1. Ross MacNames Edward Jackson Samantha Quiroga

2.  Elevated levels of Polychlorinated Biphenyls (PCBs) found in sediment of the Little Brazos River 5-100 ppm  Overview: The Contaminant The Site Remediation Strategy Monitoring/Closing Expected Results

3.  Belong to a large family of man made organic chemicals known as chlorinated hydrocarbons  Widely used throughout much of the early 20 th century Banned in 1979  Common Sources: Transformers and capacitors Oil used in motors and hydraulic systems Fluorescent light ballasts Oil-based paint Plastics

4.  EPA’s First Assessment (1987) Data was limited, results were inconclusive  EPA Reassessment(1996) Peer-reviewed by 15 PCB experts Concluded PCB was a probable human carcinogen  Can also cause other serious health conditions  Immune system  Reproductive system  Nervous system

5.  Proven to cause cancer in animals  Very persistent in the environment Highly unreactive Resistant to breakdown by acids, bases, and heat  Is known to bio-accumulate, magnifying concentrations in higher levels of the food chain

7.  Approximately 1,000 ft. of affected riverbed Tributary leads to the Brazos River Approximately 5 miles upstream of confluence with the Brazos River  Section of tributary targeted is fairly shallow Less than 10 ft. deep  Fairly straight/contiguous section of river

8.  Detailed Overview 

9.  Tributary sediment is contaminated media 60-70% coarse material (sand and gravel)  Sediment characteristics fluctuate geographically IncreasesDecreases DepthMore clayMore sand/gravel FlowMore sand/gravelMore clay

10.  Source is unknown Variety of industrial facilities in the area  Energy Production  Automotive  Manufacturing  Previous site investigation has concluded no ongoing releases exist

11.  Direct Exposure Physical contact with sediment  i.e. swimming, wading, etc.  Indirect Exposure Ingestion of contaminated organisms  i.e. fish, shellfish, etc.

12.  Before Remediation may begin, areas of highest sediment contamination must be located  Sediment samples to be taken every 40 ft. Sampling should begin at the most downstream location  A more precisely targeted sampling regime is not feasible Lack of a known contaminant source

13.  Dredging will be used to bring contaminated sediment to the surface Small scale dredgers  Silt curtains will implemented Will reduce contaminant transportation offsite

14.  Soil washing is a technology that uses liquids and a mechanical process to scrub soils. Separates soils by particle size Concentrates contaminants into a smaller volume PCB’s preferentially bind to silt and clay soil fractions

15. ProductFate Clean Sand/Gravel Returned to site Contaminated Clay Fines Hazardous Waste Facility WashwaterOn Site Treatment and Re-use Fugitive Air Emissions Collection and Filtration

16.  Technology Characteristics Relatively low cost Transportable technology/On-site Provides a closed system  Site Characteristics PCBs as primary contaminant Large coarse particle fraction

17.  Should occur once cleanup has resulted in PCB levels meeting TCEQ standards Sediment – 7.1 ppm Surface water -.00064 ug/L  Monitoring to be performed using sediment samples at key tributary locations  Monitoring Phase 1 (during dredging) Sample daily Ensure PCB contamination is not re-suspended and carried offsite  As in Hudson River Dredging Project Moderate increases in concentration, adjacent to dredging will be acceptable  Monitoring Phase 2 (post-closure) Sample monthly Ensure PCB concentrations remain at acceptable levels

18.  PCB concentrations below applicable TCEQ standards  Little to no PCB transport offsite  Goals expected to be reached within one year of commencement of dredging  Remediation will be completed in a cost-effective manner