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SVM Project List SEPTA | |
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5.7 WATER RESOURCESThis section contains information on groundwater, surface water, drinking water supplies and floodplains/floodways. This section is closely related to the Natural Resources and Ecosystems (Section 5.6). All wetlands data are contained in the Natural Resources and Ecosystems Section. 5.7.1 REGULATORY SETTING
5.7.2 METHODOLOGYData regarding groundwater and surface water conditions, and groundwater wells and surface water supply intakes in the study area were obtained from publications and on-line geographical information system and tabular system databases, as available. Information sources included contacts with private and public water suppliers, PA inventory of Public/Private wells, U.S. Geological Survey (USGS), Federal Emergency Management Agency (FEMA), PA Geological Survey (PGS), Pennsylvania Department of Natural Resources (PADNR), Pennsylvania Department of Environmental Protection (PADEP), U.S. Coast Guard, and Delaware River Basin Commission (DRBC). Findings were placed on mapping prepared for the project study corridor.Data regarding floodplains and floodways for the Schuylkill River and its tributaries were obtained from the 100-year and 500-year floodplain boundaries and 100-year floodway boundaries provided on Flood Insurance Rate Maps (FIRM) and Flood Boundary and Floodway Maps (FBFM), respectively. These maps were obtained on a CD-ROM from FEMA and downloaded into the project's GIS database and the project's CADD mapping. Flood Insurance Study reports for several municipalities were reviewed. Existing alignment and station areas were reviewed with respect to inundation during a 100-year flood. The build alternative alignments and station area footprints were reviewed with respect to potential encroachment within the 100-year floodway and 100-year floodplain. 5.7.3 AFFECTED ENVIRONMENTGroundwaterThe relative importance of the geologic formations present in the project area as water supply aquifers is summarized in Exhibit 5.7-1 Groundwater, Wells, Surface Water Intakes, and Sinkhole-Prone Areas [PDF]. Registered water supply wells in the vicinity of the alignment are shown in Exhibit 5.7-1 Groundwater, Wells, Surface Water Intakes, and Sinkhole-Prone Areas [PDF]. There is only one registered supply well down gradient from the alignment. Single home residential wells are typically not registered. Unregistered wells down gradient from the alignment are present in the Mont Clare section of Upper Providence Township, the Linfield area of Limerick Township, and in the Monocacy Creek area of Amity Township. Recharge of regional aquifers from precipitation generally is confined to upland areas. With the exception of recharge to shallow alluvial sediments within the floodplain, areas close to large rivers, such as the Schuylkill River, are typically groundwater discharge zones. Groundwater in areas underlain by fractured bedrock, such as the project area, is present in the fractures within the bedrock below the water table. Groundwater flows from areas of higher elevation to areas of lower elevation and discharges to streams and rivers, which are at the lowest elevation in a watershed. Between storm runoff events, most or all of the water within a stream channel is from groundwater discharging into the channel (or an upstream tributary stream channel). Groundwater can, under the appropriate hydrologic, topographic, and geologic conditions, discharge to wetlands. Surface Water The entire project area is within the Schuylkill River watershed. Streams crossed by the alignment are presented in Exhibit 5.7-2 Waterbodies Crossing or Adjacent to Alignment [PDF]. Exhibit 5.7-3 Stream Crossings and Floodplains [PDF] lists the stream crossings. Exhibit 5.7-4 Stream Crossings and Floodplains - Station Areas [PDF] show areas at and near stations. The Schuylkill River is a major tributary of the Delaware River and estuary. The mean daily flows at Reading and Philadelphia are 884 cubic feet per second (cfs) and 1660 cfs, respectively. The alignment generally parallels the course of the Schuylkill River from Reading to Philadelphia. The existing Norfolk Southern and SEPTA R6 Norristown alignments are generally positioned at the outer edge of the floodplain flanking the river. With a few exceptions, the alignment is generally within a thousand feet or less of the river. The Schuylkill River and its tributaries provide drinking water for approximately 1.2 million people. Water supply intakes within the corridor area are shown on Exhibit 5.7-1 Groundwater, Wells, Surface Water Intakes, and Sinkhole-Prone Areas [PDF]. Water from the Schuylkill River is also extracted for commercial, industrial, fossil fuel and nuclear thermoelectric power, and mining uses. Historically, the Schuylkill River was one of the most polluted rivers in the state. It received poorly treated or untreated industrial and domestic wastewater, and wastewater and sediments associated with upriver coal mining and washing operations. Considerable improvement in Schuylkill River water quality has been achieved over the last 50 years as a result of dredging of coal sediments from the riverbed and major advances in industrial and municipal wastewater treatment in watershed communities. Recreational uses of the Schuylkill River within the project area include: boating - canoes, kayaks, racing shells and powerboats; water-skiing; and fishing. The Schuylkill River within the project area is a Pennsylvania Scenic River. The river has been nominated for designation as an American Heritage River. Within the project area, the Schuylkill River has the following classifications:
