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West Clay Property - 2 - 31 October 2016
<br />639 West Clay Street
<br />Stockton, San Joaquin County
<br />The well is proposed to be screened from 75 to 85 ft bgs, and is proposed to be located in the
<br />vicinity of existing well MW-29 to define the vertical and down-gradient extent of petroleum
<br />hydrocarbon impacts. Soil samples are proposed to be collected every five (5) feet from the
<br />well borehole from 35ft bgs to the total depth, for lithologic logging, field screening for volatile
<br />organic compounds (VOCs) using a photo-ionization detector (PID), and potential laboratory
<br />analysis. The final screen interval depth of the proposed well may be modified based on
<br />observed hydrogeological conditions. After completion and development, AGE proposes to add
<br />the newly installed well to the existing groundwater monitoring program to be sampled on a
<br />semi-annual frequency.
<br />AGE proposes to analyze grab groundwater samples for total petroleum hydrocarbons (TPH) as
<br />gasoline (TPH-G), TPH as diesel (TPH-D), benzene, toluene, ethylbenzene, total xylenes
<br />(collectively BTEX), methyl tert butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary-butyl
<br />ether (ETBE), tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), ethylene dibromide
<br />(EBD), and 1,2-dichloroethane (1,2-DCA).
<br />Central Valley Water Board staff concur with the scope of work presented in the Work Plan,
<br />provided our comments below are adequately addressed. Therefore, by 15 April 2017, submit
<br />a Site Assessment and Well Installation Report. Staff have the following comments on this
<br />project:
<br />In the Work Plan, AGE proposed to collect depth discrete grab groundwater samples using
<br />a direct push rig. Use of a direct push rig is acceptable. However, if drilling refusal is met
<br />and your consult is unable to collect both depth discrete grab groundwater samples, at
<br />approximately 50 ft bgs and 85 ft bgs, than staff will request that your consultant utilize an
<br />alternate drilling method to collect both samples.
<br />The selection criteria for laboratory analysis of soil samples was not included in the Work
<br />Plan. Please assure that all samples with observed petroleum hydrocarbon staining and
<br />odors, and PID readings above 200 parts per million are submitted for laboratory analysis.
<br />Soil samples should be analyzed for TPH-G, TPH-D, BTEX, MTBE, DIPE, ETBE, TAME,
<br />TBA, 1,2-DCA, EDB, lead, and naphthalene.
<br />Grab groundwater samples need to also be analyzed for naphthalene. Naphthalene is a
<br />common gasoline additive, and is a threat to human health and the environment.
<br />Therefore, please add naphthalene to the parameter list for grab groundwater samples.
<br />Groundwater samples, including samples collected during semi-annual groundwater
<br />monitoring events and grab groundwater sampling events, need to be analyzed for
<br />dissolved lead. Based on the age of the former tank, it was likely used to store lead.
<br />In a letter dated 26 July 2016, staff requested submission of a sensitive receptor survey by
<br />15 September 2016. To date, the sensitive receptor survey has not been received. A
<br />sensitive receptor survey needs to be performed to assure protection of all surface water
<br />bodies and water supply wells within 2,000 feet of the Site, with field verification of any wells
<br />identified within 1,000 feet of the Site. Therefore, please include in the Site Assessment
<br />Report due 15 April 2017, results of a sensitive receptor survey.
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