The WPSC Two Rivers MGP Site located at 200 21^st Street, encompasses approximately 4-acres.  Features include historic concrete building foundations.  A chain link fence secures the Site perimeter.  A wetland exists in the center and western portion of the property (approximately 2 acres).  Large portions of the Site east of the wetland are covered in crushed stone and asphalt.  The vegetation in the wetland consists of a fringe scrub-shrub on the eastern edge of the wetland dominated by aspen and dogwood.  Emergent and wet meadow species such as green bulrush and horsetail are located closer to the bank of the West Twin River.

 The Site has elevations ranging from approximately 579 feet (MSL) to 584 feet MSL.  Surface water drainage flows overland to the West Twin River.  The majority of the Site is within the 100-year flood zone as mapped by Federal Emergency Management Agency (FEMA, 2011).

The approximately 4-acre Site is located on vacant land between 22^nd Street and School Street in Two Rivers, Manitowoc County, Wisconsin.  

·         2022 School Street to the south, owned by Manitowoc County

·         School Street right-of-way and the following private properties to the east:

o   2100 School Street

o   2104 School Street

o   2110 School Street

o   1913 22^nd Street

·         1926 22^nd Street to the north, owned by the US Oil Company, Inc.

The high levels of hazardous substances in surface and sub-surface soil at concentrations that exceed U.S. Environmental Protection Agency Removal Management Levels (RMLs) and the Wisconsin Department of Natural Resources (WDNR) Removal Action Levels (RALs), the Site’s plans for future construction, the potential of exposure to children trespassers and the industrial/commercial use of nearby property requires that this action be classified as a time-critical removal.  Analytical results from historical samples in the proposed removal areas indicate the presence of elevated concentrations of polynuclear aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) in the DNAPL present in both the surface and subsurface.  In particular, this past data indicates the presence of TCLP benzene concentrations exceeding 0.5 mg/l in addition to concentrations exceeding the 340 mg/kg RML.  Depth to groundwater in the area varies from 2-5 feet below ground surface.  Groundwater flows east toward Lake Michigan and organics contained in the DNAPL, may leach into the groundwater and migrate to Lake Michigan. 

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results

Previous actions at the Site include a 1986 Phase 1 Investigation performed by EDI Engineering and Science, Inc. and the 1994 Phase II Investigation performed by NRT.  NRT performed the Phase II Addendum Investigation in 1996, a Pre-Remedial Design Site Investigation in 2003, and annual Groundwater Quality Data Transmittals from 2005 through 2013.

Contaminants such as VOCs, specifically benzene, toluene, ethylbenzene, and xylene ('BTEX"), PAHs, metals, and cyanide were detected in sediment, soil and groundwater samples collected in various locations at the WPSC Two Rivers MGP Site as summarized by Natural Resource Technology Inc. ('NRT"), on behalf of WPSC, in the 1994 Phase II Investigation and 1996 Phase II Addendum Investigation.  Concentrations ranges are as follows:  BETX detected above Wisconsin Action Concentrations ("WAC") NR 720 Residual Contaminant Levels values; total PAHs at surface and subsurface ranging from 0-616 ppm; groundwater samples with BETX, cyanide, cadmium, lead detected in some instances above WAC NR 140 Enforcement Standards.

NRT conducted a pre-remedial design investigation during development of a Remedial Action Options Report in 2003 (NRT, 2003), the RAOR is included as Appendix A. Soil samples collected in August 2003 from test pits in the vicinity of the former MGP structures were generally unsaturated to moist and contained large amounts of fill material (ash/cinders, wood, brick, etc.). Soil samples collected from test pits and soil borings west of the former MGP structures were generally saturated and represent the intervals exhibiting potential MGP impacts based on visual and/or olfactory observations or elevated PID measurements. Emulsified coal tar was observed in soil borings and test pits generally located within and to the west of the wetland area. Beneath a majority of the Site, a clay layer was present between 4 and 7 feet bgs and extends to the bottom of the piezometer borings (25 to 30 feet bgs).

Analytical results of soil sampling indicated the following contaminant distribution trends:

■        Off‑property soils to the north were not impacted by benzene and naphthalene.

■        Analytical results of off‑property soils to the south indicated benzene and naphthalene concentrations above the generic groundwater pathway NR720 RCLs, in effect at the time.

Site soils are generally above the NR720 standards for benzene and naphthalene at low levels across the Site. Concentrations are significantly higher at select locations where coal tar was observed to occur within the soil matrix. 
 

The PRP shall implement the EPA approved Removal Action Work Plan for WPSC Site, dated February 24, 2014.  The main components of the work plan include the following provisions which require compliance:

a)  Preliminary activities such as site security and controls.

b)  Site preparation, including clearing and grubbing.

c)  Targeted excavation within defined removal areas A, B and C.

d)  Transportation and off-site disposal of excavated material from areas A, B and C.

e)  In-Situ Solidification/Stabilization construction and operations in area B and C.  ISS

      solidified material will remain on-site until future land use requires removal

       and disposal.

f)  Backfilling with excess swell material and/or clean fill.

g)  Compliance with State and Local requirements.

h)  Construction Quality Assurance Measures such as

            -  Air Monitoring

            -  Fugitive Emission Management Plan

            -  Health and Safety Plan

            -  Sampling and Analysis Plan

            -  ISS Construction Quality Assurance Plan

i)  Schedule for Completion.

j)  Submission of Weekly and Final Reports.

k)  Take any other response actions to address any release or threatened release of a

      hazardous substance, pollutant or contaminant that the EPA OSC determines

      may pose an imminent and substantial endangerment to public health or the

      environment.