(From 1997 Open Space and Recreation Plan, Town of Hamilton Open Space Working Group

ENVIRONMENTAL INVENTORY AND ANALYSIS

A. Geology, Soils, and Topography

(1). Description

Much of the town's land is level to gently sloping, with a few steeply sloped hilly areas, at elevations from about 40 to a little over 200 feet above sea level.

Hamilton's geological surface can, for open space planning purposes, be roughly divided into:

- swampy areas in topographic depressions and floodplains along watercourses where sediments and plant matter accumulate over other materials deposited by glacial action

- low, flat areas in the eastern half of town covered with sediments deposited in beach and nearshore environments during a period of higher sea level after the last glacial episode

- low flat to rolling terrain covered a mixture of deposits laid down when the last glacial ice was wasting away (ice contact deposits like eskers, and outwash)

- hills and high spots mantled in older glacial till

- Beneath all this, and in spots (scattered and mostly small) showing on the surface, is bedrock, mostly of the kind of granite that underlies most of Cape Ann.

Each of these terrains has its own characteristic soils, vegetation, visual qualities, land use patterns and potentials.

Geology and soils in Hamilton wetlands and floodplains

The most extensive area of swamp deposits is the Great Wenham Swamp, which extends into the southwest part of Hamilton near Asbury Grove. At several places nearby upland surrounds or nearly surrounds smaller areas of swamp (as north of Linden Street and near Day Avenue in South Hamilton). Similar conditions and soils in prevail in flat areas bordering the Ipswich River and its larger tributaries such as the Miles River, Long Causeway Brook and Black Brook.

On the US Natural Resources Conservation Service maps, the characteristic soil shown is Freetown muck, made up chiefly of organic material to a depth of 5 feet or more. The water table is near or at the surface, consequently the soil is very poorly aerated and only supports vegetation particularly tolerant of wet conditions (red maple swamp, shrub swamp). The lack of oxidation gives the soil a very dark color.

Marine sediments

Post-glacial marine sediments are at the surface in a band a mile or two wide roughly parallel to Bay Road. The railroad line to Ipswich corresponds more or less with its western edge. These sediments are clayey to silty in texture, and develop soils that are typically classified as Merrimac soils on the soil map, therefore differing little from the soil characteristics of the ice contact-outwash deposits discussed below, except perhaps in being on the average in lesser slope categories.

Ice contact deposits and outwash

These deposits can have a complicated history of deposition in winding channels inside or underneath the glacier (giving the sinuous form of an esker, like those which give interest to the terrain in several parts of Hamilton) or between the side of a glacier and an adjacent hill, perhaps with subsequent slumping. There are sizeable areas of such deposits developed in contact with the ice of a wasting glacier in the low-lying areas of Hamilton outside of the area of marine deposits. These deposits are in many places thick enough and permeable enough to be important aquifers.

Sand and gravel outwash deposits accumulated downstream from a melting glacier and will show the earmarks of having been deposited from moving water, typically including stratification. There is an area mapped by USGS geologists as outwash in the south central part of the town, west of Bay Road and south of Savin Hill.

All these processes around a waning glacier can give rise to complex patterns of grain size distribution, stratification and field relationships that can be deciphered with some subtlety (though not necessarily with certainty) by experts, but for our present purposes, most of these variations can be grouped together.

These parts of town are mapped by the US Natural Resource Conservation Service in the Merrimac-Hinckley-Urban land association. The Merrimac and Hinckley soils are characterized by a sandy subsoil underlain by sand and gravel.

Till uplands

Several drumlins (Brown's Hill, Vineyard Hill, etc.) make up the town's most conspicuous high ground. The highly characteristic material of these and adjacent areas is "till", with its widely varying assortment of particle sizes from sizeable rocks down to silt and clay. Till is distributed over a wider area than the drumlins in Hamilton, but it is often associated with "foothill" areas close to the drumlins, as in the area between Vineyard Hill and Willowdale Hill in the west of the town. Another sizeable till area is near the lakes in East Hamilton.

