond and its watershed. Diagnostic survey data is then analyzed to define methods for controlling causes of eutrophication in a Phase I feasibility study. The most cost- effective procedure to improve or preserve the quality of the pond is determined and a technical plan for implementing the restoration is developed. Phase II is the actual implementation of the recommended restoration plan. The Hardy Pond study is a Phase I Diagnostic/Feasibility study. Hardy Pond Description and Problems Hardy Pond is a Great Pond with a surface area of if approximately 42 acres, a mean depth of about 2 feet and a
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METCALF ft EDDY / maximum depth of about 4 feet. The location of the pond is shown in Figure 1-1. The pond is located in the northern section of the City of Waltham, with more than half of its watershed in the Town of Lexington. The principal inlet is an unnamed tributary entering the pond via a concrete box culvet at the northern end of the pond. The pond outlet is also at the northern end of the pond, with flows over an outlet structure into Chester Brook. Historically, Hardy Pond has been used for a variety of recreational activities. There are several public accesses to the pond, including a large recreational area abutting the south shore of the pond and an area available for public boat launching. Currently the recreational and aesthetic value of the (^ pond is severely degraded. The present problems at Hardy Pond include: Shallow depth Excessive growth of aquatic plants (macrophytes) Excessive algal blooms due to high nutrient concentrations Offensive odors due to algal blooms Degraded water quality due to release and resuspension of bottom material Exposed rock and shoreline sediments, partially due to lowered water level Deteriorated fishing due to degraded pond condition. C
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METCALF & EDDY- c
c
FT
635M
FIG 1-1. HARDY POND LOCATION
MCTC ALF B f DOT I These problems have generated an intense public concern and desire to clean up Hardy Pond. The City of Waltham successfully applied for Chapter 628 funds to conduct a Diagnostic/Feasibility study under the Clean Lakes Program. ~ Eutrophication Eutrophication is a process whereby a body of water becomes enriched with nutrients. Eutrophication is a natural process which occurs gradually and slowly. However, the process may be greatly accelerated by nutrient input from the routine activities of man when such nutrient sources as wastewater, fertilizer, decaying vegetation, and others are carried to the lake by stormwater runoff, tributaries, and the groundwater. Excess nutrient input to a lake encourages the growth of V undesirable plants and algae. Aquatic plants (macrophytes) generally thrive in shallow parts of a lake where temperatures are warm and light is plentiful. Excessive phytoplankton growth stimulated by excess nutrients causes undesirable turbidity, thus decreasing the clarity of the water body. Some algae can also cause odor problems. The dead plant material settles to the lake bottom. Decomposition of this material exerts a demand on the dissolved oxygen in the water, thereby reducing oxygen levels and discouraging fish life. Further plant growth is encouraged since decaying plant material provides more nutrients to the lake sediments and the water column. Hardy Pond exhibits signs of advanced eutrophication both in terms of phytoplankton activity .- and macrophyte growth.
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METCALF A EDDY f Report Organization The Hardy Pond Diagnostic/Feasibility Study report is organized according to major tasks conducted. These are briefly described as follows: Environmental Description (Chapter 2) - A discussion of the pond and its drainage area including morphometric features, land uses, recreational uses/ historical water quality data, and other pertinent information. Diagnostic Data Collection and Analysis (Chapter 3) - A description and analysis of a full year of limnological data, as well as other data collected such as stormwater and sediment data. Hydrologic and Nutrient Models (Chapter 4} - Hydrologic ( and nutrient "budgets" or models are calculated for the Pond. The hydrologic budget is an accounting of all contributions and losses of flow to and from the Pond, This calculation is performed to determine the major factors that affect the lake level and the flushing time. The nutrient budget calculations are used to investigate the sources of nutrients such as nitrogen and phosphorus. Both the hydrologic and nutrient budget calculations are calibrated using the available data. Restoration Alternatives (Chapter 5) - An assessment of a variety of alternatives to mitigate the existing problems of the pond was conducted using the hydrologic and nutrient budgets. Lake eutrophication can be reduced by various preventative alternatives. These include direct control by such methods as
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METCALF A EDDY / reduction of nutrients and sediments entering the lake or dredging, and indirect control by the use of herbicides or by the harvesting of aquatic plants. The latter category of controls tends to address symptoms, while the former type addresses causes. Recommended Restoration Plan (Chapter 6) - A recommended plan has been developed based on the alternatives evaluation. Selection criteria included ability to achieve restoration goals, environmental impacts, costs, available funding, and public input. For the recommended plan, a budget, work schedule, and other information has been prepared so that the restoration project can be advanced into Phase II implementation. Appendix. The appendix contains all data collected during ( the study.
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METCALF ft EDDY ( CHAPTER 2 ENVIRONMENTAL DESCRIPTION
As part of the diagnostic study of Hardy Pond, an environmental description of the pond and its drainage area has been prepared. This description is based upon both historical and new data and includes: Pond morphometry Watershed description Recreational use Historical chemical data This environmental description serves as an information source for evaluation of existing conditions and projection of future / alternatives, Morphometric Description It is reported that in 1937, the average depth in Hardy Pond was 3.4 feet. Depth soundings obtained in 1972 (Process Research, 1975) indicated that Hardy Pond was between 2 and 6.5 feet deep, with an average depth of 4.5 feet. A baseline survey conducted in 1978 (MDWPC, 1981) indicated the morphometric data in the following table:
Morphometric Data From 1978 Survey ~Area (acres)41 Maximum depth (ft) 6 Mean depth (ft) 2.7 Volume (acre-ft) 111 Maximum length (ft) 2350 Maximum width (ft) 1550
2-1 METCALF ft EDDY / The pond depths reported in these previous investigations vary somewhat, most likely due to water level fluctuations and differences in measurement locations. To verify and update this previous morphometfic information, a bathymetric survey of Hardy Pond was conducted during May, 1985. Nine transects across the pond were surveyed with depth measurements taken approximately every 100 ft. A total of 58 depth measurements were obtained. Transects were located from shoreline stations, and distances and stations across each transect were measured using a tag line anchored on shore. The results of this survey are presented in Figure 2-1 in the form of a bathymetric map. The maximum depth measured was 4 ft, with a total volume of water in the lake of approximately ( 80 acre ft. The average pond depth is 1.9 ft. The depth-volume relationship determined from this survey is presented in Figure 2-2. In addition to water depth soundings, measurements of sediment depth were obtained at each station along each transect. Sediment depth was determined by driving a one-half inch diameter metal rod by hand to refusal. From this survey it has been determined that sediment depths in the pond range from 5 to 25 feet, with the shallowest depths found closest to the shoreline. The average depth of sediment is on the order of 20 feet. Thus, over 1,000,000 cubic yards of relatively soft sediment is at the pond bottom. In 1937 it was reported that f about 750,000 cubic yards of sediment had accumulated at the pond bottom (Process Research, 1975).
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METCALF ft EDDY TRAPELO ROAD
NOTE: Water Depth Contours in F«,
nG.2., BATHYMETRIC MAP OF HARDY POND
a too* tj uU.l a. u 2 -J Q
1 -^
20 40 60 8O WATER VOLUME (ACRE-FEET)
FIG. 2-2 HARDY POND DEPTH - VOLUME RELATIONSHIP / Watershed Description General Description and Topography. The Hardy Pond watershed includes areas in both the City of Waltham and the Town of Lexington. The total drainage area upstream of Hardy Pond is estimated to be 907 acres, of which approximately 196 acres are considered marginal in that they often also contribute to another watershed (Vulgaropulos, 1978). The Hardy Pond drainage basin is shown in Figure 2-3. The main inlet to the pond is a 39 in. by 42 in. concete box conduit at the northeast corner of the pond, just off Hardy Pond Road. This conduit primarily drains the watershed area within the .Town of Lexington. In addition, numerous storm drains discharge directly into the pond during rainfall-runoff events. The locations of these storm drains are ( presented in Figure 2-4. It is also reported (Veach, 1979) that several springs feed Hardy Pond as well. The pond outlet consists of an overflow weir-type structure at the northeastern section of the pond, which drains into Chester Brook. The topography of the watershed is also shown in Figure 2-3. The terrain within the watershed is varied, with elevation varying from approximately 197 ft to 360 ft (National Geodetic Survey mean sea level datum of 1929). Most of the watershed in Lexington is residential and lowland undeveloped area, in Waltham, residential areas compose most of the drainage i area.
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METCAi-F A EDDY c
c 635M FIG. 2-3. HARDY POND DRAINAGE AREA c
800 FT
244M
FIG. 2-4 HARDY POND STORM DRAINAGE OUTLETS
IETCALF ft tDOl f . Land Use. The Hardy Pond watershed contains multiple land use areas, including single and multiple family residential areasp commercial areas, recreational land, and restricted "conservation land and easements^- Development within the - watershed area is governed by the zoning regulations of the City of Waltham and the Town of Lexington. Land use zoning within the Hardy Pond watershed was reported in Vulgaropulos (1978). The following table summarizes the percentage of the watershed that each land use classification represents.
Land Use Classification By Zoning Laws ClassificationPercent of Watershed One and two family dwellings 73 Multiple family dwellings 5 Conservation land and easements 15 ( Business 7
In addition to the land uses shown above, a small section of land in the southwest section of the drainage basin is used as farm land to raise vegetables for human consumption. A large and densely populated multiple family development (Windsor Village) borders the pond in the northeast shore. The impact of pollutant loads from these land uses is addressed in Chapters 3 and 4. Lawn fertilizers, animal wastes, roadway salts and other debris all contribute a pollutant load to the pond during rainfall runoff. Stormwater runoff sampling has been conducted to establish the characteristics of this inflow. f Results of this monitoring program are presented in Chapter 3.
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METCALFft EDDY / Soil Types. Soils mapping in the Hardy Pond drainage basin is available from the U.S. Soil Conservation Service (SCS). This information has been summarized in a previous hydrologic study of Hardy Pond (Vulgaropuloa, 1978), The soils in the drainage basin are varied, ranging from poorly drained organic muck to well drained sandy loam and stony sandy loam. The slopes of the soils in the drainage basin are also widely varied, ranging from flat lowlands to steep slopes. In general, poorly drained, mucky soils are found in the central lowlands in the upstream drainage basin and in the wetlands on the northwest shore of the pond. Steeper sloping, more well drained sandy loam soils are generally present around the perimeter of the drainage basin. C Recreational Uses Historically Hardy Pond has provided boating, fishing, skating and swimming activities for a large number of people. Several residents recall swimming in the pond during the 1930's and 1940's. Since that time the condition in Hardy Pond has degraded, and currently the recreational uses of the pond are significantly impaired. Siltation, decreased depth and increased plant growth have all contributed to the deterioration of the pond. Swimming in the pond is no longer possible, fishing and boating activities are negligible, and the aesthetic value of the pond is severely degraded. Complaints of unpleasant odors emanating from the pond are common during the summer months.
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METCALF ft EDDY s Hardy Pond has the potential to be a high quality, well used recreational resource. The available park land surrounding the pond which is presently under-utilized could become an enjoyable area in the setting of a viable^recreational body of_ _ water. With improved water quality conditions the pond could be used for boating and fishing again, and its aesthetic value would be vastly improved. It may also be possible to develop the pond as a swimming area if it is so desired and sufficient improvements can be made. Hardy Pond is located in an area of Waltham that is accessible to a large number of people by. auto or public transportation (buses). Many residents live within walking distance of the pond, and a large housing development (Windsor ( Village) is located on the east shore of the pond. Hardy Pond is abutted in many areas by city owned land providing public access to the pond. On the south shore of the pond, there is a city owned park with facilities for softball and general recreation. This parkland extends to the pond shoreline. In addition, there is public access to the pond at the end of Shore Road, Hibiscus Avenue, and Hardy Pond Road. Historical Chemical Data Data documenting conditions in Hardy Pond in the past are available from several sources. A partial listing of past data collected in the pond is presented in Table 2-1. Nutrient concentrations (phosphorus and nitrogen) measured in the past C
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METCALF a EDDY TABLE 2-1. SUMMARY OF PREVIOUS WATER QUALITY MEASUREMENTS IN HARDY POND
Wai tham Wai tham Board Board Wai tham Parameter of M . of MDWPC Conservation Health City of Walthanr1' Health Survey_ Commission 8-2-71 7-28-72 8-31-72 10-17-72 10-30-72 9-19-73 7-20-78 7-19-79 8-1-79
Nitrogen (mg/1)
- Ammonia .07 0.8 0.01 0 . 08 0 . 07
- Nitrate 0.0 .28 .23 .20 0.0 0 . 08 1.9
- Kjeldahl (TKN) 1.59 2.2 2.3 0.8 2.8 1.7 Phosphorus (mg/1) - Ortho <0.1 <0.1 0.02
- Total .44 .31 .16 .11 0.21 0.12 0.13 0.28
pH 7.0 8.2 8.2 8.0 8.8 7.7 7.0
Dissolved Oxygen {mg/1) 11 7.5 9.5 Color (std. color units) 70 222 183 86 95 109 45
solids - Fecal Coliform <5 1600 - Fecal Streptococci 270 340 From "Hardy Pond - Final Report"to the City of Waltham", Process Research, 1975 . have been high. At total phosphorus and total nitrogen concentrations greater than approximately 0,03 and 0.5 mg/1, respectively, it is often considered that eutrophic conditions -exist (Wetzel, 1975). Past measurements show that these levels are greatly exceeded in Hardy Pond. Dissolved oxygen concentrations measured in the past have indicated that very low concentrations do not occur in the pond during the daylight hours. This is due to the fact that the pond is shallow, and the water column is generally completely mixed from surface to bottom. Reaeration at the water surface and photosynthetic oxygen production both add oxygen to the water column. Additional discussion of water quality conditions in the pond and their implications is given in Chapter 3, Diagnostic ( Survey. A variety of efforts have been conducted in the past to improve conditions in Hardy Pond. A summary of these activities is presented in Table 2-2. These efforts have been successful to varying degrees. Chemical treatment and weed harvesting in general provide temporary relief from in-pond problems, but these activities must be ongoing if improved conditions in the pond are to be maintained. Recent construction of the outlet dam has resulted in a lowering of the pond level. This has helped to alleviate flooding problems, but has also resulted in reducing the lake depth and exposing bottom sediment in some areas. Alternatives for improving conditions in Hardy Pond will be presented and evaluated in Chapter 5, Assessment of Alternatives. 2-12 MCTCALFA EDDY TABLE 2-2, SUMMARY OF PREVIOUS POND C IMPROVEMENT ACTIVITIES Date Activity7 Remarks 1960 Major Sewer Construction Removal of major nutrient source 1963-1979 Chemical Treatment Various levels of chemical treatment to control summer plant growth in pond. Chemicals not applied every year. 1972 Weed Harvesting 300 cubic yards of weeds, equal to about 80 tons wet weight harvested 1973 Weed Harvesting 600 cubic yards of weeds, equal to about 160 tons wet weight removed Weed harvesting continued to 1975 1982 Construction of Outlet Part of the city's Structure and Channel flood control project. Modifications C 2-13 METCALFft EDDY *- REFERENCES Massachusetts Division of Water Pollution Control, "Baseline Water Quality Studies of Selected Lakes and Ponds in the Charles River Basin", by Michael T. Ackerman, December, 1981 Process Research Inc. "Hardy Pond - Final Report to the City of Waltham", 1979. Veach, P. "Hardy Pond: A Preliminary Report", May 14, 1979. Vulgaropulos, A. A., "Study of Hardy Pond, Waltham, Massachusetts," 1978. Wetzel, R. G., "Limnology", W. B. Saunders Company, 1975. C < 2-14 METCALF « CODY f CHAPTER 3 DIAGNOSTIC SURVEY A Phase I Diagnostic Survey of Hardy Pond has been conducted to provide baseline information on the pond and to aid in the development and evaluation of methods for improving conditions in the pond. The Diagnostic Survey includes collection of data on in-pond water quality, inlet and outlet flow and quality, stormwater runoff quantity and quality, pond bottom sediments, and macrophyte and phytoplankton growth in the pond. The data collection programs conducted are described in this Chapter, followed by a presentation and analysis of these data. Sampling techniques, sample preservation, and analytical methodology are conducted in accordance with Standard Methods and ^ EPA Methods for Chemical Analysis of Water and Wastewater. Description of Field Measurement Program A one year data collection program has been conducted at Hardy Pond from June 1984 to June, 1985. A schedule of the surveys conducted is presented in Table 3-1. The locations of monitoring stations are shown in Figure 3-1. The various data collection efforts are described in detail in the following paragraphs. In-Pond Data. Measurements were obtained at four stations at the pond. Stations 1 and 3 were located at the two inlets to the pond, and station 4 at the pond outlet. Station 2 was located in the deepest section of the pond. Data collection 3-1 METCALF & EDDY LEGEND 0 In-Pond £ Tributary and Outlet A Sediment DEPTH CONTOURS IN FEET 91M NOTE: Water Depth Contours in Feet FIG. 3-1 HARDY POND MONITORING STATIONS MCTC *LF B IODV TABLE 3-1. SCHEDULE OF SURVEYS CONDUCTED AT HARDY POND C Survey Type Date In-pond water quality June 8, 1984 In-pond water quality June 21, 1984 In-pond water quality July 2, 1984 In-pond water quality July 26, 1984 In-pond water quality August 8, 1984 In-pond water quality August 28, 1984 In-pond bottom sediments August 28, 1984 Macrophyte survey August 30, 1984 In-pond water quality September 10, 1984 In-pond water quality September 26, 1984 In-pond water quality October 11, 1984 Stormwater sampling October 22, 1984 In-pond water quality October 25, 1984 In-pond water quality November 19, 1984 In-pond water quality December 18, 1984 In-pond water quality January 17, 1985 In-pond water quality February 14, 1985 In-pond water quality March 7 and 14, 1985 In-pond water quality March 26, 1985 In-pond water quality April 16, 1985 In-pond water quality May 1, 1985 Stormwater sampling May 3, 1985 In-pond water quality May 15, 1985 C 3-3 METCALFa EDDY ( TABLE 3-1 (Continued). SCHEDULE OF SURVEYS V CONDUCTED AT HARDY POND Survey TypeDate Bathymetric and sediment survey May 14 and 30, 1985 In-pond water quality May 30, 1985 Stormwater sampling July 31, 1985 surveys were conducted twice per month during most of the survey period, and once per month during the winter months (November to February). Direct in-pond measurement of various water quality parameters was conducted using a HYDROLAB Model 4041 water quality instrument. In addition to these in situ measurements, discrete samples were collected. The parameters measured during 1 these surveys are listed in Table 3-2. At Station 2 data on the vertical variation of water quality were obtained. In situ measurements of temperature, dissolved oxygen, pH, and conductivity were taken at approximately 1-ft depth intervals. Discrete samples were taken at 20 percent and 80 percent of the total depth. Samples for coliform, chlorophyll-a and phytoplankton analyses were collected near the water surface only. Due to the shallow depth of the pond, no extended periods of temperature stratification were measured during the diagnostic survey. For an indication of water transparency, 20 cm diameter Secchi disk with alternating black and white quadrants was used to record Secchi depth (the , depth at which the disk is no longer visible). 