AN INVESTIGATION OF ARSENIC IN SPY POND

by

Kathryn J. MacLaughlin

B.S. in Civil Engineering B.A. in History Bucknell University, 1994

SUBMITTED TO THE DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF ENGINEERING IN CIVIL AND ENVIRONMENTAL ENGINEERING AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY

JUNE 1999

@ 1999 Massachusetts Institute of Technology. All rights reserved

Signature of Author LI) (% partment of Civil and Environmental Engineering May 7, 1999

Certified by James E. Gawel Doctor of Civil and Environmental Engineering Thesis Supervisor

Certified by Harold F. Hemond Professor of Civil and Environmental Engineering Department Reader

Accepted by Andrew J. Whittle Professor of Civil and Environmental Engineering Chairman, Committee for Graduate Studies

MASSACHUSETTS OF IWO MAY 2 8

LIBRARIES An Investigation of Arsenic in Spy Pond

by

Kathryn J. MacLaughlin

Submitted to the Department of Civil and Environmental Engineering on May 7, 1999 in Partial Fulfillment of the Requirements for the Degree of Master of Engineering in Civil and Environmental Engineering

ABSTRACT

In early 1997, high concentrations of arsenic were discovered in the sediments of Spy Pond in Arlington, Massachusetts. Further investigation revealed that the highest concentrations of arsenic were closest to the surface of the sediments. Spy Pond is a hypereutrophic lake with a residential-based catchment area draining into it.

A multi-pronged investigation of the source type and location of the arsenic contamination was conducted including stormwater sampling, sediment sampling, catch basin sampling, Geographic Information Systems (GIS) analysis and historical research.

With average concentrations of arsenic in Spy Pond's surface sediment samples around 500 ppm to 800 ppm, estimates of the total quantity of arsenic in the surface sediments range from 1,200 to 1,920 kg. Contouring of the sediment sampling results identify a concentration of arsenic in the North Basin of the Pond. Preliminary results indicate less than 4 kg/yr of arsenic enters Spy Pond through the stormwater drainage system. Less than 1 kg arsenic has been attributed to the historical use of pesticides. The result of this study points towards a groundwater plume entering the Pond in the vicinity of the North Basin.

Thesis Supervisor: James E. Gawel Title: Doctor of Civil and Environmental Engineering LIST OF FIGURES ...... 5

LIST OF TABLES ...... 6

1. INTRODUCTION ...... 7 1.1 SPY POND ...... --- 9 1.1.1 Spy Pond Limnology...... 13 1.2 THE W ATERSHED ...... 14 1.3 GEOLOGY ...... - -..------...... 14 2. PREVIOUS STUDIES ...... 19

2.1 SEDIMENT SAMPLING WITHIN SPY POND ...... 19 2.2 W ATER COLUMN CHEMISTRY ...... 23 2.3 DRAIN OUTFALL SAMPLING...... 28 3. STORMWATER AND SEDIMENT SAMPLING AND MAPPING...... 30 3.1 INTRODUCTION ...... 30 3.2 METHODS...... - ..---...-.--.. 30 3.2.1 Stormwater Sample Collection ...... 30 3.2.2 Catch Basin Sample Collection...... 31 3.2.3 Surface Sediment Sample Collection...... 33 3.2.4 Stormwater Sample Preparationand Analyses ...... 33 3.2.5 Energy Dispersive X-Ray Fluorometer (ED XRF) Sample Preparationand A n a ly sis...... 3 5 3.3 RESULTS ...... -. .---.----...... 35 3.3.1 Stormwater Sampling Results...... 35 3.3.2 Catch Basin Sampling Results...... 52 3.3.3 Sediment Sampling Results...... 53 3.4 GEOGRAPHIC INFORMATION SYSTEMS (GIS)...... 58 3.4.1 GIS Software...... 58 3.4.2 Data Sources...... 58 3.4.3 Raw Analytical Data Layers...... 61 3.4.4 Derived Data Layers ...... 61 3.5 CONCLUSIONS ...... 62 3.5.1 Arsenic Loading to Spy Pondfrom Stormwater Runoff ...... 62 3.5.2 Road Salt Runoff as a Potential Source...... 64 3.5.3 PreliminaryQuantification of Arsenic in Spy Pond...... 64 3.5.4 Mass Balance Calculations...... 66 4. HISTORICAL INVESTIGATION...... 68 4.1 INTRODUCTION ...... 68 4.2 M ETHODS AND DISCUSSION...... 69 4.2.1 Sanborn Fire Insurance M aps of Spy Pond...... 69 4.2.2 PresentDay Uses...... 75 4.2.3 LiteratureReview ...... 76 4.3 POTENTIAL ARSENIC SOURCES IN SPY POND ...... 79

3 4.3.1 Ice Harvesting...... 79 4.3.2 Market Gardening...... 80 4.3.3 Treatment History of the Pond ...... 80 4.3.4 Gypsy Moth Infestation...... 83 4.3.5 Other Potential Sources...... 83 4.4 CONCLUSIONS ...... 84

REFERENCES...... 85

ACKNOW LEDGEM ENTS...... 87

4 List of Figures

1-1: Spy Pond Locus Map...... 8 1-2: Spy Pond Bathymetry...... 10 1-3: Profile of Spy Pond...... 11 1-4: Spy Pond Drain Outfall Locations...... 12 1-5: Spy Pond Watershed ...... 15 1-6: Spy Pond Landuse...... 16 1-7: Surficial Geology Spy Pond Region...... -17

2-1: Distribution of Arsenic in the Surface Sediments of the Alewife Brook and Mill Brook Watersheds...... 20 2-2: Spy Pond Sediment Core...... 22 2-3: Change in Amount of Solid Material with Depth in Spy Pond Sediment Core...... 22 2-4: Spy Pond Temperature vs. Depth...... 25 2-5: Spy Pond Dissolved Oxygen vs. Depth...... 26 2-6: Spy Pond Arsenic vs. Depth...... 27

3-1: Timed Stormwater Sampling Data Sheet...... 32 3-2: Catch Basin Sediment Sampling Locations...... 34 3-3: Stormwater Sampling 11/11/98 Nitrate and Sulfate Results...... 37 3-4: Stormwater Sampling 11/11/98 Drain 36 & 36A Phosphate Results...... 38 3-5: Stormwater Sampling 11/11/98 Drain 20 Phosphate Results...... 39 3-6: Stormwater Sampling 12/8/98 Nitrate and Sulfate Results...... 41 3-7: Stormwater Sampling 1/24/99 Arsenic Results...... 43 3-8: Stormwater Sampling 1/24/99 Nitrate, Sulfate and Chloride Results...... 44 3-9 Stormwater Sampling 1/24/99 Phosphate Results...... 45 3-10: Stormwater Sampling 2/18/99 Arsenic Results...... 47 3-11: Stormwater Sampling 2/18/99 Nitrate, Sulfate and Chloride Results...... 48 3-12: Stormwater Sampling 2/18/99 Phosphate Results...... 49 3-13: Drain 4 2/18/99 Phosphate, Nitrate, Sulfate and Chloride Results...... 51 3-14: Arsenic Contours Surface Sediment Samples...... 54 3-15: Arsenic vs. Lead Surface Sediment Samples 12/11/98 and 2/19/99...... 57 3-16: Arsenic as a Function of Chloride...... 65 3-17: Arsenic in Spy Pond...... 67

4-1: Spy Pond - 1900s...... 70 4-2: Spy Pond - 1910s...... 71 4-3: Spy Pond - 1920s...... 72 4-4: Spy Pond - 1951...... 73 4-5 Spy Pond - 1971...... -...... 74

5 List of Tables

1-1: Spy Pond B asins...... 9

2-1: Surface Sediment Sample Collection Summary...... 19 2-2: Drain Outfall Sampling July 1998...... 29

3-1: Stormwater Sampling Results 11/11/98...... 36 3-2: Stormwater Sampling Results 12/8/98...... 40 3-3: Stormwater Sampling Results 1/24/99...... 42 3-4: Stormwater Sampling Results 2/18/99...... 46 3-5: Stormwater Sampling Results 2/18/99 Drain 4 Sequenced Results...... 50 3-6: Selected Catch Basin Sampling Results...... 53 3-7: Sediment Sampling Results 12/11/98...... 55 3-8: North Basin Sediment Sampling Results 2/19/99...... 56 3-9: G IS D ata Sources...... 60 3-10: Spy Pond Stormwater Runoff Loading Calculations...... 63

4-1: Summary of Weed Control in Spy Pond...... 82

6 1. Introduction

In early 1997, Ivushkina collected sediment samples from Spy Pond (the Pond) as part of an investigation of toxic elements in the sediments of the Alewife Brook and Mill Brook Watersheds (see Figure 1-1) [Ivushkina, 1999]. The sediment samples were analyzed for a number of trace metals, including arsenic. Unexpectedly, the results indicated exceptionally high concentrations of arsenic in the Spy Pond's sediments. The discovery of high concentrations of arsenic in the sediments prompted a number of studies including, a water column investigation; sediment mapping; and the foci for this thesis, stormwater monitoring, and a historical investigation of potential arsenic sources.

Compounds containing arsenic have been used for hundreds of years for medicinal purposes and as a pesticide [National Research Council, 1977; Aurilio, 1992]. Despite this history of medicinal use, arsenic is known to be acutely toxic to humans at high doses [International Agency for Research on Cancer, 1980; Aurilio, 1992]. Strong epidemiological evidence also shows that some forms of arsenic are carcinogenic [International Agency for Research on Cancer, 1980; Aurilio, 1992]. Background arsenic concentrations of 0.4 to 40 mg/kg are considered typical for soils with no natural or anthropogenic arsenic inputs [National Research Council 1977; Aurilio, 1992].

Arsenic concentrations in surface sediment samples in Spy Pond, however, are generally above 500 ppm, with a maximum concentration of 2,650 ppm. Although the Environmental Protection Agency (EPA) has not adopted maximum concentration limits (MCL) for sediments, they currently use Ontario Ministry of the Environment standards of 30 ppm for arsenic. Additional studies focusing on possible ecological effects and human exposure may be warranted. Finally, it should be noted that dredging the Pond has been considered as a possible solution to improve the degraded conditions of the Pond. Removing the arsenic-laden sediments from the Pond would involve treating them as hazardous materials, according to regulations promulgated by EPA and Massachusetts Department of Environmental Protection (MADEP).

7 Source: MassGIS 1:25,000 scale Spy Pond Locus Map Community Boundaries Datalayer, 1991 and 1:25,000 Hydrography Datalayer. Figure 1-1

8 1.1 Spy Pond

Spy Pond (42' 24' 30"N, 71' 9' 19" W) is a 39.8-hectare kettle-hole pond with a surface level 9 meters above mean sea level (MSL) in the town of Arlington, Massachusetts, about 12.9 kilometers northwest of Boston (see Figure 1-1)[MassGIS, 1998]. The pond has a volume of 1.43 million cubic meters with a maximum depth of 11+ meters and an average depth of 4 meters [Massachusetts Division of Fisheries and Wildlife; MassGIS, 1998]

The pond is split into two distinct basins by Elizabeth Island (14,620 meters squared, m2 and a relatively shallow sill (water depth of less than 2 m). The North Basin is considerably larger and deeper than the South Basin (see Table 1-1 and Figures 1-2, 1-3) [MassGIS, 1998]. The bottom consists of sand overlain by deep muck deposits [MacLaughlin, 1998; Massachusetts Division of Fisheries and Wildlife].

Table 1-1: Spy Pond Basins

North Basin South Basin

2 Area (M ) 235,956 171,432

Perimeter (m) 2,199 1,941

Maximum Depth (m) 11+ 6+

Note: areas and perimeters calculated using Arcview 3.1

Although Spy Pond has no natural inlet, a total of 43 drains empty into the pond, 40 of which are municipal storm drains (see Figure 1-4) [MacLaughlin, 1998; Chesebrough and Duerring, 1980]. During this investigation of the Pond, the author noted only one drain, Drain 20, has dry weather base flow. Drain 20 drains the largest portion of the watershed, Figure 1-2 Spy Pond Bathymetry

9 Bathymetry

Bathymetry

Figure1-2

Source: MassGIS 1:5000 scale Black& White DigitalOrthophoto Images MassachusettsFisheries, Wildlife & EnvironmentalLaw:Fisheries & WildlifeDivision Bathymetry A-A'P rofi le 0 0 0

Q)C4 0

4

C1) LCO 0)

Distance (m) Figure 1-3

Profile of ~SpyPond StormDrain OutfallLocations

Figure1-4

Source:Arlington Department of PublicWorks recorddrawvings and Chesebroughand Duemrng(1982) as well as directs flow from Hills Pond located in Menotomy Rocks Park to Spy Pond to help maintain a constant water level in Spy Pond. The remainder of the drains flow during wet weather and carry urban runoff into the pond.

