Attachment C Hypothetical Scenario.docx

Solicitation W912DR-10-R-0107, Attachment C, PWS For CONUS Sample Task

Performance Work Statement CONUS Sample Task Hypothetical Scenario Investigative and Interim Remedial Measures at Landfill X

1.0 SITE BACKGROUND

Landfill X is a fictional 36-acre inactive landfill, located in Southeastern PA, which was in operation from the 1950’s through the mid-80’s. The bulk of the landfill was used for municipal solid waste; however, some industrial waste was known to have been received. The landfill was operated under a Pennsylvania Department of Environmental Resources (PADER) permit from the mid-70’s through its closure in the mid-80’s, after which a low permeability soil cap was constructed over the landfill. Incidences of groundwater contamination in the vicinity of the former landfill in the late-80’s were investigated by PADER and the USEPA, which resulted in the site becoming CERCLA listed as a NPL site in the late 90’s, with a Remedial Investigation (RI) completed in 2004. The landfill operators are no longer in business, and while the USEPA is seeking responsible parties from contributors to the landfill, the USACE has been directed to perform interim remedial measures to mitigate groundwater contamination. The interim remedial measures will be designed to be in service for up to two (2) years. The example problem scenario will assume access is provided to all previous investigative data performed by others, and it will be assumed these data are accurate.

The landfill is situated on unconsolidated glacial material, overlying a bedrock valley. The bedrock has low permeability, and acts as a hydraulic barrier to groundwater flow in the area of the landfill. Depth of unconsolidated overburden in the area of the landfill varies from 20-feet to 100-feet, and consists of variable mixtures of silt, clay, sand, gravel and cobble. A water table aquifer within the unconsolidated overburden is used locally for private and municipal water supply, and exhibits low to moderate hydraulic conductivity. The 2004 RI revealed groundwater contamination down-gradient of the Eastern Section of Landfill X in concentrations exceeding Federal and Pennsylvania Maximum Contaminant Levels (MCLs), including benzene, vinyl chloride, 1,1-dichloroethylene, and 1,2-dichloroethylene, with total volatile organic compounds (VOCs) detected ranging from below MCLs to 1000-ug/l (labeled “VOC Plume” on attached sample site drawing). Assume average concentrations of benzene within the plume are 200-ug/l.

The landfill comprises a total area of 36 acres, and is bisected by No-Name Creek, which flows to the south, and is a tributary to a PADEP classified High Quality Waters stream. The original landfill was located to the eastern side of the creek, reportedly placed over a compacted low permeability soil liner, and subsequently capped with a low permeability soil liner, which is now well vegetated. The eastern landfill encompasses a 16 acre area, and some portions of the cap are in poor condition. The landfill operation expanded to the western side of the creek, encompassing a 20 acre area. The western portion of the landfill was opened in the mid-70’s, and is underlain by a leachate collection system which drains to a lined lagoon, where collected leachate is pumped to the publically owned treatment works (POTW). The POTW has a 2-year moratorium on accepting applications for any additional influent streams.

2.0 EXAMPLE PROBLEM CONTRACTING BASIS

For the purpose of this example problem it will be assumed that the Contractor will be given a Task Order under this MAES contract with the performance objectives and standards detailed below. The contract will be firm fixed price as a Performance Based Contract (PBC). The PBC will require that the contractor perform all necessary environmental services required to meet the performance objectives and standards, including addressing any unforeseen environmental, scheduling, and/or regulatory issues, and assume all contractual liability and responsibility for the work.

3.0 SCOPE OF WORK

3.1 Groundwater Investigation

Groundwater contamination above MCLs has been identified along the southern boundary of the Eastern Section of Landfill X, adjacent to No-Name Creek, in 8 of 12 existing monitoring wells, with three wells exhibiting over 1000-ug/l total VOCs. The known plume extent covers an approximately 20 acre area outside the landfill boundary, roughly 1000-feet by 800-feet, and the down-gradient extent is no longer fully delineated. The 2004 RI included complete plume delineation, but a subsequent round of sampling in 2009 indicated the plume had migrated beyond the previously down-gradient monitoring wells. The subject area is an open grass covered field, owned by the local municipality (no significant access issues).

3.2 Interim Remediation

An interim remediation system is required to prevent further migration of the groundwater plume.

Based on hydrogeologic data reported in the 2004 RI report, it is known that in the subject area water table, aquifer depths average 45-feet below grade, with predominantly silty sand & gravel, depth to water averages 5-feet below grade, transmissivity is 15,000 gpd/ft, recovery well specific capacity is 1.0 gal/ft, and natural gradient is to the south at 0.003 ft/ft. Based on analyses conducted during the aquifer pumping tests, average influent VOC concentrations anticipated are 250-ug/l (including 50-ug/l benzene), and total iron concentration is 2.5-mg/l; all other water quality parameters are nominal. The interim remedial action should be designed to operate for two years, by which time it will be incorporated into a more permanent solution.

4.0 TECHNICAL APPROACH

41. Performance Objectives and Standards

1. Approved Project Management Plan (PMP) and Quality Assurance Surveillance Plan (QASP):

· Draft PMP and QASP within 20-days of Notice to Proceed (NTP)

· Final PMP and QASP within 10-days of Contracting Officer’s Representative (COR) comments on draft USACE approval of PMP and QASP by Contracting Officer’s Representative (COR)

4.2 Overall Technical Approach

Provide an overall technical approach for the task order, addressing each of the following:

1. Health and safety considerations

2. Regulatory considerations

3. Stakeholder considerations

4. Portions of work to be self performed and portions to be subcontracted

5. Labor hours by technical discipline for each major task

6. Any assumptions not provided above

4.3 Sample Problem Submittal

The Sample Technical Problem is a stand-alone submittal, separate from the Cost Evaluation. It should include the technical approach, project schedule and labor hours for each task of the sample problem.

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