No waterways within the SVM study area are classified Wild or Scenic. As described in Section 5.6.2, Valley Creek, which the alignment crosses in Valley Forge National Historic Park, is a Class A Wild Trout Stream. The alignment crosses or parallels numerous streams between Wyomissing and Philadelphia. The larger streams include Monocacy Creek, Manatawny Creek, Sprogles Run, French Creek, Valley Creek, and Wissahickon Creek. The locations of these and other streams crossed by the alignment are shown on Exhibit 5.7-2 Waterbodies Crossing or Adjacent to Alignment [PDF]. The alignment crosses 45 streams with drainage areas greater than 1.5 square kilometers (km2) and 10 streams with drainage areas greater than 0.4 km2, but less than 1.5 km2. (1.5 km2 and 0.4 km2 are threshold drainage areas triggering Pennsylvania Chapter 105/106 regulations for water obstruction permits.) The alignment crosses the great majority of these streams near their downstream terminus at the Schuylkill River. Floodplains The geographic relationship between the existing alignment and the 100-year and 500-year floodplain and the 100-year floodway is shown in Exhibit 5.7-3 Stream Crossings and Floodplains [PDF]. West of Norristown, the alignment trackbed is above the elevation of the Schuylkill River's 100-year flood. In this area the alignment trackbed is within the 100-year floodplain where the alignment crosses the floodplains of the larger tributaries. The edge of the 100-year floodway is frequently touching the alignment's berm shoulder. At no place west of Norristown is the existing alignment trackbed within the 100-year floodway. At several locations, such as Manatawny Creek (west of the Pottstown Station) and at the Schuylkill River crossings, the alignment crosses over the 100-year floodway. The area proposed for the Perkiomen Junction station and parking lot is within the 100-year floodplain. The areas proposed for Phoenixville Station parking lot and a portion of the Pottstown Station parking lot are within the 100-year floodplain. East of Norristown, SEPTA's existing R6 alignment is within the 100-year floodplain for most of the alignment between Norristown and Miquon. The alignment is within the 100-year floodway in the vicinity of Spring Mill and Miquon. Three existing SEPTA R6 stations, Conshohocken, Spring Mill, and Miquon, are within the 100-year floodplain. During the September 1999 flood associated with Tropical Storm Floyd, flood waters from Plymouth Creek and the Schuylkill River converged near the Conshohocken station causing the flooding of tracks and the stranding of a Norristown R6 Regional Rail train with passengers and crew aboard. Tracks were also inundated in the vicinity of Spring Mill and Miquon stations. The Schuylkill River floodplain between Reading and Upper Merion was inundated, however Norfolk Southern reported no loss of service during the flood event. The flood has been preliminarily rated as approximately the 10-year flood event at Pottstown and the 25-year flood event at Philadelphia. Flooding on some of the larger tributary streams in the eastern portion of the project area (e.g., Valley Creek and Wissahickon Creek) exceeded the 100-year event. Plymouth Creek is within this area and may have incurred flooding of a similar frequency to these streams. 5.7.4 ENVIRONMENTAL CONSEQUENCES (IMPACTS)GroundwaterConstruction activities, if not properly managed, could result in groundwater contamination. Construction activities would be short-lived and will be in areas that do not serve to recharge regional groundwater. The build alternatives would utilize active freight and commuter railroad alignments. Threats to groundwater quality during operation would not be substantially greater than for existing conditions. Reduction in groundwater infiltration will occur due to new station parking lots. Watershed impacts are modest due to the location of the stations in lower areas of the watershed. Surface Water Project construction and operation would have no measurable negative impact on surface water quantity during low flow conditions in the Schuylkill River or its tributaries. Due to the present use of the rail corridor for diesel powered locomotives transporting a mix of freight including petroleum products and other chemicals, the potential threat to public water supply intakes from spills and other pollution incidents would not be more than marginally greater with this project. The impact on water quality under the No-Build Alternative would be from non-point source contaminants (e.g. petroleum fuels and lubricants) from automobiles and buses. These pollutants would increase over time in proportion to the increase in automobile traffic associated with not constructing a transit system. These pollutants could be washed into local drainage areas through surface runoff. The impact on water quality from the TSM Alternative would result in short-term erosion and sedimentation impacts from the construction of the SEPTA R6 extension to Port Kennedy, park-and-ride facilities, and increased water runoff from paved areas and increased non-point source contaminants from automobiles and buses. Sediment and pollutants would be washed into local drainage areas through surface runoff, increasing the total suspended solids and chemical concentrations. The impacts are not, however, expected to be significant. The potential impacts on the