The outlet from Spy Pond is a rectangular standpipe with wooden flashboards located in the south corner. From the standpipe, Spy Pond's overflow enters a large culvert and flows about 300 m underground, and then enters Little Pond. From here the water flows into Alewife Brook [Shanahan, 1997].

1.1.1 Spy Pond Limnology

Spy Pond is a dimictic lake and, depending on the season, shows a particular temperature and dissolved oxygen profile. During the summer season, the epilimnion, or warm surface water, occupies the top zone and is well mixed by wind action. Below this is a metalimnion that is characterized by a thermocline, the zone of rapid temperature change with depth. The bottom waters, or hypolimnion, contain colder waters that tend not to circulate nor replenish oxygen. During the spring and fall, these regions break down due to temperature change and the entire lake circulates as one body. A high level of productivity in the surface waters often results in low concentrations of oxygen in the bottom-waters. This is the case for Spy Pond [Chesebrough and Duerring, 1982].

Spy Pond is a hypereutrophic lake, meaning it has depleted oxygen levels and an overabundance of aquatic weeds. Eutrophication is a normal lake degradation process that occurs at a slow rate under natural conditions. This process is accelerated by the addition of excessive nutrients, especially nitrates and phosphates, into lakes and ponds. The hypolimnion becomes anoxic during summer stratification and water transparency is very low.

13 1.2 The Watershed

The 340-hectare Spy Pond watershed lies within the Mystic River Basin and is divided between the towns of Arlington and Belmont (see Figure 1-5) [MassGIS, 1998]. Approximately 73 percent of the watershed is in Arlington and 27 percent is in Belmont [Ivushkina, 1999]. Route 2, an 8-lane state highway, abuts the southwest shore of the South Basin of Spy Pond and forms the division between Arlington and Belmont [MassGIS, 1998]. The entire watershed of Spy Pond, with the partial exclusion of Menotomy Rocks Park (a small park to the west of Spy Pond), is serviced by a stormwater collection system that empties into the Pond.

The watershed is defined by steep slopes to the northwest (Arlington Heights, Menotomy Rocks) and flat terrain to the east and southeast. With the exception of Menotomy Rocks, the entire area is developed, mainly as single- and multiple-family homes (see Figure 1-6).

The watershed has an average annual temperature of 10 degrees Celsius, a mean annual precipitation of 110.2 cm, and the average snowfall is 1.3 m [Logan International Airport Data, 1999].

1.3 Geology

Spy Pond is located within an area known as the "Fresh Pond Buried Valley." This is a deep sediment-filled bedrock valley that extends from the town of Wilmington southeastward to Boston Harbor (see Figure 1-7). This geologic feature underlies Halls Brook Holding Area, Woburn; Wedge Pond, Winchester; the Mystic Lakes, Winchester and Arlington; Spy Pond, Arlington; Fresh Pond, Cambridge; and the Aberjona River. A thin, discontinuous layer of till covers the highlands bordering the buried valley while stratified deposits predominate in the valley itself. The northeast portion of Spy Pond lies along the central axis of the buried valley.

14 F~I44~

tU,

1 405,289 3,627 2 213,481 2015 3 133,582 1,756 4 163,607 1,661 5 194,829 2227 6 163,658 1,693 7 1,570,760 6,108 8 115,102 2,081 9 45,583 1,026 10 315,637 2,465 11 23,236 644 12 SA430 10s0

Figure 1-5 \0 m Townjorabostbounda 0 LanduseClmmifcations

&~~ Puncip~um Roc..don e SPY .,...,.,nr....ln

too0.202 lre -\ \ Reeidbntll-> 3.2 hAm~r

-Lnduse Spydnd --. FgurbnOpen ----s Traportedon

- Spy Pond 000 Landuse

-eFigure 1-6 Source:MassGIS statewide 1:25,000 21 -category landuseclassifications interpreted from 1:25,000 scaleaerial photographytaken 1971,1985 and in some areas1990 or 1991/1992. Streetlines are combinedlinework of MassGIS1:100,000 scale roadsdatalayer and supplementallinework providedby MassachusettsHighway Dept. [ II

a

ii

I /

Surnm an swamp dp.wcA

c ut#ft. h ,. & E e e

2 Co.4b4a ,*~ iW144E Zd sa~md -4

Figure 1-7 Surficial Geology Spy Pond Region

17 Igneous outcrops are common to the northwest of the lake in and around Menotomy Rocks. The soil of the eastern and southern section of the pond's watershed is composed primarily of sand, gravel, and clay. The depth to bedrock here is about 50 meters. The land between Spy Pond and Fresh Pond was once all a swamp known as "the Great Swamp." The land has been filled artificially and reworked over hundreds of years to make it "usable" land [Shanahan, 1997].

18 2. Previous Studies

2.1 Sediment Sampling within Spy Pond

To determine the kinds and amounts of inorganic elements of public concern present in the Alewife Brook and Mill Brook watersheds, Ivushkina and Durant performed an investigation of surface sediments in 1997. Three surface sediment samples, one from the North Basin and two from the South Basin of Spy Pond were collected as part of the study. The samples were collected at depths of 4 to 5 meters in the South Basin and 8 meters in the North Basin using a 0.125 ft3 Ekman Dredge. The sediment samples were analyzed using Instrumental Neutron Activation Analysis (INAA). A summary of the results is shown in Table 2-1 [Ivushkina, 1999].

Table 2-1 Surface Sediment Sample Collection Summary [Data from Ivushkina, 1999]

Sample No. Location Depth Arsenic SPSS South Basin 4-5 meters 69 ppm SPSS2 South Basin 4-5 meters 860 ppm SPNS North Basin 8 meters 300 ppm

Arsenic concentrations found in water bodies other than Spy Pond range from 73 ppm (Lower Mystic Lake) to 10 ppm (Mystic River). Concentrations of arsenic in surface sediment samples within the Alewife Brook and Mill Brook watersheds are shown in Figure 2-1.

Overall, Spy Pond's sediments were representative of an urban environment, having elevated concentrations of metals. However, analyses of these sediments revealed inordinately high concentrations of arsenic, as well as selenium and lead [Ivushkina, 1999].

19 0.5 1 ile

Niorth 05 1kI

t0

My= k-

LUnkre

Source: Ivushkina, 1999

Distribution of Arsenic in the Surface Sediments of the Alewife Brook and Mill Brook Watersheds

Figure 2-1

20 Following the Spy Pond surface sediment results, a 1-meter deep sediment core sample at the deepest point (11 meters) within the North Basin of Spy Pond was collected on January 30, 1998 [Ivushkina, 1999]. Arsenic concentrations were measured with depth using INAA. The results of this analysis are given in Figure 2-2. The concentration of arsenic was highest in the top 20 cm of the core, varying from 310 to 510 ppm. At depths greater than 20 cm, arsenic concentrations drop to between 13 and 91 ppm [Ivushkina, 1999].

One interpretation of the sediment core results suggests that a major event in the depositional history of sediments in Spy Pond might have been the 1968 filling of 2 hectares in the southwest end of the South Basin for the expansion of Route 2. The expansion involved the removal and redistribution through the Pond of all organic matter from the 2 hectares [Cortell, 1973; Senn, 1998]. This, along with the vibration associated with heavy construction may have caused a large increase in sediment deposition in a short time. Some 15 to 30 cm of sediment may have been deposited over the course of several months as a result of the filling [Cortell, 1973]. This deposit may explain observations of an approximately 40 cm section of the sediment core which is highly enriched in crustal material and has a substantially higher percent solid ratio than the rest of the sediment core (see Figure 2-3) [Senn, 1998]. If the "bulge" in percent solids from 15 to 50 cm can be attributed to the extension of Route 2 in 1968, then the sediment depositional rate can be estimated as approximately 0.5 cm per year (15 cm accumulated from 1968 to 1998).

Several theories have been postulated to explain the core sample's arsenic profile. One interpretation is the major increase in arsenic concentrations began around 1968 (-45 cm depth) and continues to today, suggesting that the source still injects arsenic into the pond. Another possible explanation is arsenic inputs began at 60 cm (approximately 1940s using 0.5cm/yr depositional rate) depth and the rapid sediment deposition that occurred with the filling of the Pond "diluted' the concentrations of arsenic during that period. This event caused a low concentration arsenic profile from 45 cm to 20 cm depth.

21 Figure2-2: Spy Pond Sediment Core Figure2-3: Change inAmount Solid of Material withDepth inSpy Pond Sediment Core Arsenic(ppm)

0 100 200 300 400 500 600 Changein Percent Solid Material (%) 0 0 5 10 15 20 0

20 10

20 40 t") 30 E

E 40 0. 60 2 (D 50

o' 60 80 70

80 100 90

100 1201 The same source from 60 cm then "reappears" in the profile above 20 cm depth and continues to input arsenic to the Pond today. Finally, a possible explanation for the arsenic profile is the Pond's hypereutrophic condition. Arsenic has a tendency to be remobilized within the sediment during anoxia potentially resulting in the continual upward mobilization of arsenic. This interpretation of the sediment core profile suggests that a past input of arsenic may be migrating towards the sediment-water interface (see Section 4-2) [Harrington, 1998].

Lead-210 dating of the core has yet to be performed and may reveal new information on sedimentation rates. A possible alternative to accurately date the core sample is to further investigate the source of a sharp spike in copper concentration at approximately 10 cm depth.

The sediment core sampling results indicate a strong correlation between arsenic, chloride, and selenium. These chemical associations indicate the potential source of the contamination is from road runoff, specifically runoff concentrated with road salt, into the Pond. This correlation implicated runoff from runoff from Route 2 as a potential source of high levels of arsenic in Spy Pond [Senn,1998; Ivushkina,1999].

2.2 Water Column Chemistry

In the summer of 1998, Senn and Gawel began collecting water column data from the North and South Basins of Spy Pond to observe trends in arsenic concentrations and speciation as well as monitor other constituents in the water. Samples were collected biweekly until October, when sampling was increased to every week in order to capture the Pond's seasonal turnover (loss of thermocline). As of this writing, water column sampling continues. For each sampling date, water samples are collected from a designated location in the center of the North Basin at depths ranging from 1 to 10 meters. Samples are also collected from a designated central location in the South Basin at depths ranging from 1 to 6 meters. Representative data from two sampling dates for

23 temperature, dissolved oxygen, and total arsenic are shown in Figures 2-4 through 2-6 [Senn and Gawel, 1999].

The amount of oxygen in Spy Pond is relevant because it influences arsenic cycling. Arsenic predominately occurs in the oxidized pentavalent state as arsenate (As(V)) or in the reduced trivalent state as arsenite (As(III)). The depletion of oxygen in the bottom waters initiates the remobiliztion of arsenic from the sediments to the water column. Under highly reducing conditions (as evidenced by the presence of sulfide), arsenic has been observed shifting from As(V) to As(II) [Spliethoff, 1995]. The biological availability and physiological and toxicological effects of arsenic depend on its chemical form. As(III) is much more toxic, more soluble, and more mobile than As(V) [Nriagu, 1994].

The water column study results show a thermocline forms at -4 meters in both the North and South Basins in the summer. The thermocline erodes in both basins in late fall, with the shallower South Basin turning over before the North Basin [Senn and Gawel, 1999].

Bottom waters of Spy Pond during stratification are anoxic and highly reducing, as evidenced by the presence of sulfide. These conditions allow for the remobilization of arsenic from the sediments to the water column and the predomination of As(I) (results not shown). Preliminary evidence suggests the As(III) may reoxidize with the turnover of the Pond, bind to particles, and settle into the sediment again [Senn and Gawel, 1999].

The remobilization of arsenic in a highly toxic state may have some significance for the recreational use of Spy Pond. Traditionally, the EPA has considered toxic metals in sediments to be of minimum concern because they are difficult to remobilize. However, in extremely reducing and anoxic conditions, like Spy Pond, arsenic may be reduced to its more toxic, soluble form and released to the overlying waters [Senn and Gawel, 1999].

