SITE INFORMATION AND CORRESPONDENCE

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(P.M" The fiollowing alternative tasks have been included in the event that the proposed off-site investigation identifies petroleum hydrocarbon downgradient and off site. The alternative tasks are proposed to conduct remediation at and near the source of the hydrocarbon impact at the site and to remove mass to allow the LTCP to be applied. The alternative tasks include a 60-day HVDPE event and one year of subsequent groundwater monitoring to document the dissolved concentration trends. ALTERNATIVE 1 —60-DAY HVDPE PILOT TEST AND REPORTING Conduct a Pilot Test using HVDPE based on the observed petroleum concentrations in MW-2 and north of the former underground storage tank (UST) pit. The proposed monitoring well outside the site building (near former MW-1)and monitoring well MW-2 onsite will be included in the Pilot Testing. GHD anticipates conducting a 60- day dual-phase extraction (HVDPE) pilot test event at the site. The Pilot Test will be performed in two 30-day HVDPE events(60 days total). The second event will be scheduled if the initial pilot test data proves to be effective. Concentration trends and mass removal rates will be monitored. The Pilot Test event will be evaluated to estimate long-term results for this option. Other parameters will be assessed such as extraction well flow rate that can be sustained, projected mass removal rates, review dissolved concentration trends, and prepare recommendations.Assume 60 days of extraction and 20,000 gallons of water to contain, treat and discharge to the sanitary sewer system. 1. GHD will prepare a Workplan and submit to the CVRWQCB for approval. 2. Coordinate with the CVRWQCB and property owner(s)for access to conduct required site work under agreement developed by CVRWQCB. 3. Conduct up to two (2) 30-day HVDPE events. Data will be evaluated and determined if additional HVDPE activities are necessary to reach the site closure goal. 4. Prepare a Pilot Test Report based on the 30-day HVDPE events.After the completion of the Pilot Test HVDPE events, summarize the data, compare initial and ending dissolved groundwater concentrations, estimate radius of influence, and mass removed. Evaluate the option for additional events. Evaluate and recommend HVDPE as a remedial option and projections to reach cleanup goals. ALTERNATIVE 2—QUARTERLY GROUNDWATER MONITORING,SAMPLING,AND REPORTING(4 QUARTERS) GHD will conduct four(4) consecutive quarters of groundwater monitoring for 2014 and two (2) quarters of 2015, sampling, and reporting to evaluate the groundwater quality. If site conditions warrant case closure consideration, this action will be recommended in the associated quarterly monitoring and sampling reports. The proposed work is as follows: 1. Coordinate with the CVRWQCB and property owner(s)for access to conduct required site work under agreement developed by CVRWQCB. 2. Conduct four(4) consecutive quarterly groundwater monitoring events using the new and pre-existing monitoring wells (6). Measure the groundwater parameters of temperature, pH and conductivity during well purging and document on the field forms. 3. Contain purged groundwater and decontamination waste in DOT approved drums, labeled and stored on site until disposal can be arranged. 4. Collect groundwater samples and submit the samples to an analytical laboratory for the following analyses: TPH-G, BTEX, 5 fuel oxygenates and 2 lead scavengers by EPA Test Method 8260B. TPH-D by EPA Test Method 8015 modified. Samples will be analyzed on a normal turnaround time (10 business days). 5. Collect groundwater samples for Naphthalene(base extraction)on a one time basis only according to EPA Method 8270. 6. Prepare a Groundwater Monitoring and Sampling Report for each sampling event. The report will include a summary of the analytical data, site map, field sheets, laboratory analytical report, and recommendations. Deliverable: Four(4) separate Quarterly Groundwater Monitoring and Sampling Reports, plus upload data to GeoTracker. 03009-10017 Siebold Construction 3 of 4 - February 2014