3-4 METCAL.F A EDDY TABLE 3-2, PARAMETERS MEASURED DURING WATER QUALITY SURVEYS Measurement Detection Limit DIRECT IN-POND MEASUREMENTS Temperature ±0.1 deg C Dissolved Oxygen 0.1 mg/1 PH 0.1 unit Conductivity 1 umho/cm Secchi Disk Transparency Inflow/Outflow 0*1 cfs SAMPLES WITHDRAWN FOR LABORATORY ANALYSIS Physical-Chemical Parameters Suspended Solids 1.0 mg/1 Dissolved Solids 1.0 to 5.0 mg/1 Turbidity 0.2 NTU Chlorides 0.5 mg/1 Alkalinity 0.1 mg/1 Oil and Grease 5 mg/1 Nutrients Total Phosphorus 0.01 mg/1 Total Kjeldahl Nitrogen (TKN) 0.05 mg/1 Ammonia-Nitrogen 0.05 mg/1 Nitrate-Nitrogen 0.01 mg/1 Biological Parameters Phytoplankton Genus level Chlorophyll-a 0.1 mg/m3 Bacteria Total Coliform 1 colony/100 ml Fecal Coliform 1 colony/100 ml Metals Iron 0.03 mg/1 C 3-5 METCALF ft EDDY r Water quality measurements were obtained just downstream of the pond outlet and at the pond inlet, in addition to the water quality measurements, the flow rate entering and leaving the pond was measured. The ma in" pond inlet (Station 3) is a concrete box culvert under Hardy Pond Road, draining much of the northern section of the drainage basin. Inflow at this station was determined by measuring the depth of flow and flow velocity. At the other inlet station (Station 1) no flow was observed during the in-pond surveys except during periods of rainfall runoff. The pond outlet is controlled by an overflow structure, although on occasion the crest of this structure is submerged due to downstream backwater. Flow at the outlet is determined from depth of flow and velocity measurements at the ( weir or in the channel just downstream of the outlet. Stormwater Runoff. To determine the cause and effect relationship between nutrient input and eutrophication response of Hardy Pond, it is necessary to quantify the sources of nutrients to the pond. Source quantification requires both flows and nutrient concentrations, in order to calculate mass loadings to the pond. One of the sources of nutrient loadings to Hardy " Pond is stormwater runoff piped directly to the pond. The relative importance of stormwater runoff as a source of contaminants to Hardy Pond may be significant. Three rainfall events were monitored to assess the impact of stormwater runoff entering the pond. The stormwater subdrainage areas entering the f Pond are shown in Figure 3-2. 3-6 METCALF« EDDY INFLOW - OUTLET STRUCTURE MONITORED SUBAREA 800 FT 244M FIG. 3-2 HARDY POND STORMWATER RUNOFF BASINS / Two sites were selected for monitoring of the flow and quality of storm runoff. Site selection criteria were as follows: 1. Representative land use - based on information given previously, the predominant land uses surrounding the pond are single family residential, multi-family residential and paved roadways. 2. Accessibility for field sampling - because of the location of many of the storm drains, they can not be sampled at the outlet. Field equipment therefore must be installed in manholes. If a hydraulic backwater effect occurs, storm flow and quality can't be accurately sampled. Therefore, free flowing storm drains with unobstructed outlets to the pond were sought. The two subbasins selected for monitoring are shown in Figure 3-2. The subbasin on the south side of the pond ( represents a primarily single family residential area with a relatively low use roadway (Shore Road). The subbasin on the northeast shore of the pond is a high density, multi-family residential development (Windsor Village) with relatively high- use private roadways and parking areas. These two subbasins typify the local stormwater runoff basins within the drainage area. The data collected at these sites will be extrapolated to the remainder of the subbasins. Stormwater runoff surveys were conducted during the fall, spring and summer seasons. Discrete flow and water quality measurements were obtained at time intervals during each rainfall event so as to monitor runoff to the pond for approximately two , hours, with a total of about eight samples at each monitoring 3-8 METCALF S EDDY, I" site per storm event. The parameters analyzed are listed in Table 3-3. Flow measurements were obtained using either a portable weir or a portable flow velocity meter. Total rainfall was measured on-site during each event. TABLE 3-3. PARAMETERS MEASURED DURING STORMWATER RUNOFF SURVEYS Measurement Parameter Detection Limit Suspended solids 1.0 mg/1 Dissolved solids 1.0 to 5.0 mg/1 Total Kjeldahl nitrogen 0.05 mg/1 Ammonia nitrogen 0.05 mg/1 Nitrate nitrogen 0.01 mg/1 Total phosphorus 0.01 mg/1 Total and fecal coliform 1 colony/100 mg/1 Heavy metals I1) Chromium 0.05 mg/1 Manganese 0.01 mg/1 Iron 0.03 mg/1 ( Copper 0.02 mg/1 Zinc 0.01 mg/1 Cadmium 0.01 mg/1 Lead 0.05 mg/1 Discharge 0.01 cfs Total rainfall TlFlow weighted composite at each site. ~~ Sediment Data. Sediment samples were taken at two stations (Figure 3-1) in Hardy Pond on August 28, 1984. Samples were taken with a hand-operated, stainless steel van Veen grab sampler, transferred to bottles and preserved for transport to the laboratory. Each sample was analyzed for the parameters listed in Table 3-4. The results of the sediment analyses are presented later in this Chapter. C 3-9 METCALF ft EDDV TABLE 3-4. SEDIMENT ANALYSIS Total phosphorus Total nitrogen Organic fraction Oil and-grease — Sodium Heavy metals*1' PCB's 1. Chromium, manganese, iron, copper, zinc, cadmium, lead, arsenic, mercury, nickel, and vanadium. Macrophyte Survey, A macrophyte survey of the pond was performed on August 30, 1984 to determine areal coverage and identify dominant genera of submerged, emergent and floating aquatic macrophytes. In order to characterize any adjacent wetlands, marsh, meadow, swamp and bog, plants were also identified around the edges of the pond and in the adjacent wetlands. Distribution and abundance of identified species are presented in this Chapter in the pond biology section. The remainder of this Chapter includes presentation and discussion of the data collected during the Diagnostic Survey of Hardy Pond. The following general categories are included: Pond Hydrology Pond Water Quality Pond Biology Water Quality of Incoming Sources Pond Hydrology The Hardy Pond surface water drainage area is f approximately 907 acres. The surface area of the pond itself is 3-10 METCALF & EDDY f approximately 42 acres. As was discussed previously, the principal inlet to the pond is a box culvert under Hardy Pond Road, draining much of the area upstream of the pond. This inlet carried flow to the pond during most of the Diagnostic Survey Period. In addition, stormwater from the area surrounding the pond drains into the pond either as direct runoff or via storm drains. The bathymetry and drainage area of Hardy Pond have been discussed previously in Chapter 2. The following paragraphs present data and detailed information on the pond inflow, outflow, stormwater runoff, precipitation and evaporation. Inlet/Outlet Data. The pond inlet connects the eastern section of the drainage basin via a 39"x42" concrete box culvert ( passing under Hardy Pond Road. This pipe outlet is above the pond water level, and thus flows freely into the pond. The drainage area upstream of the inlet is approximately 640 acres, and is primarily in the Town of Lexington. From the information presented previously on land use, most of this area is composed of single family residences and undeveloped land. Discharge at the outlet is over a weir-type structure 20 ft. wide. The outlet has a 4 ft. section with slots for installation of stop-log boards. The boards can be used,to lower the pond water surface elevation. Outflow is a function of the pond level and the height of the weir board in place. The present outlet structure was built approximately 3 years ago. In connection with the construction of the new 3-11 METCALF ft EDDY r outlet structure the channel downstream of the structure was widened to provide for a greater flow capacity. These modifications were made to help alleviate flooding problems around the pond. The crest of the"concrete outlet structure Is at elevation 202 ft, Waltham datum (5.65 ft. below 1929 mean sea level datum). At elevations above approximately 204, flooding problems begin to occur (Vulgaropulos, 1978). During the Diagnostic Survey period/ no water surface levels above elevation 202.7 were observed. Due to the wide length of the outlet structure (20 ft) it has the capacity to pass a high rate of flow. However, the downstream channel at times controls the water level in the pond during high water periods. Frequently the pond water level dropped below the crest of ( the outlet structure, although a very small amount of flow can pass around the side of the structure. A summary of the inflow, outflow and lake water surface elevations measured during the Diagnostic Survey period is given in Table 3-5. Useful parameters to consider in the hydrology and water quality of the pond are the flushing rate and residence time. The flushing rate is defined as the number of times per year inflow to the pond will replace the pond's volume. The residence time is the inverse of the flushing rate, and is defined as the residence time of a conservative constituent, assuming the pond is completely mixed. High flushing rates are normally found in lakes fed by major inflow sources. The flushing rate and 3-12 METCALF A EDDY, TABLE 3-5. SUMMARY OF HARDY POND INFLOW, OUTFLOW, c AND LAKE ELEVATION MEASUREMENTS Water Inflow Outflow Surface Station 3 Station 4 Elevation Date (cfs) (cfs) in. above weir 6/8/84 1.5 3.1 7.7* 6/21/84 0.3 0.2 - 7/2/84 0.3 0.9 2.2* 7/26/84 T 3.0 -0.8** 8/8/84 2.3 0.4 ** 8/28/84 T T ** 9/10/84 1.0 0 ** 9/26/84 T 0 ** 10/11/84 T 0 ** 10/25/85 T 0 ** 11/19/84 0.5 0.5 0.2 12/18/84 0.8 0.6 2.0* 1/17/85 0.11 0.1 2/14/85 1.1 5.3 7.5— * 3/7/85 1.6 1.8 0.75* 3/14/85 - - 4.5 3/26/85 1.1 0.1 0.5 4/16/85 0.7 1.4 0.2 5/1/85 0.4 0 ** 5/15/85 T T 0 5/30/85 0.7 1.6 ** T = trickling flow, not measureable * = weir submerged by downstream channel ** = pond level below weir elevation retention time indicate how rapidly short term pollutant loads from the inlet or from other sources will be diluted and passed through the pond. Based on the bathymetric survey of Hardy Pond (presented in Chapter 2), the volume of water in the pond at normal water level is approximately 80 acre-ft. The average outflow measured during the Diagnostic Survey was approximately 0.9 cfs. Thus, the average flushing rate in the pond during this period was on C 3-13 METCALF a EDDY s the order of 8 times per year/ which corresponds to a residence time of approximately 45 days. This flushing rate is fairly high, since the volume of water in the pond is small. The pond flushing rate varies throughout the year. = Due to the proximity of the pond inlet (Station 3) to the outlet (Station 4), some of the inflow may not reach the main body of the pond. Due to this short-circuit effect, the flushing rate determined from the measured outflow measurements is most likely higher than the actual flushing rate. The average pond inflow at Station 3 during the Diagnostic Survey period was approximately 0.6 cfs. If this flow is assumed to short circuit the calculated flushing rate is reduced to approximately 3 times per year or a residence time of approximately 135 days. The ( actual annual average flushing rate at Hardy Pond most likely lies somewhere between 3 and 8 times per year. Stormwater Inflows. Much of the surface water flow to the pond occurs during rainfall events. As was presented previously, the Hardy Pond drainage area can be divided into several subareas, each of which contributes runoff to the pond. The purpose of the stormwater sampling program is to characterize the stormwater inflow to the pond from storm drains discharging directly to the pond. Two subbasins were monitored during rainfall events. From these, volumetric runoff coefficients were determined. The results of these measurements are summarized in Table 3-6. The drainage areas given in Table 3-6 do not include the direct runoff portions of the subbasins. 3-14 METCALFft EDDY TABLE 3-6. SUMMARY OF RUNOFF MEASUREMENTS c OBTAINED DURING RAINFALL EVENTS Date 5/3/85 10/22/84 7/31/85 Shore Road Subarea (2.8 acres) Total rainfall (in.) 0.30 0.75 0.38 Duration of monitoring (hrs) 2 2 1.6 Total runoff (ft3) 67 1380 470 Runoff coefficient 0.02 0,2 0.1 Windsor Village Subarea (2.9 acres) Total rainfall (in.) 0.30 0.75 0.23 Duration of monitoring (hrs) 1.8 2 1.7 Total runoff (ft3) 1050 4420 480 Runoff coefficient 0.3 0.6 0.2 The stormwater runoff measurements indicate that on the order of 2 to 20 percent of the rainfall within the Shore Road drainage basin reaches the pond as direct runoff. This drainage basin is expected to typify the single family residential area around the pond. By comparison, measurements at the Windsor Village drain indicate that between 20 to 60 percent of the total rainfall reaches the pond as direct runoff. It is expected that the runoff coefficient at this development will be higher since a greater percentage of the basin is paved, and the slope of the basin is relatively steep. Factors such as soil moisture conditions prior to rainfall and rainfall intensity during the runoff period affect the runoff coefficient as well. Precipitation and Evaporation. Hardy Pond receives an average of about 42 in. of rain per year (Vulgaropulos, 1978). Daily precipitation measurements at the nearby Chestnut Hill 3-15 METCALF ft EDDY f weather station are available from The U.S. Climatological Data Center. In addition, daily rainfall records are kept by the City of Waltham at two locations in Waltham. For purposes of defining conditions at Hardy Pond, the rainfall data collected by the City of Waltham has been used. Evaporation measurements available from the weather station at Rochester, Massachusetts have been used to estimate evaporation. These rainfall and evaporation data are used in defining the hydrologic budget for the pond (Chapter 4). Pond Water Quality The various physical, chemical, and biological measurements obtained during the Diagnostic Survey are presented in this section. A brief description of the significance of each ,. parameter is provided/ as well as specific interpretation of the data collected at Hardy Pond. The Massachusetts Water Quality Standards define Hardy Pond as a Class B water. Reference will be made to the State's Standards for those parameters for which water quality criteria have been established. A listing of all water quality measurements obtained during the Diagnostic Survey is presented in Appendix A. Due to the shallow depth of Hardy Pond the depth at which the bottom samples were taken at Station 2 was always within a foot of the bottom. The sediments were found to be soft, and small currents caused by natural events (wind) or due to the sampling process (boat oars or operation of the sampling C equipment) may have on some occassions stirred up the bottom. 3-16 METCALF A EODV introducing sediments into the water sample. Thus, solids, nutrients, alkalinity, pH and metals data from the lower layer of Station 2, which is very close to the sediment-water interface, must be considered with this factor in mind. Temperature and Dissolved Oxygen. Wide variations in water temperature occur in Hardy Pond over the course of the year due to variations in climatic conditions. Hater temperature influences a variety of biological and water quality processes, including dissolved oxygen concentrations. At colder temperatures water has the capacity to retain higher dissolved oxygen (DO) concentrations. The maximum stable DO concentration that water will retain at a given temperature is termed the saturated DO concentration. It is possible for supersaturated DO concentrations to occur, although this situation is unstable and the water will release oxygen to the atmosphere. Phytoplankton growth produces oxygen, and may cause supersaturated conditions near the water surface. The vertical variation of temperature in the water column is important for a number of reasons. Temperature affects water density, with 4 degrees Centigrade being the point of maximum density. As water temperatures increase above 4°C, density decreases. During the summer months solar radiation raises the temperature of the surface waters more readily than deeper waters, and thus a layer of warmer, less dense water may sometimes overlay the colder, denser water. 3-17 METCALF a EDDY f Mixing between the upper and lower layers of the lake is limited due to density differences. This layered effect is referred to as stratification. During periods of stratification it is possible-to develop very low. dissolved.oxygen concen- trations in the bottom waters due to sediment oxygen demand and lack of oxygen influx from the surface waters. Due to the shallow depth of Hardy Pond and the impact of wind mixing, stratification does not develop for extended periods of time in the pond. Extended periods of low dissolved oxygen are undesirable for several reasons. Fish require oxygen and several desirable game species are more sensitive to low DO than less desirable species. Also, when the DO concentration approaches zero at the ( sediment/water interface, it is possible for nutrients to be released from the sediment into the water column, thus further Stimulating plant growth. In extreme situations low dissolved oxygen concentrations (near zero) may cause offensive odors. The State water quality standard for dissolved oxygen in Hardy Pond is 5.0 mg/1, minimum. It is not uncommon to find DO concentrations below this standard near the bottom of stratified lakes with a reasonable amount of biological productivity. Temperature and dissolved oxygen profiles were measured bi-weekly from March to October and monthly during the remainder Of the year at Hardy Pond. Figure 3-3 shows the temperature and dissolved oxygen profiles measured in Hardy Pond on June 8, 1984. On this date stratification of the pond was present, and 3-18 METCALF A EDDY c TEMPERATURE (°F) 74 DISSOLVED OXYGEN (MG/U FIG. 3-3 HARDY POND TEMPERATURE AND DISSOLVED OXYGEN PROFILES C JUNE 8, 1984 f the DO concentration near the pond bottom was very low. Figure 3-4 shows the temperature and DO measurements obtained approximately 2 weeks later on June 21, 1984. On this date both the temperature and DO profiles~were fairly uniform and no - — stratification was present. This pattern of brief periods of stratification followed by periods of wind mixing and no stratification occurs in Hardy Pond during the summer months. It is likely that nutrients are released from the bottom sediments during stratified periods and introduced to the water column when wind mixing occurs and stratification is broken. Suspended Solids/ Turbidity/ and Secchi Depth. Suspended solids concentrations in the pond have varied from 1.6 to 470 mg/1. There was a definite seasonal pattern in the surface ( waters (20 percent of depth) at Station 2 as shown in Figure 3-5. Highest values (15-25 mg/1) occurred in summer and lowest values (2-6 mg/1) through winter and spring. Suspended solids at the 80 percent depth at Station 2 are shown in Figure 3-6, with the highest readings most likely caused by resuspension of the unconsolidated bottom sediments found in Hardy Pond. Turbidity, which is a measure of the clarity of the water, has ranged from 2.5 to 40 NTU {Figure 3-7). The highest turbidity measurements correspond to the highest suspended solids concentrations. Secchi depth measurements in the pond have ranged from 0.3m (1 ft) to 0.6 m (2 ft), thus showing that the clarity of the r pond water is very poor. 3-20 METCALF ft EDDY TEMPERATURE (°F| 68 70 72 74 76 78 80 82 i 1- TEMPERATURE 2- 3 - DISSOLVED OXYGEN 4- DISSOLVED OXYGEN (MG/L) FIG. 3-4 HARDY POND TEMPERATURE AND DISSOLVED OXYGEN PROFILES JUNE 21, 1984 MFTC ALT a 26.0 Q 13 cOn Q LU Q. cn 3 I(O 0.0 150 250 350 450 550 JULIAN DAY JUL AUG SEP I OCTI NOV 1 DEC JAN 1 FEB I MAR I APR I MAY 1984 1985 FIG. 3-5 SUSPENDED SOLIDS MEASUREMENTS, NEAR WATER SURFACE - STATION 2 500.0 D UPPER LAYER + LOWER LAYER 0.0 150 250 350 450 550 JULIAN DAY JUN I JUL I AUG I SEP I OCT I NOV IJA DEN IC FEB I MAR I APR I MAY 1984 1985 FIG. 3-6 SUSPENDED SOLIDS MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 80.0 70.0 D UPPER LAYER 60.0 + LOWER LAYER 50.0 40.0 - Q CD o: 30.0 - 20.0 10.0 0,0 150 250 350 450 550 JULIAN DAY JUN I JUL | AUG | SEP I .OCT I NOV I DEJAN CI FEB I MAR I APR I MAY 1984 1985 I FIG, 37 TURBIDITY MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 f Nutrients. A variety of elements are required to stimulate plant growth in a water body. Most commonly/ the elements in least supply are the nutrients nitrogen and phosphorus. Total phosphorus, nitrate-nitrogen (N03-N), ammonia nitrogen (NH3-N), and total Kjeldahl nitrogen (TKN) were measured during each in-pond water quality survey. These nutrients are present in commercial fertilizers, animal manure, septic tank seepage and phosphorus based detergents, some of which can enter the lake from the drainage basin. Available evidence suggests that when a water body develops an increase in phytoplankton and macrophyte growth as the result of pollution, it is due to the increased supply of nutrients. Although nitrogen is required in much greater quantities { for plant growth, it is most commonly phosphorus that is the limiting nutrient in lake systems. The concentration of nitrogen in most natural waters exceeds that of phosphorus by at least an order of magnitude. Some types of algae {e.g. filamentous blue green algae) are able to fix nitrogen from the atmosphere, and thus have an unlimited nitrogen source. As a general guideline, it is assumed that phosphorus limits primary productivity when the ratio of nitrogen to phosphorus is greater than 15:1 (Tsia, 1979). In