24 NorthBasin SouthBasin

Temperature(C) Temperature(C)

0.00 10.00 20.00 30.00 0.00 10.00 20.00 30.00 0- 0-

2 1

2 4- (A E -4-8/17 3- +-8/17 6 10/27 CL -- c24 0-4 8 5

10 W 6

12 - 7

Figure 2-4 Source: Senn and Gawel, 1999 Spy Pond Temperature vs. Depth NorthBasin SouthBasin

DissolvedOxygen (mg/L DissolvedOxygen (mg/L)

0.00c 5.00 10.00 15.00 0.00 5.00 10.00 15.00 0- 0

2 2 4 E -+-- 8/17 E 3 -*-8/17 6 -A- 10/27 -A- 10/27 4) 0. 4 0 8 5

10 6

12 7

Figure 2-5 Spy Pond Source: Senn and Gawel, 1999 Dissolved Oxygen vs. Depth NorthBasin SouthBasin

TotalArsenic, unfiltered (nM) TotalArsenic, unfiltered (nM)

0.00 100.00 200.00 300.00 0.00 1000.00 2000.00 0 0-

2 1

E E 3 6 -+-8/17 -+- 8/17 CL CL -A- 10/27 4 a) -A- 10/27 0 8 5

10- 6

12 7

Figure 2-6 Source: Senn and Gawel, 1999 Spy Pond Arsenic vs. Depth 2.3 Drain Outfall Sampling

Preliminary drain outfall sampling, conducted over a period of three field sessions in July, 1998, revealed the presence of arsenic in low concentrations in stormwater runoff entering the Pond [Gawel, 1998]. Drain 36A, which drains a portion of Massachusetts Avenue, showed the highest concentration of arsenic (9.9 ppb), while other drain samples showed trace amounts. A summary of the results is in Table 2-2 (see Figures 1-2 and 1-4 for watershed boundaries and drain locations). Initial sampling results indicate potentially significant amounts of arsenic entering the Pond via the stormwater drainage system, however further sampling and investigation is necessary to define the impact of the stormwater drainage system on total arsenic loads.

28 Table 2-2 Drain Outfall Sampling July 1998 [Data from Gawel and Chin, 1998]

29 3. Stormwater and Sediment Sampling and Mapping

3.1 Introduction

The overall goal of this thesis work was to locate and define potential sources for the elevated levels of arsenic found in Spy Pond sediments. Past investigations have

prompted the author to further explore the potentially significant arsenic input of 43

storm drain outfalls carrying urban runoff into the Pond. Based on a strong correlation

between arsenic and chloride, road salt entering the Pond via runoff was investigated as

another potential source. Also, drains which carry stormwater runoff from Massachusetts

Avenue were targeted because preliminary stormwater sampling indicated rather high

concentrations of arsenic in Drain 36A. Furthermore, Massachusetts Avenue is the only

commercial area in Spy Pond's watershed.

The sampling strategy had a multi-pronged approach.

1. Determine the amount and location of arsenic entering Spy Pond via the stormwater

drain system.

2. Establish a more accurate quantification of the total amount of arsenic in Spy Pond

sediments through intensive surface sediment sampling.

3. Analyze and interpret the results using Geographic Information Systems (GIS)

mapping and establish a preliminary mass balance for arsenic in Spy Pond.3.2 Methods

3.2.1 Stormwater Sample Collection

Stormwater sampling is the collection of grab samples from stormwater drains flowing

into the pond during a rain event. Two sampling methods were employed for Spy Pond.

1. Time-sequenced samples were collected at one location over a period of 2 or more

hours. " November 11, 1998 " December 8, 1998 * February 18, 1999

30 2. Grab samples were collected at various locations around the pond. " January 24, 1999

e February 18, 1999 An example of the data sheet used for the time-sequenced samples is included in Figure 3-1.

The majority of samples were collected by directly placing a 15 ml plastic vial (acid- washed using 1 M HCl) into the storm runoff streamflow coming from the drain outfall. Some samples were collected using an ISCO autosampler programmed to collect 12 samples at specific times over a period of 2 hours. Samples collected by the autosampler were placed automatically into 1-liter plastic containers cleaned using soap and reverse osmosis (R.O.)-treated water. All samples were immediately put on ice in the field and transferred to a refrigerator at 4'C for storage prior to analysis.

3.2.2 Catch Basin Sample Collection

To fully understand the stormwater collection system's influence on arsenic and other contaminants within the Pond, the author conducted sampling of sediments from 11 catch basins around Spy Pond on April 12, 1999. Samples were collected at selected catch basins elected to represent sediment from the entire watershed.

31 Spy Pond Storm Sampling

Drain Number: Samplers: Date: Weather:

Sample Real

Sample No. Time (min) Time (hr:min) Temp pH Notes:

fl (Rtc~ 9 nnI~A 0 00

1 0.30

2 5.00

3 10.00

4 15.00

5 20.00

6 25.00

7 30.00

8 45.00

9 60.00

10 90.00

11 120.00 1

Figure 3-1 Timed Stormwater Sampling Data Sheet Samples were collected in 125 ml acid-washed (1 M HCl) plastic jars. Sample locations are shown in Figure 3-2.

3.2.3 Surface Sediment Sample Collection

Surface sediment samples were collected using a Russian Corer and a 0.125 ft3 Ekman Dredge on two dates, November 18, 1998 and February 19, 1999. Sample locations were recorded using a Trimble GPS unit with a differential correction unit to measure the geographic coordinate location of the sample. To collect sediments near the shore (water 0.75 m to 1.35 m deep), the researchers waded into the Pond and used a Russian Corer to collect sediment at soil depths ranging from 0 cm to 33 cm. The remainder of the samples were aquired using the Ekman Dredge from a boat to collect the top 20+ cm of sediment at each specified location.

All samples were transferred to 125 ml acid-washed (1 M HCl) plastic jars using a stainless steel spoon. The dredge and spoon were rinsed with surface pond water (having arsenic concentrations <200 ppb)between sample locations. Sediment samples were stored on ice in the field.

3.2.4 Stormwater Sample Preparationand Analyses

Stormwater samples were analyzed for total arsenic, sulfate, nitrate, chloride, and phosphate. Sulfate, nitrate, chloride and phosphate samples were analyzed within 1 week of collection.

Total arsenic was measured using a Graphite Furnace Atomic Absorption Spectrometer

(GF-AAS). Samples were acidified with 5 percent nitric acid (5 mls concentrated HNO 3 added to 95 ml sample) and allowed to equilibrate overnight. Five-point calibration curves were established at the beginning of each analysis run. The curve was quality assured for stability every 6 to 10 samples. The author measured phosphate using the Stannous Chloride Method (Standard Method #424E). Nitrate, sulfate, and chloride were

33 CatchBasin SedimentSampling Locations

Figure3-2

Source:Arlington Department of PublicWorks recorddrawings and Chesebrough andDuerring (1982). measured by ion chromatograph with an attached chart recorder. Five-point standard calibration curves were run each day and checked after every 5 samples.

3.2.5 Energy Dispersive X-Ray Fluorometer(ED XRF) Sample Preparationand Analysis

Within 12 hours of collection, the samples were placed into a drying oven at 80'C for 5 days, or until dry. Once dried, 4 grams of sediment were placed in a stainless steel cylinder with a ball bearing and ground for 5 minutes using a mixer/mill (SPEX CertiprepMixer/Mill 8000). Then, 0.90 gram of binder was added and the sample was homogenized again for 1 minute. Once the sample was fully ground and homogenized, it was pressed into a pellet using a hydraulic press at 20 metric tons for 1 mintue. All equipment was cleaned thoroughly between samples.

An Energy Dispersive X-Ray Fluorometer (ED-XRF) was used to analyze for a full suite of elements in the catch basin sediment samples and the surface sediment samples from Spy Pond. Instrument accuracy was confirmed using both San Joaquin soil NIST- certified standard materials (SRM #2709) and Spy Pond samples spiked with known concentrations of arsenic.

3.3 Results

3.3.1 Stormwater Sampling Results

Stormwater sampling results are included in Tables 3-1 to 3-5 and Figures3-3 through 3- 13. Several aspects of the nature of the urban runoff were discovered through the sampling. The time-sequenced samples show a definite "first flush" was captured on December 8, 1998 and February 18, 1999. A first flush is the high loading of nutrients such as nitrate, sulfate, and phosphate, that flows into the Pond with the storm runoff as urban pollution is mobilized by the rain. However, the timed samples do not show any variations in arsenic concentrations consistent with changes in nutrient loading. Since the GF-AAS is only accurate to ±2 ppb, many of the arsenic measurements are not

35 Table 3-1 Stormwater Sampling Results 11/11/98

Time Nitrate Sulfate Phosphate Arsenic (min) (ppm) (ppm) (mg P04-P/L) (ppb) Drain 36A 0.5 0.8 2.2 0.293 1 5 0.8 2.2 0.311 1 10 0.8 2.1 0.284 1 15 0.7 2.0 0.255 0.5 20 0.6 1.8 0.250 0.5 25 0.6 1.8 0.257 1.5 30 0.6 1.8 0.259 0 45 0.6 2.0 0.256 0 60 0.6 1.8 0.348 0 90 0.5 1.8 0.267 0 120 0.6 1.9 0.316 0.5 Drain 36 0.5 0.5 1.6 0.330 0 5 0.5 1.6 0.345 0 10 0.5 1.5 0.325 0 15 0.4 1.2 0.248 0 20 0.4 1.1 0.242 0 25 0.4 1.1 0.225 0 90 0.4 1.1 0.222 0 Drain 20 0 6.3 18.8 0.042 0 0.5 0.9 2.9 0.444 0 5 0.9 2.9 0.622 0 10 0.5 2.7 0.600 0 15 0.9 2.7 0.585 0 20 0.9 2.7 0.514 0 25 1.9 2.7 0.497 0 30 1.2 2.4 0.429 0 45 0.8 2.3 0.489 0 60 0.9 2.6 0.543 0 90 1.2 3.7 0.397 0 120 1.9 3.5 0.473 0 Drain 19 0 0.8 1.1 0.042 0

Note: Although two significant digits are shown for all arsenic concentrations, the GF-AAS is only accurate to 2 ppb

36 Sulfate 11/11/98

4.0

3.5

3.03

E2.5

2.0 (U( 1.5

0.0 1.0-

0.5

.0 0 20 40 60 80 100 120 140 Time (min)

Nitrate 11/11/98 36 7.0

6.0- 0.0 5.0

200 36

200

201 - 3

10

0 20 40 60 80 100 120 1 40 Time (min)

Figure 3-3

Stormwater Sampling 11/11/98 Nitrate and Sulfate Results

37 Drain 36A: Phosphate 11/11/98 North Basin

0.000 -

0.050 -

0 0.100 0 a. 0.150 - o> 0.200 - 3 S0.250 0. IA 5 0.300

0.35

0.400 - 0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 Time (min)

Drain 36: Phosphate 11/11/98 South Basin

0.000. ------0.050

0 0.100- a- 0.150- drain stopped flowing 0) E 0.200 0.250-

0. M) 0.300- CL 0.350-

0.f400 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 Time (min)

Figure 3-4

Stormwater Sampling 11/11/98 Drain 36 & 36A Phosphate Results

38 Drain 20: Phosphate 11/11/98

0.700 -

0.600

0.500

0 0 0.400 co

0.300 0 MU C. 0.200

0.100

0.000 - 140.0 0.0 20.0 40.0 60.0 80.0 100.0 120.0 Time (min)

Figure 3-5

Stormwater Sampling 11/11/98 Drain 20 Phosphate Results Table 3-2 Stormwater Sampling Results 12/08/98

Time Nitrate Sulfate Arsenic (min) (ppm) (ppm) (ppb) Drain 36A 0.5 10.1 15.6 2.5 5 6.3 14.6 2 10 1.9 8.5 1 15 2.3 9.9 0 20 2.0 7.0 0.5 25 1.1 3.9 0 30 1.5 4.3 0 45 0.8 2.6 1 60 0.7 2.3 0 90 0.7 2.5 0 120 0.7 2.6 1 Drain 36 0.5 NA NA 1 5 NA NA 2 10 NA NA 1.5 15 NA NA 1.5 20 NA NA 3.5 25 NA NA 1 30 NA NA 1.5 45 NA NA 0.5 60 NA NA 0 90 NA NA 0.5 120 NA NA NA Drain 20 0 4.7 16.6 0 2 4.9 16.4 0 3 4.7 15.1 0 8 4.8 15.5 0 18 4.7 15.4 0 33 3.6 25.1 0 53 1.4 5.6 0 78 0.9 2.0 0 108 1.2 3.3 0 153 1.6 4.4 0

NA = Not Available Note: Although two significant digits are shown for all arsenic concentrations, the GF-AAS is only accurate to 2 ppb

40 Sulfate 12/8/98

30.0

25.0

E 20.0

CL15.0

Co 10.0

5.0

0.0 0 20 40 60 80 100 120 140 160 180 Time (min)

Nitrate 12/8/98

12.0

10.0

8.0 a CL e 6.0

U 4.0

2.0

0.04! I I I I 0 20 40 60 80 100 120 140 160 180 Time (min)