Hamilton's till soils are mapped in the following soil associations :

1. Paxton-Montauk-Urban land association ("hills and sloping uplands" (US Natural Resource Conservation Service description); Willowdale-Vineyard Hill area, Brown's Hill area, and Sagamore Hill area; often with a relatively impermeable substratum).
2. Canton-Woodbridge-Freetown association ("low irregular hills"; Pigeon Hill area and the till area south of Sagamore Hill)

Chatfield-Hollis-Rock outcrop association ("low irregular hills, ridges and plains with frequent bedrock exposures"; eastern Lakes District from Gravelly Pond west to Route 22 and Essex Street; often shallow to bedrock)

(2). Effects on Community

The glacial outwash sediments giving rise to Merrimac and related soils make Hamilton's best agricultural land, and it also is favorable for building residences and septic systems. Many of Hamilton's residential subdivisions are built on this type of material. The sandy texture makes for fast drainage (sometimes faster than a farmer would prefer from the point of view of keeping water in the root zone after rain).

In the glacial till areas, the matrix of superfine grains in till often makes for "tight", relatively impermeable soils, often creating problems in siting septic systems. Because of the occurrence around hills, high slope is sometimes a limitation for residential development. Additionally, many of the areas of Hamilton where soils have a shallow depth to bedrock are on glacial till.

Concerning the development potential for Hamilton's areas on wetlands and floodplain soils, the limitations for buildings and septic systems are obvious, and severe.

B. Landscape Characteristics

A visitor driving through Hamilton for the first time would likely get the sense that the essential character of the landscape is that of gentle rolling farmland. This first impression would be obtained from the large open fields which line some of the major thoroughfares, such as along Route 1A. If the visitor were to stop their car and spend some time hiking in some of the forested areas, such as Bradley Palmer State Park, Appleton Farms Grass Rides, or Willowdale Mill Reservation, they might get the impression that the essential landscape character of Hamilton is one of upland forests with numerous hiking and bridle paths. However, if the visitor, or even some long time town residents, were to fly over the town, they would probably be surprised to see that much of town consists of wetlands, lakes, and streams. They would also notice a number of drumlin hills with distinctive oval shapes, generally oriented northwest to southeast. The true character of the landscape in Hamilton is therefore one of diversity, ranging from large open fields, upland forests, lakes and streams, and wetlands.

All of these landscape characteristics are important and contribute to what makes living in the Town of Hamilton so enjoyable. However, it is easy to imagine how poorly planned development could degrade the landscape characteristics which give the Town of Hamilton its special character. The remaining large open fields could be subdivided into numerous house lots, Existing hiking and bridle trails could similarly be blocked by poorly planned subdivisions. Wetlands, lakes and streams could all be degraded by not providing for their protection. Many of these impacts can already be seen. Subdivisions are nibbling away at the existing open spaces and numerous trails have been blocked by house lots. The largest lake in town, Chebacco Lake, is already severely impacted by algal blooms which are the result of poorly designed or malfunctioning septic systems. With proper planning, many of the impacts of increased development can be minimized. Cluster zoning can preserve open space and even enhance trail access while at the same time allowing for new houses. Revised regulations and aggressive enforcement of existing regulations can prevent further degradation of lake and wetland resources. Lake protection and cleanup programs can restore the lakes in town that have been degraded.

C. Water Resources

The water resources in the Town of Hamilton consist of surface water and groundwater, and are used primarily for drinking water and recreation. There are no significant water resources being used for hydroelectric or irrigation. An inventory of groundwater and surface water resources is presented below. See the "Water Resource Map".