Hardy Pond, however, both phosphorus and nitrogen levels are very high, and are sufficient to sustain high levels of plant growth in the pond. Due to these high nutrient levels and the turbid nature of the pond, it is most likely the limited amount of sunlight penetrating the lake that limits the growth of ^ algae in the pond. 3-25 METCALF ft EDDY f The total phosphorus measurements obtained at the in-pond station are presented in Figure 3-8. Measurements obtained in both the surface and bottom waters are presented in this _ _figure. Total phosphorus concentrations measured in the pond - have ranged from 0.014 to 1.5 mg/1. At total phosphorus concentrations greater than 0.03 mg/1, a lake may be considered eutrophic (Wetzel, 1975), and excessive plant growth may be a problem. Although this number varies for every pond based on several factors, including pond flushing rate, phosphorus loading, and type of algae, it is useful as a general guideline. As is seen from the Hardy Pond data, total phosphorus concentrations in Hardy Pond frequently exceed 0.03 mg/1 by an order of magnitude or more. The sediments of Hardy Pond are (^ expected to significantly contribute to phosphorus concentrations in the water column. As was discussed previously, intermittent periods of stratification accompanied by low bottom dissolved oxygen occur in Hardy Pond during the summer months. During these periods release of nutrients from the bottom sediments is expected to occur. Due to wind mixing, stratification does not persist for an extended time period, and released bottom nutrients are mixed to the surface waters. Also, during periods of strong winds bottom shear due to wind induced currents and waves is sufficient to resuspend the bottom sediments and mix them into the water column, thus raising nutrient levels in the pond. Both nutrient C 3-26 METCALF A EDDV 0.8 0.7 - D UPPER LAYER •f LOWER LAYER 0.6 - 3 x^ 0.5 - V) O X O.4 - Q. W O X Q. 0.3 - O 0.2 - 0.1 - 0.0 150 250 350 450 550 JUUAN DAY JUN | JUL | AUG I SEP I OCT I NOV I JADEN C1 FEB I MAR 1 APR I MAY 1984 1985 FIG. 3-8 TOTAL PHOSPHOROUS MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 f release due to low dissolved oxygen and resuspension of bottom material contribute to the high phosphorus concentrations shown in Figure 3-8. In addition to nutrient release during.periods of low - dissolved oxygen and sediment resuspension steady diffusion of phosphorus from the nutrient rich sediments occurs, and this phosphorus reaches the water surface due to wind mixing. As is shown in Figure 3-8, during the period of ice cover {mid-December to mid-March) the surface phosphorus concentration steadily decreased due to lack of wind mixing and release of bottom nutrients. The principal forms of nitrogen are ammonia, nitrate, nitrite, and organic-nitrogen. Total Kjeldahl nitrogen (TKN) ( represents the combined total of ammonia and organic nitrogen. Wetzel (1975) cites total nitrogen concentrations significantly greater than 0.5 mg/1 as being sufficient to cause eutrophic conditions. The combined ammonia, nitrate, and organic nitrogen concentrations measured in Hardy Pond are usually greater than 1.0 mg/1, thus indicating the presence of sufficient nitrogen to cause eutrophic conditions. Phytoplankton and macrophytes can utilize both nitrate and ammonia, although there is some discussion as to which is the preferred form during plant assimilation (Wetzel, 1975; Brezonik, 1972). Some types of algae (e.g. filamentous blue-green algal) are able to fix nitrogen from the atmosphere, and thus have an unlimited nitrogen source. 3-28 METCALFft EDDY *• Figure 3-9 shows the ammonia measurements obtained at Station 2. Ammonia concentrations in the pond ranged from <0.05 to 1.8 mg/1. The highest ammonia concentrations were measured during the summer months, with generally higher concentrations near the pond bottom. This is consistent with the phosphorus measurements obtained in the pond. The TKN concentrations measured at Station 2 are shown in Figure 3-10. Concentrations in the pond have ranged between 0.59 and 17 mg/1. The highest TKN concentrations were measured near the pond bottom. Surface concentrations ranged from 0.59 to 2.3 mg/1. The in-pond nitrate measurements obtained during the survey period ranged from <0.01 to 0.7 mg/1 (Figure 3-11), with similar concentrations in both the top and bottom samples. ( Alkalinity and pH. The alkalinity of a water body gives an indication of its buffering capacity, or ability to withstand changes in pH. The alkalinity of a lake is controlled to a large degree by the characteristics of its watershed. In Massachusetts, carbonate-rich watersheds (i.e. limestone regions) tend to have higher alkalinities, whereas lakes in the Cape Cod and other regions tend to have lower alkalinities. The alkalinity measurements obtained at Station 2 are shown in Figure 3-12. Measurements at this station have ranged from 13 mg/1 to 79 mg/1 as CaC03. As a general guideline, a well buffered lake has an alkalinity of 20 mg/1 or more. As is shown in Figure 3-12, the alkalinity in Hardy Pond is generally greater than 20 mg/1, and is considered to have a very good buffering 3-29 METCALF A EDDY 2.0 UPPER LAYER LOWER LAYER 9 E Izd o K 5 o 26 150 250 350 450 550 JUUAN DAY JUN | JUL ) AUG ] SEP 1 OCT 1 NOV I DEC JAN FEB MAR 1 APR MAY i 1984 1985 FIG. 3-9 AMMONIA NITROGEN MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 18.0 17.0- 16.0 - 15.0 - UPPER LAYER o 14.0 - LOWER LAYER 2E 13.0 - 12.0- Uol o 11.0 - a: 10.0 -J 9.O - X< 8.0 - o 7.0- UJ 6.0 - 5.0 - 4.0 - O 3.0 - 2.0- 1.0- 0.0 150 250 350 450 550 JULIAN DAY JUN | JUL | AUG | SEP I OCT I NOV IJA DEN IC FEB I MAR I APR I MAY 1984 1985 FIG. 3-10 TKN MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 1.2 UPPER LAYER LOWER LAYER o U 0,0 150 350 550 JULIAN DAY JUN I JUL I AUG | SEP I OCT I NOV I DEJANC I FEB I MAR APR I MAY 1984 1985 FIG. 3-11 NITRATE NITROGEN MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 80.0 70.0 D UPPER LAYER + LOWER LAYER 60.0 \ 5O.O 3 4O.O - _ZJ 30.0 - 20.0 - 10.0 - 0.0 150 250 350 450 550 JULIAN DAY JUN | JULl AUG I SEP I OCT I NOV I JADEN CI FEB I MAR I APR 1 MAY 1984 1985 FIG. 3-12 ALKALINITY MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 capacity. Because of this, the pond is not susceptible to changes in pH due to inflows and processes within the pond. The principal reason for considering a lakes alkalinity is because of"its affect on pH. Most lakes have pH values between 6 and 9. Figure 3-13 shows the pH measurements obtained at the water surface at Station 2. Measurements of pH have fluctuated within the expected natural range, thus indicating that acidification of Hardy Pond is not a problem. Coliform Bacteria. Total coliform and fecal coliform bacteria have been measured in Hardy Pond throughout the Diagnostic Survey. The State water quality standard for Hardy Pond is in terms of fecal coliform bacteria, which states that the log mean for a set of samples shall not exceed 200 per 100 ml. This standard is for primary contact recreation (i.e. swimming). The fecal coliform measurements obtained at Hardy Pond Station 2 are shown in Figure 3-14. The data indicates that with the exception of a brief period in March, 1985, the in-pond fecal coliform concentrations were well below 200 and violation of the water quality standard is not indicated. Thus, swimming in Hardy Pond is generally not restricted due to high concentrations of bacteria, but rather due to other problems in the pond (i.e. mud bottom, excessive plant growth, odors). Metals. Iron concentration has been measured at Hardy Pond throughout the Diagnostic Survey. Figure 3-15 shows the iron measurements obtained to date in the pond, with values 3-34 METCALFA EDDY' 10 9 - 8 - 7 - 6 - 150 250 350 450 550 JULIAN DAY JUN | JUL | AUG I SEP | OCT I NOV I JADEN CI FEB I MAR I APR I MAY 1984 1985 FIG. 3-13 pH MEASUREMENTS NEAR WATER SURFACE - STATION 2 300.0 WATER QUALITY STANDARD £ 140.0H uO 1 20.0 - g_j 100.0- uUJ. 15O 350 550 JUUAN DAY JUN | JUL I AUG | SEP I OCT I NOV I DEJANC I FEB I MAR I APR I MAY 1984 1985 {: FIG. 3-14 FECAL COLIFORM MEASUREMENTS, WATER SURFACE - STATION 2 12.0 UPPER LAYER LOWER LAYER o z o 0£ 0.0 150 250 350 450 550 JULIAN DAY JUN I JUL | AUG I SEP I OCT I NOV I JADEN C1 FEB I MAR I APR I MAY 1884 1985 FIG. 3-15 IRON MEASUREMENTS, SURFACE AND BOTTOM - STATION 2 / ranging from <0.03 mgl/ to 12 mg/1, with one outlying value of 23 mg/1 measured near the pond bottom. These iron measurements are fairly high, and are indicative of the presence of dissolved organic matter. An enrichment" of iron is commonly found in surface waters with a high content of dissolved organic matter (Wetzel, 1975). Decomposition of plant materials releases colored organic substances commonly referred for as humic substances. Humic substances have the ability to combine with and bind metal ions, including iron, therby maintaining a higher concentration of the metal in the water body. Past color measurements in Hardy Pond have been high, ranging from 45 to 222 standard color units (Table 2-1), which is characteristic of waters containing humic substances. Thus, the high iron (^ concentrations measured in Hardy Pond may be attributed to the high content of dissolved organic matter in the pond* The spike increases in bottom water iron concentration shown in Figure 3-15 generally correspond to the highest phosphorus concentrations. During periods of low dissolved oxygen both phosphorus and iron may be released from the bottom sediments. Thus, the highest iron concentrations are attributed to either sediment release or sediment resuspension. Oil and Grease. Oil and grease measurements were obtained at the water surface at Station 2 throughout the Diagnostic Survey. All measurements indicated concentrations below the analytical detection limit of 5 mg/1, with the exception of one , sample on May 1, 1985, when a concentration of 13 mg/1 was found. 3-38 METCALF A EDDY ( Pond Biology Freshwater, or lentic ecosystems, are characterized by standing water habitats and associated communities of living organisms. Lentic ecosystems can be subdivided into vertical and horizontal strata based on photosynthetic activity. The littoral or shallow water zone is the near shore zone in which light penetrates to the bottom. This area is occupied by rooted aquatic plants such as waterlilies, rushes and sedges. Beyond this is the limnetic or open water zone, which extends to the depth of effective light penetration. It is inhabited by plant and animal plankton and the nekton or free swimming organisms such as fish which are capable of moving about voluntarily. Beyond the depth of effective light penetration is the profundal ^ zone, which depends on organic material settling from the limnetic zone as an energy source. Common to both the profundal zone and the littoral zone is the benthic zone, or bottom region, which is the zone of decomposition of settled organic material. The following discussion focuses on the biological life in Hardy Pond, including phytoplankton (floating, microscopic algae) which inhabit the littoral and limnetic zones, aquatic macrophytes (rooted, aquatic plants) which inhabit the littoral zone and the fishes or nekton which inhabit all zones of lentic environments. Phytoplankton. The most fundamental level of the food web of Hardy Pond is occupied by phytoplankton which incorporate sunlight and nutrients to form plant matter. They are f photosynthetic, non-vascular, free-floating plants that exist as 3-39 METCALF A EDOV V single cells, colonies or filaments. A number of factors affect their distribution and abundance including concentrations of nutrients (nitrogen and phosphorus), penetration and intensity of light, and various physical and chemical interactions. The lower limit of phytoplankton distribution is known as the compensation depth, or the depth at which phytoplankton photosynthesis and respiration rates are equivalent. Qualitative and quantitative knowledge of the organisms growing in an ecosystem is a valuable indicator of environmental stress and in the case of Hardy Pond, trophic state. Trophic state is the stage of nutrient enrichment of a water body. The three basic trophic states that may exist in a lake are oligotrophic, in which the water body is low in nutrients, algae, ( and may be well oxygenated; eutrophic, the state which is rich in plant nutrients, algae and aquatic macrophyte growth, and in which the hypolimnion may be deficient in dissolved oxygen; and mesotrophic, the stage between oligotrophic and eutrophic. Phytoplankton biomass and its composition in general, as well as species in particularr are perhaps the best indicators of water quality and trophic condition of a lake (Vollenweider, 1974). This is because certain species are better adapted to compete under increased nutrient conditions, resulting in changes in community composition. Thus, specific algal associations may be indicative of eutrophic conditions. Excessive phytoplankton concentrations can cause adverse DO impacts such as (a) wide ( diurnal variation in surface DO due to daytime photosynthetic 3-40 METCALP ft EDDY V oxygen production and nighttime oxygen depletion by respiration and (b) depletion of bottom DO through the decomposition of dead algal and other organic matter. Excessive algal growth may also result in shading which reduces light penetration in the water (EPA, 1984). Phytoplankton samples were collected during each water quality sampling. Thus, a year-round survey of population trends is possible. Samples were collected in the pond at station 2. Concentrations of chlorophyll a, the principle photosynthetic pigment in algae and vascular plants, can provide an indication of phytoplankton biomass. Chlorophyll a samples were also collected during each in-pond sampling. Figure 3-16 illustrates chlorophyll a trends during the measurement period. Chlorophyll-a is a good indicator of algal" concentrations and of nutrient over enrichment. Chlorophyll a concentrations ranged from <1 to 60 ug/1. Readings approached 40 in August and reached 60 in September while phytoplankton counts were highest. Readings above 10 ug/1 are often evidence of eutrophic conditions, and concentrations in Hardy Pond often exceed this level. Phytoplankton species identified are presented in Table 3-7. Pennate diatoms were found but have not been addressed in community analysis because they are periphytic or benthic and do not naturally occur in the water column. Organisms grouped under "unidentified coccoid" and "unidentified £ flagellates" could not be identified to genus because of 3-41 METCALFft EDDY 70.0 60.0 - iK) 50.0 40.0 - aX. 30.0 -H o sK oX 20.0 -H 10.0 - 0.0 -|-B 150 250 350 450 550 JULIAN DAY JUN | JUL f AUG | SEP I OCT I NOV I JADEN CI FEB I MAR I APR I MAY 1984 1985 ! FIG. 3-16 CHlOROPHYLL-a MEASUREMENTS , WATER SURFACE - STATION 2 TABLE 3-7. PHYTOPLANKTON TAXA OF HARDY POND FROM JUNE 1984 TO JUNE 1985 Cyanophyta (Blue Green Algae): Anabaena Aphanocapsa Merismopedia Oscillatoria Chlorophyta (Green Algae): Ankistrodesmus Closterium Pediastrum Scenedesmus Staurastrum Tetraedron Unid. coccoid Chrysophyta (Golden Brown Algae) Dinobryon Bacillariophyceae (Diatoms): Asterionella Misc. Pennate Diatoms Synedra Centric diatoms Pyrrophyta (Dinoflagellates) Peridinium Miscellaneous: Unid. Nanoplankton Unid. flagellates Euglenophyta Euglena Trachelomonas Crypyomonas complications arising from their classification, preservation, size or lack of internal cell structure. The phytoplankton of Hardy Pond are subject to strong seasonal influences due to the great contrast between summer and c winter in the temperate climate of Massachusetts. In general the 3-43 METCAUF a EDDY ( successional seasonal pattern of phytoplankton is reasonably constant from year to year if not perturbed by outside influences such as the activities of man in the watershed and nutrient "loading. "Under perturbed conditions components of the phytoplankton community may shift to opportunistic or pioneer species which may be able to tolerate or even capitali2e on polluted conditions. The presence of these "indicator" species will be addressed later in this section. The most obvious features of the seasonal cycle at Hardy Pond are major shifts in taxonomic composition. A taxonomic list of all genera of phytoplankton identified in samples taken from Hardy Pond is presented in Table 3-7. During the winter Cryptophyta of the genus Cryptomonas and diatoms V (Bacillariophyta) of the genus Asterionella and unidentified centric forms were most common. Diatoms like Asterionella were still abundant in spring with green algae (Chlorophyta) of the genera Scenedesmusr Closterium, Pediastrum and Staurastrum, increasing in numbers. Summer phytoplankton communities shifted to dominance of blue-green algae (Cyanophyta) such as Anabaena, Aphanocapsa, Anacystis, and Oscillatoria. A significant bloom of blue-green algae with cell counts of 11,574 cells per milliliter was found during August, 1984. Accompanying the blue-greens during summer were species of green algae and unidentified centric diatoms. Seasonal patterns of phytoplankton populations can be /" quantified by cell density per unit volume and changes in 3-44 METCALFft EDDY ( taxonomic composition by percent of phyla of phytoplankton. Total cell densities from June 1984 to June 1985 are presented in Figure 3-17. Summer maximum and decline are the most obvious characteristics with cell density peaking in late July at about 220,000 cells per milliliter. Peaks like this typically occur when nutrients loads or from sources such as stormwater or sediments are input. When these nutrients are depleted, populations decline rapidly as they did in Hardy Pond (Figure 3-17). Cell densities were moderate to high during the rest of the year with cell densities of about 1,000-10,000 cells per milliliter. Changes in taxonomic composition from 1984 to 1985 at in- pond Station 2 are shown in Figure 3-18. In this diagram it is ^ important to note vertical composition rather than vertical position since the horizontal represents only the percent composition of the community. For example, in Figure 3-18 it is easy to see how dominance of blue-green algae is replaced by Cryptophyta. It is known that certain species can tolerate or even capitalize on environmental disturbances. Major changes resulting in increased nutrient availability can produce major reorganizations of phytoplankton communities. Those species indigenous to the pond may be replaced by species indicative of polluted conditions. By comparing phytoplankton species found in Hardy Pond with lists of pollution tolerant/intolerant genera it f is possible to get an indication of its trophic state. Palmer 3-45 METCALF A EDDY 140 Ul O S3 It Q. O 150 250 350 450 550 JULIAN DAY JUN | JUt I AUG | SEP I OCT I NOV I DEJANC I FEE I MAR I APR 1 MAY 1984 1985 FIG. 3-17 PHYTOPLANKTON DENSITY NEAR WATER SURFACE - STATION 2 JULY OCT JAN APRIL I 1 CRYPTOPHYTES SHHBM BLUE-GREENS IniiTiiii.iiiiMj GREENS II DINOFLAGELLATES DIATOMS FIG. 3-18 SEASONAL VARIATION OF PHYTOPLANKTON TAXONOMIC COMPOSITION IN HARDY POND, STATION 2 s (1969) developed a list of pollution tolerant genera by compiling information in 269 reports by 165 authors (Table 3-8). A score of 1 or 2 points was given to each algae reported by an author as tolerating organic enrichment, the 'larger figure being reserved for the algae that an author emphasized as being typical of waters with high organic pollution. Palmer's genus index has been criticized because the reports used address only organic pollution. Nevertheless, it does provide an indication of relative tolerance to pollution. Several genera found in Hardy Pond are listed in Palmer's Index of Pollution Tolerant Algae. Euglena, which is ranked as the genus most indicative of polluted conditions, was found in Hardy Pond in March. Oscillatoria, ranked second, was the major (^ genus contributing to blooms of blue-green algae in the summer an<3 fall. Soenedesmus, ranked fourth, appeared throughout the entire .season, and was the main component of green algae present in the summer. Numerous other genera on Palmer's Genus Index such as Closterium, Anacystis, Anabaena, Pediastrum, Trachelomonas, and Asterionella, are also found in Hardy Pond. It is important to note that a large segment of the phytoplankton community has been omitted from the analysis to this point. During summer, concentrations of an unidentified nanoplankton and flagellates rose to over 200,000 cells per milliliter on several occasions and were consistently over 70,000 cells per milliliter for the entire season. Since these cells would make overall - community analysis difficult, they will be dealt with separately. 3-48 METCALF a EDDY Table 3-8. Pollution-Tolerant Genera of Algae List of the 60 Most Tolerant Genera In Order of Decreasing Emphasis by 165 Authorities NO. Total NO. Genus Group* authors Points 1 EugUna F 97 172 2 OftclMatoHa 8 93 161 3 CMaaydMonas F 68 115 4 Seen* 6e sous G 70 112 5 ChlortlU G 60 103 6 NltzcMa D 58 98 7 Navlcula D 61 92 8 Stlgeoclonlui G 50 69 9 Snyntdra 0 44 58 10 Anktttrodesftjs G 36 57 11 Phacus F 39 57 12 PhonridluB 8 37 52 13 Ntl os Ira 0 37 51 14 GoophonMu 0 35 48 15 Cyclotalla D 35 47 16 ClQSterlun G 34 45 17 Mlcractlnlua G 27 44 18 Pandortna F 32 42 19 Anacystl s 8 28 39 20 LepKlnclls F 25 38 21 Splrogyra G 26 37 22 Anabaana - 6 27 36 23 Cryptoaonas F 27 36 24 Pedlastrui G 28 35 25 Arthrosplra 8 18 34 26 Tracnttoaonas F 26 34 27 Carttrla F 21 33 28 Chlorogonli* F 23 39 29 Fragtlarla D 24 33 30 Ulothrlx G 25 33 31 Surlralla 0 27 33 32 Stephanodlscus 0 22 32 33 EudoHna F 23 30 34 Lyngbya 8 17 28 35 Oocyttls G 20 28 36 AgMntlluB 8 19 27 37 Splrulfna 8 17 25 38 Pyrobotrys F 16 24 39 Cy»b«lla D 19 24 40 Actlnastri* G 20 41 Coelastrui G 21 42 Cladophora G 22 24 43 Hantzschla 0 18 44 Dlatoau D 19 45 Spontyloaorun F 16 46 Golenklnla G 14 19 47 Achnanthas D 16 19 Synura F 14 18 49 Plnnularla o 15 SO Chlorococcm ^G 13 17 51 Asttrlontlla 0 14 17 52 CoccontU 0 14 17 53 Conarluai . G 14 17 54 Gonlua) ^ F IS 17 55 TrlbontM G 10 16 55 Stauromfi 0 14 16 57 SeltMitruai G 13 IS 58 Olctyosphaanm G 11 14 59 Cy«atop1tura D 13 14 60 Cructgtnfa G 13 14 Droops: 8. blut-grttn; 0. tft«to*; F. flagctt't*; G, frttn. SOURCE: Palwr. 