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s STATE OF CALIFORNIA PETE WILSON, Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— CENTRAL VALLEY REGION 3443 ROUTIER ROAD. SUITE A SACRAMENTO, CA 95827-3098 � � PHONE: (916) 361-5600 FAX (916) 3615R1#bruary 1991 • R Mr. Harry Mossberger Plant Manager Kearney-KPF 1624 East Alpine Avenue 9 Stockton, CA 95208 REVIEW OF INTERIM GROUNDWATER REMEDIAL ACTION PLAN, KEARNEY-KPF, STOCKTON, SAN JOAQUIN COUNTY I have reviewed the "Interim Groundwater Remedial Action Plan, Kearney-KPF, Stockton, California" submitted by your consultant, Hargis and Associates. In general , the proposed collection system, treatment method, and treated ground water disposal method are acceptable. However, the following comments must be addressed. I have two concerns regarding the collection system. The first is the choice of Well SPW as one of the extraction wells. This intermediate zone well has relatively low levels of volatile organic compounds (VOCs). It may make more sense to use intermediate zone well KI-6 as an extraction well. KI-6 has the highest concentrations of VOCs of any well in the intermediate zone. Extracting contaminated ground water from KI-6 would help to clean up the ground water more quickly and would be more effective in preventing the spread of contamination. However, the benefits of using KI-6 as an extraction well must be weighed against disposal to the deep zone injection well of the higher total dissolved solids (TDS) levels in KI-6, relative to those in SPW. The second concern regarding the collection system is the use of PVC pipe for the buried portions of the collection system. Plastic pipe has been shown to be quite permeable to some VOCs, the permeability being enhanced by the presence of more than one Permeating chemical , Metal nines ciirh as stainless steel is a •r- better choice for the underground portions ofrthe collection system. In the air stripping treatment method only one liquid phase carbon adsorber is proposed to ensure the removal of VOCs from the air stripped ground water. It may be advisable to have a backup carbon adsorber for the liquid phase to prevent VOCs from passing through the system when the carbon in the treatment unit becomes saturated with VOCs. The chemicals that may be used for scale inhibition in the treatment system should be identified and their fate in the remediation process should be addressed. An organic vapor analyzer (OVA) is proposed to monitor the effluent airstream between the two vapor phase carbon adsorbers to determine when VOC breakthrough occurs. The sensitivity of the OVA to VOCs should be discussed and related to air quality standards for VOCs.