(1). Surface Water

a Rivers and Streams

Ipswich River

The Ipswich River serves as the boundary of Hamilton to the west with Topsfield, and to the north with Ipswich. The segment of the Ipswich River adjacent to Hamilton is proposed as a Massachusetts Scenic and Recreational River under the "Scenic and Recreational Rivers Act". Overall water quality in the Ipswich River Basin can be considered as ranging from good to excellent. According to the use classification promulgated by the Division of Water Pollution Control, the Ipswich River and its tributary streams are meeting Class A and Class B. Periodic violations of coliform bacteria and dissolved oxygen concentrations occur during late summer and early fall. The high coliform levels are generally attributed to the large wildlife population living in the Ipswich River Basin, while the low dissolved oxygen is caused by the leaching of organic materials from adjacent swamps and marshes. The Ipswich River is used for swimming, fishing, and canoeing. The Ipswich River is not used directly for drinking water in Hamilton. However, the river provides recharge for nearby wells in Hamilton and Ipswich.

Idlewild Brook

Idlewild Brook originates at Pleasant Pond and flows to the Ipswich River through Wenham Lake. Idlewild Brook provides partial drainage for the Wenham Swamp.

Black Brook

Black Brook originates at Cutler Pond and flows west to the Ipswich River, Black Brook provides drainage for wetland areas between Highland Street and Bay Road.

Miles River

The Miles River has its source in Wenham Lake and the wetlands at the eastern end of Wenham. The Miles River flows northward from Wenham Lake, through the Longham Reservoir to the Ipswich River in Ipswich. There are numerous minor tributaries entering the Miles River in Hamilton, the most important of which is Long Causeway Brook on the Hamilton-Ipswich line.

b Lakes and Ponds

Chebacco Lake

Chebacco Lake is divided by the Essex-Hamilton boundary with approximately 83 acres located in Hamilton. Some of the recreational uses of Chebacco Lake include fishing, swimming, boating and water skiing. A boat ramp providing public access to the lake is

provided on Chebacco Road.

Beck Pond

Beck Pond is approximately 34 acres. Public access to Beck Pond can be made from Chebacco Road, although parking is limited. Motorized boats are prohibited on Beck Pond.

Round Pond

Round Pond is approximately 36 acres. Well points along the shore of Round Pond are used to supply water to Gravelly Pond. The Town of Manchester has a permit to pump up to million gallons per day (MGD) from the Round Pond well field. The water is

treated to remove metals before being discharged to Gravelly Pond.

Gravelly Pond

Gravelly Pond is approximately 46 acres and is used as a drinking water supply by the Town of Manchester, The safe yield of Gravelly Pond is reported by the Town of Manchester to be 0.65 MGD per day. A 2.0 MGD water treatment plant near the shore of Gravelly Pond for the Town of Manchester is under construction. As noted above, the flow into Gravelly Pond is supplemented by the Round Pond well field. No Trespassing signs posted by the Town of Manchester limit public access to Gravelly Pond from Chebacco Road.

Pleasant Pond

Although Pleasant Pond is located primarily in Wenham, approximately 2 acres extend into Hamilton. Some of the recreational uses at Pleasant Pond include fishing, swimming, and boating. There is no public access to Pleasant Pond in Hamilton. However, Hamilton residents are permitted by Wenham to use the public beach area in Wenham.

Patton Pond

Patton Pond is located in Patton Park. This one acre pond was originally created in the 1940's by dredging a lowland swamp. Excessive problems with exotic, non-native weeds required chemical treatment in 1994. The pond is the centerpiece of Patton

Park.

Cutler Pond

Cutler Pond has a surface area of approximately 5 acres and is located in Cutler Park. Cutler Park is located on a tiny slice of land in the Historic District of Hamilton. The park was originally a graveyard and is completely overgrown and underused. There is a small, inconspicuous sign marking the entrance to the park from Route lA across from the Town Hall. Cutler Pond is the headwaters of Black Brook. There are presently no recreational uses of Cutler Pond.