1969. 3-49 MfTCAL* • tOOV (^ In the identification of phytoplankton cells, problems often arise from preservation methods, lack of recognizable internal structure of the cells, or that the cells have not been identified in the scientific literature. These unidentified cells in Hardy Pond may be individual cells of blue-green algae (which usually exist as colonies), large bacteria cells, or chloroplasts from decomposing vascular vegetation. In the case of Hardy Pond these nanoplankton are probably broken up colonies of blue-green algae, perhaps of the genus Anacystis or Microcystis. Peak abundance of these unidentified cells was concurrent with identified forms of blue-green algae. These cells must be considered as an indication of eutrophic conditions in Hardy pond to their possible identity as blue-green algae and ^ extremely high numbers. Aquatic Macrophytes. Aquatic plants play a variety of roles in lake ecosystems. They produce oxygen through photosynthesis, shade sediments and provide food and habitat for microbes, insects and fish. Although aquatic macrophytes are vital to the ecosystem, eutrophication and the subsequent overgrowth of plants may be detrimental to the water body. Oxygen depletion in the hypolimnion may be caused by decaying macrophytes. Low DO may cause fish kills and eliminate sensitive species (Boyd, 1971). The aquatic macrophytes of Hardy Pond were surveyed on August 30, 1984 by Metcalf & Eddy. Figure 3-19 depicts the areal / distribution of floating, submerged and emergent vascular plants found during this survey. 3-50 METCALF A EDDY c LEGEND PV - Potomogeton vaginatus (submerged aquatic) NO • Nuphar odorata NV - Nuphar variegatum SA - Sagittaria (atifolia PC - Pontederia cordata DEPTH CONTOURS IN FEET c 91M NOTE: Water Depth Contours in Feet FIG. 3-19 HARDY POND MACROPHYTE SURVEY MCTCALF » COOV Despite the shallowness of the Pond there was a paucity of submerged aquatic plants. This is largely attributable to the lack of light penetration due to high turbidity and background color rather than the absence of nutrients. The dominant submerged aquatic plant was bigsheath pondweed (Potomogeton vaginatus). These were chiefly found in the southwestern portion of the Pond, near the inlet. Two species of rooted floating-leaved aquatics were identified. Patches of fragrant water lilly (Nuphar odorata) occurred throughout the Pond, while the bullhead lilly (Nuphar variegatum) was prominant in the northeastern portion of the Pond near Hardy Pond and Trapelo Road. These plants were generally restricted to areas where water depth did not exceed 3 to 4 feet. ( The lesser duckweed (Lemna minor), a small floating-leaved aquatic plant occurred in small patches on the water surface, where the wind had driven it towards shore. Extensive marshland was found around the periphery of the pond. Several areas near Shore Road were characterized by small but thick stands of emergent plants such as cattails (Typha latifolia). Cattails are a valuable plant for nesting, cover and breeding of waterfoul and fur-bearing mammals and rodents. Other emergents that occurred sporadically throughout the pond included broad-leaved arrowheads (Sagittaria latifolia). Purple loosestrife (Lythrum salicaria) which is considered indicative of human disturbance, and is of minimal value as wildlife habitat, is also found at Hardy Pond. C 3-52 METCALF A EDDY v Surrounding the entire northwest corner of the pond is a thick wetland areas of rushes, sedges and higher plants and trees closer to Hardy Pond Road. Fisheries. As with the plankton, the presence or absence of certain fish species can give an indication of trophic state. Initially, eutrophication and the subsequent abundance of food organisms may cause increased growth of fish. However, undesirable conditions of temperature and dissolved oxygen in later stages force some fish to leave the affected area or perish. Fish commonly respond to changes associated with eutrophication by shifting their horizontal and vertical distribution. Some fish may be forced to move from the littoral zone to the limnetic zone where they are not usually found. ' Coldwater fishes may be forced into the thin metalimnion between the oxygen.deficient hyplimnion and the warm epilimnion causing mortalities. As eutrophication proceeds, there is a general pattern of change in fish populations toward coarse fish. Eutrophic lakes typically support species of bass, crappies, sunfish and catfish. The fisheries resources of Hardy Pond include few species. Some of the species found such as pumpkinseed, bluegill, yellow perch and largemouth bass may be considered typical of nutrient enriched conditions. Water Quality of Incoming Sources A variety of sources enter Hardy Pond, several of which f have a pollutant load associated with them. Water quality 3-53 METCALFa EDDY ( measurements have been obtained at the pond inlet and at V stormwater drains. Samples of the pond bottom sediments have been collected to determine the potential for an influx of pollutanta from the sediments into the water column. The water quality data collected at these influent sources are presented in the following paragraphs. Inlet Measurements. As was presented previously, flow has been measured at the inlet culvert under Hardy Pond Road (Station 3) throughout the Diagnostic Survey. The total phosphorus measurements obtained at Station 3 are shown in Figure 3-20. Phosphorus measurements at this location have varied from 0.02 to 0.17 mg/1. Frequently the phosphorus measurements obtained at this station are less than those (, measured at the in-pond station. The ammonia measurements obtained at Station 3 are shown in Figure 3-21. Ammonia concentrations at the inlet have varied from <0.01 to 0.9 mg/1. This is generally within the same range as the measurements obtained near the water surface in the pond. Nitrate measurements obtained at the inlet (Figure 3-22) ranged from <0.01 to 2.0 mg/1. The concentrations measured at the inlet were generally higher than the in pond nitrate concentrations. The suspended solids concentrations measured at Station 3 are shown in Figure 3-23, with values ranging from 1 to 38 mg/1. With the exception of 3 measurements, all inlet C suspended solids concentrations were less than 15 mg/1. The 3-54 MCTCALF ft EDDY 0.20 0.19 - 0.18- 0.17 - 0.16- If 0.15- o 0.14- 0.13 - en 0.12 - 1o3: o 0.11 - i 0.10 - QL W 0.09 - O X 0.08 - Q. 0.07 - 0.06- 0.05- 0.04- 0.03- 0.02- 0.01 - 0.00 150 250 350 450 550 JULIAN DAY JUN | JUL I AUG I SEP I OCT I NOV IJA DEN CI FEB IMAR I APR MAY 1984 1985 FIG. 3-20 TOTAL PHOSPHOROUS MEASUREMENTS AT INLET - STATION 3 2.0 1.9 -i 1.8 - 1.7 - 1.6 - 1.5 - O) 1.4- E 1.3 -^ z 1.2 - UJ O 1.1 - O a: 1.0 - H- 0.9 - 0.8 - 0.7 - 0.6 - 0.5 - 0.4 - 0.3 - 0.2 - 0.1 - 0.0 150 250 350 450 550 JULIAN DAY JUN | JUL I AUG SEIP I OCT1 NOV I DEC JAN I FEB I MAR I APRMAY 1984 1985 FIG. 3-21 AMMONIA NITROGEN MEASUREMENTS AT INLET - STATION 3 1.2 1.1 - o 0.0 150 250 350 450 550 JUUAN DAY JUN | JUL | AUG I SEP iToCT I NOV \ JADEN C1 FEB I MAR I APR I MAY 1984 1985 FIG, 3-22 NITRATE NITROGEN MEASUREMENTS AT INLET - STATION 3 40.O 35.0 - o 30.0 10 25.0 Q LJ 20.0 O LU O. tn 15,0 13 10.0 5.0 0.0 150 250 350 450 550 JULIAN DAY JUN lJUL | AUG I SEP I OCT | NOV I DEJANC I FEB I MAR I APR I MAY 1984 1985 FIG. 3-23 SUSPENDED SOLIDS MEASUREMENTS AT INLET - STATION 3 / total load of nutrients entering Hardy Pond at the Station 3 inlet are quantified and are presented in Chapter 4. Fecal coliform concentrations measured at Station 3 are presented in Figure 3-24, On several occasions the influent fecal coliform concentration was above 200 per 100 ml, which is higher than the fecal coliform level normally measured in the pond. Due to the dilution of flow entering the pond and coliform die-off, violation of the fecal coliform water quality standard is not caused in the main body of the pond due to the inlet flows. Stormwater Data. Three rainfall events were monitored at two storm drains entering Hardy Pond. During each event the "first flush", or initial runoff has been sampled. In general, ( the highest pollutant concentrations occurred near the beginning of runoff, with concentrations frequently decreasing with time. A complete listing of the stormwater data collected is given in Appendix A. A summary of the flow weighted average concentrations of the various parameters measured is provided in Table 3-9. Results from the July 31, 1985 sampling are unavailable at the present time, and will be provided in the Final Report. The nutrient concentrations in the stormwater runoff in general exceed in-pond nutrient concentrations. In particular, the stormwater total phosphorus concentrations are significantly higher than the in-pond levels. The average nutrient C 3-59 METCALF a eoor 500.0 400.0 - 2 o o ** 300.0 - sft: O 200.0 O -1 U3J li. 100.0 - 0.0 150 250 350 450 550 JULIAN DAY JUN I JUL | AUG I SEP I OCT I NOV I DEJANC I FEB I MAR I APR I MAY 1984 1985 FIG. 3-24 FECAL COLIFORM MEASUREMENTS AT INLET - STATION 3 TABLE 3-9. SUMMARY OF FLOW WEIGHTED AVERAGE CONCENTRATIONS MEASURED DURING STORMWATER MONITORING Windsor Parameter Shore Road Basin Village Basin 10/22/84 5/3/85 7/31/85 10/22/84 5/3/85 7/31/85 Suspended Solids (mg/1) 53 92 54 52 60 47 Total Dissolved Solids (mg/1) 30 68 34 34 66 32 Ammonia Nitrogen (mg/1) 0.5 0.5 2.1 0.3 1.2 0.8 Total Kjeldahl Nitrogen (mg/1) 1.0 0.8 0.3 1.3 2.8 0.3 Nitrate Nitrogen (mg/1) 0.5 0.3 0.7 0.4 0.2 0.8 Total Phosphorus (mg/1) 0.2 0.6 0.2 0.4 0.3 0.1 Total Coliform (No/lOOml) 190,000 10,000 116,000 18,000 700,000 34,000 Fecal Coliform (No/lOOml) 3,900 <100 9,900 1,800 400 5,400 Chromium (mg/1 ) <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Manganese (mg/1) 0.024 0.061 0.11 0.056 0.036 0.028 Iron (mg/1) 1.4 1.7 2.4 2.8 2.0 1.5 Copper (mg/1) <0.02 0.026 <0.02 <0.02 0.026 <0.02 Zinc (mg/1) 0.08 0.045 0.12 0.33 0.05 0.13 Cadmium (mg/1) <0.01 <0.01 <0.005 <0.01 <0.01 <0.005 Lead (mg/1) <0.1 0.25 <0.1 <0.1 0.12 <0.1 1. Heavy metals concentrations are from flow composited samples. concentrations measured at the storm drains have been similar at both drains during both storms. The coliform concentrations entering the pond in the stormwater are much higher than the in-pond concentrations, but are generally within the normal range expected in stormwater (104-105 per 100 ml). Although many of the pollutant concentrations measured in the stormwater are high, the pollutant loads entering the pond 3-61 METCALFa EDDY and associated water quality impacts are dependent on the total runoff volume, and will vary significantly from one event to the next. This is taken into consideration when modeling the ponds nutrient budget, as presented in Chapter 4. Bottom Sediments. Sediment samples were collected at two in-lake stations in Hardy Pond (Figure 3-1). The results of the analyses of these samples are presented in Table 3-10. A complete discussion of the classification of the Hardy Pond sediments in terms of suitability for dredging is presented in Chapter 6. 3-62 MET CALF • EDDY TABLE 3-10. HARD* POND SEDIMENT SAMPLING RESULTS Sediment Station 1 Sediment Station 2 Total Solids (%) 7.2 6.2 Total Volatile Solids (% Total Solids) 48.9 54.6 Total Kjeldahl Nitrogen (mg/kg) 1500 1400 Total Phosphorus (mg/kg) 1.7 0.48 Chromium (mg/kg) 1.6 1.9 Manganese (mg/kg) 190 200 Iron (mg/kg) 1000 1400 Copper (mg/kg) 4.4 6.8 Zinc (mg/kg) 27 49 Cadmium (mg/kg) <0.1 <0.1 Lead (mg/kg) 12 18 Arsenic (mg/kg) 7.6 15 Mercury (mg/kg) 0.62 0.73 Nickel (mg/kg) 0.08 1.7 Vanadium (mg/kg) <4 <4 Sodium (mg/kg) 230 120 Oil and Grease (% of Solids) 8.3 11 PCBs (Aroclor 1221, 1232, 1016, 1242, 1248, 1254, 1260, 1262 ND(Z' ND<2> 1. Samples collected on August 29, 1984 2. None detected. Detection limit 0.05 mg/kg. 3-63 METCALFa EDDY REFERENCES Belding, D. L., A Report Upon the Alewife Fisheries of Massachusetts, Division of Fisheries and Game Department, 1914. Bertin, Leon, Eels, A Biological Study, Philosophical Library, Inc., N.Y.7. Eels, A Biological Study, Leon Bertin, Philosophical Library, Inc., N.Y. Bigelow, H.R. and W.C. Schroeder, Fishes of The Gulf of Maine, Fishery Bulletin of The Fish and Wildlife Service, Vol. 53, 1953. Brezonik, P.L., Nitrogen: Sources and Transformations in Natural Waters, in Nutrients in Natural Waters, H.E. Allen and J.R. Kramer, editors, Wiley and Sons, 1972. Brater, E.F and King, H.W., Handbook of Hydraulics, McGraw-Hill, Inc., 1963. Carlson R.E. 1977 A Trophic State for Lakes Limnology and Oceanography, 22, No.2, pp. 361-369. Environmental Protection Agency 1984 Technical Support Manual: Waterbody Surveys and Assessments for Conducting Use Attainability Analyses Volume III: Lake Systems. Fahay, Michael J., Biological & Fisheries Data on American Eel, Anguilla rostrata. August, 1978. Frey, D.G. Ed. 1963. Limnology of North America. The University of Wisconsin Press. Goldman, C.R. and A.J. Home, 1983. Limnology. McGraw-Hill, Inc. Hormark, P. and M. Hutchins, 1978. Input/Output Models as Decision Criteria for Lake Restoration Technical Completion Report Project C-7232, Land and Water Resources Institute, University of Maine at Orono. Hutchinson, G.E., 1973. Eutrophication 61:269 In: Skinner B.J. 1981 Use and Misuse of Earth's Surface, The Scientific Research Society, Inc. Lagler,K.F., J.E. Bordach, R.R. Miller,Icthyology. John Wiley & Sons, Inc., N.Y. 1962. C 3-64 METCALF ft EDDY REFERENCES (Continued) Eels, A Natural and Unnatural History, Christopher Moriarty, Universe Books, NY, 1982. National Academy of Science and National Academy oC Engineering, Water Quality Criteria. A Report of the Committee on Water Quality Criteria, Washington, D.C. 1972. National Academy of Sciences, 1969. Eutrophication: Causes, Consequences, Correctives. NOAA, National Climatological Data Center, Climatological Data for New England. Norotny, V., and Chesters, G. Handbook of Nonpoint Pollution, Sources and Management Van Reinhold Company, New York, 1981. Palmer, C.M. A Composite Rating of Algae Tolerating Organic Pollution. Journal of Phychology, 5: 78-82. Rost, T.L. et al. 1979. Botany. John Wiley & Sons, Inc. Smith, R.L. 1980. Ecology and Field Biology, Third Edition. Harper & Row, Publishers, New York. Tsia, K.-C. and Ju-Chang Huang, "P, N and C Head the Critical List," Water and Wastes Engineering, April 1979. US Environmental Protection Agency. The Relationships of Phosphorus and Nitrogen to the Trophic State of Northeast and North-Central Lakes and Reservoirs National Eutrophication Survey Working Paper No. 23. Vollenweider, R.A., M. Munawar and P. Stadelmann, 1974. A comparative review of phytoplankton and primary production in The Laurentian Great Lakes. J. Fish. Res. Board Can. 31:739- 762. Wetzel, R.G., 1975. Limnology. Saunders College Publishing/ Holt, Rinehart and Winston. Whittaker, R.H., 1975. Communities and Ecosystems, Second Edition, MacMillan Publishing Co., Inc., New York, N.Y. C 3-65 METCALF * EDDY ( CHAPTER 4 ASSESSMENT OF EXISTING CONDITIONS In this Chapter, the available data described in Chapter 3 are utilized to prepare lake "budgets" or models. The purpose of these budgets is to mathematically define the time-varying inputs of flow and pollutant loads to Hardy Pond and to calculate the response of the pond to these inputs. Once these models are established for existing, conditions, they are used in subsequent Chapters as a basis for projections of impacts associated with lake restoration alternatives in Hardy Pond. Assessment of Trophic State Trophic state assessments attempt to relate physical ^ features of lakes, such as depth and flushing rate, with nutrient input to the lake using empirical correlations. By comparing characteristics of large numbers of lakes and developing correlations, a projection is made of the conditions in other lakes. Trophic state assessments began with Vollenweider (1968) and have been improved by many others (for example Dillon (1974) and Kirchner and Dillon (1975)) to account for additional factors which affect the eutrophication of lakes. As pointed out by Snow & DiGiano (1976) and others (Najarian, 1981), however, there are several drawbacks to these methods including: 1. They do not apply to all lakes since the methods are c empirical. 4-1 METCALF a EDDY. f 2. The time varying nature of the eutrophication process, v- for example the response time of a lake to a change in loading, is ignored. 3. Effects of individual processes are combined though they may not be interrelated. However, as a rough estimate, the trophic state assessments are useful and are widely used. The trophic state of Hardy Pond is shown in Figure 4-1. According to this calculation, which is based on the method of Vollenweider (1975) Hardy Pond is in a eutrophic state. This is in agreement with the in-pond quality data discussed in Chapter 3. There is sufficient phosphorus and nitrogen in the lake to support growth of algae and aquatic weeds, which is verified by the nutrient and algae data and macrophyte mapping. (^ The calculations used to define Figure 4-1 are based on approximations of the total phosphorus loading to Hardy Pond from external sources, the flow through the pond, and the pond bathymetry. The principal sources of external phosphorus loading to the pond are inlet flow, stormwater runoff, and direct precipitation. A summary of the calculated external phosphorus loads entering the pond is given in Table 4-1. Additional discussion of these loading sources follows. Measurements of total phosphorus at the storm drains ranged from 0.2 to 0.6 mg/1, on a flow weighted average basis. The runoff coefficient from the single family residential sections of the stormwater drainage basin is estimated as 0.1, ^ based on runoff measurements to date. A higher runoff 4-2 METCALF a EDDY c EUTROPHIC TOTAL LOAD cc < UJ 1.0- EXTERNAL LOADS ONLY z o tn O^ cc o O I a. OLIGOTROPHIC 0.01 I I 1.0 10 100 MEAN DEPTH /RESIDENCE TIME (M/YR) C FIG. 4-1 TROPHIC STATE OF HARDY POND TABLE 4-1. ESTIMATE OF EXTERNAL PHOSPHORUS LOADING TO HARDY POND Annual Average Annual Average Total Phosphorus Flow Phosphorus Loading Source (cfs) (mg/1) (kg/yr) Stormwater f1) 0.13 0.4 46 Inlet 0.6 0.09 48 Direct Precipitation^1) 0.2 0.01 to 0.06 2-10 Total - - 104-112 Outflow*2) 0.9 - - 1. Based on 42 inches annual average rainfall. 2. From measurements to date; used in calculation of flushing rate. coefficient of 0.4 has been used for the Windsor Village housing , development based on measurements obtained at this site. The section of the stormwater drainage basin containing the wetlands and farm area adjacent to the pond is less developed, and is expected to have a lower runoff coefficient (approximately 0.05). Using this information with the average annual rainfall of 42 inches, the annual phosphorus loading from stormwater can be estimated. In addition to external phorphorus loads the pond bottom sediments are a major source of phosphorus entering the water column. The trophic state classification shown in Figure 4-1 is also shown with this internal load added in. The classification of Hardy Pond is highly eutrophic. The method of quantifying the phorphorus load from the sediments is presented later in this \ chapter. 