Fall River Open Space Plan
IV. ENVIRONMENTAL INVENTORY AND ANALYSIS
A. Geology, Soils & Topography
i.) Topography and Geology
Fall River's unique physical landscape is highlighted by terraced bedrock slopes dropping sharply into the Taunton River and Mount Hope Bay on the western side of the City and the extensive forest and watershed lands east of the Watuppa Ponds. Many small hills are scattered throughout the city boundaries. The Quequechan River flows from east to west dividing the city as it drains South Watuppa Pond into Mount Hope Bay. The western section of the river has, unfortunately, been engineered underground.
The city's topography has played a key role in land development patterns in Fall River. The present heart of the city was the site of the falls of the Quequechan River, giving the name "falling river", now Fall River. Early roads were constructed in the valley north of this river and along the ridge paralleling the Taunton River. A street grid developed, despite steeply terraced slopes, with streets in some cases exceeding a 30% grade. The small lot, high-density residential development was the result of several factors, but primarily to enable industrial workers to reside within walking distance of the mills. Due to the high cost of excavating through the granite bedrock to provide for water and sewers, development was necessarily concentrated along the western slope near the surrounding area of trhe Central Business District.
There is significantly more information regarding surficial geology, soils, and groundwater characteristics in the eastern end of the city surrounding the Watuppa and Copicut Ponds than in the now entirely urbanized western section of Fall River along the Taunton River and Mount Hope Bay. In 1987 the city hired a consultant to prepare a Moratorium District Impact Study to evaluate the potential impacts on the city water supply from future development. This report compiled a large volume of information regarding the geology, hydrology and natural resources of the eastern end of Fall River. Surficial geology in that part of the City is summarized below.
Surficial Geology in the Watuppa and Copicut Watershed
Glacial till is a compact, unstratified mixture of silt, sand, gravel, cobbles, and boulders. The dense soil is nearly always either unsorted or poorly sorted. This means that there is no clear gradation of the soil by grain size, such as fine grading to coarse or vice-versa. It is deposited on bedrock in most areas and may occasionally include beds and lenses of poorly sorted, stratified gravel, sand, and silt. At the edges of the till near other types of deposits and locally within the till, a mantle of thin, sometimes stratified, deposits have been noted. These contain a mixture of gravel, sand, silt, and clay. Bedrock outcroppings have also been observed within the till areas, especially in the northern half of Fall River.
Kame delta deposits are also present in Fall River and are divided into three distinctive layers. The first unit encompasses the uppermost 15 to 20 feet,.It consists of well-sorted fine gravel and medium to coarse sand. The middle unit is slightly finer containing fine to coarse sand with some fine gravel. The lower unit is the finest having only fine sand, silt, and clay of variable thickness. The kame delta deposits are mostly laid down over till, but in a few localities they mantle sand and gravel deposits. Because of their configuration and the direction of ice movement, the deposits generally grade from coarse to fine grained from north to south.,
Kames typically contain fine to coarse gravel and fine to coarse sand. The sediments may be stratified, although the physical evidence may have been distorted or destroyed by settling. Outwash plains usually consist of beds of fine to coarse sand. The deposits may be loose or medium dense and may be stratified or uniform. Both types of deposits are usually well-sorted and tend to grade to finer sediments southward. Some beds or lenses of gravel, silt, and clay may also be present.
NORTH WATUPPA WATERSHED
The North Watuppa watershed includes North Watuppa Pond and its surroounding area bound by topographic high points. The wartershed includes Route 24 and Meridian Street to the West, the Fall River Corporate Boundary to the South, the Rattlesnake Brook Watershed to the north and northeast, and by the Bread and Cheese Brook Watershed to the southeast and the Copicut Watershed due east, the last two of which drain to the Westport River.