Figure 3-6

Stormwater Sampling 12/8/98 Nitrate and Sulfate Results

41 Table 3-3 Stormwater Sampling Results 1/24/99 Collected 11:30 am to 2:30 pm

Drain Nitrate Sulfate Phosphate Chloride Arsenic Outfall (ppm) (ppm) (mg P04-P/L) (ppm) (ppb) 1 0.0 2.1 0.246 8.1 6 3 0.4 1.0 0.633 12.1 10 4 0.5 2.8 0.163 20.6 2.5 5 0.0 0.8 0.205 16.1 5 6 0.0 1.1 0.211 18.5 6 8 0.2 1.1 0.313 28.2 4 9 0.1 0.6 0.896 22.8 1.5 10 0.1 0.8 0.986 15.5 1 11 0.0 1.4 0.247 40.0 1.5 13 0.1 1.7 0.123 41.3 0 19 0.0 0.7 0.186 19.1 1.5 20 0.7 3.4 0.203 95.8 1.5 21 0.0 1.7 0.237 37.7 3 22 0.3 2.3 0.423 64.8 2 23 0.0 0.0 0.132 5.6 0 24 0.3 3.3 0.184 73.2 3.5 25 0.0 1.5 0.27 19.7 5 30 7.5 4.4 0.165 17.8 0 31 0.2 3.1 0.288 16.1 3 35 0.5 3.8 0.171 18.7 0.5 36 0.4 2.6 0.74 22.3 1.5 36A 0.3 2.9 0.193 46.3 1.5 37 NA NA 0.198 30.3 3

NA = Not Available

Note: Although two significant digits are shown for all arsenic concentrations, the GF-AAS is only accurate to 2 ppb

42 CL E a IF C*D r: a

SI

.3 t a0)D

; -wo ih ~ ~ O P

co

JI 0 0

co

C'',

j 002M

43 Chloride 1/24/98

100.0 90.0 80.0 ' 70.0 0. 60.0 .8 50.0 _ 40.0 6 30.0 20.0 10.0 0.0 Drain No.

Nitrate 1/24/98

8.0 7.0 6.0 E 0. 5.0 4.0 3.0 z 2.0 1.0 0.0 Drain No.

Figure 3-8

Stormwater Sampling 1/24/98 Nitrate, Sulfate, and Chloride Results

44 Figure 3-9: Stormwater Sampling 1/24/99 Phosphate Results

3.500

9

3.000 -

3 2.500-

0 2.000- 36 0) E 10 *~1.500- 0. 0 0.

1.000 - 22

11 36A 0.500 - 24 20 31 19 25 4 13 8 37

0.000 Drain Number Table 3-4 Stormwater Sampling Results 2/18/99

Drain Nitrate Sulfate Phosphate Chloride Arsenic Outfall Date Time (ppm) (ppm) (mg P04-P/L (ppm) (ppb) 4* 2/17/99 18:00 1.5 4.5 0.057 11.6 0.5 5* 2/17/99 18:00 0.0 2.5 0.036 23.2 1 1 2/18/99 11:40 0.0 0.5 0.081 23.2 0 2 2/18/99 8:45 1.9 7.5 0.077 554.4 4 3 2/18/99 8:40 2.3 5.2 0.140 372.0 2.5 3A 2/18/99 8:35 3.3 6.4 0.101 388.4 9.5 5 2/18/99 8:58 2.7 17.1 0.124 1376.7 0 6 2/18/99 8:55 2.0 12.3 0.131 994.0 0.5 7 2/18/99 9:02 1.0 4.0 0.155 91.6 2.5 9 2/18/99 9:21 1.5 10.9 0.098 1492.5 0 9A 2/18/99 9:40 1.0 4.1 0.099 252.9 0 10 2/18/99 9:50 1.0 5.4 0.048 649.6 0 11 2/18/99 10:05 0.9 7.4 0.093 713.9 2 13 2/18/99 10:12 0.6 5.5 0.051 391.8 1 19 2/18/99 10:25 0.0 1.9 0.045 177.9 1 20 2/18/99 10:20 0.6 4.2 0.111 298.8 1.5 21 2/18/99 10:35 0.2 2.6 0.090 109.3 0.5 22 2/18/99 10:45 0.4 3.0 0.104 247.4 2 23 2/18/99 10:52 0.1 2.3 0.087 205.1 3 24 2/18/99 11:00 0.3 2.2 0.094 106.3 2.5 25 2/18/99 11:05 0.1 2.4 0.153 141.0 2.5 26 2/18/99 11:10 0.0 1.3 0.128 35.5 1.5 30 2/18/99 11:15 0.5 1.4 0.065 47.8 1.5 31 2/18/99 11:15 0.0 0.1 0.088 11.9 0 34 2/18/99 11:20 2.7 4.8 0.000 9.4 0 35 2/18/99 11:18 0.2 3.6 0.042 47.1 0 36 2/18/99 11:30 0.0 0.3 0.043 24.6 0 36A 2/18/99 11:30 0.1 1.6 0.087 55.1 0.5 37 2/18/99 11:37 0.1 0.7 0.079 18.5 0 2 2/18/99 11:50 0.2 1.8 0.069 61.0 2 3 2/18/99 11:55 0.1 0.3 0.037 12.5 0.5 3A 2/18/99 12:00 2.2 1.0 0.071 53.5 2 3*4 2/18/99 12:05 0.0 0.0 0.051 5.6 0 5 2/18/99 11:55 0.1 1.2 0.101 41.6 0 6 2/18/99 11:50 0.1 1.0 0.102 38.5 0 Hill's Pond Inlet* 2/18/99 0.3 7.1 0.086 523.7 0 Hill's Pond Spring* 2/18/99 0.0 7.3 0.061 24.6 0

* Collected while it was not raining

Note: Although two significant digits are shown for all arsenic concentrations, the GF-AAS is only accurate to 2 ppb

46 StormdralnSampling Locations Arsenic Concentrations(ppb) StormdrainNetwork

BathymetricContours / Shoreline 1 - 3 Meters 4S belowmean surface 4 - 5 Meters belowmean surface 4 6 - 8 Meters below mean surface 9 - 11 Meters belowmean surface

StormwaterSampling -4 2/18/99 vi ArsenicResults

Figure 3-10 OrthophotographySource: MassGIS Drainage Network Source:Arlington Department of PublicWorks recorddrawings Nitrate 2/18/99 3.5

3.0 34 2.5 3

E 2.0- 6 C. 26

)1.5~ 9 1 10 1.0 7 1130 0.5 213 2 35 3 37 0.0 1 -0.5 Drain No.

Figure 3-11

Stormwater Sampling 2/18/99 Nitrate, Sulfate, and Chloride Results

48 Figure 3-12: Stormwater Sampling 2/18/99 Phosphate Results 0.180

0.160 - 7 25

0.140 - 3 6 26 5 0.120 - 20 2--' 9 6 22 0 2 a. 0.100 9A 1 3A 11 24 -1a 21 0.080 21 23 0. 3A 0 a- 13 0.060 2 3*4 30

19 0.040 35 10 1

0.020 -

0.000* Drain Outfall No. 34 Table 3-5 Stormwater Sampling Results 2/18/99 Drain 4 Sequenced Results

Time Nitrate Sulfate Phosphate Chloride Arsenic (min) (ppm) (ppm) (m P04-P/L) (ppm) (ppb) o 1.5 4.5 0.057 41.6 0.5 0 2.7 7.1 0.048 482.7 0 0.3 2.7 8.0 0.054 604.2 0 5 3.1 20.6 0.125 1951.1 0 10 4.3 27.9 0.081 5354.2 0 15 2.1 16.2 0.100 1486.3 0 20 2.0 15.2 0.246 1449.3 0 25 2.0 16.5 091697.8 0 30 1.8 15.5 0.100 1612.9 0 45 2.2 15.0 0.129 1314.6 0 60 1.9 11.7 0.144 953.4 0 90 1.0 6.0 0.125 471.8 0 120 0.6 3.6 0.068 228.5 0 240 0.3 1.2 0.079 60.2 0

Note: Although two significant digits are shown for all arsenic concentrations, the GF-AAS is only accurate to 2 ppb

50 Drain 4: 2/18/99 0.3

0.25 3 02 CUD' - 00.15 -- o 0)a E.E 0.1 0.05

0 0 50 100 150 200 Time (min)

-+- N03- (ppm) Drain 4: 2/18/99 --- S04 2- (ppm) 30 25 20 E a.15 10 5 0 0 50 100 150 200 Time (min)

Drain 4: 2/18/99

6000 5000 - EA 0. 4000 . 3000 . 2000 - 1000 0 * 0 50 100 150 200 250 300 Time (min)

Figure 3-13

Drain 4 2/18/99 Phosphate, Nitrate, Sulfate and Chloride Results

51 statistically significant from zero. Sampling performed on February 18, 1999 at Drain 4 appears to have captured two flushes of nutrients with no change in arsenic concentrations (see Table 3-5 and Figure 3-13).

The grab sampling revealed several "hot spots" along the North Basin which showed sporadically elevated arsenic concentrations over the period of sampling. The first area of elevated arsenic concentrations is along the south cove of the North Basin, including

Drains 3 through 8. The second area of interest is along the northwest shore, near Elizabeth Island. These areas had maximum arsenic concentrations of 10 ppb and 5 ppb, respectively. Drain 20 (Route 2) and drains 36 and 36A (Massachusetts Avenue), however, which account for the majority (59%) of the total stormwater inflow into Spy Pond, recorded low levels of arsenic.

Two samples were collected from Menotomy Rocks Park on February 19, 1999 to compare to Spy Pond stormwater samples. One sample was collected from the drain outfall at Hill's Pond, prior to the mitigation wetland. The other sample was collected from a spring in the park that flows into drain 20. Analysis of both samples revealed no arsenic.

Chloride was measured on several dates after roads were salted to determine the effect of road salt on Spy Pond arsenic loading. Very high levels of chloride were recorded at several drains, however, high chloride levels did not correspond to high arsenic levels. Direct analysis of road salt samples collected from the storage facility for this portion of Route 2 also revealed undetectable levels of arsenic.

3.3.2 Catch Basin Sampling Results

Catch basin sampling results are included in Table 3-6. Sample locations are shown in Figure 3-2. The results indicate that the catch basin sediments mainly consist of sand and are low in arsenic. On the other hand, relatively large amounts of iron are present in the catch basin samples. Since arsenic is readily sorbed by iron oxides, the small amounts of

52 arsenic found in the catch basin samples may be associated with iron precipitates. The elevated lead concentrations in samples 75, 78, and 81 warrant further investigation.

Table 3-6 Selected Catch Basin Sampling Results

Sample Silicon Phosphorus Chlorine Iron Lead Arsenic Number % % % % ppm ppm 75 32.00 0.0477 0.01176 1.135 290.2 <3.1 78 31.07 0.0876 <0.0037 1.083 568.0 <4.3 79 32.71 0.02146 <0.0040 1.516 54.33 3.4 80 34.96 <0.0019 <0.0037 1.332 32.5 1.7 81 26.89 0.3096 <0.0033 3.012 314.9 8.6 82 33.85 0.02871 <0.0041 1.506 68.7 1.8 84 34.72 0.00963 <0.0041 0.9723 46.8 2.3 85 32.81 0.0407 <0.0039 1.056 75.9 2.8 86 29.90 0.0851 0.00399 1.364 92.4 <1.8 87 33.73 0.02406 <0.0039 0.9104 39.9 2.3 88 32.29 0.02396 0.0542 1.296 66.8 2.4

3.3.3 Sediment Sampling Results

Results of our intensive sediment sampling program are included in Tables 3-7 and 3-8 as well as Figures 3-14 and 3-15. The results from the first sampling round (samples 1 through 40) show large concentrations of arsenic are found in surface sediments throughout Spy Pond. However, the North Basin has maximum concentrations almost 3 times as high as sediments in the South Basin.

