Past and current operations at former/active military bases and department of defense sites have included the manufacturing and production of equipment needed by the military and personnel housing the bases/facilities. Some of the daily activities, including degreasing operations, leaking of drums from storage areas and underground storage tanks (USTs), accidental surface spills, fuel line spills and other cases of improper handling of waste have led to environmental areas of concern.

Contaminants of concern (COCs) at these facilities have included a wide range of contaminants such as trichloroethene (TCE), tetrachloroethene (PCE), cis-1,2-dichloroethene (cis-1,2-DCE), vinyl chloride, chloroform, 1,1,1-trichloroethane (1,1,1-TCA), ethanol, benzene, toluene, ethylbenzene, xylenes (BTEX), chlorobenzene, carbon tetrachloride, PCBs, pesticides, explosives and total petroleum hydrocarbon-gasoline/diesel range organics (TPH-GRO & DRO) to name a few.

Department of Defense Facility (Isotec Case Study 14)

• Site Location: Eastern Pennsylvania
• Contamination: Carbon Tetrachloride (1500 ppb); and Chloroform (190 ppb) in groundwater.
• Geology: Sandy silt with some gravel to a depth of about 6 ft; below this it changes mostly to silt with some sand underlain by weathered bedrock. The water table is approximately 6-7 ft bgs.
• Area Treated: ~5,650 Sq. ft area at 5-20 ft bgs vertical depth interval.
• Effectiveness: Site-wide Carbon Tetrachloride reduced by 86% and Chloroform by 76%.

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• Site Location: Tulsa, Oklahoma
• Contamination: TPH in soil ranged from 5,000 mg/kg to 8,000 mg/kg
• Geology: Coarse, sandy soil and native fill underneath an 8-inch concrete slab
• Area Treated: 3,750 Sq. ft area at 1.0-2.5 ft bgs vertical depth interval.
• Effectiveness: TPH was reduced by >90%.

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• Site Location: Southern CA
• Contamination: Trichloroethene (96,000 ppb in groundwater).
• Geology: Poorly sorted medium to fine grain sand; water table at approximately 20 ft bgs.
• Area Treated: 1,250 Sq. ft - 3 treatment intervals, 20-30, 35-45, 50-60 ft bgs.
• Effectiveness: - Overall 60% reduction in most heavily contaminated zone with one well showing 95% reduction.

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• Site Location: Mechanicsburg, PA
• Contamination: Bedrock aquifer impacted with VOCs, SVOCs, PAHs, PCBs and pesticides. Primary site COCs include Chlorobenzene (817 ug/l), cis-1,2-Dichloroethene (1,673 ug/l), 1,4-Dichlorobenzene (51 ug/l), Vinyl Chloride (141 ug/l) and Trichloroethene (3,712 ug/l).
• Geology: Clay and silt extends from ground surface to 30 ft bgs underlain by fractured limestone bedrock.  Depth to groundwater is approx. 30 ft bgs; hydraulic conductivity is between 4.3x10 -4 cm/sec and 8.6x10 -3 cm/sec.  
• Area Treated: Approx. 130,000 Sq. ft total area.  Target treatment zone ranged from approx. 30 ft bgs to 100 ft bgs within the fractured bedrock.
• Effectiveness: 87% site-wide reduction of VOCs from average baseline. 20 wells sampled. CB below RGs in 15, 1,2-DCE and VC below RGs in 12 wells, TCE below RGs in 8 wells, Aroclor 1260 below RGs in 14 wells, 1,4-DCB below RGs in 19 wells, 4,4-DDT below RGs in 18 wells and alpha-BHC below RGs in 19 wells.

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• Site Location: Rome, New York
• Contamination: Chlorobenzene (CB), 1,2-dichlorobenzene(1,2-DCB), 1,3-dichlorobenzene(1,3-DCB), 1,4-dichlorobenzene(1,4-DCB).  GW Average VOC Concentrations: CB (1,333 ug/l), 1,2-DCB (94 ug/l), 1,3-DCB (7 ug/l) and 1,4-DCB (111 ug/l).
• Geology: Silty sands with minor quantities of clay, bedrock approximately 25 feet bgs.   Depth to groundwater is ~10-12 ft bgs; GW flow is moderate and to the southwest.  
• Area Treated: ~8,000 Sq. ft total area.  Target treatment zone ranged from ~10-25 ft bgs.
• Effectiveness: For GW , VOC reduction was achieved at all monitoring locations with reduction rates ranging between 39% to 99%.  Average VOC concentrations were reduced by 78%. Average concentrations of CB were treated from a baseline concentration of 1,333 µg/l to 263 µg/l. Conservative mass calculation estimated between 5.9 -10.5 lbs VOC mass removal following Phase I and between 17.4 -17.6 lbs. of VOC mass removal following Phase II.

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• Site Location: Middle, Georgia
• Contamination: VOCs including Chlorobenzene (7,412 µg/l ), TCE (2,455 µg/l ), cis-1,2-DCE (7,039 µg/l), DCB Isomers, arsenic, lead, cadmium, chromium and SVOCs including polycyclic aromatic hydrocarbons (PAHs).
• Geology: Fill material consisting of clay, silt and sand from ground surface to a depth of approximately 10 feet bgs underlain by a clay unit to approximately 40 feet bgs.
• Area Treated: Source area and plume (estimated to be 307,500 sq ft). Target treatment interval from 30-50 feet bgs for majority of site and from 10-20 feet bgs for the southern most areas of the site.
• Effectiveness: A 90% reduction in all 10 compliance wells was noted after 5th full-scale injection event. The 10 compliance wells selected for the site performance criteria remediation goals showed reductions ranging from 70%-99%.

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• Site Location: East Coast, United States
• Contamination: Chlorinated VOCs including PCE, TCE, Vinyl Chloride and cis-1,2-DCE.
• Geology: Fine to medium silty and clayey sand matrix underlain by a sandy clay semi-confining unit at 35 feet bgs. Average hydraulic conductivity was 1.02 x 10 -2 cm/sec in the shallow water bearing unit. Depth to GW is approximately 15-20 feet bgs; with flow in the easterly direction.
• Area Treated: Target treatment area was approximately 4,500 sq ft targeting the 20-35 feet bgs vertical interval.
• Effectiveness: Treatment program results indicated a sharp reduction in the concentration of VOCs, with overall site-wide contamination reduced by over 87% on average and over 92% in the treatment area.

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• Site Location: East Coast, United States
• Contamination: Carbon Tetrachloride (500 µg/l ); and Chloroform (18 µg/l ) in groundwater.
• Geology: Fine to medium silty and clayey sand matrix underlain by a sandy clay semi-confining unit at 35 feet bgs. Average hydraulic conductivity was 1.00 x 10 -4 cm/sec. The water table is approximately 4.5-12 ft bgs.
• Area Treated: ~9,000 Sq. ft area at 20-35 ft bgs vertical depth interval.
• Effectiveness: Treatment program results indicated an overall VOC destruction of 87% in the treatment area with chloroform being treated to ND values.

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• Site Location: Northern California
• Contamination: Dichlorobenzene isomers and VOCs. Primary COCs were 1,2-DCB and 1,4-DCB.
• Geology: The subsurface is comprised of interbedded layers of silt, silty sand and sand.
• Area Treated: Target treatment area covered a portion of the 11-acre site containing dissolved phase COCs. The target vertical treatment zone covered the 9-15 feet bgs depth interval. Approximately 360 temporary DP points were utilized to perform ISCO throughout the site.
• Effectiveness: Concentrations of 1,4-DCB and 1,2-DCB in groundwater were reduced by 99% and 96%, respectively.

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