Southside Chicago - PCE Remediation in Active Alley Brochure

Under contract to Malcolm Pirnie, TRS Group, Inc. (TRS) designed, installed and operated the ERH remediation sys-tem at this dry cleaner facility in an active alley behind a shopping mall. The goal of the remediation project was to reduce tetrachloroethene (PCE) concentrations in soil to less than 11 milligrams per kilogram (mg/kg). While site soil also contained other chlorinated volatile or-ganic compounds (CVOCs), PCE was the most prevalent contaminant. Soil sampling before and after heating showed that the ERH system surpassed every project goal, and average PCE concentrations within the treatment vol-ume were reduced by 99.996%.The treatment area was previously injected with Fenton's reagents (peroxide and soluble iron) and sodium permanga-nate for in situ chemical oxidation of PCE. Significant PCE rebound occurred following the oxidant injection. The property owner and consultant chose ERH for source area remediation to expedite the cleanup so redevelopment plans could proceed. The alley or fire lane was required to remain open to vehicle and pedestrian traffic during ERH. The ERH system was installed below grade in the active alley (see Figure 1) between a shopping mall and resi-dences. The system incorporated six electrodes and six horizontal vapor recovery (VR) wells to treat an area that measured 370 square feet. The treatment volume meas-ured approximately 343 cubic yards (yd3). The subsurface lithology consisted primarily of gravel, clay, silt and sand. Perched water was located at five feet below ground sur-face (ft bgs) and bedrock was encountered at 30-ft bgs. TRS Project Manager: Chris BlundySite Geology and Hydrology: Gravel, clay, silt, sand with bedrock at 30-ft bgs; perched water at 5-ft bgsTreatment Area Size, Volume, and Depth: 370 ft2; 343 yde; 31-ft bgsPre-ERH PCE Concentrations: 2,110 mg/kg average PCE in soilPost-ERH PCE Concentrations: 0.089 mg/kg average PCE in soilRemedial Goal(s): Reduce PCE in soil to less than 11 mg/kgActual Cleanup Achieved: 0.089 mg/kg average PCE in soil = 99.996% reductionPeriod of Performance: End of July 2007 to middle of October 2007Contract Terms: Standard Fixed Price RemediationProject SummaryBackground Site Characteristics & Design ParametersFigure 1. ERH operations in active alley behind shopping mall.TRS Contact InformationMr. David Fleming, (425) 396-4266 dfleming@thermalrs.comwww.thermalrs.comRemediation of PCE Belowgrade in an Active AlleySouthside Chicago, ILInstallation of six electrodes and one TMP to 31-ft bgs be-gan on June 5, 2007. Active subsurface heating extended from 5 to 30-ft bgs. Subsurface temperatures were meas-ured at a centrally located temperature monitoring point (TMP) containing six thermocouples spaced at 5-foot inter-vals through the heating interval. Public access on top of the electrode field remained unrestricted throughout the remediation. The footprint for the system was kept to a minimum by placing all the vapor recovery conveyance pip-ing and electrical conductors that transfer steam, water and energy from the treatment area to the equipment com-pound on the roof of the Parkview Plaza building. A security system was also included to restrict unauthorized access to the equipment compound and the ERH compo-nents on the roof.The ERH system operated for 2.5 months and applied a total of 183,669 kilowatt-hours (kWh) of energy to the sub-surface. This was approximately 25 percent less energy than was estimated during the design stages of the project as necessary to reach the site remediation goals. The re-sulting energy savings were subsequently passed on to the site owner. System Construction and OperationsProject ResultsThe goal of the remediation project was to reduce tetra-chloroethene (PCE) concentrations in treated soil to less than 11 milligrams per kilogram (mg/kg). The highest con-centration of PCE detected in the pre-ERH samples was 9,750 mg/kg. The average PCE concentration in the 14 pre-ERH soil samples was 2,110 mg/kg. The average PCE con-centration in the five post-ERH soil samples was 0.089 mg/kg. This represents a 99.996% reduction in average PCE concentrations from pre-heating to post-heating conditions.Average concentrations of other CVOCs such as TCE, VC and c-DCE prior to ERH treatment were at 39.8 mg/kg, 8.2 mg/kg and 176.4 mg/kg, respectively. Following ERH treat-ment, c-DCE and VC concentrations were reduced to below the detection limit of 0.005 mg/kg and the average TCE concentration was 0.008 mg/kg. At a minimum, this repre-sents a 99.9% reduction in the average concentrations of each of these CVOCs. Percent reductions are shown below in Figure 2.cis 1,2 DCEPCETCEVCpost-ERH Site Averagepre-ERH Site Average176,4622,110,05739,7748,2002.5 89.28.02.50500,0001,000,0001,500,0002,000,0002,500,000% Reduction99.999% 99.996%99.98% 99.97%Figure 2. CVOC Pre- and Post- ERHTotal CVOCs (ug/kg)