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August 29, 2019 Mr. Brad Shelton Regional Water Quality Control Board Central Valley Region 11020 Sun Center Drive, #200 Rancho Cordova, CA 95670 Dear Brad: Subject: Forward, Inc. Landfill, Waste Management Unit FU-19 Design Report Comments This letter is in response to your 16 August 2019 comments on the Design Report for WMU FU-19 at the Forward Landfill. Responses to Questions 2 and 3 of your 16 August 2019 letter were provided in a 19 August 2019 letter from Lewis Engineering to you. This letter provides the response to Question 1. Question 1: Operations Layer Specification A typical sample of operations layer soil was collected from the operations layer stockpile on 13 August 2019. The sieve analysis for this sample (see attachment) indicates approximately 65 percent sand content and 34 percent fine content. Hydraulic conductivity tests were performed to validate the operations layer hydraulic conductivity assumed in the HELP Analysis. The HELP Analysis was performed to size the LCRS components and assumed a 10-ft thick lift of refuse was in place, which was considered the conservative case for leachate generation conditions. A 10-ft thickness of refuse at an assumed density of 65 pcf results in a load of approximately 650 psf or 4.5 psi. The hydraulic conductivity test was, therefore performed at a confining stress of 5 psi and resulted in a hydraulic conductivity of 3.4 x 10-4 cm/sec (see attachment). This result confirms the hydraulic conductivity assumption made in the HELP Analysis is valid. During the 8 August 2019 meeting held with the CVRWQCB, the question was also raised regarding the operations layer hydraulic conductivity when a larger stress is applied due to additional refuse thickness. Although this question does not correlate with the assumptions made in performing the HELP Analysis, a hydraulic conductivity test was also performed at a confining stress of 60 psi, which is the loading limit for the permeameter. The hydraulic conductivity of the operations layer soil under a 60 psi confining stress is 2.3 x 10-4 cm/sec (see attachment), which is also consistent with the assumption made for the HELP Analysis. We appreciate your review of the WMU FU-19 Design Report and continued assistance with the Forward Landfill project. As you are aware, excavation of WMU FU-19 has been initiated to allow Forward to complete cell construction prior to the wet season, LEWIS ENGINEERING 98 Ramona Ave., Piedmont, CA 94611 Tel: 510.601.7223 Fax: 510.601.7206