As one would expect, in general higher concentrations are found in deeper portions of Spy Pond due to sediment focussing However, comparing the concentration contours for the North Basin in Figure 3-14 to the bathymetry in Figure 1-2, one notices the highest

53 ArsenicSediment Sample Contoum inteval: 300 ppmn F 40-" Acontour A A 4111 300 -600 601-900 901 - 1200 *A 41201 -1500 3 1501-2400

S A/ PondBoundary 18 seiment A ASample Location 4 A9

33 A 38 A 29 - A S34 Arsenic Contours

Surface Sediment Samples

Figure 3-14

OrthophotographySource: MassGIS ArsenicSamples Contoured usingArcView Spatial Analyst with a 4-metergrid and300 ppm contourinterval Table 3-7 SedimentSampling Results SamplesCollected 12/11/98 by Gawel and Lukacs

Data Depthof Water Arsenic Lead Phosphorus Sulfur Chlorine Chromium Iron Copper Zinc

Points (m) (ppm) (ppm) % % % % % - i(ppm) (ppm) 1 2.5 146.3 1347 0.2346 1.448 0.0763 0.0153 3.168 643.7 643.7 2 1.9 221.2 1312 0.2572 1.597 0.1338 0.00805 3.339 300.7 606.1 3 3.1 826.8 1713 0.2649 2.132 0.0841 0.00586 3.761 450.7 809.1 4 1.8 87.5 483.9 0.1139 1.55 0.3133 0.00285 2.167 149.4 408.0 5 4.0 1570.0 1877 0.2745 2.431 0.1288 0.00826 4.139 634.5 927.2 6 7.0 1858.0 1901 0.3155 2.524 0.1016 0.00547 4.581 520.5 888.5 7 9.8 2043.0 2486 0.3036 2.349 0.0987 0.0051 4.502 425.5 968.4 8 3.7 1720.0 2164 0.2768 2.122 0.0812 0.00485 4.284 407.4 890.1 9 3.8 1480.0 2106 0.2663 2.293 0.1194 0.00598 4.228 415.5 882.0 10 7.9 1736.0 2395 0.3014 2.394 0.1097 0.00742 4.645 466.2 1047.0 11 10.2 1737.0 2416 0.2725 2.251 0.1203 0.00454 4.423 484.7 1010.0 12 7.5 815.6 2232 0.3304 2.5 0.1456 0.00537 4.584 355.8 971.5 13 4.2 738.7 1956 0.268 2.487 0.1942 0.0024 4.305 350.9 918.8 14 1.2 1577.0 1977 0.2665 2.304 0.1352 0.00584 3.897 503.1 930.2 15 2.0 2644.0 2011 0.2632 2.033 0.1128 0.00765 4.163 502.1 882.1 16 6.8 1415.0 2395 0.2832 2.18 0.1581 0.00473 4.223 502.6 935.6 17 2.8 696.6 1632 0.3106 2.068 0.0848 0.028 3.740 432.8 733.4 18 2.5 274.7 1124 0.2184 1.574 0.0733 0.01021 3.107 327.3 569.7 19 2.7 252.4 1138 0.206 1.92 0.1609 0.0137 3.398 426.3 606.5 20 1.9 617.6 1844 0.2105 1.578 0.1399 0.00553 3.752 437.5 782.0 21 4.9 605.9 1839 0.1872 1.687 0.0682 0.00307 3.643 428.4 768.9 22 3.2 870.1 1836 0.2167 1.54 0.1072 0.00409 3.772 427.5 753.5 23 0.9 594.6 1917 0.2155 1.521 0.1521 0.00646 3.794 398.3 804.3 24 5.5 1074.0 2032 0.2256 1.479 0.1211 0.00595 3.952 426.2 763.3 25 4.0 971.9 2232 0.2285 1.441 0.1271 0.00474 3.948 416.7 766.6 26 2.2 154.1 1063 0.2078 1.647 0.1315 0.00457 3.383 244.4 712.0 27 5.7 845.0 2156 0.2449 1.293 0.1192 0.0051 4.000 408.9 811.2 28 6.1 853.2 1899 0.25 1.43 0.3558 0.00491 4.242 339.9 807.7 29 1.7 568.1 1276 0.2219 1.485 0.1662 0.00344 3.584 343.6 621.9 30 1.0 153.8 1353 0.2049 1.405 0.0528 0.0166 3.469 248.0 682.3 31 5.0 510.4 1411 0.2081 1.437 0.0936 0.00371 3.619 352.5 600.9 32 5.5 656.0 2104 0.2311 1.526 0.2986 0.00645 4.087 330.7 799.0 33 5.8 815.8 1958 0.2537 1.413 0.3622 0.00673 4.242 323.0 780.7 34 4.8 813.1 1745 0.2411 1.319 0.0999 0.0052 3.794 363.9 752.2 35 1.0 118.3 610.3 0.287 1.062 0.4941 0.00933 3.636 270.2 677.3 36 2.1 261.6 932.3 0.2502 1.374 0.9064 0.01031 4.506 304.6 742.2 37 2.2 152.7 500.2 0.1619 0.7244 0.0677 0.0313 3.393 100.8 270.4 38 2.0 159.2 856.6 0.0816 1.196 0.1995 0.00283 2.498 113.8 331.6 39 1.5 202.2 555.5 0.1613 0.8794 0.0995 0.00255 3.472 115.9 266.7 40 5.3 363.7 1243 0.3031 2.349 0.00827 0.0039 4.595 929.4 774.4 Table 3-8 North Basin Sediment SamplingResults Samples Collected2/19/99 by Gawel, Lukacs, MacLaughlinand Senn

Data Depth of Water Arsenic Lead Phosphorus Sulfur Chlorine Chromium Iron Copper Zinc Points (m) (ppm) (ppm) % % % % % (ppm) (ppm) 44 0.75 8.7 30.1 0.03013 0.04603 0.0045 0.01318 1.702 <1.3 53.7 45 0.9 278.5 214.9 0.1012 0.5886 <0.0038 0.00256 3.448 29.9 134 46 0.75 14.2 60.9 0.02693 0.2171 <0.0046 0.00207 1.304 9.9 78.6 47 0.75 19.7 102.6 0.0437 0.3638 <0.0039 0.0287 1.282 15.6 90.5 48 0.7 8.6 37.1 0.0506 0.07495 <0.0047 0.00176 1.938 <1.3 52 49 1 33.2 227.2 0.1232 0.9651 0.0995 0.00359 1.601 50.3 277.2 50 0.6 3.5 144.9 0.0698 0.194 0.01492 0.0576 1.646 23.8 166.9 51 0.9 11.5 98.5 0.0471 0.0958 <0.0042 0.00456 1.898 13.1 74.7 52 0.9 8.8 138.9 0.02187 0.2267 <0.0042 0.00188 1.252 9.3 48.4 53 0.9 1.9 45.7 0.02136 0.2021 <0.0043 0.01717 1.267 <1.3 28.8 54 0.9 3.4 33.8 0.0437 0.1786 <0.0043 0.01012 1.285 <1.3 20.1 55 1.05 11.9 86.1 0.0495 0.3194 <0.0036 0.01714 1.576 18.7 116.2 56 1.2 8.7 66.5 0.0339 0.1447 <0.0042 0.0377 1.390 2.6 58.2 57 1.35 3.0 65.9 0.0566 0.08434 <0.0042 0.0729 1.913 3.0 48.4 58 1.35 1.6 59.3 0.0304 0.07305 0.00844 0.0366 1.637 16.0 39.9 59 1.35 0.7 41.2 0.02677 0.05829 <0.0042 0.00687 1.276 3.6 24.1 60 1.2 12.3 46.9 0.0543 0.1273 <0.0039 0.0789 2.170 4.9 52.5 61 0.9 3.6 64.0 0.0506 0.1067 <0.0044 0.0355 2.139 1.4 47.8 64 1.35 65.9 198.5 0.0665 0.6013 0.0612 0.01628 1.730 55.0 193 65 1.35 250.8 619.1 0.1144 0.7128 0.01933 0.0324 2.449 73.2 281.8 66 1.2 6.0 217.3 0.02225 0.06217 <0.0044 0.077 1.867 9.9 59.6 67 5 310.5 1106.0 0.255 2.246 0.2148 0.01055 3.889 297.7 560.5 68 7 973.4 2543.0 0.273 2.491 0.0946 0.0056 4.514 394.3 974.6 69 9 2314.0 2453.0 0.3138 2.456 0.0992 0.00639 4.539 480.1 1038 70 9 2246.0 2374.0 0.2979 2.463 0.1562 0.00438 4.599 522.0 1044 71 7 819.0 2651.0 0.3066 2.217 0.184 0.0058 4.390 416.3 1006 72 5 1212.0 2216.0 0.3021 2.286 0.1648 0.00494 4.375 445.2 945.6 73 6 522.1 1999.0 0.2902 2.318 0.1191 0.0066 3.985 369.8 914.7 74 5 960.2 1837.0 0.3015 2.163 0.096 0.00531 3.847 413.8 885.7 76 1.2 3.6 142.6 0.02011 0.04056 <0.0044 0.1262 1.788 4.4 52.8 SedimentCore Sample ConcentrationBars

[ Arsenic (0.7 to 2,644) Lead (30.1 to 2,395)

Concentrationin ppm

StormdrainNetwork

Arsenicvs. Lead SurfaceSediment Samples

12/11/98and 2/19/99

Figure3-15 OrthophotogrpahySource: MassGIS Drainage Network Source:Arlington Department of PublicWorks record drawings arsenic concentrations do not correspond to the deepest section of the Pond. An area of high arsenic concentrations appears in Figure 3-14 near the south shore of the North Basin which is inconsistent with what would be expected from standard sediment focussing. The second round of sampling (samples 41-76) concentrated on further defining the North Basin hot spot. High concentrations of arsenic were found close to the shore in the area of the hot spot (Sample 45, 278.5 ppm). Extensive near-shore surface sediment sampling in the North Basin area did not reveal any other area near shore where arsenic concentrations were as elevated.

Figure 3-15 compares arsenic concentrations to lead concentrations in the surface sediments. A possible significant source of arsenic to Spy Pond is through the historical use of lead arsenate as a pesticide (see Section 4.3). A comparison of the two elements does not reveal any apparent correlation however, lead concentrations may be skewed by its use for other purposes (including leaded gasoline).

3.4 Geographic Information Systems (GIS)

3.4.1 GIS Software

The author established an understanding of the site and the sampling results using ESRI's Arcview 3.1 and ARC/INFO in conjunction with digital topography, land use, and orthophotography data developed by MassGIS, a Division of the Massachusetts Executive Office of Environmental Affairs. 3.4.2 Data Sources

To accurately capture the many layers of geographic data in a consistent format, the author digitized all new data against the NAD83 Massachusetts State Plane Coordinate System. MassGIS is a valuable resource that is consistently maintained and updated. To ensure easy integration with future data supplied by MassGIS, the author converted all digitized data layers to the Metric System.

58 The author digitized the majority of layers using ESRI's ARC/INFO and CalComp 9100 48-inch digitizing tablet. Paper maps were registered to common features on the existing data, ensuring a maximum root mean square (RMS) error of 0.02. Typically, one aims at a lower RMS to improve absolute accuracy; however, given the nature of the project and the quality of the source documents, the RMS was appropriate [Thomas, 1999].

All digitizing was performed based on the State Plane Coordinate System. The watershed boundary delineation was created by the Metropolitan Area Planning Council and adjusted according to topography and the existing stormwater drainage system. The author digitized the stormwater drainage system using current Arlington Department of Public Works (DPW) records. The drainage system was digitized from the paper map such that the GIS data has an understanding of the direction of flow of the system. This data layer could be used for future modeling and further understanding of the existing stormwater loading on the Pond.

The author digitized the bathymetry data layer using data from the Massachusetts Division of Fisheries and Wildlife. However, the paper data source was developed prior to the filling of 2 hectares of the Pond for the expansion of Route 2. Therefore, the author adjusted the depth breaklines to reflect approximate current conditions on the southwest shore of the South Basin. The adjustment of the Pond edge boundary was made using MassGIS orthophotography (1-m resolution). The historical mapping was digitized based on Sanborn Map & Publishing Company, Limited Fire Insurance Maps. Data sources for digitizing are summarized below in Table 3-9.

59 Table 3-9 GIS Data Sources

Base Layers Data Layers Source United State Geological Massachusetts Executive Office of Environmental Survey (USGS) Topography Affairs MassGIS (MassGIS) Quadrangle Maps Orthophotographs MassGIS Land Use MassGIS Hydrography MassGIS Hypsography MassGIS Digitized Layers Data Layers Source Stormwater Drainage System Arlington Department of Public Works record drawings Watershed Delineation Metropolitan Area Planning Council GIS Bathymetry Massachusetts Division of Fisheries and Wildlife Historical Information Sanborn Map & Publishing Company, Limited. Fire Insurance Maps Raw Analytical Data Layers Data Layers Source Surface Sediment Samples Trimble Global Positioning System Unit with Locations Differential (GPS) Stormwater Samples Locations Arlington Department of Public Works record drawings and GPS Water Column Sample Logbooks (1998) and MassGIS orthophotography data Locations layer Catch Basin Sample Locations Logbooks (1998) and Arlington Department of Public Works record drawings Derived Layers Data Layers Source Surface Sediment Sample Arcview 3.1 Spatial Analyst Concentration Contouring Spy Pond Profile Arcview 3.1 3-D Analyst

60 3.4.3 Raw Analytical Data Layers

MacLaughlin, et al recorded all sediment sample locations in geographic coordinates (longitude and latitude in degree/decimal minutes) using a Trimble global positioning system receiver with a differential (GPS). Furthermore, coordinate locations were recorded approximately every 6 meters along Spy Pond's shoreline to establish the accuracy of the GPS. For a final check on accuracy, the data points collected by Trimble receiver were compared to data collected by a Garmin GPS receiver. The author transformed the geographic coordinates into NAD83 Massachusetts mainland state plane meters by calculating negative decimal degrees from the degree decimal minutes in MS Excel and then projecting the decimal degrees to state plane meters using Arcview 3.1 coordinate projection algorithms. For positional accuracy confirmation, the author viewed the transformed points in conjunction with MassGIS digital USGS topography and orthophotography data layers.