Within this watershed area nearly fifty percent of the land area is underlaid with glacial till. Two separate deposits of kame soils are distinguished on the geologic map. One is located at the southern city line adjacent to North Watuppa Pond. The other is the large area of kame deposits located towards the northern end of the watershed. It extends from the edge of North Watuppa Pond to the border with the Rattlesnake Brook Watershed. The kame delta deposit is located partly in this watershed but mostly in the Bread and Cheese Watershed. It lies northeast of the first and smaller kame deposit near North Watuppa Pond. A small deposit of outwash occupies Pond Swamp due north of and adjacent to North Watuppa Pond. The final material, sandy till, occupies the space between the outwash plain and the second and larger kame deposit. Like the kame, the sandy till deposit also extends from North Watuppa Pond to the border with the Rattlesnake Brook Watershed. The only bedrock outcroppings present in this area are located along the northwest side of North Watuppa Pond, outside of the moratorium district. In the order of abundance of soil types by surface area, the North Watuppa watershed breaks down as follows: most abundant are glacial till, kame deposits, sandy till, and outwash.
RATTLESNAKE BROOK WATERSHED
The Rattlesnake Brook Watershed includes much of the area of the Freetown-Fall River State Forest. This watershed is bounded by the North Watuppa Watershed to the south and west, the Copicut Watershed to the east, and the Fall River Corporate Boundary to the north. Unlike the other watersheds which drain south into coastal drainage basins, the Rattlesnake Watershed drains north into the Taunton River Basin.
Three surficial types have been distinguished within the Rattlesnake Watershed. Glacial till is overwhelmingly the most common. Bedrock outcrops are noted to be scattered all around the areas of till, and are not present within the other two soil types within the City of Fall River. A large deposit of sand lies north of the corporate boundary, but only a very small portion of it actually extends to within City bounds. This "small" deposit is believed to be outwash. The third soil type was previously referred to an an unclassified unit of sandy gravel. This deposit borders the deposit of sandy till and also a small portion of the large kame area, both of which are described within the section on the North Watuppa Watershed. The most abundant soil types by surface area in the Rattlesnake Watershed are glacial till and sandy gravel.
COPICUT RESERVOIR WATERSHED
The Copicut Reservoir Watershed is part of the larger Westport River coastal watershed and includes the Copicut Reservoir and its surrounding areas to the east, north and west. This watershed study area is bounded by the Fall River Corporate Boundary to the north and south, the Shingle Island Watershed to the east, the Rattlesnake Watershed to the northwest, North Watuppa Watershed due west, and the Bread and Cheese Watershed to the southwest.
Three surficial types have been denoted within the Copicut Watershed, They are glacial till, kame deposits, and outwash plains. These materials are each associated with their characteristic landforms and general topography. The till areas occupy steep and elongated hills (drumlins) which are aligned north-south. These two separate hilly areas of till (including Copicut Hill) comprise more than half of the land surface within the watershed. The kame and outwash deposits alternate also in a north-south alignment between the till deposits and the north of the reservoir. Before the reservoir area was flooded, it too was a low, swampy flood plain for the Copicut River which was likely underlaid with outwash soils. The kame areas north of the reservoir still occupy relatively low ground but show a slightly pitted surface. The outwash plains between the kames appear to be even lower, flatter areas of swamp (including Copicut Swamp) or wetlands. The only bedrock outcrops noted within this watershed are located within the area of till north of Copicut Hill. The most abundant soil types by surface area in the Copicut reservoir watershed are glacial till and kame deposits.
SHINGLE ISLAND WATERSHED
The Shingle Island Watershed encompasses the easternmost section of Fall River. This watershed is bounded by the Fall River City Boundary to the north, east, and south, and the Copicut Watershed to the west. There are no actual streams within this section of the city, only two separate wetland areas. The Shingle Island River formally begins in Freetown, MA. but is located mostly within Dartmouth, MA. draining to Lake Noquochoke at the head of the East Branch of the Westport River.
One single surficial type makes up the entire study area. Glacial till is noted as covering all of the Shingle Island Watershed within the City of Fall River. No outcrops of bedrock are noted on the geologic maps within the watershed.
BEDROCK
All sources of reference indicate that the east end of Fall River in the areas surrounding the Watuppa and Copicut is underlaid chiefly with granite rocks. Specifically, Dedham Quartz Monzonite is the most common type of rock bordering the Narragansett Basin, located to the west, within Massachusetts. The Barefoot Hill Quartz Monzonite is the second most common rock bordering the Narragansett Basin. The Barefoot Hill variety is considered a porphyritic equivalent of the Dedham Granodiorite, which may also occur within the area. The porphyritic variety refers to a textural term for rocks within different crystal sizes. General (unnamed) granite has also been identified in some U.S. Geological Survey wells in both Rattlesnake Brook and North Watuppa watersheds.