(2). Flood Hazard Areas

Seasonal flood hazards exist in the lowlands adjacent to Wenham Swamp, the Miles River, Black Brook, the Ipswich River and shores of the many lakes and ponds. Development is restricted and/or discouraged in these sensitive areas where surface waters can rise quickly and/or there is shallow depth to groundwater.

(3). Wetlands

Wetlands constitute an integral part of the natural environment, and more specifically, the hydrologic system. In addition to diversifying the landscape, wetlands often play a significant role in the storage of water, flood control, and the maintenance of

water quality. Wetlands also serve as habitat for a variety of wildlife species. Additionally, wetlands may serve as groundwater recharge or discharge areas.

The existence of wetlands depends on the relative stability of a variety of natural parameters, including groundwater elevation, soil type, topography, and surface waters. The alteration of one or more of these parameters may result in profound changes in both the structure and function of wetland communities. For example, the lowering of the water table or the diversion of surface water away from a wetland may result in conditions suitable for upland vegetation, and thus the eventual loss of the wetland. Figure x shows the locations of the wetlands in Hamilton. There has been no town-wide detailed mapping of wetlands in Hamilton by the Commonwealth or the Town, and therefore the wetlands shown in Figure xx are approximate. The 1965 Master Plan noted there was about 1870 acres of swamps and wetlands based on the following:

TABLE 4-1. Swamp and Wetland Areas

(4). Aquifer Recharge Areas

The drinking water resources and associated aquifer recharge areas in the Town of Hamilton were analyzed and mapped in a report entitled "Report on Aquifer Planning Study, Hamilton Massachusetts" by Haley and Aldrich, Inc., Consulting Engineers and Geologists, 1981. The mapping of aquifer recharge area in this study formed the basis of the Groundwater Protection Overlay Zoning District. As noted above, the Town of Manchester has two surface water drinking supplies in Hamilton: Round Pond and Gravelly Pond. Hamilton does not utilize any surface water for drinking water supplies. An inventory of the groundwater resources in current use follows (see also "Water Supply System" on page 12):

TABLE 4-2. Hamilton's Municipal Water Wells

The Idlewood and Pine Tree wells provide water to meet normal demands. Peak demands are met by supplemental pumping of Patton and School Street wells. There is also a well field of numerous small diameter well and two gravel packed wells located adjacent to Bridge Street. This well field, however, has been abandoned.

The Chebacco Lake watershed also contains two groundwater wells in Essex which supply water for Essex. The Town of Ipswich has three wells north of the Ipswich River near the confluence of Black Brook. Although the Essex and Ipswich wells are not located in the Town of Hamilton, their cones of depression may extend into the town.

D. Vegetation

(1). Forest Land

Northern hardwoods, typified by red oak in well drained areas, and red maple in wet or poorly drained areas are the predominant forest cover in Hamilton. Northern hardwoods include soft and hard maples, beech, birch, cherry, oaks, hickory, and sassafras. Other dominant species of vegetation includes red pine, white pine, eastern hemlock, and some rare occurrences of native rhododendron.

(2). General Inventory

Hamilton has large areas of forested swamp and shrub swamp with abundant red maple, arrowwood viburnam, sweet pepperbush, winterberry, highbush blueberry, swamp azalea. Cinnamon fern, skunk cabbage and tussock sedge are characteristic of the lower layers.

Some wetland areas, notably on the Miles River floodplain, have been extensively invaded by purple loosestrife.

There are some fairly extensive areas of upland currently under cultivation, in some cases grading down into wet meadow and wetland. Of course the preponderance of the current woodland areas were formerly cultivated, and show characteristic New England "old field" vegetational patterns.

(3). Rare, Threatened and Endangered Species

The rare plant species recorded in the Hamilton area include the showy lady's slipper, pale green orchis, terrestrial starwort, and the river-bulrush. The first two are orchid species and have been historically reported to occur in the area.

The terrestrial starwort is a rare plant likely to be found on muddy flats and trails near lakes in the area. The tidal river shore species, the river-bulrush, is rare but recorded in the vicinity.

