3.0 Remedial Investigation/Feasibility Study (RI/FS)

3.0 Remedial Investigation/Feasibility Study(RI/FS):

The objectives of the site investigation as noted by the RI/FS were as follows:

§  Delineated the horizontal and vertical extent of soil contamination in Site soils, groundwater and river sediment

§  Delineate the horizontal and vertical extent of groundwater contamination

§  Identify and characterize potential sources (and types) of contamination

§  Gather information to evaluate remedial alternatives

§  Gather data to support a risk assessment and treatability studies

3.1 Workplan for the Remedial Investigation/Feasibility Study (RI/FS):

           

§  Subcontracting

·         Surveying for establishment of boundary lines, monuments for vertical and horizontal control, topographic survey, surveying sampling points in order to locate any utilities on-site, as well as location survey of on-site buildings/foundations, roads, fences, manholes etc.

·         Assigning a driller for soil sampling, and monitoring well installations, as well as for digging test pits at the landfills

·         Subcontract for sampling elevated pipe insulation

·         Electrical subcontract to ensure on-site transformers were not “live”

§  Mobilization and Demobilization

·         Locations for soil borings, surface soil samples, and groundwater monitoring wells

·         Field team operations management

§  Site Survey and Mapping

·         Develop a base map, for locations of wells, determining contamination distribution, and establishing a Site boundary, will also assist the field team in identifying swampy areas at sampling locations

§  Soil Sampling

·         Samples taken at depths from the surface to approximately 18 feet bgs (2 feet below the maximum estimated depth to the water table on site)

·         Data from previous sampling as well as from this (1989) testing will be used to assess soil contamination on Site, the purpose being to determine the extent of contamination vertically as well as horizontally

¨      Surface samples (0-2”); included 37 areas previously found to contain contamination, 3 off-site background locations, 13 proposed monitoring well locations, 10 off-site playground locations, and 4 deep soil boring locations, for a total of 67 locations

¨      Shallow subsurface (2-24”); included collection at the sample locations as surface samples, except playground samples will consist of 3 locations beneath the water tower and 1 sample (2-24”) obtained from the shallow cluster wells (MW18s and MW24s), for a total of 62 locations

¨      Deep (one sample approximately at water table and one from approximately 2 feet below the water table); included collection of 4 deep boring sites (DB1 to DB4), 8 sites designated for well clusters (MW5, MW8, MW18, and MW24), and 1 deep borehole location (MWD1), for a total of 17 locations.

·         Analysis included Target Compound List (TCL) and Petroleum Hydrocarbons.  In addition selected soil samples were also analyzed for cation exchange capacity, metal speciation, total organic carbon, and TCLP.  The more rigorous program of testing provides a greater degree of assurance that contaminants are present is detected. 

§  Hydrogeologic Program

·         Collected geologic and hydrologic data at the Site in order to define the stratigraphy and groundwater regime and to evaluate contaminant transport in order to determine remediation and remedial alternatives

·         Contaminants, if they were found in groundwater, were thought to be in the shallow unconfined aquifer system due to the presence of a shallow confining layer at the Site.  Therefore, vertical extent of potential groundwater contamination was not to be thought of high concern.

·         Hydrogeologic program also determined tidal effects on the water table, water table gradients, soil characterization, and provide a contour map allowing for the determination of groundwater flow on Site.

§  Groundwater Monitoring Well Installations        

·         Installation of 8 shallow, 4 well clusters, and 1 deep groundwater monitoring well, in addition to 17 pre-existing wells.

·         Boreholes were expected to penetrate clay at about 30 feet – this accomplished the following – clay is an excellent marker bed for correlation of stratigraphy, and the presence of the layer confirms lateral continuity of the clay layer, which is an important aquitard separating the unconfined aquifer from the lower aquifer.  Care was taken to prevent complete penetration of this layer, which could provide inter-aquifer communication.  Shallow wells will have a 15 foot screen extending approximately 5 feet above the water table as encountered during the boring process to 10 feet below it.  This would ensure that “floating” contaminants, such as oil, could be sampled within the wells. 

§  Groundwater Sampling

·         Determined whether contamination from the overlying soil has reached the unconfined aquifer and determine extent of any contaminant plume. 