All three rock classifications mentioned, granite, monzonite, and grandiorite, fall into the same "family" of rocks. They are all silica-rich rocks composed of quartz and potash feldspar, with or without plaglioclase feldspar. Simply stated, this means that they all possess roughly the same properties, but may vary in physical appearance. They are usually very hard rocks that are not easily weathered. They may contain joints and fractures. These could be limited only to the surface or may extend in a complex network for miles. Outcroppings of the rocks usually occur on hills, knolls or cliffs within the areas of glacial till. Isolated instances of U.S.G.S. well information shows three bedrock refusals in each of two watershed areas. The well and boring data from the North Watuppa Watershed provided three depths to bedrock as follows: four feet, 22 feet, and 32 feet. The three bedrock depths in the Copicut Watershed were as follows: eight feet, 22 feet, and 24 feet. It is important to remember that these are six isolated examples. (Moratorium Study)
In general, the soil profile of Fall River is characterized by a mix of moist textured, rough and stony, nearly level to moderately steep soil occurrences. Predominant soil associations in Fall River are Paxton-Woodbridge-Whitman and Paxton-Woodbridge-Ridgebury, with large areas of Freetown Muck occurring east of North Watuppa Pond, along with other soils of lesser extent.
Because of the dense urban development and recreational use of land west of the North Watuppa Pond, soils have been so disturbed that any identification of soil types in this part of the city would be extremely difficult. East of the North Watuppa Pond, however, approximately one-half of the total acreage of Fall River lies in primarily undeveloped areas of forest, swamp, and watershed lands. Herein, soil types are much more easily identified in that very little has occurred to disturb the land.
The following is a narrative description of predominant soil types found in East Fall River (east of North Watuppa Pond). More detailed information on the soil types common to Fall River can be found in the 1981 "Soil Survey of Bristol County, Massachusetts, Southern Part"by the USDA Soil Conservation Service.)
Freetown muck(Fm)--This soil is nearly level, deep and very poorly-drained. This soil occurs in areas ranging from 4 to 500 acres in size, the average occurrence being about 20 acres. The upper part of this soil is characterized by about 2 inches of reddish-brown mucky peat. The next part of this soil is darker reddish-brown to almost black, mucky, and occurs to depths of 5 feet or more. In the eastern part of Fall River, this soil type is found in the Copicut Swamp area. A predominant characteristic of this soil is a high water table, at or near the surface most of the year. This high water table, along with the low strength of the soil, are the main limitations for construction, septic tanks, and community development in general.
Paxton(PhB)--Extremely stony fine sandy loam, 0 to 8 percent slopes. This soil is nearly level to gently sloping, deep, and well-drained. It is found on the tops and sides of ridges and hills. Approximately 3 to 15 percent of the surface is covered by stones and boulders. This soil occurs in irregular shapes and ranges from 10 to 1,000 acres in size; 300 acres is the average size of occurrence. The surface layer is typically 2 inches of very dark, grayish-brown, fine sandy loam. The subsoil is 20 inches thick, fine sandy loam. The substratum is very firm, brittle, gravely, sandy loam to a depth of 5 feet or more. The permeability of this particular Paxton soil is moderate in the surface layer and subsoil, and slow in the substratum.
This soil is found mainly in woodland areas. Stones, boulders, and a seasonal perched water table are the main impediments to community or agricultural development and especially as a building site for sanitary landfills. The slow permeability of the substratum is a limitation for septic tank absorption fields.
Paxton(PhC)-- Extremely stony fine sandy loam, 8 to 15 percent slopes. This soil is moderately sloping, deep and well-drained. It is on the sides of ridges and hills. Stones and boulders cover 3 to 15 percent of the surface. This soil occurs in irregularly-shaped areas ranging from 10 to 500 acres; 150 acres is the average size of occurrence. The surface layer is typically 2 inches of very dark, grayish-brown, fine, sandy loam. The subsoil is 20 inches thick, fine sandy loam. The substratum is pale olive, very firm, brittle, gravely sandy loam to a depth of 5 feet or more.