4-4 MET CALF A EDDY c Massachusetts Lake Classification The State of Massachusetts has a lakes classification system (State of Massachusetts, 1982), the purpose of which is to provide input for the State lake restoration program. This classification scheme is used to assist in prioritizing restoration grant applications. It is useful to classify Hardy Pond according to this scheme in order to 1) develop an understanding of the severity of Hardy Pond's problems in relation to other lakes in the State, and 2) supplement the trophic state analysis to check on the overall pond status (i.e.: eutrophic)- A summary of the classification of Hardy Pond is provided in Table 4-2. Points are assigned based on diagnostic survey data from July and August, 1985. A total of 15 points are obtained for Hardy Pond based on this recent data, which places it in the eutrophic category (12 to 18 points). This agrees with the trophic state classification (Figure 4-1) of eutrophic. Based on a total of 295 lakes rated within Massachusetts (State of Massachusetts, 1982), Hardy Pond falls in approximately the 95th percentile range in terms of severity, verifying the extensive problems in the pond. There were 14 lakes with higher (more eutrophic) scores, 280 lakes with lower scores, and 11 other lakes within Hardy Pond's classification. The median score for the 295 lakes was 8. The empirical trophic state assessments are subject to wide variations depending on the assumptions used to develop the 4-5 METCALF ft EDDY TABLE 4-2. STATE CLASSIFICATION SYSTEM APPLIED TO HARDY POND Concentration or Parameter Degree of Severity Unit Points^ 1) Hypolimnetic 4.0-10.8 mg/1 1 dissolved oxygen Secchi disk 1-2 ft. 3 transparency Phytoplankton >1,500 cells/ml 3 Epilimnetic 0.23-0,55 mg/1 2 ammonia plus nitrate v Epilimnetic 0.14-0.69 mg/1 3 total phosphorus Aquatic vegetation very dense - 3 TOTAL 15 T~. Points vary from 0 to 3 for each parameter, higher points A indicate greater severity. inputs. A large amount of judgment is required to utilize these methods. For the Hardy Pond restoration study, the extensive data available (described in Chapter 3) allows a more detailed modeling approach to be undertaken. The modeling considers time varying conditions based on the data, and results in a greater degree of confidence in the recommendations made for the restoration program. A hydrologic model was first developed to define inflows and outflows to the pond. Subsequently, a nutrient model was developed based on the hydrologic calculations. As part of the development of these models for existing conditions, the models / were calibrated by comparison with data presented in Chapter 3 to 4-6 METCALF a CODY generate confidence in their predictive capability. These models are used in subsequent chapters to evaluate restoration alternatives. Hydrologic Model The model used for analysis of Hardy Pond is known as MELAKE (Metcalf & Eddy Lake Model). It contains both hydrologic and water quality components. The model formulation and solution method is described as follows. Model Formulation. The hydrologic model computes changes in lake total volume and stage based on the time variation of inflows and outflows to the lake. The equation defining the hydrologic budget is given below. ^X=R+T+S-E-0+GW V = lake volume (L3) t = time (T) R = direct rainfall, (L3/T) T = tributary inflow, (L3/T) S = stormwater inflow, (L3/T) •3 E = evaporative loss, (L 0 = outflow from lake, (L3/T) GW = groundwater flow, (L3/T) The equation is solved on a daily time scale/ with values of rainfall, inlet inflow, stormwater inflow, and evaporative loss as known inputs to the model. The net groundwater flow to or /" from the pond is treated as an unknown and is used for model 4-7 METCALF « EDDY f calibration, since all other parameters are well defined. The lake outflow is computed based on the computed lake stage and a stage-discharge rating curve. From the calculated volume the corresponding lake stage is determined from the bathymetric relationship that was presented in Figure 2-2. Comparison between measured and calculated lake stages is used to verify the accuracy of the hydrologic model. Hydrologic Model Input and Results. Available data discussed previously were used to develop input to the hydrologic model. Daily precipitation data from City of Walt ham gauges and monthly evaporation data from the Rochester, Massachusetts weather station have been used as input to the model. To adjust evaporation gauge measurements to actual lake evaporation values v a pan coefficient of 0.7 was used (Linsley et. al., 1975). Runoff coefficients of 0.05 to 0.4 based on field measurements have been used to account for runoff from the various segments of the stormwater drainage basin area. Inflow at the main inlet to the pond is input to the model based on the measurements obtained during the Diagnostic Survey. Flowrates are input to the model on a daily basis, with values determined by extrapolating between measurements. In order to use the model to assess possible changes in the pond hydrology, it is necessary to establish a relationship between the pond level and the outflows. The existing outflow structure normally behaves as a weir. The structure consists of /' a concrete wall approximately 16 ft. in length adjacent to a 4-8 METCALF ft EDDY 4 ft. stop log structure to control the pond level. Normally the stop-logs are set at the same elevation as the concrete wall. The general equation defining flow over a weir can be used for this structure. This equation is of the form: Q = CL(H)1'5 where Q is the outflow, C is the weir coefficient, L is the weir length, and H is the head on the weir. The weir coefficient for this structure is estimated as 2.9. On some occasions the outlet structure is submerged due to downstream backwater effects. During these periods the structure does not act as a weir, and flow out of the pond is controlled by the downstream channel. Simulation of the downstream channel water level is not included in the pond hydrologic model. Based on the input described above, the hydrologic model has been used to simulate the pond elevation for the Diagnostic Survey period. The hydrologic input parameters used in the model are summarized in Table 4-3. The simulated water surface elevation was fairly stable, with the water level within a few inches of the outlet crest elevation. This is in general agreement with the measured water surface elevation during the Diagnostic Survey. During periods of outlet submergence measured water levels were somewhat higher than the model predictions. No substantial decreases in the pond level were predicted by the model assuming no groundwater inflow, and thus groundwater flow was not found to be a major segment of the hydrologic budget of the pond. 4-9 METCALFa EDDY (_ TABLE 4-3. INPUT PARAMETERS FOR HYDROLOGIC MODEL Parameter Value Rainfall Daily values from City of Waltham rain gauges. Evaporation Monthly values from Rochester, MA weather station Tributary Inflow Measurements from Diagnostic Survey Groundwater Inflow 0 cfs Stormwater inflow Computed from rainfall input and measured runoff coefficients Outflow Outlet rating curve Nutrient Model After the development and calibration of the hydrologic model, it is used as input to the nutrient model of Hardy Pond. Controlling phosphorus input to the pond is the most effective means of limiting plant growth in the pond. Thus the nutrient model used here is based on the total phosphorus budget in the pond. The model formulation and input are described in the following paragraphs. Model Formulation. The phosphorus model is used to compute the total phosphorus concentration in the lake. The flow and lake volume variations from the calibrated hydrologic budget model are utilized to compute the phosphorus balance in the lake. The phosphorus concentrations in the various inflows to the lake are input to the model based on measurements made during 4-10 METCALFft EDDY the Diagnostic Survey. The equation defining the total phosphorus budget is given below* p + T p + S(p at - R< r> < t> s> " + Sed ± GW (Pgw) P! = in-lake total phosphorus concentration (M/L3) V = lake volume (L3/T) t = time (T) R = direct rainfall (L3/T) 3 Pr = total phosphorus concentration in rainfall (M/L ) T = tributary/inlet inflow (L3/T) Pt = total phosphorus concentration in tributary inflow (M/L3) S = stormwater inflow (L3/T) 3 V PS = total phosphorus concentrations in stormwater (M/L ) 0 = outflow from lake (L3/T) L = loss due to settling (1/T) Sed = total phosphorus released from bottom sediment ,(M/T) GW = groundwater flow (L3/T) 3 Pgw = total phosphorus concentration in groundwater (M/L ) This equation is solved for the "in-lake phosphorus concentration on a daily time scale in conjunction with the hydrologic model using an explicit finite difference numerical solution technique. In this technique, the outflow and settling loss terms in the phosphorus equation use the in-pond concentration from the previous day as a starting estimate to compute the in-pond concentration on the current day. An 4-11 METCALF a EDDY iterative solution scheme is used to refine the calculated value to within an acceptable tolerance. The phosphorus model has the option of considering the lake as a completely mixed system or as a two layer system. As was presented in Chapter 3, extended periods of stratification do not occur in Hardy Pond. Due to the shallow depth of the pond the water column is frequently mixed from top to bottom. Thus, the one layer model is used to simulate conditions in the pond. Model Input and Results. Data available from the Diagnostic Survey have been used to define the input parameters for the nutrient model. The sources of phosphorus loading to the pond were discussed previously in regard to the trophic state assessment. The principal external sources of phosphorus loading to the pond are inlet flow, stormwater runoff, and direct precipitation. Phosphorus loss from the pond occurs by outflow through the pond outlet and due to settling of material to the bottom sediments. The computed in-pond phosphorus concentration is used to determine the loss due to these factors. In addition to external loading sources it is expected that phosphorus in the bottom sediments reenters the water column in Hardy Pond. Release of phosphorus from the bottom sediments can be enhanced during periods of low bottom dissolved oxygen concentrations. Mixing of bottom phosphorus with overlying water also occurs during periods of water column mixing. 4-12 METCALF « EDDY V Phosphorus settling rates in natural water bodies are highly variable, and a wide range of values is reported in the literature. Most commonly settling rates are reported in terms of a phytoplankton settling velocity. Since only part of the total phosphorus in the pond is tied up in the phytoplankton, the settling rates used in the phosphorus model will be somewhat lower than phytoplankton settling rates. Settling velocity (m/day) can be converted to a settling loss rate (I/day) by dividing by the mean depth of the Pond (approximately 0.6 for Hardy Pond). A commonly used approximation for sedimentation rate (U.S. EPA, 1983) is: VT5 -Z , /-1 Where Ks is the sedimentation rate (per year) 10 represents a particle setting rate of 10m per year, and z -is the'lake depth (meters). For Hardy Pond, this expression results in a value of about 0.04 per day. Variation in settling loss rates may be correlated with phytoplankton concentration. The variation in phytoplankton density measured in Hardy Pond during the Diagnostic Survey period was presented previously (Figure 3-17). A significant drop in phytoplankton density occurred during August, and an even more dramatic decrease occurred during November and December. During the winter months the population remained fairly stable. During a period of decreasing phytoplankton concentration the f~ total phosphorus settling rate is expected to increase since die- 4-13 METCALF A EDDY ^ off and settling of phytoplankton is occurring. To reflect the phytoplankton density changes measured during the Diagnostic Survey, settling rates of 0.05 per day for August and 0.06 per day for November and December have been input to the model, while a settling rate of 0.04 per day is used for the remainder of the year. To illustrate the significance of the phosphorus loading from bottom sediments a model simulation is presented in Figure 4-2 including only inlet, stormwater and direct precipitation phosphorus loads. The water surface phosphorus measurements are used for comparison with the simulation. As is shown, the simulation is much lower than the actual in-pond measurements. This shows that the bottom sediments contribute a major source of phosphorus to the water column. To account for internal loading from the sediments a source term has been added to the phosphorus model during open water conditions (March through December). During the period of ice cover wind mixing and thus mixing of the nutrient rich bottom sediments with overlying waters does not occur. The sediment phosphorus load has been determined by calibrating the simulation to the actual measurements. All other inputs to the model have been established either from direct measurements or from the literature. Thus, the phosphorus model was calibrated by varying the sediment phosphorus load within the range of literature values. A sediment load of 3.2 mg/ra2 day has been used in the f calibrated model. The model simulation compared with actual 4-14 METCALF a EDDY /-s 0.8 0.7 0.6 0.5 O X 0.4 Q. V) O X 0. 0.3 O 0.2 SIMULATION WITH INLET STORMWATER, AND PRECIPITATION ONLY 0.1 0.0 150 250 350 450 550 JULIAN. DAY JUN | JUL I AUG | SEP I OCT I NOV IJA DEN CI FEB I MAR I APR I MAY 1984 1985 FIG. 4-2 PHOSPHOROUS MODEL SIMULATION WITHOUT SEDIMENT LOAD measurements is presented in Figure 4-3. The correlation between the simulation and measurements is very good when phosphorus input from the bottom sediments is included. The two high phosphorus concentrations measured in August were not reproduced by the model. These spikes could result from rapid, short term influxes of phosphorus from the sediments due to low dissolved oxygen conditions or strong wind mixing. A summary of the input parameters used in the calibrated phosphorus model is given in Table 4-4. The input parameters used in the phorphorus model were within the range of measured and literature values. The model will be used to assess pond restoration alternatives in Chapter 5. TABLE 4-4. INPUT PARAMETERS FOR PHOSPHORUS MODEL Measured or Value Used Parameter Literature Range For Calibration Stormwater runoff (flow 0.2 - 0.6 0.4 weighted average) (mg/1) Direct rainfall f1) 0.01 - 0.06 0.03 (mg/1) Inlet (mg/1) 0.025 - 0.17 Daily values intepolated from measurements. Sediment recycling 0.7 - 7.7 *3^ . 3.2 (March (mg/m2 day) through December) Settling Rate 0.046 (4J 0.04 to 0.06/day d/day) TT Literature range (Brezonik, 1972) 2. Includes septic inflow 3. Great Lakes values: oxygenated winter conditions and anoxic summer conditions (Golterman, 1975) 4. Calculated for U.S. EPA (1983). 4-16 METCALF ft CODY 0.8 0.7 0.6 o 0.5 o x 0.4 0. OTo X Q. 0.3 -I SIMULATION INCLUDING 0.2 SEDIMENT LOAD 0.1 0.0 150 250 350 450 550 JUUAN DAY JUN I JUL | AUG \ SEP I OCT I NOV I JADEN CI FEB I MAR I APR I MAY 1984 1985 FIG. 4-3 PHOSPHOROUS MODEL SIMULATION INCLUDING SEDIMENT LOAD REFERENCES Brezonik, P.L., "Nitrogen: Sources and Transformations in Natural Waters", in Nutrients in Natural Waters, H.E. Allen and J.R. Kramer, Editors, Wilely and Sons, 1972. Dillon, P.J., "The Phosphorus Budget for Cameron Lake, Ontario: The Importance of Flushing Rate to the Degree of eutrophy in Lakes", Limnology and Oceanography 20(1), 1974. Golterman, H.L. Physical Limonology, Elsevier Scientific Publ. Co,, New York, 1975. Kirchner, W.B. and Dillon, P.J., "An Empirical Method for Estimating the Retention of Phosphorus in Lakes", Water Resources Research, February, 1975. Linsley, R.K., Jr., M.A. Kohler, and J.L.H. Paulhus, "Hydrology for Engineers," McGraw Hill, Second Edition, 1975. Massachusetts, State Division of Water Pollution Control, "Massachusetts Lakes Classification Program," Technical Services Branch, Westborough, Massachusetts, January, 1982. Najarian, T.O., and Taft, J.L., "Nitrogen Cycle Model for Aquatic Systems: Analysis", Journal of the Environmental Engineering Division, ASCE, Vol, 107, No. 6, December, 1981. Snow, P.O., and DiGiano, F.A., "Mathematical Modeling of Phosphorus Exchange Between Sediments and Overlying Water in Shallow Eutrophic Lakes", Report No. Env. E. 54-76-3, Dept. of Civil Engineering, Univ. of Massachusetts, Amherst, Mass., 1976. U.S. EPA, "Technical Guidance Manual for Performing Waste Load Allocations, Book IV Lakes and Impoundments, Chapter 2 Eutrophication", August, 1983. Vollenweider, R.A., "Scientific Fundamentals of the Eutrophication of Lakes and Flowing Waters with Particular Reference to Nitrogen and Phosphorus as a Factor in Eutrophication", Report No. 27, DAS/CIS/68, Organization for Economic Cooperation and Development, Paris, 1968. Vollenweider, R.A. "Input-Output Models with Special Reference to the Phosphorus Loading Concept in Limnology, "Schweiz. Z. Hydrol., 1975 4-18 METCALF A EDDY CHAPTER 5 ASSESSMENT OF ALTERNATIVES The objective of the restoration program for Hardy Pond is to develop recommendations to correct problems identified in the pond. In order to develop these recommendations, a number of alternatives were formulated and analyzed, as presented in this Chapter. Initially, specific problems were identified at Hardy Pond. Based on these problems, a set of objectives was identified which would alleviate the problems. Alternatives were then formulated and evaluated. Certain of the alternatives were then selected to become a part of the recommended restoration plan, which will be described in Chapter 6. Hardy Pond Problems and Objectives The first step in the alternatives assessment was to define the problems in the pond and to develop a set of objectives which, when achieved, would overcome these problems. In order to provide input to the problem assessment process, public input was sought at a general public meeting. In addition, a special meeting of the Committee to Save Hardy Pond was held. During these meetings, desired uses of the pond were identified along with complaints and problems which currently inhibit those uses. The desired uses of Hardy Pond, in order of preference, are as follows: 1. Aesthetics * 2. Passive recreation - boating 3. Fishing 4. Swimming 5-1 METCALF ft EDDY Based on these desired uses, along with analysis of the diagnostic survey data collected for the pond, the objectives for the Hardy Pond restoration program have been developed, as summarized in Table 5-1. TABLE 5-1. HARD* POND PROBLEMS AND OBJECTIVES Problem Cause Objective Algae growth, Excessive nutrient Phosphorus < 0.06 mg/1 decay and odor concentrations Low water level Outlet structure Increase pond depth operation, siltation Highly turbid Resuspension of Increase pond depth water bottom sediments, to 6 to 8 feet; reduce algal blooms, and nutrient concentra- plant decay tions Shoreline and High nutrient Reduce phosphorus in-pond macro- concentrations, concentrations; remove phyte growth shallow depth nuisance species No swimming in Mucky bottom Create swimming pond sediments, poor beach water clarity The problems which have been identified in Hardy Pond relate to eutrophication, excessive turbidity, water level control and aesthetics. Table 5-1 also shows the objectives set to alleviate the problems. The following is a discussion of each problem and its corresponding objective. Algal Blooms. In order to alleviate the documented algal bloom problem, the quantity of nutrients in the pond, must be reduced. Phosphorus (P) concentrations typically ranged from 0.1 c to 0.3 mg/1, and large algal populations were sustained 5-2 METCALF ft EDDY ( throughout most of the late spring, summer and early fall period. Odor problems were associated with periods of extensive algal growth. A P concentration of 0.06 mg/1 has been set as an upper limit on Hardy Pond to protect against problems of excessive algal growth. This criteria is somewhat arbitrary, because of the difficulty in precise prediction of the growth of algae in response to nutrient loadings. However, based on the measured data, literature values, and modeling presented in Chapter 4, the criteria is judged to be reasonable. Monitoring of the pond after implementation of the restoration plan can be used to verify this criteria. Low Water Level. Prior to the installation of the new outlet structure and channel modifications, flooding due to high V pond levels was common around Hardy Pond. Flooding complaints are received above elevation 204 (Vulgaropulos, 1978). The existing outlet weir is at elevation 202.0, which has resulted in a drop in pond level since this weir was put in. Although this has alleviated flooding problems, the current pond level results in a maximum depth of 4 feet. The shallow water depth has resulted in exposed debris, inhibited boating, and generally has made the pond less desirable. In order to correct this situation, a greater pond depth is required. High Turbidity. In addition to algae growth, a major problem in Hardy Pond is the turbidity, color and solids content. The pond water is a brownish color throughout most of C the year. This degrades the aesthetic value of the pond and 5-3 METCALF a EDDY C encourages a public attitude that this potentially valuable resource is hopelessly polluted. The high solids content of Hardy Pond is due to several factors, including the shallow depth which allows wind mixing to resuspend the soft mucky type of sediments on the pond bottom and the solids loading entering the pond from various sources in the drainage basin. In order to correct this condition, the pond depth should be increased. This would also address the low water level problem. A depth of at least 6 feet, but more preferably up to 8 feet/ is recommended to reduce resuspension of bottom sediments. High algal growth also causes turbidity and water color problems. During the summer months phytoplankton density is f high, thus reducing the clarity of the water. Also, high organic content due to excessive algal growth and decay causes an increase in the background color of the water and reduces clarity. Thus, by limiting the growth of algae in the pond through nutrient reduction the turbidity and clarity of the pond can be improved. Hacrophyte Growth. Excessive densities of undesirable macrophytes occur within the pond and along parts of the shoreline. Although some species can provide useful habitat for aquatic life, nuisance species interfere with the aesthetic value and recreational use of the pond. During the Diagnostic Survey period, it was evident that aquatic macrophyte growth was f detrimental to Hardy Pond's aesthetic value. 