Ø  MWD-1 – Evaluate the deeper aquifer below the Site

Ø  MW-18 – Well cluster, in an area of potential contaminants such as VOCs and metals

Ø  MW-19 – Located on the river side downgradient of a slag/fill area

Ø  MW-20 – Downgradient of one of the landfill areas

Ø  MW-21 – Downgradient of the baghouse dust pile

Ø  MW-22 – Between existing tanks and a residential area

Ø  MW-23 – Located near the trailer rehabilitation area, a potential source of VOCs

Ø  MW-24 and 25– Well cluster, river side downgradient of the sludge lagoons

Ø  MW-26 – Off-site, in an area up-gradient of the Site, installed to measure background water quality

Ø  MW-27 – Off-site, in an area influences by tidal fluctuations

·         Groundwater Shallow wells were analyzed for TCL (target compound list), total organic carbon (TOC), and total dissolved soils.  Deep wells were analyzed for TCL compounds only.  Monitoring wells were sampled two weeks after development. 

§  Off-site Groundwater Sampling

·         Allowed for evaluation of contamination off-site.  Five off-site monitoring wells were analyzed for TCL, TOC, and TDS.

§  Surface Water Sampling

·         Completed during REM II’s RI/FS

§  Sediment Sampling

·         Completed during REM II’s RI/FS.

§  Air Sampling

·         Assessment of type and magnitude of contaminants migrating off of the Site.  The Site history was reviewed and particulates containing heavy metals and Petroleum hydrocarbons were identified.  Gaseous contaminants included VOCs.  Air monitoring stations were designated around the borders of the Site in order to assess particulate transport. 

§  Source Sampling

·         6 potential contamination sources were investigated in order to chemically characterize the actual or potential threat to human health and the environment, as well as determine extent of contamination.  Those being transformers, tanker cars, chemical piles, compressed gas cylinders, baghouse dust piles and the on-site tank farm.

§  Building Sampling

·         4 wipe samples were collected from each of the 55 buildings on-site, totaling 220 samples. 

·         58 floor dust samples were taken from 22 buildings

·         30 water and 26 sludge/sediment samples were collected from sumps/pits

·         16 reside samples and 15 waste samples were collected from waste piles and equipment

§  Railroad Car Sampling

·         52 railroad cars were inspected and waste material within them were sampled

·         Cars which contained no waste material were characterized by collecting wipe samples from inside the walls

§  Tank Sampling

·         106 samples were collected from existing tanks.  If separate phases were found within the tanks, each phase was sampled.  Empty tanks were characterized by collecting wipe samples from the inside walls.

§  Pipe Insulation Sampling

·         200 pipe insulation material samples were collected throughout the Site.  The insulation material appeared to be asbestos, separated insulation materials were sampled in the field for asbestos containing material.

§  Sludge Lagoon Sampling

·         12 sludge samples were taken from the 2 existing (1989) lagoons, which were situated within the wastewater treatment plant.  6 samples from the lagoon from 3 different locations were taken at 2 different depths. 

§  Slag Pipe and Slag Sampling

·         5 slag pile samples, taken a few feet away from the river bank, were taken from 2 on-site slag piles

·         Slag samples were also taken from the western portion of the Site, which abuts the Delaware River.  A grid consisting of a layout of 200’x 200’ over a 20 acre plot was delegated, and 4 grab samples were taken from each grid.  Samples were analyzed for TCL metals and extractable petroleum hydrocarbons.

§  Landfill Sampling

·         20 samples were collected from the suspected landfill area.  Ten test pits were excavated to a depth of 5 feet across, and 2 samples were obtained from each pit.  If drums were encountered, operations ceased, the drum was removed, and contents were identified.

§  Settling/Flocculation Tank Sampling

·         6 water and 6 sludge samples were collected from the tanks of the wastewater treatment plant.  2 samples were also collected from two tanks, a chemical feed tank and a mixer tank, inside the wastewater control building.

§  Waste Disposal

·         All material generated from field investigations was containerized and stored on-site until final disposition was approved by the EPA.

3.2 Conclusions of the Remedial Investigation/Feasibility Study (RI/FS):

      The Site was spilt into 5 Operable Units (OU); OU-1 addressed the removal of drums, transformers, tanks, a baghouse dust pile, chemical piles, tires and contaminated park soils, OU-2 addressed contaminated playground soils, OU-3 addressed the cleanup of the slag area by way of installing a soil cap which will support a storm water management system, OU-4 addressed the removal and disposal of underground storage tanks (USTs), above-ground storage tanks (ASTs), pits, sumps, underground piping, process dust, friable asbestos abatement, decontamination and demolition of building, and restoration of the Main Gate House, and OU-5 addressed the contamination problems at the Site in regards to the site-wide soils, river and creek sediments and groundwater.  The Focused Feasibility Study was completed in July 1996.