CORRESPONDENCE_1982-1983 - Laserfiche WebLink

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August 26, 1983 _ .. - Project 116-1.4 - 3 - 9 dimensions of 1 foot deep and 1.5 feet wide. Commonly, the edge of the liner material is pliced in this trench such that it covers the . near sidewall, the floor of the trench and approximately half way up - the far sidewall of the anchor trench. Earth material is placed on top of the liner in the trench and wheel rolled to effect a tight seal. During installation, quality control will be provided by our field engineer on site to insure that the above procedures are followed and that the liner is properly anchored and, if necessary, properly vented to prevent wind billowing. - We have added details to the drawings and additional dimensions as requested in your memorandum. - In our conversation, you stated that the removal and closure details discussed in our last series of comments was adequate to satisfy your department's needs. - With respect to contingency planning, we submit the following; The: leachate retention pond will contain the 20 mil, low density polyethylene liner placed over a 2 foot compacted clay liner with a permeability of approximately 1 R 107 cm/sec. Assuming the worst case scenario, if the polyethylene liner becomes ruptured, the fluid, with a head of 10 feet will rest on the underlying compacted clay liner. With a permeability of 10-7 cm/sec, this will create an infiltration rate of approximately .01 foot per year per foot of head. Assuming a full head of 10 feet over the expected liner life of 1 year, we assume that 1 foot of the compacted clay liner would be penetrated. This would leave 1 foot of clay liner to provide additional integrity against leachate migration out of the pond. These design criteria should provide backup contingency for any unanticipated tearing or rupturing of the synthetic liner. As we discussed in our telephone conversation, construction is proceeding at a very rapid rate and will continue through the weekend of August 27. With your verbal approval, we are going ahead with the construction of the leachate retention facility and this letter will confirm our agreement on the issues of concern. If you wish to conduct a field inspection of the facility while it is open and under construction, this inspection should be scheduled no later than Monday or Tuesday, (August 29 or 30, 1983) . The issues covered in this letter were discussed by telephone with John Marshak (Regional Water Quality Control Board #5). He was in general agreement and had no objection to our resolution of the issues discussed. Mr. Marshak intends, if possible, to make a site inspection during construction on August 29, 1983. 9Beta v4ssociates Q