Service: Environmental Engineering, Construction Management, Operation and Maintenance
Project: Design/Build In-Situ Soil and Groundwater Remediation Systems
Client: Chevron Texaco
Site Location: Milford, MA
Period of Performance: 2005 – 2007

H&S completed a Massachusetts Contingency Plan compliant Phase III Evaluation of Remedial Alternatives that included laboratory bench-scale and pilot testing to evaluate technologically and economically feasible means of reducing the concentrations of petroleum hydrocarbons in soil and groundwater. MCP Method 1, GW-1 groundwater standards apply to this site due to the existence of nearby municipal drinking water wells. H&S developed a comprehensive soil and groundwater remediation strategy that quickly and cost effectively contained and remediated the groundwater contaminants. 

H&S designed, oversaw construction for and operated a system that included operation of 11 soil vapor extraction (SVE) wells and in-situ oxidation using aqueous potassium permanganate injected into 12 specially designed injection wells which satisfied our client’s goal of quickly reducing downgradient concentrations to avoid impacting the drinking water wells and to decrease potential third-party liability. In addition, this combination of SVE and in-situ oxidation addressed gasoline-impacted source areas, soils both above and below the water table, to achieve clean-up objectives for substantially less cost than other potential remedial options. 

In-situ oxidation, using injected aqueous potassium permanganate quickly reduced the petroleum hydrocarbon concentrations. Use of aqueous potassium permanganate resulted in fewer injection wells since it did not rely solely on advection, dispersion, and natural groundwater movement to disperse it through the treatment area.

After only eight injection events, monitoring data results showed significant improvement in groundwater quality across the site indicating that dissolved volatile petroleum hydrocarbons (VPH) concentrations had decreased more than 80%, and GW-1 standards were met at several key down-gradient wells. 

H&S developed construction specifications and assisted the client in procuring contractors to install the remediation system. Reviewed pre-construction submittals and cut-sheets to ensure specified materials and equipment were supplied prior to installation. Provided CQC and health and safety oversight during field activities to ensure safe compliance with design and specifications. Reviewed contractors daily production reports and performed QC testing including soil compaction tests and pipe leak testing. Verified operational status of systems prior to authorizing final payment of retention to contractors.