E. Fisheries and Wildlife

(1). Inventory

Aquatic Habitats

The ponds, stream, and marshes provide habitat including food and cover for black duck, mallard duck, and wood duck in addition to many migratory species of waterfowl.

Muskrat, otter, mink, and raccoons may be found in wetland areas. Major game fish include brook trout, brown trout, rainbow trout, largemouth bass, and chain pickerel.

Terrestrial Habitats

Songbirds indigenous to the area include various sparrows, wrens, chickadees, titmouses, cardinals, doves, and mockingbirds. Whitetailed deer are the only large game animal found in Hamilton. Small game includes ring-neck pheasant, quail, ruffed grouse, woodcock, cottontail rabbits, raccoons, fisher, opossum, grey squirrel, and grey fox.

(2). Corridors

Protectged corridors of open space for wildlife habitat are an important goal of Hamilton's planning process.

The Hamilton Conservation Commission's Discover Hamilton Trail project, the greenway extending from Patton Park and Myopia Hunt Club area through the Devon Glen Farm conservation restriction, the Harvard Forest, the Pingree Restriction and the Ipswich River conservation restrictions of the Arbella Trust and G. Horne is a critically important wildlife corridor.

Continuous with this greenway is a section of the Hamilton bank of the Ipswich River extending from a portion of the Wenham Swamp within the Massachusetts Audubon Ipswich River Wildlife Sanctuary through Bradley Palmer State Park, with a side branch in Topsfield at Willowdale State Forest, through Essex County Greenbelt's Willowdale Dam reservation and through restrictions granted by the Winthrop family, and by G. Horne almost to the Mill Street-Highland Street bridge. This corridor complex also connects to the Appleton Farms Grass Rides and adjacent open spaces.

On the eastern side of this complex, the corridor extends via the wooded parts of the Myopia Hunt Club to open spaces in East Hamilton, Wenham, and Manchester in the "Lake District" including Gordon Woods, the Town of Manchester Water Supply area surrounding Round Pond and Gravelly Pond, the Iron Rail area, and the wooded part of the old landfill site. This section is in need of serious future vigilance since large parts of it have no durable protection and, such as the Gordon Woods, are vulnerable to sale for development very soon.

(3). Rare, Threatened and Endangered Species

The Massachusetts National Heritage Program (MNHP) considers five animal and four plant species recorded in Hamilton to be rare, uncommon, or ecologically sensitive.

The rare animal species include the blue-spotted salamander, spotted salamander, eastern box turtle, golden-winged warbler, and New England medicinal leech.

The rare blue-spotted salamander may occur near wooded swampy areas or moist woods. The spotted salamander, although more common, is considered ecologically sensitive and may be found in similar areas around Hamilton.

The eastern box turtle is considered to be declining and threatened in Massachusetts by some experts. It prefers open woodlands and wet meadows and was sighted in Hamilton in 1977.

The Massachusetts Division of Fisheries and Wildlife lists the golden-winged warbler as "State Rare." This species has been sighted infrequently in the area. It prefers overgrown fields of wet shrubby deciduous thickets.

The New England medicinal leech, a rare invertebrate, has been found in local vegetated freshwater ponds and streams within the coastal plain. Habitat alteration or pollution have severely threatened the status of this animal.

F. Scenic Resources and Unique Environments

Hamilton has an abundance of scenic resources and unique environments which blend together to give the town it diverse character. These resources include rivers, lakes, parks, reservations, wetlands and historic areas.

Rivers

The portion of the Ipswich River adjacent to Hamilton is proposed for possible inclusion as a Massachusetts scenic and recreational river. The river is widely used for fishing, swimming and canoeing. The Ipswich River is susceptible to pollution from increased development. The river may also experience reduced flows in the future as upstream communities increase their drinking water supplies.

