A pilot-scale demonstration of surfactant-enhanced aquifer remediation (SEAR) was conducted during the summer of 2000 at the Bachman Road site in Oscoda, MI. Part two of this two-part paper describes results from partitioning and nonpartitioning tracer tests, SEAR operations, and post-treatment monitoring. For this field test, 68 400 L of an aqueous solution of 6% (wt) Tween 80 were injected to recover tetrachloroethene-nonaqueous phase liquid (PCE-DNAPL) from a shallow, unconfined aquifer. Results of a nonreactive tracer test, conducted prior to introducing the surfactant solution, demonstrate target zone sweep and hydraulic control, confirming design-phase model predictions. Partitioning tracer test results suggest PCE-DNAPL saturations of up to 0.74% within the pilot-scale treatment zone, consistent with soil core data collected during site characterization. Analyses of effluent samples taken from the extraction well during SEAR operations indicate that a total of 19 L of PCE and 95% of the injected surfactant were recovered. Post-treatment monitoring indicated that PCE concentrations at many locations within the treated zone were reduced by as much as 2 orders of magnitude from pre-SEAR levels and had not rebounded 450 days after SEAR operations ceased. Pilot-scale costs ($365 900) compare favorably with design-phase cost estimates, with approximately 10% of total costs attributable to the intense sampling density and frequency. Results of this pilot-scale test indicate that careful design and implementation of SEAR can result in effective DNAPL mass removal and a substantial reduction in aqueous concentrations within the treated source zone under favorable geologic conditions

The Boston Water and Sewer Commission (the Commission) has conducted a comprehensive assessment of pollutant loadings from its closed conduit and open channel drainage systems to the receiving waters of the Charles River, Neponset River, and Boston Harbor. A uniquely detailed Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) computer model was adapted from an existing system-wide 4,000 node hydraulic model and used to assess sources, loads, and mitigation alternatives for 13 pollutants discharging from the city's drain systems to its receiving waters. The model is calibrated to baseflow and stormwater runoff observed throughout a five-month flow monitoring program, water quality data obtained at 20 sites over six rainstorms and six dry-weather sampling events during the flow monitoring program, and historic data. The model has been used to assess the potential of improved best management practices, green stormwater infrastructure implementation, and low-impact development practices for meeting total maximum daily loads (TMDLs) and water quality standards. The model simulates pollutant buildup and washoff across nine land uses as well as contributions from groundwater, illicit flow, and rainfall. It simulates pollutant conveyance through open and closed conduit systems, first-order decay of oxygen demand, bacteria die-off, bacteria resuspension from sources in sediment bed load and pollutant removal through natural and constructed detention/treatment systems.

Since 1983, construction-site projects in the Los Angeles Basin area have been reviewed under the Construction-Site Plan Review Program of the Department of Conservation's Division of Oil, Gas, and Geothermal Resources. Under its auspices and before issuing building permits, local permitting agencies review and implement the division's pre-construction, oil-well recommendations and requirements. Oil-well proximity to proposed structures statistics derived from division data suggest there are three types of urbanized oil fields in the Los Angeles Basin area. This information may prove valuable to anyone involved in oilfield land development. Introduction The Department of Conservation's Division of Oil, Gas, and Geothermal Resources (division) is charged with implementing Section 3208.1(a) of the Public Resources Code, which states, in part, that "To prevent, as far as possible, damage to life, health, and property, the supervisor or district deputy may order the reabandonment of any previously abandoned well...because the owner of the property on which the well is located proposes construction on the property that would prevent or impede access to the well for purposes of remedying a currently perceived future problem." After the statute was enacted in 1983, the division developed the "Construction-Site Plan Review Program," which assists local permitting agencies that regulate land-use development by identifying and reviewing the status of oil wells near or beneath proposed structures. Los Angeles Basin Area and Local Permitting Agencies The division's District 1 staff is responsible for the Construction-Site Plan Review Program in the Los Angeles Basin area (Fig. 1). Urban development here is a model for residential, commercial, and industrial development in oil fields because the area contains 44 producing oil fields, 3 inactive oil fields, and 22 abandoned oil fields. Each oil field occupies an area where one or more local permitting agencies regulate land use and issue building permits. Incorporated cities generally are the local permitting agencies for portions of oil fields falling within their boundaries. The county is the local permitting agency for portions of oil fields outside of incorporated city boundaries. Fire departments also may have authority for granting and reviewing building permits. As an example, the Huntington Beach Fire Department grants building permits for construction projects within the City of Huntington Beach. Oilfield Maps and Construction-Site Plan Reviews Local permitting agencies regularly receive updated division oilfield maps with approximate oil-well locations and division administrative boundaries for oil and gas fields. When developers apply to local permitting agencies for building permits, agency representatives plot the project locations on these maps. If oil wells are located near or within a project's boundaries, the local permitting agency refers the developer to the division for assistance. The developer must follow the requirements of the division's Construction-Site Plan Review Program, including those of the project-evaluation letter listing recommendations and requirements for each well on the project site. A typical project-evaluation letter will state whether or not a well must be plugged and abandoned or reabandoned, tested for leaks, and offer recommendations for surface-gas control (Fig. 2).

No abstract