The author established stormwater sample locations using a combination of GPS points, Arlington DPW record drawings and information recorded in the field logbook. To create the catch basin sampling location data layer, the author used locations recorded in the field logbook and Arlington DPW record drawings.

3.4.4 Derived Data Layers

The author used Arcview 3.1's Spatial Analyst extension tool for surface and volumetric calculations. The tool extrapolated the bathymetry data layer to create the basins of the pond in three dimensions. Spatial Analyst split the Pond into various shapes and fractions to determine volumes and surface areas for preliminary mass balance calculations.

Furthermore, the author used Spatial Analyst to analyze the raw surface sediment data by establishing preliminary arsenic concentration contours throughout Spy Pond. Spatial Analyst produces contours from a set of data points by processing the analytical results

61 through a triangular irregular network (TIN). The number of sediment samples was insufficient for Spatial Analyst to provide completely accurate contouring, however, the contours provide a preliminary suggestion of concentrations throughout the Pond [Thomas, 1999].

The author used ArcView 3.1's 3-D Analyst extension tool to visualize the data in three dimensions. To generate profiles of Spy Pond, the author employed 3-D Analyst to interpret the bathymetry data layer in three dimensions. Once the data layer is interpreted in three dimensions, a profile can be produced from any direction along the Pond.

3.5 Conclusions

The comprehensive sampling and data analysis discussed in this chapter have resulted in the formation of several initial hypotheses concerning the character of arsenic contamination in Spy Pond. A prognosis of the effect of stormwater runoff and road salt loadings on the Pond uncovers a minimal arsenic impact delivered through the 43 drain outfalls. A comparison of chloride and arsenic in sediments and stormwater reveals no correlation, suggesting road salt is not a significant source of arsenic. Finally, a first attempt at an arsenic mass balance in Spy Pond, as discussed below, discloses a large unidentified input of arsenic, probably entering the Pond via groundwater.

3.5.1 Arsenic Loading to Spy Pondfrom Stormwater Runoff

Table 3-10 summarizes preliminary stormwater runoff arsenic loading calculations. The calculations use the equation: Q = CIA Where:

Q = peak rate of runoff in m 3/y I = rainfall intensity in rn/yr A = Drainage area in m2 C = Runoff Coefficient

62 Figure 3-16

Spy Pond StormwaterRunoff LoadingCalculations

Average Est. Est.

Watershed Percentof Arsenic Arsenic Arsenic Load Storm Drain Outfalls Subbasins Area Drainage Area Storm Intensity C Flow, Q Conc. Load over 30 yrs

mA2 % m/yr mA3/yr 10A-6g/L g/yr kg

# 21, 22, 23 2 213,481 7 1.09 0.65 151,251 1.75 265 8 # 24 3 133,582 4 1.09 0.65 94,643 3.00 284 9 # 25 -35A 4 163,607 5 1.09 0.65 115,916 1.40 162 5 # 36, 36A, 37 5 194,829 7 1.09 0.9 191,127 1.08 207 6 # 9A, 10 6 163,658 5 1.09 0.65 115,952 0.63 72 2 # 20, 20A 7 1,570,760 52 1.09 0.65 1,112,883 1.50 1669 50

# 11 8 115,102 4 1.09 0.65 81,550 1.75 143 4

# 7, 8, 9 9 45,584 2 1.09 0.65 32,296 2.00 65 2 # 1, 2, 3, 3A, 4, 5, 6 10 315,638 11 1.09 0.65 223,630 3.83 857 26

# 19 11 23,237 1 1.09 0.65 16,463 1.25 21 1 # 12, 13, 14,15, 16, 17, 18 12 55,430 2 1.09 0.65 39,272 0.50 20 1 Total Drainage Area 2,994,908 100 1.09 0.65 2,121,892 1.70 3606 108 annual precipatation = 43 in/year = 1.09 m/yr [Logan Internation Airport Data] C = Runoff Coefficient [Robertson, 1988] See Figure 1-4 for Storm Drain Outfall Location See Figure 1-5 For Watershed Subbasins An average annual rainfall of 1.09 mlyr based on Logan International Airport data was used. The runoff coefficient was estimated at 0.65 for the entire urban residential watershed. The area of each basin was determined using Areview 3.1.

Arsenic concentrations recorded for each drain outfall were averaged and applied to an overall average for the drainage basin. The calculations indicate less than 4 kg of arsenic enter the pond annually via the storm drainage system. If this result is extrapolated over 30 years, the total input from the storm drains from 1969 to 1999 is approximately 108 kg. If the highest concentration of arsenic measured in the stormwater runoff, 10 ppb, is applied to the entire watershed and expanded over 30 years, the stormwater system contributes an absolute maximum of 630 kg total.

3.5.2 Road Salt Runoff as a PotentialSource

Road salt was initially considered a viable potential source of arsenic to the Pond based on the high concentrations measured in the South Basin sediment samples and the sediment core results of Ivushkina (1999). Stormwater samples were collected on two occasions after salt had been placed on the roads. Figure 3-16 shows the relationship between arsenic and chloride concentrations. Arsenic and road salt applications do not appear to be correlated.

3.5.3 Preliminary Quantificationof Arsenic in Spy Pond

The total amount of arsenic in Spy Pond sediments can be estimated using the surface sediment data collected on December 12, 1998 and the surface area of the sediments calculated using ArcView Spatial Analyst. Based on sampling results, arsenic concentrations of 500 ppm to 800 ppm were used to calculate the total arsenic load in the top 15 cm of pond sediments. The results of these calculations place the total amount of arsenic in the top 15 cm of Spy Pond sediments between 1,200 kg and 1,920 kg.

64 Figure 3- 16: Arsenic as a Function of Chloride

12

10

.0 8 0. . 6 -4- * As

4 ------+ - -*- - -- -

2 -+ 0 1 10 100 1000 10000 Chloride (ppm) 3.5.4 Mass Balance Calculations

Figure 3-17 summarizes a preliminary mass balance of arsenic fluxes in Spy Pond using the stormwater, sediment, and water column data along with areas and volumes found using Arcview Spatial Analyst. Our estimate of the amount of arsenic entering the Pond annually via stormwater runoff (as described in Section 3.5.1) is less than 4 kg/yr, with an absolute maximum of 21 kg/yr. Shanahan's (1997) estimate of the Pond's turnover, 0.8 volume/year, and the concentration of arsenic in the surface waters during the summer (-100 nM) were used to calculate the amount leaving the Pond annually, approximately 17 kg/yr. Finally, the arsenic flux from the water to the sediments was calculated using an estimated 0.5 cm/yr sediment deposition rate (see Section 2.1) and a total arsenic load for the top 15 cm of sediments of 1,200 kg to 1,920 kg (see Section 3.5.3). Using these estimates the arsenic flux to the sediments is between 40 kg/yr and 64 kg/yr. Therefore, according to the mass balance, 36 to 77 kg /yr is entering the Pond from sources other than the stormwater system. The most likely culprit is groundwater entering the Pond which led to an investigation of possible historical arsenic sources to Spy Pond.

66 4-21 k

me

17 kg/yr /36 - 77 kg/yr?

40 - 64 kg/yr

Figure 3-17 Arsenic in Spy Pond 4. Historical Investigation

4.1 Introduction

The preliminary mass balance indicates that stormwater runoff is not the primary input of arsenic to Spy Pond. A potential significant source may be an arsenic groundwater plume, originating from previous land use, migrating to the Pond. Therefore, historical land use and maintenance of the Pond was extensively researched in an attempt to explain the presence and quantity of arsenic in the pond. Resources explored include: " Arlington Public Library, including Arlington Advocate archives e Arlington Town Planning Office e Boston Public Library e Massachusetts Highway Department Library e Massachusetts State House Special Collections Library * Arlington Historical Society e Arlington Spy Pond Committee * Residents of Spy Pond.

All available previous reports on Spy Pond were researched, as well as historical books and maps of Arlington to understand development around and use of the Pond. Pictures and anecdotal information were acquired from the Arlington Historical Society. Arlington Advocate articles on market gardening and gypsy moth infestation were reviewed to glean any information about arsenical pesticide use.

Information from the Sanborn Maps and Publishing Company, Limited, Fire Insurance maps (Sanborn Maps) dating from 1885 to 1971 were digitized using Arcview 3.1 (see Section 3.4) to create convenient maps displaying the changes around Spy Pond over a period of almost 100 years. These maps show how Spy Pond's watershed changes from a commercial and agricultural center to an almost purely residential area.

68 4.2 Methods and Discussion

4.2.1 Sanborn Fire InsuranceMaps of Spy Pond

An in depth investigation of the industry and use of the land surrounding Spy Pond was conducted using Sanborn Maps and available historical literature. Arlington has a long history of industry and mills. At its peak, Mill Brook had seven major mill ponds. The watershed of Spy Pond has a somewhat less industrious history. Market gardens and ice houses cropped up along its shores at the turn of the century. However, since the 1950s, the vast majority of the watershed of Spy Pond has been residential (see Figures 4-1 through 4-5).

Figure 4-1 shows industry first appearing around Spy Pond in the late 1800s. By the 1900s, several ice houses began to appear to store and ship ice harvested from the pond. In conjunction with the ice harvesting business, an ice tool manufacturing company existed adjacent to the Pond. Several small businesses appeared along Massachusetts Avenue, near the north end of the Pond including: a garage and blacksmith, a painting shop, a barber, an upholsterer, a printing shop, and a large greenhouse farm. To the north of the Pond, just out of the present-day drainage basin, a large lumber yard, a coal, wood and hay distributor and an insecticide manufacturer existed along the railroad tracks (now the Minute Man Bicycle Path).

The next decade, the 1910s, saw the ice tool manufacturing business being replaced by a building materials shop, a greenhouse/market farm appearing along the east shores of Spy Pond, and a livery opening on Massachusetts Avenue (see Figure 4-2).

Figure 4-3 describes the 1920s, which enjoyed the largest expansion of businesses along Spy Pond. One truly understands how central the Pond was to the lives of those living near it. Market gardens explode around Spy Pond in this decade. Several more ice houses appear along the south shore and a foundry is shown along the southern shore of

69 Spy Pond - 1900s

Sc A Jw-

r

fIJA~

7.0 0-

Spy Pond Industry 1900s boat house coal pit farm/green houses Little garage 1 Wood & Co. Ice Tool Mfg. -ook 2 NewEngland Ice CoJArl.&BelmontIce ice house C-16 insecticidemfg. V 3 NewEngland IceCoJAr.&Belmont Ice shops 4 CambridgeIce Co/Gage Ice Co. tool manufacturing 5 Richard's Coal, Wood, Hay lumberyard 6 Frost Insecticide Co. ",Spy PondWatershed 7 Blanchard Kendall& Co. Lumber Yard 8 Rawson's Green Houses 41 I I 9 Wood & Co. Ice Tool Mfg. 10 MenotomyBoat House Data Sources: 11 Wood & Co. IceTool Mfg. hot house Spy Pond Industry History digitizedfrom SanbomMap & PublishingCompany., Limited 12 various shops Fire InsuranceMaps 13 Garage, Blacksmith, Painting Shop Spy Pond Watershedboundaries adjusted from MetropolitanArea PlanningCouncil 14 Garage & Repair Shop stormwaterbasin GIS data 15 hamess, barber, upholestry,printing