Lakes

Hamilton has several lakes and ponds which contribute to the scenic character of the town. Of these, Chebacco Lake is the largest and most important. It is also the most threatened. As a result of the large number of poorly operating septic systems, the lake is experiencing increase algal growth which leads to eutrophication.

Parks, Reservations, and Open Space

Hamilton also has several parks and reservations which contribute to the scenic character of the town, The largest of these include Bradley Palmer State Park, Appleton Farms Grass Rides, Willowdale Mill Reservation, and Patton Park. The parks and reservations are protected and are not at risk of being developed.

There are other open space areas in town which are very scenic but are unprotected, These include the Harvard Forest, Myopia Schooling Fields, Iron Rail, Gordon College lands including Gordon Woods, and Pingree School lands.

Wetlands

Hamilton has several very scenic wetland areas, most notably: Wenham Swamp, Miles River, and Black Brook, and on the fringe of Chebacco Lake. Development pressure is constant in these areas. As the availability of buildable land decreases, house lots are put right on the very edge of the wetlands. This can have a negative impact on the function of wetlands because it may change sunlight or drainage patterns, or can interfere with wildlife which live on the edge of wetlands and need buffer zones. Development in wetland buffer zones is closely monitored by the Hamilton Conservation Commission.

Unusual Geologic Features

One of the most striking geologic features of Hamilton is its sharply rising hills, which afford spectacular views from their tops. Examples are Candlewood Island, Sagamore Hill (and surrounding hilltops such as Eveleth Hill), the Hamilton Ski Hill, and Cilly's Hill, which is close to the business center of town. Also attractive are the expansive bedrock outcroppings below and to the south of Sagamore Hill and the rock ledges and outcroppings of the former Prince estate, now owned by Gordon College. Historic Areas

Hamilton is fortunate to have a well defined and protected historic district. There are other historic features of the town which are protected, such as the burial site of Chief Masconomet on Sagamore Hill.

Areas of Critical Environmental Concern

There are currently no ACECs in Hamilton, as defined by the state ACEC process.

G. Environmental Problems

(1). Hazardous Waste Sites

Presently, there is only one DEP certified hazardous waste site in Hamilton. The site is on town property behind the town hall where diesel and gasoline fuel tanks are stored. The tanks store 5,000 gallons each. There was leakage from the original tanks and they were replaced in 1986. In addition monitoring wells were put down. Shortly thereafter a plume of hydrocarbons was discovered on the surface of the groundwater. In 1987, a vapor recovery system was installed as a precaution. The town has an on-going contract with Zecco for monitoring the tanks and the groundwater. The site should be decertified in the next few years.

(2). Landfills

Hamilton's town landfill is located at the end of Chebacco Road in the Gravelly Pond watershed. It was capped in 1983. The landfill is monitored and tested four times a year for leachate: it currently tests clean.

(3). Erosion and Sedimentation

There are several sites in Hamilton where substantial erosion is taking place but because they are outside of the 100 ft. buffer zone, they are outside of the jurisdiction of the Conservation Commission. Therefore it is difficult to mandate preventative measures.

Continually, there are open construction sites that need erosion control but are presently not addressed because they are outside of the buffer zone.

In addition, there is an erosion control problem with Gordon Conwell's new library parking lot. It has no adequate means for drainage. It ends at the top of a hill on Bridge Street and causes a tremendous amount of sediment to wash into the street. Approximately 200 tons of sediment eroded over the course of one winter.

There are exposed gravel banks along Chebacco Road adjacent to Beck Pond. Presently gravel is being washed across the street and into Beck Pond. The embankments need stabilizing with a retaining wall.

Prior to 1994 there was an erosion problem along the access drive to the US Air Force installation on Sagamore Hill. Large amounts of runoff were coming down the access drive and eroding the western shoulder of Sagamore Street. In 1994 the town installed a slotted drain pipe across the driveway entrance which captures the run off and any sediment. The sediment is captured by a series of sedimentation basins before water goes on to the Miles River. The catch basins and sedimentation basins need to be monitored and maintained.

