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MEMORANDUM • <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A Phone: (916) 361-5600 <br /> Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 <br /> TO: GREG VAUGHN FROM: JEAN McCUE <br /> Senior Engineer Water Resource Control Engineer <br /> DATE: 19 September 1991 SIGNATURE: Qe <br /> SUBJECT: REVIEW OF SUPPLEMENTAL INFORMATION FOR SURFACE IMPOUNDMENT CLOSURE PLAN FOR <br /> RE-MANUFACTURING LTD. , STOCKTON, SAN JOAQUIN COUNTY <br /> On 16 August 1991 we received a plan entitled "Supplemental Information for Surface <br /> Impoundment Closure" for Re-Manufacturing, Ltd. . The plan was superseded by the <br /> submittal of the "Addendum to Surface Impoundment Closure and Post Closure Maintenance <br /> Plan" on 3 September 1991 . The plans were prepared by Water Work Corp. in response to <br /> our 26 June 1991 memorandum, which contained comments on Re-Manufacturing's 27 May 1991 <br /> Closure Plan. Many of our comments on the previous closure plan were addressed in the <br /> recent submittal . The concept of the plan is acceptable. However, more detail is <br /> required before the plan can be implemented. In reviewing the most recent submittal <br /> I referred to the comments in our 26 June 1991 memorandum. Remaining closure plan <br /> comments are presented in the order they appeared in that memorandum, for reference <br /> purposes. Following are comments which must be addressed prior to our approval of the <br /> Closure and Post Closure Maintenance Plan: <br /> Comment No. 3 <br /> The plan states that regraded and compacted embankment material will be used for cover <br /> foundation and that the soils are more than suitable for that purpose. However, no <br /> laboratory analysis of the engineering properties of the foundation material have been <br /> conducted, nor are they proposed. The plan states that since no vehicular traffic will <br /> occur on the capped area and no structures will be placed on the cap, engineering <br /> properties of the material will ultimately have little significance. However, Re- <br /> Manufacturing must show that the soils used for the foundation layer will have <br /> sufficient strength to support the engineered final cap. According to Section <br /> 2581(a) (1) of California Code of Regulations, Title 23, Division 3, Chapter 15 (Chapter <br /> 15) , the foundation layer must be compacted to the maximum density obtainable, at <br /> optimum moisture. Laboratory data need to be submitted, showing the embankment <br /> material is suitable foundation material and demonstrating what the optimum moisture <br /> content is. <br /> Also, one foot lifts for the foundation material are not adequate. In general , the <br /> lift should be thin enough for the roller feet to penetrate sufficiently to properly <br /> bond with the preceding lift. What type of roller will be used to compact the soil? <br /> How will the lifts be tied together? The plan states that soil density and moisture <br /> will be measured with a nuclear gauge at four tests per lift. <br /> Comment No. 4 <br /> The proposed final cap will consist of two feet of clay soils, compacted to 1 x 10-' <br /> cm/sec or less. The cap will be compacted in six-inch lifts. Field density and <br /> moisture measurements will be conducted in eight locations per lift by a qualified <br /> technician using a nuclear gauge. The plan also proposes to collect a sample for lab <br />