The permeability of this particular Paxton soil is moderate in the surface layer and subsoil, and slow or very slow in the substratum. Available water capacity is moderate, and during or after rainy periods a water table is often between depths of 16 to 22 inches. This soil is found mainly in woodland areas. Stones, boulders, a seasonal perched water table, and slope are the main limitations of this soil for community or agricultural development. These characteristics especially make this soil unenviable for building sites or as a site for a sanitary landfill. Slow permeability in the substratum is an additional limitation for septic tanks.
Ridgebury(ReA,ReB)--Extremely fine sandy loam, 0 to 3 percent (ReA) and 3 to 8 percent (ReB) slopes. This soil is deep, nearly level, somewhat poorly to poorly-drained. This soil is found in depressions and drainageways. Stones and boulders commonly cover 3 to 15 percent of the surface associated with this soil. Areas of this soil occur in irregular shapes, and range from 5 acres to 300 acres, the average occurrence being about 50 acres. Most areas of this soil are found in woodland. Typically, the surface layer is black fine sandy loam, about 7 inches thick. The subsoil is mottled, and is 22 inches thick. The substratum is light olive gray, mottled, very firm sandy loam to a depth of 5 feet or more. The permeability of the Ridgebury soil is moderate or moderately rapid in the surface layer and subsoil, and slow or very slow in the substratum. A seasonal high water table is at or near the surface in both winter and spring. The seasonal high water table and stony surface make this soil poorly suited to agricultural development.
Although some areas of this soil are used for homesites and other community development, the seasonal high water table poses some practical limitations, especially as a building site and as a site for septic tank absorption fields and sanitary landfills. The slow permeability in the substratum is an additional limitation for septic tanks.
Whitman(WhA)--Extremely stony fine sandy loam, 0 to 3 percent slopes. This soil is nearly level, deep and very poorly-drained. It id found in depressions and in low-lying areas adjacent to drainageways. Stones and boulders cover 3 to 15 percent of the surface associated with this soil. Areas of this soil occur in irregular shapes and range from 5 to 750 acres in size, the average occurrence being 200 acres. Typically, the upper layers of this soil consist of 1 inch of matted organic material over 5 inches of black muck. The subsoil is gray fine sandy loam, 15 inches thick. The substratum is olive gray, firm, mottled sandy loam and silt loam to a depth of 5 feet or more.
The permeability of this Whitman soil is moderate or moderately rapid in the surface layer and subsoil and slow or very slow in the substratum. A seaasonal high water table is at or near the surface in the fall, winter, spring, and after periods of heavy rainfall. The seasonal high water table is the main limitation of this soil for community development, especially as a site for building, sanitary landfills, or septic tank absorption fields. The slow permeability in the substratum is an additional limitation for septic tanks.
Woodbridge(WtB)--Extremely stony fine sandy loam, 0 to 8 percent slopes. This soil is nearly level to gently sloping, deep, and moderately well-drained. It id found on the tops and sides of hills. Stones and boulders cover 3 to 15 percent of the surface associated with this soil. Areas of this soil occur in irregular shapes, and range from 5 to 200 acres, the average occurrence being 100 acres. Most areas of this soil are found in woodland. Typically, the surface layer is dark brown fine sandy loam about 4 inches thick. The subsoil is brown fine sandy loam and mottled gravely fine sandy loam, 23 inches thick. The substratum is light brownish-gray, very firm, mottled gravely sandy loam to a depth of 5 feet or more. The permeability of this Woodbridge soil is moderate in the surface layer and subsoil, and slow or very slow in the substratum. Available water capacity is moderate. The surface layer of this soil is friable. After prolonged periods of rain, a water table between depths of 20 and 27 inches is perched above the substratum.
Some areas of this soil are used for pasture, while a few are used for homesites or community development. Herein, the main limitations are stones, boulders, and a seasonal perched water table. These characteristics are especially limiting concerning the use of areas associated with this soil type for building sites, septic tank absorption fields, and sanitary landfills. The slow permeability in the substratum is also a limitation for septic tanks.
Source: SCS, Soil Survey, Bristol County, Massachusetts: Southern Part, 1981
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