water quality for the build alternatives construction and operation are the same as those for the TSM Alternative: short-term erosion and sedimentation, increased water runoff from paved parking areas and modest increased non-point source contaminants from paved areas and the railroad trackbed. Railroad bed pollutants, which have the potential to affect water quality, include lubrication oils, rust protection materials, antifreeze, window washing fluid and particulates of carbon, metals and brake linings. These pollutants will be deposited in low concentrations in the railroad bed. These pollutants could impact the water quality through surface water run-off at watercourse crossings and other locations where the alignment is adjacent to watercourses. Herbicide applications along the alignment right-of-way will be required as part of ordinary railroad maintenance operations. Herbicides could impact the water quality through surface water run-off. These impacts are not expected to be significant, particularly in light of the existing use of the alignment for freight trains or commuter train service. Floodplains The project build alternatives footprint was developed with knowledge of the position of the existing Norfolk Southern and SEPTA R6 alignments with respect to the floodplain and the 100-year floodway. West of Norristown, where the footprint used for the impact analysis is generally wider than the existing alignment, widening was nearly always made on the side of the alignment away from the Schuylkill River. This guidance was included in the basis for design for the following reasons:
The footprint at most stream and river crossings is wider than the embankment and trackbed of the existing alignment. This may result in fill being placed in some areas mapped as floodway (for example, at Barbadoes Island, immediately west of Norristown). As all bridge widening and rebuilding will maintain hydraulic openings having no less capacity than the structures' existing openings, no actual impact to upstream floodway areas and flood elevations are expected at the bridge locations. There are no new stream, floodway or floodplain crossings. There are locations west of Norristown where the 100-year floodplain includes areas on the side of the alignment opposite the river. This is due to backwater from the river flowing up tributary stream channels, under bridges and culverts, and subsequently spreading out into the adjacent low-lying areas. Footprint widening and filling in these areas will not cause upstream flood elevations to rise on either the Schuylkill River or the tributaries, as these potentially filled areas are already ineffective in conveying floodwater flow. East of Norristown there is no new project footprint in effective flow floodplain areas, except immediately east of the Norristown station; the alignment plan and profile will be the same as current. (The footprint widening east of the Norristown Station will be north of the current alignment in an area of ineffective flood flow.) Operational issues during infrequent flood events will be the same as under current operating conditions. There will be times when the track between Norristown and Miquon will not be operational. The areas most susceptible to flooding are the areas near Plymouth Creek (west of the Conshohocken Station) and Mill Creek adjacent to the Spring Mill Station. Flooding in these areas causing service disruption will have approximately 10 percent chance of occurring in any given year. No new flood related impacts are associated with the No-Build Alternative. Impacts associated with the TSM Alternative would include the above-noted potential impact east of Henderson Road. None of the new TSM park and ride facilities are in the 100-year floodplain. 5.7.5 MITIGATION5.7.5.1 NO-BUILD ALTERNATIVENo mitigation is required since there are no significant water quality impacts associated with the No-Build Alternative.5.7.5.2 TSM AND BUILD ALTERNATIVESGeneralIn addition to mitigation controls discussed below, the following measures for railroad bed pollutants and herbicide applications could be taken. An operational plan for herbicide application and an overall vegetative management plan would be developed. Herbicide applications could be restricted to areas outside of the primary recharge areas for public drinking water supplies, private water supply wells, standing water, watercourses, wetlands, agricultural and residential areas. In these restricted areas, vegetation could be manually controlled. Where watercourses and drainage ditches have eroded parts of the right-of-way, the drainage channels will be repaired and the watercourses will be rechannelled. Retaining walls will be used to control erosion caused by the watercourses. Where appropriate, watercourse flow velocities could be regulated by the use of riprap, energy dissipaters, and vegetation. Surface Water Resources Various engineering controls would be used to minimize the water quality impacts during construction and operational activities. An erosion and sedimentation control plan would be developed that would employ design and construction methods to minimize erosion and intercept material before discharge to streams. The plan would be incorporated into all construction activities and erosion and siltation barriers would be positioned to prevent erosion and other materials from entering the watercourses. Construction activities in sensitive areas could be scheduled during drier seasons to reduce the impacts of sedimentation. A Storm Water Pollution Prevention Plan (SWPPP) would be developed and implemented in compliance with the National Pollutant Discharge Elimination System (NPDES) permit for construction activities. A general permit would authorize discharges from a number of sources. Coordination with the county conservation districts and the individual municipalities would occur to ensure that the drainage and operation plans are consistent with existing NPDES permit and municipal requirements for urban storm water runoff in the corridor. The process will require the development of a pollution prevention plan to identify the erosion and sediment controls that will be employed. These controls are "designed" after the assessment of the runoff potential from each area. Controls may include stabilization (temporary seeding, permanent seeding, mulching) or structural control measures (earthen dikes, silt fences, sediment traps, sediment basins). Where required by individual municipalities, on-site drainage features such as gravel infiltration beds, pervious landscaped areas and detention/retention basins would be incorporated into the design of the alignment and stations to eliminate pollutant discharge into the watercourses from water runoff and comply with storm water management requirements. No significant impacts to water quality at surface water supply intakes along the Schuylkill River are projected. Mitigation for the TSM Alternative will be the same as for the build alternatives. Engineering controls will be used to minimize the water quality impacts during construction and operational activities. Siltation barriers will be positioned to prevent erosion and other materials from entering the watercourses, and ground cover will be applied to disturbed soil areas. On-site drainage features will be incorporated into the design of the alignment and stations. The design measures will include diverting trackbed runoff through grassed waterways and buffer strips to collect sediment before discharge to receiving watercourses. Means for mitigating the increase in the quantity of storm water runoff associated with newly paved areas, particularly at stations/parking areas, will be developed on a site-by-site basis. All municipalities along the alignment have storm water management requirements in their codes and ordinances. The goals of these requirements are typically, that the peak rates of runoff after development are no greater than prior to development. These requirements can be met. Frequently used techniques for storm water quantity management include detention and retention ponds or swales and infiltration galleries beneath paved surfaces. Much of the SVM alignment is within watersheds for which PA Act 167 storm water plans are in the process of being developed. During the project's Preliminary Engineering phase, the project team will work with local municipal authorities so that the mitigation to be incorporated onto the design will be consistent with the watershed plans. Groundwater No significant impacts to groundwater quality and supplies are projected. The position of the majority of the alignment and footprint at the bottom of tributary watershed outside of headwaters areas mitigates against infiltration of contaminants into regional groundwater. Of the state registered wells situated within 500 feet of the alignment, all but one of them are upslope from the alignment. There are some homes between Exeter and Oaks downgrade from the alignment that have unregistered wells. Potential impacts to these wells must be viewed within the context of the existing freight traffic and the floodplain areas generally being groundwater discharge areas. Mitigation would be consistent with those described for surface water. Floodplains Floodplain impacts have been preemptively minimized by placing the project footprint on the side of the existing alignment opposite the Schuylkill River and by specifying that all bridge and culvert openings must have equal or greater hydraulic capacity than currently exist. Final design will be required to meet the codes and ordinances of each municipality with regard to floodplain development. The potential floodway impact noted west of the Douglassville Station in Amity Township should be able to be eliminated during design by use of either a steeper berm or retaining wall. The encroachment into the 100-year floodplain east of Henderson Road in Upper Merion Township should be evaluated using the HEC-2 flood profile hydraulics computer model developed by FEMA for the Flood Insurance Study for Upper Merion Township. A PA Chapter 105 permit will be required for any encroachment. State and local municipal requirements for building within the 100-year floodplain will need to be considered in the Chapter 105 permit application and local subdivision processes. Bridge and culvert openings requiring modification for streams draining 0.4 km2 or more will be subject to Chapter 105 permitting requirements. HEC-2 (or HEC-RAS) model analysis will be required as part of the application documentation. No changes in plan and profile are proposed for the SEPTA R6 alignment east of Norristown within the 100-year floodplain. Consideration might be given to improving the capacity of the Plymouth Creek and Spring Mill Creek bridges. Improvements at Plymouth Creek would need to be performed in concert with improvements to the downstream property, which is not owned by SEPTA. Raising the existing railbed east of Norristown above the 100-year flood would cause numerous impacts and has not been considered.
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