5-4 METCALF ft EDDY V In order to reduce macrophyte growth, limitation of nutrients is required. Therefore, the objectives set to control algal blooms are expected to assist in control of macrophyte growth. Because macrophytes can utilize the sediments as a supply of nutrients, it is difficult to identify specific concentrations needed to limit macrophyte growth. Physical characteristics of certain pond areas, such as depth of water and substrate type, are conducive to macrophyte growth. For areas of very dense growth, reduction of nutrients alone may not result in significant reduction of this growth. For these areas, the nuisance species must be removed. Also, removal of nutrient rich bottom sediments will help reduce macrophyte growth. This should enhance the aesthetic value of the pond and facilitate recreational activity such as boating. Deepening the pond will also have a beneficial impact upon the growth of aquatic macrophytes. Several in-pond nuisance species would not grow well at a depth of over 6 feet. By deepening the pond the area of sunlight penetration to the pond bottom will be reduced, limiting the growth of submerged aquatic plants. In-Pond Rocks. Anyone looking out over Hardy Pond will immediately see large rocks protruding above the water surface. These rocks serve as habitat for birds, and many feel they are aesthetically beneficial. Some of the rocks were not exposed until the recent lowering of the pond level. Shoreline residents living quite near the rocks located in the inlet/outlet area of 5-5 METCALP A EDDY r the pond are less appreciative of their aesthetic value. It is reported by residents that these rocks limit circulation in the shoreline area behind them, causing stagnant water conditions. During the development of the restoration program, more beneficial in-pond locations for these rocks will be considered. Swimming.. Data indicate that bacteria is not a problem in the pond. The main limitation to swimming is water clarity, water depth and the mucky bottom sediments. Because swimming is a desired use for Hardy Pond, the restoration alternatives will consider this possibility. The remainder of this chapter will be devoted to development and analysis of various possible alternatives to meet the objectives set for Hardy Pond. It should be noted that the ( reduction of in-pond phosphorus concentrations and high turbidity will be the most difficult and costly. Trade-offs may be required between the desirability of achieving every objective and the economics of doing so. Alternatives Development A set of alternatives has been developed for Hardy Pond in order to meet the restoration objectives. These are described in the following paragraphs. Phosphorus Reduction. In order to meet the goal of 0,06 mg/1 of phosphorus, several alternatives were considered. In general, these consist of reduction of sources of P entering the pond, or direct reduction of in-pond P. The calibrated model . developed in Chapter 4 was used to evaluate several possi- 5-6 METCALF A EDDY f bilities. As shown in Figure 5-1, phosphorus concentrations in Hardy Pond were calculated separately removing each of the major sources; the internal sediment load, the stormwater, and the Inlet. Removal of the sediment load produced by far the greatest reduction in concentration. Removal of stormwater load resulted in a slight decrease. Removal of the inlet actually resulted in an increase in concentration. This occurred because currently the inlet often has lower P concentrations than the pond, thus diluting the pond concentration. Since the sediment load is the major nutrient source, methods to reduce it were evaluated first. The following methods were considered: ( Aeration Nutrient inactivation Capping with soil Synthetic liner Dredging These are discussed in the following paragraphs. Aeration - Aeration involves pumping air into the pond to insure that dissolved oxygen concentrations remain high. As shown in Chapter 3, Hardy Pond occasionally stratifies, which enhances nutrient release. However, a large part of the sediment loading results from turbulent mixing of the bottom sediments C 5-7 METCALF A EDDY 0.4 — INLET FLOW REMOVED 0.35- — EXISTING CONDITIONS — STORMWATER REMOVED — SEDIMENT LOAD REMOVED 0.3 o c/i 0.25 Z> Qi O X 0.2 - CL (/) O X 0. 0.15- 0.1 - 0.05 - 150 250 350 450 550 JULIAN DAY JUN I JUL I AUG I SEP I OCT I NOV I JADEN CI FEB I MAR I APR I MAY 1984 1985 FIG. 5-1 COMPARISON OF VARIOUS PHOSPHOROUS LOAD REDUCTIONS f because of the shallow pond depth. Thus, aeration would not alleviate this situation. Nutrient Inactivation - To control release of nutrients from pond sediments, as well as reduce nutrient concentrations in the pond water itself, the nutrient inactivation technique can be used. This involves addition of chemicals to cause precipitates of P to form and settle to the lake bottom. Upon settling, this precipitate tends to bind sediment P, thus controlling release of sediment nutrients. This method is temporary and does not address the actual sources of nutrients. The chemicals used are also potentially toxic to aquatic organisms. The major reason why this technique is not expected to work is that the resuspension effect discussed earlier would still occur. v Capping with Soil - This technique involves placement of clean fill or sand on top of the nutrient rich bottom sediments. This is not considered feasible because it conflicts with the other major objective of deepening Hardy Pond. Synthetic Liner - A variety of types of pond liners are manufactured. The liner would be placed on top of the existing sediment, and would allow water to pass through so that any connection with the groundwater would be maintained. The liner would destroy all bottom dwelling organisms, which serve as food for certain types of fish. However, clean soil could be placed on the liner. A liner is not considered feasible for Hardy Pond, because again it conflicts with the objective of making the pond f deeper. 5-9 METCALF ft EDOV f Dredging - The most costly, but the most effective restoration measure for Hardy Pond would be dredging. Nutrient and solids influx from the bottom sediments would be reduced due to sediment removal. It is also consistent with the objective of increasing the pond depth. Although dredging is not expected to completely eliminate sediment phosphorus loading, substantial reductions could be accomplished. The reduction in sediment phosphorus loading achieved is dependent on the extent of the dredging program (ie. depth of material removed). By removing the surface layer of the bottom sediments the most nutrient rich, highly organic material would be eliminated. Additional dredging would move the sediments further from the wind forces at the water surface, and V would therefore reduce the diffusion and resuspension of bottom materials into the overlying waters. Temperature stratification is likely to extend for longer periods of time during the summer months depending on the ultimate depth of the pond. It is doubtful that the pond would be dredged deep enough so that straf if ication would be maintained all summer. Therefore, intermittent periods of low dissolved oxygen in the pond bottom waters would occur. The factors that presently exert a high demand for dissolved oxygen will be reduced due to removal of the highly organic surface sediments and reduction in the nutrient input to the overlying waters. By reducing these factors that cause depletion of bottom dissolved 5-10 METCALF ft EDDY oxygen, reduction in the release of nutrients from the sediments would be accomplished. It is not possible to precisely quantify the reduction in sediment nutrient loading that will result from dredging, due to uncertainty in the extent to which the dredging program will be carried out and the complex nature of the nutrient release process. The extent of the dredging program is dependent on the availability of sediment disposal locations, the level of project expenditure, and the results of a monitoring program that will be conducted in conjunction with the dredging program. Each of these factors is discussed in more detail in Chapter 6. Depending on the success of the dredging program, additional controls on external nutrient sources may be required. Reduction of stormwater load through rerouting of drainage subareas was therefore investigated. As is shown in Figure 5-2 there are a total of 11 stormwater runoff subareas entering the pond. All of these areas have piped discharges to the pond, with the exception of subarea No. 8, which has only overland flow via the wetlands area on the northwest shoreline. Table 5-2 summarizes the estimated annual average runoff and phosphorus load from each of these subareas based on the information obtained during the Diagnostic Survey and presented in Chapter 3. From review of the storm drainage system around the pond it would be possible to reroute some of the existing drainage away from the pond. The drainage from Windsor Village 5-11 METCALF a EDDY INFLOW OUTLET STRUCTURE 800 FT 244 M FIG. 5-2 HARDY POND STORMWATER RUNOFF BASINS TABLE 5-2. SUMMARY OF STORM DRAINAGE FOR HARDY POND Subarea Area Flow Phosphorus Load No. (acres) (ft3/day) (kg/yr) -1 46 1920 7.9 2 19 3170 13.1 3 1 40 0.2 4 2 80 0.3 5 3 120 0.5 6 34 1420 5.9 7 24 1000 4.1 8 100 2090 8.6 9 30 1250 5.2 10 2 80 0.3 11 2 80 0.3 (subarea 2) could be piped directly to the outlet area, bypassing the pond. Drainage from subarea no. 6 could potentially be piped to the Lake St. drainage system, away from the pond. Also, runoff currently entering the pond at Brook Road (subarea no. 9) could potentially be routed directly to.the outlet area. Rerouting these three subareas would result in approximately a 50 percent reduction in the phosphorus load entering the pond for stormwater runoff. It is not recommended that any stormwater drainage be rerouted until after the dredging program has been completed and its effectiveness has been determined through post- dredging monitoring. Low Water Level. There are two methods of increasing the depth of Hardy Pond: dredging and raising the water level. Dredging has already been discussed. This section addresses increasing the water level. 5-13 METCALF A EDDY ,- To increase the water level, modification of the pond outlet structure is required. This is very inexpensive compared to dredging. Therefore/ any rise in water level which can be achieved by outlet structure modification is beneficial. Basement flooding complaints are received at about elevation 204, and the outlet structure is currently operated at about 202. Only an elevation between these two would be acceptable. Highly Turbid Waters. Dredging Hardy Pond would help alleviate the turbidity problem. Analyses were performed which demonstrated that external sediment sources (stormwater and inlet) are not causing the problem. The high turbidity is mainly due to resuspension of bottom sediments and excessive algal growth caused by sediment P loads. Because of this, other ( alternatives were not considered extensively. Macrophyte Growth. Removal of nuisance in-pond and shoreline macrophyte growth is considered necessary for aesthetic and recreational reasons. Removal of in-pond macrophytes can be accomplished by the following methods. Herbicide application - Herbicides can be applied to control macrophytes, however this method has drawbacks. The herbicides may be toxic, the plant matter is recycled to the pond bottom, and the source of the problem (excessive nutrients) is not treated. It is therefore a maintenance activity which provides short-term relief. Harvesting - Purchase of a plant harvester or hiring a firm to remove nuisance growth is somewhat costly. Sometimes, 5-14 ( the plants must be removed two or three times in a summer. There is a net removal of P when harvesting is accomplished. This P removal is affected by the method of harvesting and density of vegetation. Harvesting may, howeverf eliminate existing high quality vegetation and allow invasion by opportunistic species. Harvesting, like herbicide application, provides only short-term relief. It is interesting to note that both of these techniques have been used at Hardy Pond in the past, herbicide application in the 1960's, and harvesting in the early 1970's. In both cases, short-term relief from macrophyte growth was attained, but the long-term problems still remain. Dredging - The most costly but perhaps the most effective ' method of removing emergent and nuisance submergent vegetation is dredging. The plant substrate is removed, and the area is deepened which helps limit future growth. The eutrophication potential of the dredged area may be reduced by a substantial number of years. However, a disposal site for the material must be available and the appropriate permits obtained. Removal of nuisance in-pond macrophyte growth is another reason to undertake a dredging program in Hardy Pond. For shoreline macrophyte growth (in particular purple loosestrife), raising the pond level to elevation 203 will destroy some of the plants which have colonized the shoreline areas. Any further plant removal would be undertaken by s individual homeowners, or by the City on City property. 5-15 METCALF ft EDDY' / Swimming. It will be feasible to create a swimming beach if the dredging program is undertaken. This can be done after dredging by placement of sand at an area of land owned by the City. The aesthetic problems that currently restrict swimming would be reduced through the dredging program (ie. - removal of mucky bottom sediments and reduction in algal growth). A possible site for a beach is at the end of Shore Road. Summary. Based on the alternatives analyzed and the goals set for the Hardy Pond restoration program, a summary of the components of the recommended plan is provided in Table 5-3. TABLE 5-3. HARDY POND RECOMMENDED PLAN RecommendationPurpose Dredging Deepen Pond, Remove ( Sediment Nutrient Load Outlet Structure Modification Deepen Pond Shoreline Improvements Remove Nuisance Shoreline Macrophyte Growth, Improve Aesthetics Develop Swimming Beach Allow for Swimming in Pond Public Education Program Keep Public Informed of Restoration Activities Monitoring Program Assess Effectiveness of Other Recom-mendations This program implemented in total would meet the Hardy Pond restoration objectives. Each aspect of the restoration program is developed in more detail in Chapter 6. The major and most C 5-16 METCALF A EDDV expensive part of the recommended plan is dredging. Dredging has been recommended in several past studies of the pond (e.g. Process Research, 1973; A. Vulgaropulos, 1978). It has never been undertaken due to its expense. At this stage in the life of Hardy Pond, the hypereutrophic conditions are rapidly turning the pond into a marsh. Dredging, although expensive, seems to be the only approach to restoration which would address many of the problems in Hardy Pond and thus provide long-term benefits. Without dredging, the other restoration activities presented in Table 5-3 would have little effect. C 5-17 METCALF a EDOY REFERENCES Process Research, "Hardy Pond: Report to the City of Waitham", 1973. Vulgaropulos, A.A., "Study of Hardy Pond, Waltham, Massachusetts", submitted to the City of Waltham, 1978. C 5-18 METCALFft EDDY CHAPTER 6 RECOMMENDED PLAN The recommended restoration plan for Hardy Pond includes a number of alternatives which* when implemented, will achieve the restoration objectives for the pond. The purpose of this chapter is to set forth the specifics of the restoration plan, including: Engineering description Environmental impacts and mitigation measures Post-implementation monitoring program Implementation Schedule Cost estimates Funding sources This recommended plan may then be used during Phase II (implementation) of the restoration project. In the following sections, each recommendation is presented in terms of its engineering concept. Also, potentially adverse environmental impacts and mitigation methods (where appropriate) are discussed. Dredging In order to achieve effective recreational use of Hardy Pond, both deepening the pond and removing the large phosphorus load from the sediment is considered essential. This requires that a dredging program be undertaken. This section presents the evaluations and conclusions related to dredging of Hardy Pond. Evaluation of Data. Field programs were undertaken to identify the extent of sediment deposition and the physical and 6-1 METCALF A EODY > chemical characteristics of the sediment. A sediment depth map of Hardy Pond is shown in Figure 6-1. This map was prepared by driving lengths of pipe into the sediment to refusal. This was done at 9 transects along the pond, at spacings of about 100 feet, for a total of 58 individual probings. The depth of soft sediment, assumed to be organic silt, averages about 20 feet throughout the pond. This translates to 68,000 cubic yards of material per foot for the 42 acre pond. The total volume is over 1.4 million cubic yards. The sediment is extremely soft. Virtually no force is required to push the rod through at least 15 feet. The material at the surface is easily resuspended by turbulence. Data on sediment chemical and physical characteristics f were collected at two stations (See Figure 3-1); one in the center of the pond and one in the western cove area. A summary of Hardy Pond sediment chemical data was given in Table 3-10. These values are compared with information from three sources, as follows: 1. Massachusetts dredge material disposal classification (314 CMR 9.00, 1979) (Table 6-1). 2. Massachusetts regulations for land application of sludge (310 CMR 29.00, 1983) (Table 6-2). 3. Great Lakes sediment rating criteria (Mass. Dept. of Environmental Quality Engineering, 1982) (Table 6-3). These comparisons show that Hardy Pond sediments are quite clean. Two parameters, arsenic and mercury, both by a small. f margin, cause the sediment to be rated as Category Two 6-2 METCALF ft EDDY ROAD C SEDIMENT DEPTH CONTOURS IN FEET 91M 91M C. NOTE: Contours in Feet FIG. 6-1 HARDY POND SEDIMENT DEPTH MFTCALF ft tOOY c TABLE 6-1. CLASSIFICATION OF DREDGE OR FILL MATERIAL Allowable Concentrations (ppm) Parameter Category One^1^ Category Two^2) Category Arsenic (As) < 10 10-20 > 20 Cadmium (Cd) < 5 5-10 >10 Chromium (Cr) <100 100-300 >300 Copper (Cu) <200 200-400 >400 Lead (Pb) <100 100-200 >200 Mercury (Hg) <0.5 0.5-1.5 >1. 5 Nickel (Ni) < 50 50-100 >100 Polychlorinated Biphenyls (PCB) <0.5 0.5-1.0 >1.0 Vanadium (V) < 75 75-125 >125 Zinc (ZN) <200 200-400 >400 1. Category One materials are those which contain no chemicals listed in Table 6-1 in concentrations exceeding those listed in the first column, 2. Category Two materials are those which contain any one or more of the chemicals listed in Table 6-1 in the concentration range shown in the second column. 3. Category Three materials are those materials which contain any chemical listed in Table 6-1 concentrations greater than shown in the third column. TABLE 6-2. CLASSIFICATION OF SLUDGE FOR LAND APPLICATION Allowable Concentrations (ppm) Parameter Type I Type II Type III Cadmium < 2 2-25 > 25 Lead < 300 300-1000 >1000 Nickel < 200 - > 200 Zinc <2500 - >2500 Copper <1000 - >1000 Chromium (Total) <1000 >1000 Mercury < 10 — > 10 Molybdenum < 10 — > 10 Boron (water soluble) < 300 — > 300 PCBs in Type I — sludge which is a commercial fertilizer < 2 2-10 > 10 PCBs in Type I sludge which is a commercial C soil conditioner < 1 1-10 > 10 6-4 METCALF ft EDDY TABLE 6-3. GREAT LAKES SEDIMENT RATING CRITERIA (mg/kg dry weight) Moderately Heavily Parameter Nonpolluted Polluted Polluted TKN <1,000 1,000-2,000 >2,000 Lead <40 40-60 >60 Zinc <90 90-200 >200 Ammonia <75 75-200 >200 Phosphorus <420 420-650 >650 Iron <17,000 17,000-25,000 >25,000 Nickel <20 20-50 >50 Manganese <300 300-500 >500 Arsenic <3 3-8 >8 Cadmium * * >6 Chromium <25 25-75 >75 Copper <25 25-50 >50 Mercury * * >1 *No lower limits defined. Source: Mass. DEQE, 1982 (Table 6-1) according to the dredge material classifications. Category One is the cleanest classification, however, there is little difference in the regulating between the two classi- fications, except with respect to ocean disposal. Ocean disposal of Hardy Pond sediments is not feasible due to economic considerations because of the long distance to any disposal site. Under Category Two, land or in-harbor disposal with bulkheading is allowable. Comparison with land application of sludge criteria show that the material would be rated Type 1. This is the cleanest rating, which means that it may be "...used, sold, or distributed or offered for use, sale, or distribution on any site without further approval..." (310 CMR 29.00, 1983). Thus, depending on the physical characteristics of this sediment it could 6-5 METCALF ft EDDY potentially be used for fill, topsoil or other purposes without harming the environment. The final comparisons with Great Lakes data shows the sediment to be nonpolluted except for TKN and arsenic. Physical sediment characteristics for the Hardy Pond sediments were also shown in Table 3-10. The sediments are composed mainly of silt, very high in organic content and also high in water content. These samples represent the upper few inches in the sediment profile. Deeper in the sediment profile, organic content is expected to be less due to the greater age of the deposits and breakdown and stabilization by organisms. These values may be compared with the State dredge material disposal classifications, as given in Table 6-4. Based on the physical characteristics of the top few inches of the pond bottom sediments the material is classified as Type C. Type C material may be disposed of on land with bulkheading, but effluent control will be required. TABLE 6-4. CLASSIFICATION OF DREDGE OR FILL MATERIAL BY PHYSICAL CHARACTERISTICS Parameters Type A Type B Type C Percent silt-clay < 60 60-90 > 90 Percent water < 40 40-60 > 60 Percent volatile solids (NED methods) < 5 5-10 > 10 Percent oil and greases (hexane extract) <0.5 0.5-1.0 >1.0 6-6 METCALFa EDDY y Due to the high organic content and water content of the sediment, it is not suitable for use as topsoil. It would have to be mixed with at least an equivalent amount of sand or bank run gravel to bring the organic content down to below 25 percent, which would be acceptable for topsoil or agricultural purposes. The sediment would not make good structural fill material without dewatering and mixing with more solid material. Thus, extensive handling of the sediment would be required, at a high cost, in order to make it desirable for various types of common use. Sediment Removal Technique. A number of dredging methods were considered for use at Hardy Pond. These include drawdown and excavation, bucket dredging and hydraulic cutterhead dredging. Drawdown and excavation is not considered feasible ( because the material is soft and deep. Of the remaining methods, hydraulic cutterhead dredging is considered to be the best. These dredges have certain advantages over bucket types including a continuous operating cycle and capability of rapid removal of large volumes. The hydraulic pipeline dredge should work well on the soft material in Hardy Pond. Bucket dredging would be more applicable for small sediment volumes in localized areas. The hydraulic cutterhead dredge consists of a hydraulic suction pipe combined with a cutterhead for loosening the sediment. The dredged material is piped from the dredge through a pipeline, often set on pontoons, to the containment area. These dredges are widely available and have been used locally. f For example, the Charles River Purgatory Cove area was dredged 6-7 METCALF a EDDY several years ago using this method. Dredged material was spread on a nearby MDC golf course. Typical dredging rates would be about 50 to 100 cubic yards per hour for a 12 inch diameter suction line in the soft Hardy Pond sediments, depending on the length of the discharge pipeline. This rate is also dependent on the experience of the dredging crew, machine down time, obstacles encountered, containment area size, and other factors. Typical cost for this type of dredging may range from $2 to 5 per cubic yard, not including transport to the ultimate disposal site. Containment Area. The purpose of a containment area is to allow the hydraulically dredged sediments to dewater and consolidate. A typical containment area cross-section is shown in Figure 6-2. It would consist of a diked area with available storage for the material, and underdrains and an overflow weir for drainage. It is desirable to provide sufficient storage volume for an adequate dredging production time. Assuming a dredging rate of 60 cy/hour, and a bulking factor of 1.5 (initially dredged material is expected to expand), a three acre pond with a depth of 8 to 9 feet could be designed to hold two months productions volume. The diked area should be designed with a somewhat higher berm elevation to allow for temporary storage of extra water from hydraulic dredging and sufficient freeboard in the diked area. Dredging could be done in spring for two months, then the material would be allowed to dewater through the summer and be trucked away. In fall, another two months of dredging could be 6-8 METCALF a EDDY c -. / \ EMBANKMENT CONTAINMENT BASIN UNDERDRAtNSv. | | | |) X| | | 1 VARtABLEWE.R, 1 - 1 , | 1 , 1 1 1 1 ]l r 1 1 1 > 1 1 . 