Figure 4-1 a t Spy Pond - 1910s r~

V

t,, i

Spy Pond Industry1910s farm/green houses tool manufacturing lumber yard 3 livery Spy Pond Industry1900s boat house 2 New EnglandIce GoJArl.&belmont Ice coal pit 3 New EnglandIce CoiArl.&Belmont Ice farm/green houses L ittle 4 CambridgeIce CoiGage Ice Co. garage PO Z 5 Richard'sCoal, Wood, Hay ice house P,rAf 6 Frost Insecticide Co. insecticidemfg. 7 Blanchard Kendall& Co. Lumber Yard shops k 8 Rawson's GreenHouses tool manufacturing lumber yard 10 MenotomyBoat House Spy Pond Watershed 11 Wood & Co. Ice Tool Mfg. hot house 12 various shops ilk 13 Garage. Blacksmith,Painting Shop 14 Garage& RepairShop Data Sources: 15 hamess,barber, upholestry, printing Spy Pond Industry History digitizedfrom Sanbom Map & PublishingCompany., Limited 16 Uvery Fire InsuranceMaps 17 Arlington & Belmont Ice Co. (replaces 1) Spy Pond Watershed boundaries adjustedfrom MetropolitanArea Planning Council 18 Davis & Son Building Materials (replaces9) stormwaterbasin GIS data 19 J. LyonsGreen Houses

Figure 4-2 SpyPond Industry 1920s

Icehouse shops houses autorepair shop foundary ordIndustry 1910s Lfarmfgreenfarmfgreenhouses toolmanufacturing lumberyard

py 91ond Industry 19009 boathouse coalpit farm/greenhouses garage 10 Menotomy Boat House 20 Tires,upholstering (replaces12) Icehouse 2 NewEngland Ice CoiAzl.&Belmont Ice 11 Wood &Co. e ToolM . hot house 21 Arlington AutoCo. RepairShop (replaces14) if, Insecicidemfg. 3 New EnglandIce CoJAr.&Belmont eo. I22 AlingtonAuto Co. RepairShop (replaces13) / shops 23 M.E.Moore Green Houses tool manufacturing 4 CambridgeIce CoiGage Ice Co. lumberyard 5 Richard'sCoal, Wood, Hay 24 Tappan GreenHouses -J SpyPond Watershed 6 Frost InsecticideCo. 15 hamess,barber, upholestry, printIng 25 ArlingtonFoundry Co. I 7 Blanchard Kendall& Co. LumberYard | 16 | Livery 26 1Wyman Bros. Farm V IiII if I ~ninaron. .. -. & maimoni- . .. ice LO.-. ireoracesvi a ~.. I Lemunuuu ice ~,g. -"Flvdan ' - I o0~1 rsawsonrwwson a '.,rean Wrean riwusesnausea 1- Anington a n ) 4er t,8mon0GOsee w. r18 Is& SonBuilding Materials (replaces 1) 28 ICambriNdgeIce Co. Data Sources: 19 J. Lyons Green Houses 29 1Lyons Green Houses Spy Pond IndustryHistory digitized fromSanbom Map & Publishing 30 Wyman Bros. Farm Company.,Limited Fire InsuranceMaps 31 GeorgeHill Green Houses Spy Pond Watershed boundariesadjusted from Metropolitan Area PlanningCouncil stormwater basin GIS data

Figure 4-3 at Spy Pond - 1951 :j c~

U3

~urtd

Spy Pond Industry 1951 IJ! Wshops 321 AcmeWindow Conditioning Co. ArlingtonPipe & Supsoy Co. a33 "O 34 FillingStation Spy Pond Watershed 35& Service 36 Filling Station K'1 7 -- 0 37 Roofer Data Sources: 38 ArlingtonCenter Motor Co.

SpyPond IndustryHistory digitizedfrom Sanbom Map & Publishing Company.,Limited Fire InsuranceMaps SpyPond Watershed boundariesadjusted fromMetropolitan Area PlanningCouncil stormwaterbasin GIS data

Figure 4-4 16 a Spy Pond - 1971 xl

-I .lS

Spy Pond Industry 1971 U2 dry cleaners I 1968condos p Pond Industry 1951 shops 32 AcmeWindow Conditioning Co. lumber yard 33 ArlingtonPipe & Supply Co. auto repair shop gas station 34 FillingStation Spy Pond Watershed 35 iAutoSales & Service

49 37 roorer _ 41 rI Data Sources: 38 ArlingtonCenter MotorCo. 39 DryCleaning & Pressing(replaces 36) Spy Pond IndustryHistory digitizedfrom SanbomMap & Publishing 40 Condominiums Company.,Limited Fire InsuranceMaps Spy Pond Watershedboundaries adjustedfrom MetropolitanArea Planning Councilstormwater basin GIS data

Figure 4-5 the north basin. The blacksmith shops along Massachusetts Avenue disappear and are replaced by automobile tire and repair shops. The pesticide manufacturing, lumberyard, and coal, wood, and hay distributor still exist to the north of the Pond.

The next Sanborn Map available is for 1951 (see Figure 4-4) and shows a dramatic change in land use around the Pond. All of the industry and farming around Spy Pond disappears and is replaced by residential housing. The exception is along Massachusetts Avenue, where small businesses such as filling stations, a pipe supplier, a window supplier, a roofer and automobile sales shops exist. The large businesses along the railroad are no longer present. This is, for the most part, how Spy Pond looks today. Condominiums are built along the east shore of the Pond in 1968, but otherwise no major construction took place near the Pond after World War II (see Figure 4-5).

4.2.2 Present Day Uses

The entire watershed of Spy Pond is densely developed except for 11.9 hectares within Menotomy Rocks Park [Chesebrough and Duerring, 1982]. The major land use in the Spy Pond watershed is residential single family housing (see Figure 1-6). Apartment houses and condominiums are found along portions of Pleasant Street, Massachusetts Avenue, and adjacent to the pond. Massachusetts Avenue and portions of Pleasant Street are also zoned for commercial use [MassGIS, 1998]. The entire area is serviced by the Metropolitan Sewer District (MSD) with treatment provided by Deer Island and no overflows or bypasses from the Arlington system are known to exist [Shanahan, 1997].

There is no current industrial water use within the Spy Pond watershed. The town landfill, closed in 1969, is located downstream and outside of the watershed. No areas of intense development or construction exist in the watershed, and all major farming ended prior to 1950.

75 4.2.3 LiteratureReview

A review of literature regarding high arsenic concentrations in lake sediments was conducted in an attempt to further comprehend the situation in Spy Pond. Three cases of extremely high arsenic concentrations in sediments, each through different routes, are presented.

Arsenic in sediments within the Aberjona River watershed has been heavily researched. The source of arsenic contamination in this region has been traced to its industrial history, including the manufacturing of arsenical pesticides. Another example, Lake Rotoroa, New Zealand, has elevated levels of arsenic due to heavy applications of sodium arsenate for weed control. Finally, Coeur d'Alene Lake, Idaho, has significant arsenic contamination from mine tailings. This case is significant because data indicates an upward movement of arsenic concentrations in the sediment, potenitally due to eutrophic conditions within the lake.

Aberjona Watershed The Aberjona River watershed encompasses an area of 65 km and contains a multitude of hazardous waste. Soils and sediments at and near one site, the Industri-Plex Superfund Site, have been found to contain extremely high concentrations, up to 30,800 mg/kg (dry weight) of arsenic [USEPA, 1986]. The geology of the Aberjona River watershed, like the Spy Pond watershed, does not suggest a significant geological source for elevated levels of arsenic [USGS, 1944; Aurilio, 1992]. For the Aberjona River watershed, historical investigations reveal industrial sources.

Arsenic contamination has moved from the Industri-Plex site to sediments in the Aberjona River and the Upper and Lower Mystic Lakes, strongly implying that the river is an important migration route for arsenic from the Industri-Plex sites to the lakes (see Figure x). Arsenic peaks from several cores from the lakes range from over 500 to almost 2,000 mg/kg (dry weight), and 30 to 450 mg/kg (dry weight) for the Upper and

76 Lower Mystic Lakes, respectively [Aurilio, 1992; Knox, 1991; Spliethoff, 1992]. In the Halls Brook Storage Area, which receives runoff from the Industri-Plex site, measurements of arsenic in sediments range from 35 mg/kg (dry weight) to as high as 9,830 mg/kg (dry weight) [Aurilio 1992; Roux Associates, 1991; Knox, 1991].

Historical records compared to the current distribution of arsenic concentrations in soils and sediments suggest that arsenical wastes produced during chemical manufacturing at the Industri-Plex site was the most important source. The processes of producing sulfuric acid and arsenical insecticides, specifically lead arsenate, continued in high volumes from the late 1800s to the 1930s [Aurilio, 1992]. The Aberjona Watershed may be significant to Spy Pond for two reasons. One reason is because research points to insecticide manufacturing as a significant arsenic source, and insecticide manufacturing took place near Spy Pond. Secondly, Figure 1-7 describes the surficial soils surrounding Spy Pond. A highly transmissive soil, glacial outwash, underlies Spy Pond along the line of maximum sediment contamination. This may mean that the source is further from Spy Pond than initially perceived. The glacial outwash valley that underlies Spy Pond includes the contaminated Aberjona River and the Upper and Lower Mystic Lakes upgradient of the Pond.

Lake Rotoroa, New Zealand Lake Rotoroa in New Zealand (370 48'S, 175' 16'30"E) is a 54-hectare urban lake with a 138-hectare residential catchment area and no significant anthropogenic or natural arsenic inputs. In 1959, 39 hectares (70% of the lake surface area) were treated with 11,000 liters of sodium arsenate in addition to a 0.5-hectare trial, supplying over 5,500 kg of arsenic to the lake or about 100 kg/ha. The application targeted the shallow weed- infested areas of the lake (0-3.7 m) and no other sodium arsenate applications were made to the lake. This application successfully killed plants until 1970 [Nriago, 1994].

Elevated levels of arsenic were noted in sediments (540-780 mg/kg) and additional sediment and core samples were collected. A close relationship between arsenic concentration and lake depth was evident, with the highest arsenic levels recorded in the

77 deepest part of the lake. The overall mean arsenic sediment concentration was 224 mg/kg. This suggests little of the original 5,500 kg of arsenic applied for aquatic weed control was lost from the lake [Nriago, 1994].

Arsenic migration within sediment and interstitial waters has been reported by Aggett and O'Brien (1985) in association with seasonal hypolimnetic deoxygenation (present in Spy Pond). When compared to several lakes in the Wisconsin area, with similar cumulative sodium arsenite application rates (kg/ha), Lake Rotoroa has a significantly higher concentration in its sediments [Nriago, 1994]. Section 4.3.3 and Table 4-1 discuss the sodium arsenite and arsenic oxide applications to Spy Pond. The total amount of arsenic applied to Spy Pond for weed control purposes is estimated to be less than 1 kg, which is much less than Lake Rotoroa and the Wisconsin Lakes. Even if the amount applied to Spy Pond is underestimated by a factor of two, the total arsenic input from herbicides is still much less than the amount of arsenic found in the Pond.

Coeur d'Alene Lake, Idaho Sediments of Coeur d'Alene Lake, Idaho, are heavily contaminated with mine tailings that contain, among other toxic elements, high levels of arsenic. Several authors have raised a concern that eutrophication and the concomitant development of a seasonally anoxic hypolimimion, the case in Spy Pond, could combine to significantly raise concentrations of toxic trace elements, as well as soluble nitrogen and phosphorus. The possibility that lake eutrophication and the development of a seasonally anoxic hypolimnion could mobilize arsenic from the sediments into overlying waters led Harrington, et al., to evaluate arsenic phase associations. Although Coeur d'Alene Lake is not currently classified as a eutrophic lake, it did experience periods of anoxia in the 1970s [Harrington, et al., 1998].

The mean concentration of arsenic in the Coeur d'Alene Lake sediments is 201 mg/kg. In examining sediment core samples (-0.5 m deep), enrichment of arsenic within 15 cm of the sediment-water interface is evident in nearly every core examined. Arsenic was found to correlate strongly with iron and manganese, but not lead and zinc, in the

78 sediment core profiles. In general, Harrington, et al. (1998), found the lake sediments to be highly reduced, with most redox potentials consistently below zero mV. They concluded that the maximal abundance of redox-active elements (including As, Fe, and Mn) occurs near the sediment-water interface in the region of the redox boundary (2-6 cm). This pattern suggests diagenetic cycling of these elements by oxidation-reduction reactions resulting in the migration of arsenic upward, into surface sediments [Harrington, et al., 1998].

Such a hypothesis as developed for the Coeur d'Alene Lake case may explain the high arsenic levels found in the upper sediments of Spy Pond if the source is found to be historic rather than current (see Section 2.1). Further sediment core analyses need to be performed for Spy Pond before any conclusions can be drawn.

4.3 Potential Arsenic Sources in Spy Pond

A combination of the sampling results, preliminary mass balance, historical mapping and literature review revealed several potential sources of arsenic. The following describes each source, its potential relevance, and whether further investigation is required.