(4). Chronic Flooding

Seasonal flooding is a concern in an area surrounding Highland Street, Howard Street and Linden Street where water overflows from a small stream which is shallow and has a large bordering wetland. Houses on Howard Street are known to be set on wooden pilings. However, areas of the streets are settling.

There have been episodes of flooding associated with beaver dams in streams crossing roads in the eastern part of town, for example on Moulton Street.

Another area of flooding is the pond in Patton Park. The pond overflows the banks and inundates a portion of the park.

The Hamilton FEMA flood maps indicate in a general way numerous other areas subject to flooding, most of which, fortunately, have not been built upon.

Water Overuse

The Ipswich River watershed is becoming increasingly overused. The river basin currently serves about a dozen communities. Hamilton draws out about 175 gallons per person every day, a level that is considered excessive. The communities of Ipswich, Manchester, Hamilton and Wenham could be facing chronic and severe water shortages in the next thirty years. At one point in the summer of 1994, a there was a draw of a million gallons in a ten hour period, leaving only 100,000 gallons in the reservoir. When the reservoir gets below a certain level mud starts entering the system.

Wetlands Resource Impacts

As the contiguous builtup area of town fills in, the development of new subdivisions and individual lots is more and more constrained to be near wetlands and in adjacent upland areas formerly providing wildlife habitat and corridors. The Conservation Commission has been disturbed by the number of applications for construction of single family homes which, although they do not actually fill wetlands resource areas directly, include structures or grading that are so close as to almost certainly affect the functioning of the wetland microenvironment and which leave wildlife no effective "wetlands fringe" area that has been shown to be as essential to many species as the wetland itself.

In response to this the Commission promulgated Regulations under the town Conservation Bylaw (Chapter 17) in 1995 which set guidelines for new construction including a 50-foot "no-build", and a 25-foot "no-impact" adjacent to wetlands. The regulations also included among wetlands protectable under the Bylaw isolated areas which, though not necessarily state-certified as vernal pools, showed significant biological signs of functioning as vernal pools.

(5). Surface Water and Groundwater Pollution: Point and Non-point

Hamilton is completely dependent on groundwater for its drinking supply. In addition, Gravelly pond, which is used as a drinking water supply for the town of Manchester, is located in Hamilton. The loss of these water resources would have devastating consequences for the towns of Hamilton and Manchester. Therefore the primary environmental problems facing the town are those which could potentially impact these drinking water resources. These include underground storage of fuel, floor drain discharges,

septic systems, agricultural practices, household hazardous waste, leachate from the town's landfill and road salting.

Underground Storage of Fuel

Leakage of tanks or piping that are subject to corrosion or puncturing can lead to contamination of water resources. Underground storage tank leaks are caused by a number of factors including defects in tank materials, improper installation, corrosive soils, problems with piping systems, weather conditions, or tank fatigue. Unprotected steel tanks have an average life expectancy of 15 years in corrosive soils which are characteristic of much of Massachusetts. Once tanks leak, gasoline can move through the ground and contaminate large volumes of water, since concentrations as minute as several parts per billion in drinking water are considered unsafe.

Petroleum fuels are mixtures of huge hydrocarbons. If a fuel such as gasoline is released into the subsurface, the more water soluble components such as benzene dissolve into the groundwater move with the ground water flow. the drinking water limit for benzene is 5 parts per billion. This problem can also occur to releases of oil, but to a less degree. Once an aquifer has become contaminated, it is very difficult and expensive to clean it up. Typically, a groundwater remediation system would be installed to intercept and treat the contaminant plume. If the contaminant plume were to reach the drinking water wells the town would have to construct a water treatment plant or find a new water source. the cost of either of these alternatives would likely be in the millions of dollars. therefore, it is important to take wherever steps are necessary to prevent the aquifer from being contaminated.