1 J i A — ' ! ! ! I . I . . ! i i • • • 1 i i ; i ' > ' CONTAINMENT AREA PLAN SCALE: 1" • 100' MBANKMENT DREDGE MATERIAL STORAGE AREA - LL—_H Q Q_ LL UNDERDRA1NS FILTER MATERIAL (SAND AND FABRIC) CONTAINMENT AREA SECTION A-A SCALE: VERT. 1" - 10* C FIG. 6-2 CONCEPTUAL LAYOUT - HARDY POND DREDGE MATERIAL CONTAINMENT AREA MCTCAIF a CDOV performed to fill the basin. This could dewater through the winter and be trucked away in spring. Using this cycle, about 1 foot of pond depth could be removed per year. Thus, to achieve a 3 foot reduction in depth, 3 years would be required. This cycle also eliminates dredging during the summer, when odors would be strong and during the main usage period of the pond. A number of containment area sites were considered. The pumping distance to the site affects the dredging cost, therefore sites near the pond were considered. A containment area within the pond itself was ruled out/ due to the need for sheet piling or other expensive construction materials for the embankment of the containment area. Two potential upland sites are the Pizzi Farm and the isolated wetlands between Brook Road and Grove Road. The Pizzi Farm site is larger and thus could hold more material. However, it is privately owned. The other site is owned by the City. A permit for construction on wetlands would be required in both cases, however, each of these areas have been disturbed and the wetlands are not of great value. Disposal Sites. Several potential sites have been identified for disposal of the dredged sediment following drying in a containment area. For the large quantity of material to be disposed of, the dredging program is governed to a large extent by the location and capacity of available disosal sites. During the Diagnostic Survey four potential disposal sites were 6-10 METCALF ft EDDY f examined. These sites are listed in Table 6-5 and the locations are shown in Figure 6-3. The disposal areas identified at these sites are approximate, and actual disposal volumes are dependent on further investigation. Also, not all of these areas are City of Waltham property, and therefore proper authorization would be required before using the areas for sediment disposal. Environmental Impact. The dredging program proposed for Hardy Pond will be a major undertaking, and a variety of environmental impacts are associated with it. There will be several short term impacts which will persist over the 3 years of the dredging program. The types of impacts that will occur during the dredging operation include pond water quality, localized noise and odors, truck traffic, impacts at the dredge \ containment and disposal areas, and general aesthetic impacts around the pond. Each of these items is discussed in the following paragraphs. Water Quality - Due to the hydraulic dredging operation the turbidity in Hardy Pond will be increased from disturbance of the bottom sediments. To limit the extent of increased turbidity silt curtains could be used to isolate the area of ongoing dredging. Water quality conditions in Hardy Pond are. severely degraded in its present state, and periods of high turbidity are not uncommon. Thus, the turbidity impacts caused by the dredging operation will not be as severe as in a cleaner lake. Downstream impacts on Chester Brook can be minimized by installation of silt C curtains. Drainage from the sediment dewatering area will also 6-11 METCALF ft EDDY TABLE 6-5. POTENTIAL SEDIMENT DISPOSAL AREAS Approximate Location Area Available Remarks Mt. Peak Cemetary 1-2 acres City of Waltham property Identified area is currently'used for stump and mulch storage. Former Oil Pits, 3 acres Privately owned property Waverly Oaks Road Pits used during World War II for oil storage; Pits are submerged; area receives backwater from Beaver Brook. Metropolitan State Disposal locations State owned land Hospital Grounds within grounds to Grounds are extensive; be defined during much of area is groomed design Some areas of scrub land may be potential disposal areas. Hiddlex County 1-2 acres County Property Hospital Grounds Area near intersection C of main drive and Walnut Street is a potential disposal area. Possibly additional areas within grounds. 6-12 METCALF ft EDDY 1 - MT. PEAK CEMETERY 2-FORMER OIL PITS 3- METROPOLITAN STATE • HOSPITAL GROUNDS 4 - MIDDLESEX COUNTY C HOSPITAL GROUNDS FIG 6-3. LOCATION OF POTENTIAL SEDIMENT DISPOSAL SITES MCTCALF B COOV s be turbid. Impacts from this drainage can be minimized by proper design of dewatering basins and by routing drainage back to the pond so as to minimize impacts on nearby areas. Short-term negative water quality impacts during the dredging operation will be well worth the long-term improvements in the pond to be gained by sediment removal. Local Odor and Noise - The hydraulic dredge will have a motor noise during operation that will be audible along the shoreline area. Dredging can be restricted to the daytime hours only. As the dredge moves to different sections of the pond, noise will be more noticable in some areas than in others. Due to disturbance of the organic bottom sediments odors will be present during the dredging operation. The recommended schedule ( is designed to avoid dredging during the summer months when odors would be the most offensive. It should be noted that odors are currently one of the major complaints about the pond. The impact will thus be less of a problem than in areas where odors are uncommon. Biological Impacts - Disruption of the benthic communities would occur during dredging. Since these serve as food for bottom feeding fish, fish populations may also be adversely affected. These impacts would be temporary, and local to the area being dredged. Rapid recolonization of benthic organisms has been documented in many dredging studies. Long-term beneficial impacts are expected by reduction of nutrient input from the sediments, and corresponding reduction of the 6-14 METCALFft EDDY (' undesirable phytoplankton communities (i.e: blue-greens) and reduction of the cell counts in the pond. Containment and Disposal Area Impact - The sediment containment area will cause impacts due to temporary storage and dewatering of sediments. The potential areas identified for sediment containment are not environmentally sensitive areas. Drainage from the diked containment area will be turbid, and this drainage will be routed back to the pond so as to avoid impacting nearby areas. As discussed earlier, chemical contamination of the material is not a major concern. After completion of the dredging operation the containment area will be restored to its original use. After dewatering at the containment area the sediment will ' be moved to disposal areas. The dredged material will remain at the disposal area, and care will be taken to assure that the material is stabilized and does not cause sediment laden runoff during rainfall events. If necessary to protect local receiving waters, runoff control of the disposal area will be instituted. Traffic - During the process of transporting dredged material from the containment area to disposal sites there will be an increase in truck traffic around the pond. This traffic can be routed so as to avoid densely populated areas as much as possible, and can be limited to the daytime hours. Summary - There will be a variety of negative impacts that will have to be tolerated during the dredging operation. These f impacts will be mitigated where possible. The long term impacts 6-15 METCALF A EDDY: / from the dredging operation will be improved water quality conditions in Hardy Pond and enhancement of its aesthetic and recreational value. Permits. Sediment removal work must comply with wetlands regulations, therefore local permits may be required for work in the pond, as well as the containment and disposal areas. A Section 404 permit from the Army Corps of Engineers would be required. A Massachusetts Waterways License and Permit (Ch. 91) from the Division of Waterways in DEQE would also be required. It is highly likely due to the size of the project that a complete environmental impact report (EIR) would be required in compliance with the State of Massachusetts Environmental Policy Act. Adequate time must be built into the project to obtain ( these permits prior to conducting the dredging. Outlet Modifications The existing outlet structure is 20 ft. long and has an overflow crest at elevation 202, City of Waltham datum. It is recommended that the outlet structure be modified to raise the overflow crest elevation one foot to elevation 203. By increasing the normal pond level the depth in the pond will be increased, which is one of the goals of the restoration program. The outlet structure could be modified by bolting a metal plate to the top of the existing concrete weir to raise the overflow crest elevation, or by pouring additional concrete onto the existing structure. The section of the existing outlet containing stop-logs will remain to allow control of the pond 6-16 METCALF « EDDY f level. Stop-log grooves and stop-logs will be extended to the modified overflow crest elevation. The proposed outlet configuration is shown in Figure 6-4. In addition to raising the outlet level a permanent staff gauge should be installed for measuring the lake elevation. The recommended modifications to the outlet structure will result in an increase in the normal pond water level by approximately one foot. Prior to construction of the existing outlet structure in 1982 the pond level was higher. Thus, raising the pond level will not result in submergence of land areas not previously submerged. The purple loosestrife plant, which is of minimal value as a wildlife habitat, has developed in the regions of the shoreline i that have been exposed since lowering of the pond level in 1982. This plant does not flourish in submerged conditions. Thus, by raising the pond level, areas of this nuisance plant will be eliminated. The recommended outlet structure will have a crest elevation of 203. At pond elevations above approximately 204 flooding problems around the pond begin to occur. Since construction of the new outlet structure and associated downstream channel improvements flooding problems in the pond have been alleviated. The proposed outlet structure would have the capacity to pass approximately 60 cfs at pond elevation 204, provided that the outlet is not submerged due to backwater effects from the downstream channel. Thus, the outlet C 6-17 METCALF A EDDY STOP LOGS AND STOP LOG GROOVES ' RAISED TO El. 203 r- AM ; ?." •'*!** A"1 -:#•'•& • 1 ., EL. 203 :>.-i: ":'&': • • . • • Jjr / • t>; *•" . • \ STEEL WEIR — t • * / / / iii/ / / i :*; - fr \ f i i C>/ t> • ^EXISTING WEIR i i f '•>::•i ' EL-202 >1 ^ I/ J. *// I/ HABDY POND V-O" FLOW SEAL TO PREVENT WATER LEAKS •*:•! ' SECTION A FIG. 6-4 RECOMMENDED OUTLET STRUCTURE MODIFICATIONS _ modification should be accomplished in conjunction with the downstream improvements already planned as part of the City's flood control project. Based on information obtained during the Diagnostic Survey it is the downstream channel that currently controls the water level in the pond during periods of high water. The 100 year design storm outflow from Hardy Pond is estimated to be approximately 44 cfs, with downstream channel improvements (Valgaropulos, 1978). Thus, modifications of the outlet structure should not cause a problem in terms of increasing flood elevations, although upstream flood storage will be reduced somewhat. If necessary the pond level can be drawn down by removing stop-logs from the outlet structure during high water conditions. f Shoreline Improvements Except at City owned property, shoreline improvements are largely up to individual homeowners. A good approach to shoreline clean-up activities would be to schedule a pond-wide clean up program. To perform the clean-up of Hardy Pond, it would first be drawn down about 18 inches using the existing stop logs at the outlet structure to expose some of the shoreline normally submerged. Through the public education program, shoreline residents will be informed regarding timing of the drawdown and methods of clean-up. The City of Waltham would participate in the clean-up, not only to clean City property, but also to provide pick-up and disposal of trash and shoreline growth. It should be stressed that the objective of the cleanup 6-19 METCALF ft EDDY is to remove unsightly trash and growth near the shoreline which can be picked up by hand or raked. Disposal of this material in trash bags at the normal dump site will be adequate. The removal of pond sediments is considered as part of the dredging recommendation. A random or poorly planned clean-up of the shallow shoreline area could unnecessarily adversely impact and eliminate valuable aquatic habitat. Rooted plants may be unattractive to the public when exposed by drawing down the pond. However, some of these plants provide important habitat for fish and invertebrates when submerged. Therefore, after drawdown of the pond, a survey by qualified ecologists should be performed to identify areas where emergent vegetation should not be removed. These areas should be marked before removal begins. The cost of the clean-up program would be minimal; about $2,000 is estimated for the ecological survey and subsequent report on clean-up activities. The remaining work required would be by shoreline residents and City forces for one day only. Volunteer groups (boy scouts, churches, etc.) could assist in the effort. Swimming-Area In order to develop a public swimming area at Hardy Pond, the following activities would be needed: 1. Site selection - The City would choose a preferred site. One site currently under consideration is at the end of the Shore Road. 6-20 METCALF ft EODY 2. In-pond beach area development - The submerged off- ( shore area would be dredged to an appropriate depth during the dredging program. Suitable material such as sand would be spread in the area to be used for swimming. 3. Shoreline development - Appropriate shoreline facilities such as a parking area, life guard seat, benches, access roadways and landscaping would be designed and constructed. 4. Operation and maintenance - Other than hiring a life guard, limited operation and maintenance activities would be required. Included would be chemical testing for contact recreation quality, possible localized addition of chlorine, and possible addition of more sand to the submerged area. A cut-off wall with pumping and chlorination facilities was considered, but is not judged to be required due to the low bacterial content of the pond water. If necessary, chlorine could be added directly to the water as is done at Whitman's Pond in Weymouth. The estimated cost for the swimming area is $7,500 in capital f costs and $4,000/yr in operation and maintenance expenses. The capital cost could be reduced if performed by City forces. Post-Implementation Monitoring Program In order to assess the effectiveness of the restoration plan, a one-year post implementation monitoring program is recommended. The program will be a scaled down version of the Diagnostic Survey undertaken during this study. It will include collection and analysis of in-pond data, focusing on assessment of post-dredging conditions in the pond. The monitoring plan will include routine sampling at the center basin of Hardy Pond at both surface and near bottom depths, in order to provide information on overall pond quality, whether the in-pond phosphorus goal has been met/ and to observe 6-21 METCALF ft EDDY f the effect of dredging on nutrient release from the sediments. These samples will be taken at a frequency of about six weeks, for a total of eight times per year. This should provide a good indication of the seasonal variation of conditions. Two sediment samples would also be taken at the sediment sampling stations shown in Figure 3-1, to identify characteristics of the pond bottom material after dredging. Samples from the in-pond station would be analyzed for the following parameters: total phosphorus, alkalinity, nitrate- nitrogen, ammonia-nitrogen, TKN, suspended solids, chlorophyll a, phytoplankton cell counts and identification, and fecal coliform bacteria. In-situ profiles will also be taken of temperature, DO, pH, and conductivity, and a secchi depth reading will be ^ taken. Sediments would be analyzed for the physical and chemical parameters as measured during the Diagnostic Survey as follows: heavy metals, oil and grease, TKN, phosphorus, organic content and water content. Monitoring during the conduct of the dredging program was considered. In-pond quality data taken during spring and fall dredging operations are not considered necessary. It is expected, as discussed previously, that water quality impacts such as increased turbidity and solids will occur, and that appropriate mitigation measures such as silt curtains would be used to localize the impact to the extent possible. However, documentation of in-pond.quality would serve little purpose in f this regard. 