4.3.1 Ice Harvesting

Ice harvesting was the most prevalent industrial use of Spy Pond. Starting at a small scale in the early 1800s, the industry steadily grew to several large ice houses from the 1840s to the 1920s. Gage, Cambridge Ice Co., and others built ice storage houses and later built a spur railroad track to connect to Charlestown. The ice business thrived until the 1920s when a combination of warmer weather and fires at the storage houses destroyed the business [Sanborn Maps & Publishing, Limited; Duffy, 1997; Arlington Heritage Trust, 1977]. Although ice houses themselves do not appear to be a source of arsenic, their success brought the railroad to Spy Pond, which may have transported and/or used arsenical pesticides.

79 4.3.2 Market Gardening

In the 1870s, one of the chief industries in Arlington was market gardening. The north and east shores of Spy Pond and many hectares along Pleasant Street were used extensively for commercial vegetable gardens. By 1907, it is said that Arlington was the number one market garden producer in the country. Apparently, the land adjacent to Spy Pond was heavily fertilized because the original land was not suitable for farming [Cortell, 1973]. In the seventeenth century most of the area south of Spy Pond was wetland. The "Great Swamp" stretched along the banks of Menotomy River (Alewife Brook) and south of the Pond. Over the generations, this area has been filled and fertilized to turn it into usable land [Arlington Historical Society Map Collection].

From the late 1800s to mid-1900s, inorganic arsenicals were used extensively as pesticides in agriculture [Nriago, 1994]. The local production of lead arsenate (see Section 4.2) likely resulted in this being the pesticide of choice around Spy Pond. Frost Insectide, a manufacturer and distributor of insecticides, was located near Spy Pond (see Figures 4-1 through 4-3). Whether Frost Insecticide produced lead arsenate has not been determined. However, the historical use and production of lead arsenate as a pesticide in the vicinity of Spy Pond should be investigated further.

4.3.3 Treatment History of the Pond

1871 marks the first report of nuisance vegetation growing in Spy Pond. In 1880, Spy Pond was declared unfit for domestic use due to the presence of a large amount of the weed Clathrocytis [Cortell, 1973]. The 1920s saw several attempts to improve the condition of the lake including raising its elevation, dredging, and copper sulfate treatments to kill the weeds [Cortell, 1973].

Annual records from the Department of Public Health between 1932-1951 show that Spy Pond was considered suitable for bathing. In 1951, it was confirmed that no sewerage entered the pond and that the entire area surrounding the pond was sewered [Cortell,

80 1973]. The pond enjoyed a period of good health in the early 1950s, although note was given to a 2-acre truck farm in the northeast cove that likely used fertilizers. By 1956, the pond was in need of weed control again and 0.55 ppm of copper sulfate was applied in the summers of 1956 and 1957 [Cortell, 1973].

In 1960, the Massachusetts Department of Public Health hired the Northeast Weed and Brush Control Corporation of Worcester to do a 5-year weed control project [Cortell, 1973]. A summary of treatments follows in Table 4-1 [Cortell, 1973]. The author made an attempt to quantify the amount of arsenic that entered Spy Pond through weed control (see Section 3.5). Using the highest application of sodium arsenate recorded (-5,000 gallons) and applying this amount to applications where the amount was not determined, the total amount of arsenic applied to the lake is less than 1 kg.

In the summer of 1963, it was very evident that the fish population was undergoing a severe decrease. Three or four out of every 100 yellow perch had one or two eyes in various stages of deformity and in some cases empty eye sockets were present. At the time, sodium arsenate was believed to be the cause, and the Massachusetts Department of Fish and Game recommended that it no longer be used to treat the pond [Cortell, 1973].

Up to 1970, the Commonwealth of Massachusetts had expended approximately $25,000 on vegetation control of Spy Pond. In 1970 a total of $500 to $750 was appropriated for the next 3 years of weed control [Cortell, 1973]. This implies that measures to control the weed population in the Pond were extremely limited between 1970 and 1973. Further weed control application information was not determined.

Unless an extraordinarily large weed control application (much larger than any recorded) occurred, the application of sodium arsenate and arsenic oxide to control weeds is not a major source of arsenic contamination in Spy Pond.

81 Table 4-1 Summary of Weed Control in Spy Pond [Cortell, 1973] Chemical Date Applied Contractor Location Amount/Dose 1921 Copper Sulfate Weston & Sampson Unspecified Unspecified 8/1956 Copper Sulfate Unspecified Unspecified 0.55 ppm 9/1956 Copper Sulfate Unspecified Unspecified Unspecified Phygon - Unspecified Unspecified experimental herbicide 8/1957 Copper Sulfate Unspecified Unspecified 0.5 ppm Rotenone Unspecified Unspecified 6/6/60 Silvex Weed & Brush Corp. of Up to 200 ft into 144 lbs at 2 ppm Worcester pond 6/24/60- Silvex Weed & Brush Corp. of Entire shoreline 4 L at 2 ppm 6/27/60 Worcester Amino Triazole Emergent 20 lbs/acre vegetation 6/30/60 - Sodium Weed & Brush Corp. Center portion of 4,624 gal at 10 ppm 7/2/60 Arsenate of Worcester pond in sections 9/60 Copper Sulfate Allied Biological Spot treatments Unspecified Control 8/24/61 Copper Sulfate Unspecified Unspecified 1400 lbs of 0.5 ppm 7/18/62 Arsenic Oxide Allied Biological Submerged Unspecified amount (As2O3) Control aquatic growths at 10 ppm Dalapon and Allied Biological Emergent Growth Unknown Amitrol T Control 7/66 Copper Sulfate Allied Biological Entire Pond 600 lbs Control and Diquat Northeastern Weed and Spot treatment 15 gal Brush Control Corp. of Worcester 8/67 Diguat Unspecified 15 acres Unspecified 5/68 Arsenic Oxide Unspecified Unspecified Unspecified amount (As2O3) at 7.5 ppm Copper Sulfate Unspecified Unspecified amount at 0.3 ppm 6/68 Copper Sulfate Unspecified Spot Blooms Unspecified amount at 0.3 ppm 6/69 Copper Sulfate Unspecified Unspecified Unspecified amount at 0.3 ppm 7/70 Copper Sulfate Unspecified Unspecified Unspecified amount at 0.3 ppm 7/28/71 to Copper Sulfate Allied Biological Unspecified Unspecified 9/17/71 Control 7/72 Aquathol-K Unspecified Unspecified 70 lbs Copper Sulfate Unspecified 200 lbs

82 4.3.4 Gypsy Moth Infestation

In the 1900s, Menotomy Rocks Park and other forested areas throughout Massachusetts were faced with an infestation of Gypsy Moths. There are chronicles in history books and the local paper describing the devastation. In 1892, F.C. Moulton of the Massachusetts Gypsy Moth Commission discovered the effectiveness of lead arsenate against gypsy moths and lead arsenate grew quickly in popularity [Aurilio, 1992; Hayes, 1954]. Historical records show that lead arsenate was used extensively in the Fells in Medford, Massachusetts to control the moths. An examination of available information on the history of Menotomy Rocks Park does not mention the use of this arsenical pesticide as a method to control gypsy moths, but it seems likely that it may have been a standard method for moth control in this area. Further investigation should reveal any significance gypsy moth control procedures had on the amount of arsenic in Spy Pond.

4.3.5 Other PotentialSources

Several other sources are worth investigating in the future based on this study's conclusions. The foundry or the large market garden located adjacent to the arsenic "hot spot" (see Section 3.3.3) may reveal historical uses of significant amounts of arsenic. Also, no information on the fill associated with the expansion of Route 2 could be found. Sampling of the soil between Route 2 and Spy Pond would confirm if this is a source of arsenic. The soils adjacent to the railroad (now the Minute Man Bike Path) may be contaminated with arsenic due to sodium arsenate applications for brush and weed control. Furthermore, lumber yards and funeral homes use small amounts of arsenic for preservation purposes. These businesses may add to the total arsenic loading to the Pond. Finally, historical records mention a pipe connecting Spy Pond to the Arlington Reservior. This may be a conduit for contaminants from other areas of Arlington.

83 4.4 Conclusions

The investigation both concluded the consideration of some potential arsenic sources and revealed new sources to investigate in the future. According to sampling results and historical research, stormwater runoff and weed control applications are not likely the major source of arsenic input to the Pond.

Several steps need to be taken in the future. This study implicates groundwater as the major conductor of arsenic pollution. Groundwater and soil sampling around the Pond need to be conducted in an attempt to discover the plume, if one exists.

84 References

1) Arlington Heritage Trust. (1977) Arlington Celebrates: The Growing Years: 1875- 1975.

2) Arlington Historical Society. Historical Map Collection. 3) Aurilio, A. (1992) Arsenic in the Aberjona Watershed. Massachusetts Institute of Technology.

4) Chesebrough, E.W. and Duerring, C. (1982) Spy Pond: A DiagnosticStudy 1980- 1981. Massachusetts Department of Environmental Quality Engineering Division of Water Pollution Control Technical Services Branch.

5) Cortell, Jason M and Associates (1973) Report of Conditions in Spy Pond, Arlington, Massachusetts:A HistoricalSynopsis. Jason M. Cortell & Associates, Wellesley Hills, Massachusetts. Prepared for Massachusetts Department of Natural Resources.

6) Duffy, Richard A. (1997) Images of America: Arlington. Arcadia Publishing, Dover, New Hampshire

7) Gawel, J., Chin, M. (1998) Unpublished Drain Outfall Sampling Results. Massachusetts Institute of Technology.

8) Harrington, J.M., LaForce, M., Rember, W., Fendorf, S., and Rosenzweig, R. (1998) Phase Associations and Mobilization of Iron and Trace Elements in Coeur d'Alene Lake, Idaho. Environmental Science Technology. Volume 32, No. 5. p6 5 0 -6 56 .

9) Ivushkina, T (1999) Toxic Elements in the Sediments of the Alewife Brook and Mill Brook Watersheds: Spatial Distributionand DepositionalHistory Tufts University.

10) MacLaughlin, K., Gawel, J., Senn, D. and Lukacs, H. (1998) Logbooks for Spy Pond Fieldwork. Massachusetts Institute of Technology.

11) Massachusetts Executive Office of Environmental Affairs. (1998) MassGIS Geographic Information Systems Database.

12) Nriagu, J.O., Arsenic in the Environment: Part I: Cycling and Characterization1994. John Wiley & Sons, Inc. NY, NY

13) Robertson, J., Cassidy, J., Chaudhry, M. (1988) Hydraulic Engineering.Houghton Mifflin Company, Boston, MA.

14) Sanborn Map & Publishing Company, Limited. (1885 - 1971). State Library of Massachusetts Special Collections Department

85 15) Shanahan, P., Spink, J., Morales, A. (1997) Review of Recommendations for the Restoration of Spy Pond, Arlington, Massachusetts. HydroAnalysis, Inc., Acton, MA and MNS Consultants Inc., Wellesly, MA.

16) Senn, David (1998) Analysis of Spy Pond Sediment Core. Unpublished. Massachusetts Institute of Technology.

17) Senn, D. and Gawel, J. (1999) Unpublished Water Column Data. Massachusetts Institute of Technology.

18) Spliethoff, H. (1995) Biotic and Abiotic Transformationsof Arsenic in the Upper Mystic Lake. Massachusetts Institute of Technology

19) Thomas, C. (1999) Personal communication. Lupine Information Systems.

20) United States Geological Survey. (1944) Surficial Geologic Map of the Mystic Lakes-Fresh Pond Buried Valley Area between Wilmington and Cambridge, Massachusetts. Scale 1:31,680.

86 Acknowledgements

My list of people to thank seems endless. This is a very challenging program and would be impossible without the support, assistance and patience of others. First, I would like to thank the Spy Pond investigation team who not only made this thesis possible, but made it a truly fun and enjoyable experience: Jim, Heather, and Dave. A special thanks goes to Cord, who showed extraordinary patience and enthusiasm even after months of teaching GIS mapmaking to a woman who never can ask enough questions. I would also like to thank Jim for introducing me the mystery and intrigue of Spy Pond and helping me stay grounded.

Help throughout the project came in the form of the Parson's Volunteer Rescue Team including, Megan, Dan, Chris and John, who volunteered to wait for rain that refused to appear. Also, Dan and Rachel where always willing to assist with sediment sample preparation and analysis. Finally, I'm grateful to the students of the Hemond Lab, who welcomed me with open arms, and made the hours of analysis fly by with their humor and helpfulness.

Other help came from John Durant of Tufts University and Pete Shanahan of Hydroanalysis, who gave their notes and knowledge on the pond, Mark Shea, of Arlington Public Works, who spent a morning without complaint assisting a strange graduate student who wanted samples of catch basin muck, and Lisa Welter, of the Arlington Historical Society, who came out in a snow storm to share the history of Arlington.

Finally, I would like to thank my family and friends. It is though their unwavering support and encouragement that I am able to accomplish my goals and dreams.

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