Litwiller, T. and J. Ruselink.
10th International Conference on the Remediation and Management of Contaminated Sediments, 11-14 February, New Orleans, Louisiana, 21 slides, 2019

Pleasant Run Creek (PRC) is an urban stream that bisects an 87-acre former manufactured gas plant where past operations left the creek contaminated with coal tar and petroleum up to 20 ft below the creek bottom. Utilizing results from qualitative and quantitative sampling, a remedial approach was designed to mitigate potential ecological risk, including sediment removal, sediment isolation, and free product capture from upland groundwater. A geosynthetic clay liner (GCL) was chosen to remediate the creek bottom due to its isolation ability, constructability, uniform thickness upon application, and long-term viability. The project included diverting the PRC with a pump-around system and temporary dam to remove >40,000 tons of sediment in "dry" conditions and installing >220,000 ft² of GCL in shingled, overlapping sheets to achieve isolation between remaining impacted sediment and surface water. Features of the project's natural restoration design included pools, riffles, flood-prone benches, and boulder cross vanes to enhance the biological function of the on-site reach of PRC and provide long-term stability based upon shear stresses. The GCL included a polypropylene geofilm coating to yield a hydraulic conductivity of 5x10^-10 cm/s while providing increased internal shear strength in steep slope and lower load applications and bedding layers of structured backfill installed above and below the GCL to protect against punctures while adding overburden pressure. The use of the GCL resulted in a consistent application and higher confidence in uniform hydraulic conductivity and transmissivity. Longer abstract: https://www.battelle.org/docs/default-source/conference-proceedings/2019-sediments-conference-proceedings/a3.-remediation-of-urban-waterways/143.pdf?sfvrsn=1bc46e79_2 Slides: https://www.battelle.org/docs/default-source/conference-proceedings/2019-sediments-conference-proceedings/a3.-remediation-of-urban-waterways/a3_1350_-143_litwiller.pdf?sfvrsn=41512924_2 For more information on the PRC Watershed Management Plan, see https://www.in.gov/idem/nps/3875.htm