COPA - PCBs and Superfund in Bloomington, Indiana

Subject: Estimate of Polychlorinated Biphenyl Mass Discharged to Conard's Branch Neal's Landfill, Monroe County, Indiana

February 23, 2001

From: TetraTech EM Inc.
200 E. Randolph Drive. Suite 4700
Chicago. IL 60601

To: Mr. Thomas Alcamo
Work Assignment Manager
U.S. Environmental Protection Agency Region
77 West Jackson Boulevard
Chicago, IL 60604

Dear Mr. Alcamo

As you requested, Tetra Tech EM Inc. (Tetra Tech) estimated the mass of polychlorinated biphenyls (PCB) discharged to Conard's Branch and in turn to Richland Creek downstream of the above- referenced site during storm events occurring within a 6-month period from June through December 2000.

Tetra Tech obtained the hydrograph information collected at Neal's Landfill by the U. S. Geological Survey (USGS) during the monitoring period and calculated the mass PCB released during the storm events. Tetra Tech's subcontractor, Earth Tech, has analyzed data collected during numerous storm events at Neal's Landfill in 1998 and 2000. Mr. John Bassett of Earth Tech has developed an equation based on linear regression analysis that correlates the PCB concentration to the volume of flow during the storm events. Tetra Tech used this equation to calculate the concentration of PCBs released during each hour of the storm events. Using the concentration of PCBs and the volume of flow during the time period of each storm event, the PCB mass released was calculated using the two equations presented below:

PCB concentration (microgram per liter [ug/L]) = -2.222l3 x 10⁰⁵ x flow rate (gallon per minute [gpm]) + 1.502

PCB mass released (gram [g] per hour) = PCB concentration (ug/L) x [ lg / 1 x 10⁰⁶ ug] x [1 L / 0.2642 gallon] x [60 minutes / l hour] x flow rate (gpm); or in shortened form without units: (PCB concentration / 264,200) x 60 x flow rate

To make the USGS data manageable, Tetra Tech analyzed the hydrograph information to identify 14 storm events generally having flow rates greater than 50 gpm. Tetra Tech used the 60-minute USGS flow data increments provided by Earth Tech as the flow volume for each hour of the storm events. Enclosure l contains a hydrograph identifying the 14 storm events during the June through December 2000 period. Enclosure 2 presents the PCB mass released during each hour of the following l4 storm event periods: 1. June 17, 2000
2. June 18, 2000
3. August 2 and 3, 2000
4. August 7 and 8, 2000
5. August 18, 2000
6. September 4, 2000
7. September 10 through 15, 2000
8. September 20 and 21, 2000
9. September 24 through October 2, 2000
10.October 44 through 14, 2000
11. October 17 through 23, 2000
12. November 9 through 20, 2000
13. November 25 through December 4, 2000
14. December 11 and 12, 2000

The total PCB mass released during these storm event periods was calculated to be 261.18 grams. This amount of PCBs has been distributed throughout Conard's Branch and its confluence with Richland Creek downstream of the Neal's Landfill site.

The enclosed data indicates that except for the storm events of June 18 and August 18, 2000, the flow into Conard's Branch during each storm event exceeded the treatment plant capacity for at least some portion of the storm's duration. The storm events having the highest PCB mass releases occurred from September 10 through 15, September 24 through October 2, October ~ through 14, and November 9 through 20, 2000.

Sincerely,
V. Rajaram, Ph.D., P.E., CPG
Site Manager

Warning! Eat no fish from Clear Creek, Pleasant Run, Salt or Richland Creeks.
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