ARCHIVED REPORTS_XR0011958 - Laserfiche WebLink

Home Browse Search

1. Additional Groundwater Investigation and Remediation Feasibility Evaluation Work Plan Stockton Center Site Authority-University Park January 25,2005 Page 5 The acquired data from the proposed work will hopefully allow consideration of options for cleanup such as monitored natural attenuation (MNA — passive cleanup by monitoring. the biodegradation':of the contamination with naturally occurring microbes), enhanced natural attenuation (bioremediation with oxygen infusion or other means), or active remediation with soil vapor extraction (SVE) and/or, ozone injection(01). Soil over-excavation is no longer considered a likely alternative for remediation due to high cost and site commercial development. In addition, all preliminary results indicate that the site contamination is not likely to be an immediate threat to health and/or sensitive receptors and probably does not justify such a costly measure. While SVE and air-sparging have been considered for the site in detail, various technical issues,potentially high cost, significant site disturbance, and the previously mentioned concerns regarding the probable lack of an immediate contaminant threat, suggest that these measures are not the best alternative (at least in tandem). Ozone injection is potentially a viable alternative because of anticipated effectiveness on perhaps the most recalcitrant site contaminant (1,2-DCA), competitive cost, and relative unobtrusiveness. It is possible, however, that ozone injection may be too aggressive for the site,relative to cost and the contaminant threat, may create other nuisance conditions, and/or may lack effectiveness because of the site lithology. Accelerated natural attenuation by oxygen infusion and/or other agents (bioremediation) is a potential remediation option because .of relatively low cost, and relative unobtrusiveness, and may be appropriate for the level of risk present at the site. Bioremediation (oxygen infusion, etc.) is, however, a long-term alternative requiring monitoring for potentially many years. The data from the proposed methods described in this work plan are anticipated to allow evaluation`hof the most viable (cost effective and feasible)method of remediation. 5.0 FIELD AND ANALYTICAL METHODS This section includes a description of the proposed site preparation; drilling and soil sampling procedures; p gP monitoring well installation, construction, surveying, development, and sampling; and laboratory testing and analyses. 5.1 SITE PREPARATION Condor will complete well permit applications for the installation of the monitoring wells and will obtain the required permits from the SJCEHD prior to the fieldwork. Condor will schedule and coordinate all drilling activities through the SCSA and the SJCEHD. The proposed monitoring well locations will be marked with white paint and Underground Service Alert (USA);will be notified at least 72 hours in advance of the fieldwork to locate and identify underground utilities in and near the work area. However, since companies contacted by USA may not identify utilities past private property lines and into the site, it is ultimately the responsibility of the property owner to identify any site utilities. 5.2 DEEP MONITORING WELL INSTALLATION PROCEDURES Three deep borings, one up gradient from the contaminant source area (west), one in the source area, and one immediately down gradient from the source area (east) will be drilled to depths of approximately 90 feet bgs, depending on field conditions. The borings will be used to collect continuous core samples for detailed analysis of the site stratigraphy and comparison with CPT interpretive stratigraphic logs, to collect discrete-depth soil samples for analyses of chemical and physical properties, and to collect..bulk soil and groundwater samples for bench scale testing to evaluate site remediation options, including ozone injection and bioremediation. The three deep borings will subsequently be completed as deep monitoring wells. The two deep monitoring wells within the site contaminant plume will be completed inside conductor casing to minimize the potential for cross-contamination between the site shallow groundwater