6-22 MCTCALF A EDDY Collection of in-pond data during the summer of each year of dredging operations would be useful in assessment of pond quality conditions at various depths of dredging. Thus, two stations are recommended, one in an area where dredging was performed, and one in an area not dredged. These would be sampled twice in summer, for the same parameters as for the post- implementation program. Analysis of these data would provide a time history of conditions during the dredging program. Water level readings should be taken by the Town Engineering Department to check the effectiveness of the modified outlet structure. These measurements should be taken at the new staff gauge and recorded on at least a monthly basis. A summer macrophyte survey after the dredging program completion should also be performed, as was done during the Diagnostic Survey. This survey is to check the effectiveness of the dredging program, as well as the overall effectiveness of the restoration plan on macrtophyte growth. The total cost of this four year sampling and analysis effort is estimated to be $30,000. Public Education Program During the Hardy Pond restoration program, it is important to keep citizens informed regarding all restoration activities. In particular, due to the environmental impacts associated with the dredging program the need is even more acute. The public education program for Hardy Pond would consist of meetings (at least annual), at which status reports of the 6-23 METCALF ft EDDY /' implementation activities would be presented. It would involve information lectures and handouts by involved parties knowledgeable about the Hardy Pond restoration program. It would serve as a forum to obtain public input regarding proposed restoration methods and would educate people regarding the methods to be used. A major thrust of the program would be to educate individuals regarding the environmental impacts and mitigation measures related to the dredging program. The Committee to Save Hardy Pond would be instrumental in the program. The Committee could serve as the focal point for. setting up meetings, developing lists of concerns (as was done during the Diagnostic/Feasibility Study), providing other input and assistance such as keeping pressure on legislators, political ! representatives, etc. in support of the program and funding, and interacting with the City as the program proceeds. A budget of $3,000 per year for six years has been estimated for the public education activities. Historical Commission Concerns The City of Waltham Historical Commission and the Massachusetts Historical Commission have both been contacted in regard to the proposed project at Hardy Pond. The Waltham Historical Commission is concerned only with historical buildings and structures, and has no comment on the proposed project. The Massachusetts Historical Commission (MHC) has reviewed the recommended plan for Hardy Pond, and has commented on the project. The MHC does not feel that the dredging activities or C 6-24 METCALF ft EDDY outlet modifications would effect historical or archaeological resources. However, the MHC has requested to review potential locations for sediment containment and disposal areas as well as any plans for shoreline development (i.e., swimming beach) early in the detailed design-implementation phase of the project. This review will be to evaluate the projects effects to historical and archaeological resources. Restoration Plan Schedule An overall schedule of activities for the restoration program is provided in Table 6-6 and Figure 6-5, The first year of the program would involve procurement of funding, consultant selection, initiating the public education program, and obtaining necessary permits for the dredging program. The dredging program would be undertaken over a three year period. Given this schedule, post-implementation monitoring would not occur until 1991. Cost Estimates and Funding Sources Cost estimates have been prepared for each of the recommended alternatives at Hardy Pond. Costs associated with dredging are presented in terms of a range due to variables involved in the dredging and disposal costs and the fact that sediment disposal sites have not yet been finalized. The costs shown reflect the difference between telephone quotes by dredging contractors, which tend to be low, and published construction costs, which tend to be high. The major cost items include design and construction of facilities (containment area, disposal 6-25 METCAt-F ft EDDY TABLE 6-6. SCHEDULE OF ACTIVITIES FOR THE HARDY POND RESTORATION PROGRAM Activity Month Year 1. Apply for Chapter 628 implementation funds 10 1985 2. Appropriate City share 4 1986 3. Select design engineering consultant 5 4. Initiate permitting process 6 5. Initiate public education program 7 6. Design and bid dredging program 2 1987 7. Construct containment area/disposal area 8 8. Shoreline improvements clean-up program 9 9. First-year dredging - fall 9-11 10. First-year monitoring - spring 3-5 1988 11. First-year monitoring - summer 7 12. Design and construct outlet structure modifications 8 1989 13. Second year dredging - fall 9-11 14. Second year dredging - summer 3-5 15. Second year monitoring - summer 7 16. Third year dredging - fall 9-11 17. Third year dredging - spring 3-5 1990 18. Third year monitoring - summer 7 19. Design and construct swimming beach area 8 20. Post-implementation monitoring 1-12 1991 sites), hydraulic dredging, and material hauling costs. Construction costs for all other items are based on the 1985 Means Construction Cost Data publication. An engineering design and contingency factor of 30 percent is included in all construction cost estimates. Table 6-7 presents a summary of the estimated costs of each of the recommended alternatives. In accordance with the restoration plan schedule, the cost are provided by year in Table 6-8. c 6-26 METCALF ft EDDY TASK 1985 1986 1987 1988 1989 1990 1991 GRANT APPLICATION * CONSULTANT SELECTION — DREDGING PROGRAM Deiign and Bid ^••B • Containment / Disposal ATM Perform Dredging Monitoring ""*" """* SHORELINE IMPROVEMENTS * PROGRAM * OUTLET STRUCTURE ^^•MM MODIFICATIONS SWIMMING AREA MBl^HiM POST-IMPLEMENTATION MONITORING PUBLIC EDUCATION PROGRAM FIGURE 6-5 HARDY POND RESTORATION PROGRAM SCHEDULE TABLE 6-7. SUMMARY OF COST ESTIMATES FOR RECOMMENDED ALTERNATIVES (1985 DOLLARS) Capital Annual Cost O&M Cost Recommendations ($) ($) Dredging 1,000,000 - 2,200,000 Outlet Structure Modification 3,000 500 Shoreline Improvements 2,500 Swimming Area 7/500 4,000 Monitoring Program 30,000 Public Education Program 18,000 - TOTAL 1,061,000 - 2,261,000 4,500 TABLE 6-8. SUMMARY OF COST ESTIMATES PROJECTED OVER THE PROJECT PERIOD*1' Recommendation 1986 1987 1988 1989 1990 199f Dredging 50 320- 335- 335- 165- 620 735 735 365 Outlet Structure 3 Modification Shoreline Improvements 3 Swimming Area 10 Monitoring Program 4 4 4 27 Public Education Program 333 4 4 4 TOTAL 53 329- 342- 342- 183- 31 629 742 742 383 T~. Costs are in thousands of dollars, based on 1985 estimates escalated at 5 percent per year. ( 6-28 METCALF a EDDY - The total capital cost associated with this program is C between 1 million to 2.3 million./ Given this amount, various funding sources were considered for program implementation. The Chapter 628 State of Massachusetts Clean Lakes program is the best available funding source. This program is administered by the State Department of Environmental Quality Engineering. Approximately $3,000,000 per year in grants are awarded for purposes of restoring publicly owned freshwater lakes in Massachusetts, such as Hardy pond. A grant application must be submitted and is then prioritized based on such factors as public support, pond uses, and status of eutrophication. The funding shares for implementation work are 75 percent State and 25 percent Local. Since the Diagnostic/Feasibility Study is funded f through this source. State review and approval is required. The total cost for the Hardy Pond project is high, given the annual level of Clean Lakes program funding, therefore other funding sources were considered. A potential source of funding is the Massachusetts Rivers and Harbors program. A one time only grant of $3,000,000 was administered by the State Department of Environmental Management, Division of Waterways. Over $27,000,000 of requests were /f \~ received, however in many cases the local match could not be raised. The local matching funds required for dredging projects are 25 percent. A bill for an additional $30,000,000 for this program is pending in the Legislature. This may be approved, given the current State budget surplus. Potential funding for C 6-29 METCALF ft EDDY f Hardy Pond would be dependent on this approval. However, it is recommended that a letter of interest be submitted in any event as a possible supplement to the Clean Lakes program. A Clean Lakes grant should be submitted by October 1, 1985. Most likely, the entire amount should be requested on the grant application, but the funding would be granted on a per year basis, for total amounts in accordance with Table 6-8. The Local share can be appropriated through Community Development Block Grant funds, since Hardy Pond is in a block grant area. 6-30 METCALF A EOOY APPENDIX DIAGNOSTIC SURVEY DATA METCALF ft EDDY A-l. IN SITU WATER QUALITY DATA METCALF a EDDV HfiRDY POND, WflLTHflM E NO ST« DOTE DEPTH TEMP PH DO COND SECCHI (M) 1 4 60884 •O - 24.7 6.8 7.7 ' 340 2 3 60634 ,O 23. 9 6. 1 6.4 470 3 '2 60884 .•i 0.3 £7.3 7.8 10.9 303 4 60684 - 0. 6 26.3 7 9.£ 1 309 5 ^ S£ - 60884 i ,P,9 £2.7 6.4 8.6 310 6 2 60884 .', 1.8 2O. 5 3.3 1.3 7- M - 60884 0 16.6 S. 5 4 243 a . 'A • 62184, 0 20.8 6.3 . 3.3 333 9 ' 3. ' 62184 O 16. £ . 6 4. £ 670 10 -. au ••" 62184 ' *' 0. 3 ~ '.£2.3 • Q 9.6 327 0. 5 11 • 2i 62 184 O.6 £2.6 • ' 8.3 9.2 327 12 " •• a- 62184 '"• 0. 9 £2.8 ' '"' 8.4 , 9.3 3£6 13 2 • 6S1B4 . • 1.2 £2. 6 • a 7 325 14 4 70284 •.-' o . £8.9 5.8 6.4 351 15 70£S4 , ££ 5.9 4.8 &04 " 3 : -.; o r •16 - -'as-: 70284 • 0.6 17 • - -. .-,". + ••: --7S6B4 0 £1 6.9 £.4 > 335 IB • " ' - 3 ':- 72664 .' •• •-: O' 17.9 6.6 7 490 19 • ;.-."• T £-'"'-'• 72684 V- :. 0.3 25.5 9 9.1 330 20 ••; •• '•'•' fir• ;-72684 V O.3 24. 1 8.9 a. 4 3£B. 21 .V-' I- "-:^d!.-, 7S684 , ' o. a 23. 3 7.7 4. 1 331 22 •/::, L .;;,4V? ' BOB84 - ~ o 23 ' 6.4 . ''3. 369 83 :1 ; BOBB4 -V o SO. 8 6.4 5.7 531 v;:.'• -:-3 "-. 24 •• • 07, 80B84 • 0. 1 £8 7 "" 7.6 371 0.3 25 -v:-"*«V- 80884 -4 ;O.3-, , 28 --. , 7.4 -7.1 370 J'i 26 V-V:../ fi'v; 80884 ' . O.6 : £7. a 7.4 6.6 370 27 '.-,. ::ieK 80884 O.9 £7 7.1 ' :i ' 4. , 371 SB .;.,>.. 4 •• 88884 • 0 28.7 & 3.6 491 29 • ..- i . '3 . 82BB4 • o , 19.4 5.7 6.2 412 30 i j : - :fi 9 • 82884 '. 0.3 ; £6.7 8.3 . 12.2 439 - 31 -• , 'a ' 82884- o.a £6.6 8. £ 1O. 8 , 441 91084 32 X -. 3 , 0 19.9 33 4 926G4 . 0 ." 19.4 , 7 1.3 419 34 3 :9S684 o ' 17.9 7.3 7.4 1O3 35 ~2 , 93684; , 0.2 £1 7.3 7. 1 392 0.5 36 a 92684 : O.6 20.9 - 7.£ 6.B 392 37 4 ; 101184 0 12.5 &.& 4.5 414 38 •' 3 101184 0 13.4 6.7 8.7 443 39 2 1O1134 0.3 14.4 7.7 9.B 3&7 0.6 40 • a " 101184 0.7 13.9 7.5 9.5 363 41 3 102584 0 11. £ 6 5.9 474 42 4 10S5S4 0 12.5 6. £ £.9 456 43 "a"" 1O2S84 0.1 14. B 6.8 a. i 377 44 s 1O25B4 0.5 14.7 6.8 a. i 376 43 4 111984 0 3.6 10. a 340 46 3 1119S4 0 4.7 5.9 9. e 4G9 47 "a 1119^4 0.3 3.5 3-4 11.6 343 48 2 111964 0.8 3.6 3.8 11.5 34£ 49 4 12J8S4 O 5.4 S. 3 9 396 50 ,3 121864 0 4 5.8 9.9 SO 9 51 2 121034 0.2 5 &. 6 11.4 3-+7 MLTHAM HflROY P»L DISCRETE SAMPLING DATA SfflMG WTE JU. MY TOT ffPTHSWBOTf rss ros TUD CHUM flU TUN AMOK MT TUT ? TCOL PCX Crt fl » D9TH 015 FE Ml (M ottu tue/Li tmm (KB/U IM6/U WB'O IB6/L) ran.) (KB/-) i/lOOML t/ioon. (KB/H3) I US/KB) r 3 112084 325 0 0 3.2 310 3 97 26 0.78 0.065 0.18 0.066 2600 24 (5 • 0.79 3 121884 353 0 0 1.4 330 120 26 0.85 0.22 0.26 0.042 240 26 (5 1.3 c - SL_3 11783 383 0 0 20 . 400 18 140 40 1.3 0.73* 0.063 0.08Z 320 33 (5 6.J 3 21485 411 0 . 0 9.9 380 8.2 150 17 1.3 0.41 1.1 O.OE3 3100 100 11 0.25 3 30783 432 1.4 * 450 2.7 180 29 1.4 0.71 0.33 O.OS5 180 10 0 1.1 3 32663 431 £ 420 2,2 190 30 1 (.01 0.22 0.03 1000 18 (3 1.1 « '• ' 3 41685 1 472 - . 4.6 430 2.9 200 29 0.96 0.1 (.01 0.033 . 700 110 (5 1.4 3 30185 487 2.8 440 7.6 180 38 1 0.23 0.02 0.061 3500 130 (5 2.6 51685 ' B02 ' 3.8 440 9.9 180 53 .2 0.38 0.084 0.089 3200 180 (5 3.4 « 3 53083 • s» '/" 2.6 370 11 140 43 .8 0.026 0.07 0.0ft 3000 380 <5 1.9 '-. 4 60884 ltt\ 0 0 8 220 4.6 SB , 46 .1 0.19 0 0.12 30 15 2.1 4 62184 173 \ 0 0 IS . 220 7.7 66 44 .5 0.027 0 0.35 0 29 (5 3.1 « "70284 o £20 0 1 . .". 4 184 ; — o 11 7.2 49 71 .1 9.27 0,13 28 (5 2.3 ' 4 72684 208 ( •""• 0 0 24 220 28 69 48 .9 0.34 0.09 0.22 8000 90 2.7 v « " " 4 80884 221 - - 0 0 23 250 38 70 55 13 0.67 1.2 4000 22 (5 3.6 ... . - 4 82BB4 • '241- ••:.:•".. 18 200 17 75 52 . 2.6 0.9 0.12 0.62 0 24 (5 3.3 4 91084 254 •'-',.. 41 160 56 77 47 5.5 1.4 0 0.37 0 30 (5 1.& 4 92784 271 . - 180 16 ,73 54 3.3 1.5 0 0.4 48 (5 2.7 -*• w "' ~" 4 101184 '" '285 ". 230 17 79 40 2 0.63 0.05 0.16 1900 70 (5 0.89 . . .- " '~8.4 4 10364 299 '"" 9 260 7.4 89 38 1.8 0.51 0 0.16 2100 110 (3 2.1 - .. ,. .jg ,-_0 4 112084 : o 6,4 230 " 5.5 68 29 1.1 0.28 0.1 O.OB5 itoo 4 (3 0.66 : "" 4 121864 - 353 -'•"• o'"' 0 , ' 11":. 260 3.9 70 " 31 2.5 1.3 0 0.22 20000 2000 0.8 •:'•••*.••• 4 11785 ':. .383 '.;•:'..• 0 1.0 390 : 3.1 110 29 0.78 -, 0.22 0.11 0.052 50 4 (5 0.9 • '4 21483 411 . ,0 O.I'1 12 330 6.3- 130 , 20 0.89 0.37 0.58 0.051 360 58 0.87 •••• " w -~ ... „!.,. y 4 30785 '""432" "•"••'*' '.', ' • • '*'? 9.2 - ' 290 4.9 120 27 1.6 0.35 0.065 0.021 90 10 0.76 : ,.,.. ^ --> .... r- - 4 32685 '» 7.8 1 450 4.2 110 ' 28 1.4 0.14 0.059 0.053 5300 310 (3 0.89 , ~ '"4 41683 " ',"472 ''*'.'••'• :*' ' 3.0 430 3.1 120 27 0.74 (.05 (.01 0.03 200 40 (5 0.65 ...... * ... _ - -g ;. •— 4 "soles •"*w,V.-f .'. • ••*•; 2,4 • 370 ' 5.1 150 ,37 1 0.17 0.03 0.06 SO 10 ' 1.2 ••"••-' •'•' . 4 51683 • 502 <•••.:!* •;,- ' f . :• 11 360 9.5 35 39 1.7 0.35 (.01 0.089 1000 90 (3 •'' 1.8 ,; ., ' > 4 33083 ' "'316 :" \ •'";' '•;. 3.1 , 310 M 1« 120 • 38 1.3 (.03 0.2 0.086 600 110 (3 1.9 ' • \ HflRDV POND, WflLTHflM E NO STft DATE DEPTH TEMP PH DO COND SECCHI (M) (DEG O (MG/1_'> (UMHO/CM) (M) 58 a i181684 0.7 4.9 6.7 11.4 347 53 :- 3 11783 . o 1.4 -3.3 14.1 ' 48G 54 3 a 1485 O 0.4 5.5 9.7 649 53 4 ai48S * 0 a. 3 3.9 1 10. 1 609 56 •• - a £.1483 .o.a 1.7 'fc. 1 IK a 183 57 ! .... a . a 1483 2.2 5.8 9. 1 31& 58 - ..... g . . a 1483 -°-•r si 3. E 5.6 7-1 58G -59 - .:•-*,- 3 -. 30783 ' . 0 1.3 3.4 8.3 864 , 60 \ *. 30783 0 3.3 6 13.4 592 ' 61 \£ 31485 . o.a 6.9 .6.7 10.3 431 63 - • . .-..'., g..'-. . ..31483 ; .0. S / 7 6.6 11 - 43£ 63 -.. a -• 326BS 0. 1 ' 3.6 6.8 5.9 508 64 a -. 32685 O. 6 3.5 7. 1 . 6. 1 519 63 ...... 3...,- • 326B5 o l.S 6.2 6.3 803 66 .•• 4 ; , 32G85 .'..•', -o' £.3 . : 6.3 6.7 671 67 ' "S .'"41685 ."•"0. 1 13.9 ': 8.2 9.4 49Q 68 •• ..•.,..», g.-, , ;4168. 3 0.3 : 15.7 3. 1 3.4 1 494 69 v •'• - a • - 4168" 3 1 14.6 a. i 7. a ' 49S 70 . - .... > , 2 :41683 1.3 - :... 14.4 ' 7. E £.3 459 71 mm_^. o ^t - 41685 .-..,;... a.. 14. 5 r- 7.7 . a. a 483 ... 72 ..-, .'.;•;•; 3..; 4168•! 5 ' • o. ; ia.6 .- 7.9 9 680 73! " .:*•• 4 "•'',•'•' 41685 •!' . O '-, 14.4 .8. 1 7.9 540 74-- - ^. - '^ :' 3 \', ',.'.'5018. 3 . /.,.' o , • 13.8 '4 6.4 8.4 703 73 - ,.:.. 4-,..>.: 50183 .0 18. 8 : 6.3 8.4 6£3 76 - ,.,_ -£•:•}•-? 50183 . o ao 6.8 9. £ ' 529 • 77,., . •.< -•;. O-.': . 6.3 ','„.. •''i, 3-r,'.-^ 31583 J 16.6 7.3 , 693 ..;. 78 > • } '''• ' *'•", '•51585 -•••';-'' 0 £0.9 .- 7.5 4.7 ' 57£ '• . 79 • t; ~2;,V ;." 51583 ","••'0.3'" •' 19. a ':; a. a : 8. £ 494 ao ; 'V"V': a—'-'' 51583 .'.'..-' 0.6 ' 19.3 - 8.2 a 494 61 * -i •""- £ '"' • 33083 O.3 ao . 7.£ 7.3 471 aa • :.•; ,a-4-"-. 53085 1 18.9 7. a , 6.7 4G6- : 83 - •-•• -y 3;,,; :: 33083 • O IS • 6.7 a. 2 5*0 ,.. l 84 *.' 4 '.". ' 53083 ' O.3 ao.9 7.£ 7.7 484 \ c A~2. DISCRETE c SAMPLING DATA METCALF A WLTHM WWDY POM) DISCSETE SWUM Mi,. NO DATE JU.MT nrr&PTNSM WTfi res TDS TIM CHLOR BLX TKN MWN NAT TOTP TCOL FCO. Di.fi «D?TH Die FE m> i1) IHS/U 0ent (NTU> tffi/L) 1K6/L) (MB/U (ffi/U (NBA) (TG/L) 1/toon. 1/100*. (KB/X3) (K67K6) t 60894 ISO 0 0 i 170 1.1 19 42 0.82 0,24 1.1 0.11 890 73 (3 2.1 Z 60864 160 1.2 0.3 1.6 200 2.6 47 41 1 0,13 0 0.075 4 20 1.6 I S2J» 173 1.2 0.3 21 220 6.6 64 47 1.7 0.31 0 0.19 1000 4 20 2.8 -a. 70284 184 0.2 12 ,220 5.3 49 69 0.81 0.22 * 0.01 0.16 1000 4 20 8 z 72684 208 0.2 26 . .240 40 68 48 2.1 0.4S 0.1 0.14 40 0 30 20 0.015 z 80664 - 221 0.2 22 830 36 61 50 2.3 0.4 0.06 0.69 00 8 36 20 <3 3.6 z Km 241 0.2 " 13.-' 190 20 73 52 2.1 0.62 0.7 0.41 200 38 39 20 0 l.S z 91084 254 0.2 18 ""' . 160 16 74 46 1.5 0.47 0 0.14 0 . 2 60 20 (5 1.2 z 92764 271 '•' -. 0.2 12 :: 170 13 75 44 1.7 0.83 0 0.17 100 110 20 (5 1 O z 101164 263 0.2 7.2 ' 210 16 71 ' 40 1.6 0.31 0.06 0.13 20 10 27 20 (5 0 z 102584 299 0.2 8.4 : 210 14 66 38 1.5 0.37 0 0.11 300 82 8.9 20 (3 0.39 z 11206* 325 0.2 12 220 7.8 63 -26 1.3 0.33 0.09 0.12 1300 2 4.8 20 (3 0.53 ; O "Z 121884 ' 353 V\ - • 0.2 — 3.4 -- 220 2.5 69 23 0.93 0.063 . • o 0.13 190 18 18 20 (5 0.38 - .- . . 11785 363 0.2 £.2 380 Z.S 97 27 0.63 0.062 0 0.052 8 0 12 20 (5 0.49 e i . .'.- 2 21485 411 0.2 3.7 ISO 4.6 52 13 0.59 0.4 0.33 0.014 60 0 2.3 20 O z 31483 439 • >kg . ... . 0.3 ~ 4.6 250 3.1 80 26 1.5 (.05 0.84 0.027 1100 230 (.1 • 20 (3 -0.89 2 32U3 431 8.2- 250 3.8 92 25 1.3 0.16 (.01 0.049 1500 760 17 20 (5 0.48 2 41683 478 1.5 0.3 •--' 4.Z :' 290 2,9 110 24 0.68 0.072 (.01 0.063 SO 24 3 20 0.96 O 2 30185 487 »- • i- ... w. , -, 320 6.3 110 31 0.8 . 0.12 (.01 ' 0.024 90 12 5.5 20 13 0.72 - r-, :. (.01 z 31683 502 '•- 3.2 310 10.6 110 31 1.1 0.15 0.072 9.1 20 (5 1.3 ; 53085 0.2 4.1 300 • 12 110 38 1.3 0.23 . 0.034 0.098 (Z £0 O z 516 - I ' ' ;i eoo J.7 i' ° t 60384 ' 160 V'1.2 " •' 0.8 • 470 ,; .200 40 30 33 1.8 0.17 0 0;i6~ ' 80 .... {3 23 I 62184 • ,- 173 '• v 1.Z 0.8 •; .390 .' 220 27 64 42 12 0.89 0 0.3 00 13 t 70284 •''; IM ft7 .' 68 , 230 ,.i e 48 79 5 0.56 0.04 0.66 ', 80 j 2.3 !-|o z 72684 --Mar •""'•: 0.6 .'"> 430 - ' 610 . 74 ' 68 40 17 1.8 0.13 1.5 • - --7 - ,, - 80 - . . . _ ,.-^ • 12 • 8 80684 ' 221 -v-.V- -- ', 0.8 -"V 380 ' 370 ."•70 ; 72 . 62 9.3 0.97 0.11 0.58 80 • 3 Z 82884 V 241 -''!',:' '.'. • 0.7 16 200 :•"- 20 '''•72 :'; 32 2.2 0.62 0.49 0.49 80 ^ • 1.7 1 z - 91084 •ir Z34- •?;•?!". T' .*' 0.7 •-.*:- »• •• 170 " 18 '• • 76 47 1.7 0.56 v o 0.16 . •" . •••*•• .' • <*• 80 ..(*.- j -1.1 -i:!° 92704 '• ••• 271 • ,*'.,- ;'/"" 0.7 #••- 11 •. 170 14 76 « 1.7 0.42 • " 0 0.2 80 'V' '•''. 1.3 z 1 z 101164 '.'I '285 i\j. 0.7 220 17 71 40 1.6 0.58 . 0.05 0.062 . 80 .0 . --/i. -'i-.' ••• • « v . . -V |:° 'Z 102584 ; -'.~TOi 0.7 , '- •' fl 220 '" IS 69 ' .' £7 • 1.3 0.31 '.' 0 0.066 ,,'; . : .• • 80 i^.. - . 0.37 ..,-.;,•. j.. •_ t 112084 ;-J325 0.7 '!' 130 220 36 62 26 12 1 ;' 0.1 0.72 80 • - 11 z 121884 "'I 353 " '"* ' ' 0.7 Jr- 3.4 '.• Z10 ' 8.7 68 S3 '0.98 0.06 : ,,J 0 0.062 - i 80 \ • 0.3 ijo 2 11785 • 383 - — '_-.-' ».; 1 '. 80 Z Z1485 411 '' , 0.8 '•• « "' BGO 6.4 83 24 1.2 0.26 : 0.19 0.057 80 0.93 Z 31485 V 43» 80 V f o Z 32683 431 • * 34- ZSO 39 J3 26 6.6 (.01 (.01 0.069 • 80 " 0.61 Z 41685 47Z 1.5 1.2 4.6 290 6.9 no 86 O.S4 (.03 0.21 0.047 80 0.6 z 50183 487 .'! 3.0 400 6.1 120 31 0.86 0.1 (.01 0.048 80 0.56 o e 3168S 502 - i -r- ' :' 80 z 53083 516 /'"' 1 0.1 14 310 jt 110 16 1.2 0.19 0.019 0.097 80 1.7 3 60864 160 ....o ' •'" 0 11 320 74 110 42 0.84 0.27 0.08 8 0.15 210 , <3 0.84 o •j 62(84 173 ***• 0 •• 0 -• ja 430 14 160 52 1.5 0.61 0.04 ' 0.17 1000 300 <5 8.3 3 7Q2U 184 '"," 0 0 14 ' 380 16 130 50 1.2 0.44 0.04 ' 0.12 200 (5 7.1 3 72684 208 - o 0 a - 330 17 120 51 1.9 0.9 0 * 0.052 600 68 , 3 i:,o 3 60684 • 221 ... 0 .. 0 7.Z - 330 13 1ZO 45 1.4 0.68 0.7 , 0.16 1700 320 . ... . Q i 4.3 3 4288* 241 1.6 180 6.1 63 40 0.94 0.33 ' 2 0.12 700 42 W 1 2.6 91084 254 Z % 3.6 38 *6 0.42) 0.12 0.29 0.625 . 10 0 1.1 O 3 ..... „. . 3 927*4 271 1 40 0.9 14 37 0.23 0.032 0 0.034 500 8 (S 0.47 3 101184 283 6.4 230 5.6 93 31 0.66 0.29 0.22- 0.16 1300 360 (3 1.8 3 102504 £99 11 290 3.6 100 38 1.1 0.23 0 0.16 3700 240 (5 8.7 u c A-3. STORMWATER SAMPLING DATA C c METCALF ft EDDY TABLE A-3.1. HARDY POND STORMWATER SAMPLIKG DATA OCTOBER 22, 1984 Total Total Suspended Dissolved Total Total Fecal Sample No. Discharge Solids Solids TKN-N Ammonia-N Nitrate-N Phosphorus Coliform Coliform and time * (FWsec) (mg/1) (mg/1) (mg/1) (rag/1) (mg/1) (mg/1) (No./lOO ml) (No./100 ml) D1-1 (8:40 pm) 0.28 560 160 10 2.4 3.9 .38 58 ( 000 28,000 D1-2 (8:55 pm) 0.16 45 89 3.7 2 4.4 .32 150,000 64,000 D1-3 (10:25 pm) 0.52 170 80 5 1.9 2.8 .84 35,000 10,000 D1-4 (10:38 pm) 0.52 190 49 2.5 .94 ' 1.3 .41 860,000 13,000 D1-5 (10:50 pm) 0.59 34 30 1.3 .71 .93 .2 110,000 4,300 D1-6 (11:05 pm) 0.63 40 28 .84 .36 .45 .16 73,000 3,600 D1-7 (11:20 pm) 0.66 33 26 .57 .28 .32 .14 43,000 2,600 D1-8 (11:40 pm) 0.80 25 25 .42 .19 .20 .12 36,000 1,900 D1-9 (12:00 am) 0.85 42 20 .56 .15 .14 .15 56,000 1,600 D1-10 (12:20 am) 0.18 12 15 .33 .17 .16 .077 35,000 2,900 D2-1 (10:40 pm) 0.11 180 65 3.9 .64 .39 1 80,000 7,000 D2-2 (10:55 pm) 0.10 38 41 2.3 .77 .87 .37 10,000 2,900 D2-3 (11:07 pm) 0.13 34 48 1.9 .51 .49 .40 14,000 1,700 D2-4 (11:22 pm) 0.13 81 41 1.3 .24 .42 .38 13,000 900 D2-5 (11:45 pm) 0.26 50 33 1.3 .34 .42 .35 9,000 2,100 D2-6 (12:00 am) 0.40 62 33 1.2 .24 .36 .38 15,000 2,200 D2-7 (12:20 am) 0.14 28 24 .95 .18 .30 .31 1,200 1,000 D2-8 (12:43 am) 0.14 16 26 .68 .25 .26 .25 1,000 500 D1 = Drain at Windsor Gardens Apartments D2 = Drain at Shore Road TABLE A-3.2. HARDY POND STORMWATER SAMPLING DATA MAY 3, 1985 Total Total Suspended Dissolved Total Total Fecal Sample No. Discharge Solids Solids TKN-N Anmonia-N Nitrate-N Phosphorus Coliform Coliform and time * (ft3 /sec) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (No./lOO ml) (No./lOO ml) D1-1 (5:10 am) 0.15 300 120 1.3 0.47 0.48 0.55 23tooo 100 D1-2 (5:30 am) 0.15 100 62 0.48 0.48 0.37 0.70 3,000 <100 D1-3 (5:«5 am) 0.15 63 68 1.3 0.81 0.24 0.75 10,000 <100 D1-4 (6:00 am) 0.15 42 63 0.63 0.31 0.57 0.12 8,000 <100 D1-5 (6:15 am) 0.15 32 57 0.50 0.29 0.29 0.75 3,000 <100 D1-6 (6:30 am) 0.15 40 48 0.63 0.49 0.20 0.81 9,000 <100 D1-7 (6:45 am) 0.15 57 51 0.55 0.37 0.24 0.92 10,000 <100 D1-8 (7:00 am) 0.15 100 73 0.72 0.55 0.27 0.28 11 ,000 100 D2-1 (5:20 am) 0.01 78 83 4.2 1.5 0.35 0.18 1,300 ,000 200 D2-2 (5:35 am) 0.01 32 78 3.2 1.1 0.26 0.12 1,200 ,000 1,600 D2-3 (5:50 am) 0.01 56 65 3.5 1.1 0.19 0.16 630,000 300 D2-4 (6:05 am) 0.01 60 69 2.7 2.7 0.18 0.26 260,000 200 D2-5 (6:20 am) 0.01 120 72 2.3 0.69 0.14 0.28 1,300,000 100 D2-6 (6:35 am) 0.01 52 61 1.9 0.65 0.11 0.59 200,000 200 D2-7 (6:55 am) 0.01 43 48 1.5 0.47 0.11 0.43 240,000 300 D2-8 (7:15 am) 0.01 37 55 3.1 1.1 0.15 0.64 340,000 200 D1 = Drain at Windsor Gardens Apartments D2 = Drain at Shore Road r\ TABLE A-3.3. HARDY POND STORMWATER SAMPLING DATA JULY 31, 1985 Total Total Suspended Dissolved Total Total Fecal Sample No. Discharge Solids Solids TKN-N Ammonia-N Nitrate-N Phosphorus Coliform Coliform and time * (Ft3/sec) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (mg/1) (No./lOO ml) (No./lOO ml) D1-1 (9:15 pm) 0.004 18 75 1.4 0.74 2.1 0.067 100,000 37,000 D1-2 (9:30 pm) 0.007 9.4 61 1.4 0.70 2.0 0.059 91,000 35,000 D1-3 (9:45 pm) 0.022 47 62 1.9 .15 1.9 0.096 75,000 23,000 D1-4 (10:10 pm) 0.089 59 31 1.8 0.48 1.0 0.10 47,000 7,100 D1-5 (10:20 pm) 0.111 22 29 0.67 .- 0.073 0.82 0.039 31,000 4,300 D1-6 (10:35 pm) 0.044 12 31 0.59 0.31 0.77 0.026 35,000 4,600 D1-7 (10:50 pro) 0.111 59 32 0.50 0.28 0.74 0.095 37,000 4,500 D1-8 (10:55 pm) 0.200 60 30 0.59 0.27 0.59 0.090 21,000 2,300 D2-1 (10:00 pm) 0.001 14 67 1.4 0.56 1.9 0.13 71,000 1,300 D2-2 (10:10 pm) 0.039 20 50 1.2 0.46 1.7 0.11 62,000 2,100 D2-3 (10:20 pm) 0.050 53 37 3.1 0.38 0.88 0.17 61,000 2,200 D2-4 (10:30 pm) 0.039 13 37 1.5 0.25 0.72 0.059 68,000 1,400 D2-5 (10:40 pm) 0.020 8.2 28 1.7 0.24 0.82 0.077 97,000 9,500 D2-6 (11:00 pm) 0.088 61 2.1 0.74^ r 65,000 9,400 33 0.32 :tfT 1u.'0/yKT&>£P , D2-7 (11:15 pm) 0.129 62 36 1.9 0.25 o.s^O-x-*- 280,000 18,000 72,000 10,000 D2-8 (11:30 pm) 0.215 64 30 2.4 0.26 o!23t^ \\ 9*y^ -- i ,*^ (11:35 pm) 0.100 -t\ ±\ » D1 = Drain at Windsor Gardens Apartments r* *— * (L{ _ii •'•"** ' D2 = Drain at Shore Road ';»"* . *• *. P L *•- ' /*„ ' V ',t X%' ^^ .--^y ". ;\ ,* ,