There is one facility storing gasoline and diesel fuel in Hamilton's water resources area. This is the filling station on the corner of Asbury Street and Highland Street. There are three known underground storage tanks on this site, all three are more than 15 years old. The total amount of gasoline and diesel stored in the study area is approximately 18,000 gallons.

In addition, within the water study area residences and institutions are storing fuel oil in 15 underground tanks throughout the study area. The total volume of fuel oil stored underground in Hamilton's water study area is approximately 68,050 gallons. The records do not indicate the ages of these tanks, but many are likely to be at least 20 years old. Almost all of them are unprotected steel tanks.

Floor Drain Discharge

Floor drains are often tied to a leaching structure such as a dry well or a septic system. Poor management practices, accidental and/or intentional discharges may result in petroleum and other hazardous materials being released into the subsurface. Once the contaminants enter the subsurface they can cause similar aquifer contamination as described above.

Septic Systems

Hamilton relies on septic systems to treat sanitary wastes with the exception of Gordon Conwell Theological Seminary, which utilizes a packaged treatment plant before discharging the treated water to the subsurface. A septic system consists of a septic tank and leaching system. The tank is a watertight structure designed to allow settling of solids and digestion of organic material. The leaching system allows the effluent from the tank to discharge into the underlying soil. In older systems, a cesspool is used instead of a septic tank and leaching field. Cesspools provide less treatment than a properly designed and operating septic system. As part of Title 5, the Massachusetts Department of Environmental Protection has promulgated new regulations concerning cesspools. Among other criteria, cesspools must be replaced by a septic system under the following conditions:

1) The system has failed.

2) The system is located less than 50 feet from a wetland.

3) The bottom of the cesspool is located in the water table.

4) A two year review of water usage indicates the holding time is less than 12 hours.

5) There is an increase in living space, such as a house addition.

Some of the ways in which cesspools and septic systems can contribute to groundwater contamination include allowing poorly treated water to enter the groundwater. This poorly treated water may contain pathogens, such as viruses, and increased levels of nutrient such as nitrogen and phosphorus. These nutrients, in turn, can contribute to eutrophication if the groundwater enters a surface water. The problem of eutrophication in Chebacco Lake is discussed below.

Another way in which septic systems can contribute to groundwater contamination is through the use of septic system cleaners. According to DEP, septic systems contain a variety of hazardous chemicals. Many hazardous chemicals are resistant to biodegradation and pass through septic systems, harming beneficial bacteria and contaminating groundwater. Six of the most commonly found chemicals in septic system cleaners are

Trichloroethylene

1,1,1, Trichloroethane

Tetrachloroethylene

Methylene Chloride

Dichloromethane

Napthalene

These chemicals have been involved in the closure of over 40 public water supplies in Massachusetts.

Agricultural Processes

Pesticides: The term pesticides includes insecticides, fungicides, herbicides and rodenticides. They are all chemical compounds used to control unwanted organisms such as insects, weeds and rodents. Since the compounds vary depending on their target organisms, their potential effects on water resources vary greatly. Pesticides may enter the ground by direct infiltration through the ground or by way of runoff. Additional impacts on water can occur with improper storage and/or disposal of agricultural products and wastes. Pesticides in ground and surface water pose a risk to aquatic and wetland plants and animals and increase public health risks.

Hamilton has two important rights of way, the Boston and Maine Railroad and a gas pipeline owned and maintained by Tenneco, Inc. Tenneco's easement is hand cut and no herbicides are used. The railroad utilizes herbicides to control all vegetation along the track since plant growth may cause degradation of the tracks and/or can lead to fires. In most cases treatment extends 12 ft. to either side of the center of the track. (Within 100 ft. of a resource area state regulations restrict application.) The railroad does not run through Hamilton's water supply study area.

There are currently several hundred acres of agriculture cropland and orchards in Hamilton, of which 238 acres is in the aquifer area. The amount of pesticide application this land is subject to is unknown. There are no local controls of pesticides in Hamilton.