May 30, 2012

Scope of Work for Pump and Treat Test atBennett’s Dump

Introduction and Background

Analysis by CBS, presented to the parties in a December 14, 2011 meeting, has indicated that the passive drain installed at the Wedge complex may have reduced PCB mass loading at the downstream Stout’s Creek location by 50 to 80 percent from the pre-passive drain levels. The same analysis also indicated that Middle Spring and related discharges may account for as much as 30 to 50 percent of the remaining mass loading. CBS conducted a pump and treat test of MW-BC10 for a 30-day periodfrom March 6 through April 4, 2012 in order to see how much the PCB mass discharge might be affected at the Stout’s Creek downstream station. Despite an apparent reduction in MW-BC10 yield, an additional 30-50% reduction inPCB mass discharge at the Stout’s Creek Downstream station (SCD) was noted for this test.

In this SOW, CBS is proposing to rehabilitate MW-BC10, and repeat the test with the addition of pumping from well MW-B13. As noted in the Report of Results for the first test, MW-B13 had a yield of approximately 1 gpm and a PCB concentration of 28 µg/l.

If a storm event occurs during this test period, CBS will increase level monitoring in piezometers in an attempt to ascertain how much additional flow a storm event might contribute to a capture system.

A pump and treat system can then be evaluated as one of the remedial options remaining at the Bennett’s Dump site. This test isintended to be conducted while Middle Spring has a flow at a minimum of 2 gpm.

Scope of Work

  • Rehabilitate well MW-BC10 according to the procedure in Attachment 1.
  • Install cleaned and decontaminated submersible electric well pump nearthe bottom of MW-BC10 (pump to be capable of pumping up to 15 gpm).
  • Provide low-level cutoff or float controlat MW-BC10 to protect pump from running dry. Also provide rotary flow meter and throttling valve on discharge line from MW-BC10.
  • Install a submersible electric well pump near the bottom of MW-B13 (pump to be capable of pumping up to 5 gpm).
  • Provide low-level cutoff or float control at MW-B13 to protect pump from running dry. Also provide rotary flow meter and throttling valve on discharge line from MW-B13.
  • Install 500 gallon poly tank for intermediate storage of water to be treated.
  • Install mobile Granular Activated Carbon (GAC) treatment trailer capable of treating up to 15 gpm (~600 lbs of carbon). Trailer to be equipped with separate electric pump to transfer water from poly tank based on a level switch. Treatment trailer to utilize bag filters for pre-filtration.

Pre-Test Activities (Day of Test):

  • Take baseline PCB samples at Stout’s Creek upstream and downstream at the low detection limit (0.01 ppb) with staff reading, flow measurements and field parameters of temperature and conductivity.
  • Take baseline water levels at:
  • MW-BC10
  • MW-B13
  • PZ B1415
  • PZ CD1213
  • PZ B1213
  • PZ AB1112
  • PZ BC1112
  • PZ CD1112
  • PZ AB1011
  • PZ BC1011
  • PZ C1011
  • PZ CD1011
  • PZ B910
  • PZ BC910
  • PZ CD910
  • PZ AB89
  • PZ BC89
  • PZ CD89
  • PZ B67
  • PZ CD67
  • Take baseline PCB sample and flow measurement at Middle Spring.
  • Take baseline PCB sample and visual flow estimated at Rusty Spring.

Begin the Test:

Begin pumping from MW-BC10 and MW-B13at maximum sustainable flow (likely 5-10 gpm for MW-BC10 and 1-3 gpm for MW-B13) and adjust pump flow rate as necessary via the throttling valves.

  • After startup, recordwell pump flow rate every 15 minutes for first hour, every 30 minutes for the next 3 hours, and then hourly for the next 8 hours. After the first 12 hours, record well pump flow rate 3 times daily.
  • Check on system 3 times per day to make adjustments, record data including flow measurements at Middle Spring, refuel generator, change bag filters, etc.
  • Take daily PCB samples at Stout’s Creek downstream and once a week samples at Stout’s Creek upstream at the low detection limit (0.01 ppb), with flow measurements and a staff gauge readingalong with field parameters of temperature and conductivity.
  • Take water levels at the following locations 24 hours after test start-up and thereafter three times a week:
  • MW-BC10
  • MW-B13
  • PZ B1415
  • PZ CD1213
  • PZ B1213
  • PZ AB1011
  • PZ BC1112
  • PZ CD1112
  • PZ AB1011
  • PZ BC1011
  • PZ C1011
  • PZ CD1011
  • PZ B910
  • PZ BC910
  • PZ CD910
  • PZ AB89
  • PZ BC89
  • PZ CD89
  • PZ B67
  • PZ CD67
  • Take a daily visual flow estimate at Middle and Rusty Spring and once a week PCB sample if flowing.
  • Take a PCB sample of each pump’s discharge individually 24 hours after test start-up, and thereafter once per week.
  • Take a PCB sample of treatment trailer effluentat startup and then weekly. The discharge standard will be 0.3 ppb.
  • Continue test for 15 days. At the end of 15 days, collect water level measurements and a Stout’s Creek Downstream sample.

Storm Event Monitoring

  • In the event of a storm, that is predicted to exceed 0.5 inches within a 4 hour period, take a round of water levels in the listed piezometers and wells and flow measurement/estimate of Middle and Rusty spring just prior to the onset of rain.
  • After rainfall has ceased take hourly water levels from the listed piezometers and flow measurement/estimate from Middle and Rusty spring (if not inundated)
  • Continue hourly measurements until pre-storm levels are reached, then revert back to previous schedule.
  • Evaluate results and issue a report. The report will address any issues related to interferences and quantitation of the PCB results in a consistent manner so all these data are comparable and comparison can be made to pre-test and pre-Remedy data.