SITE INFORMATION AND CORRESPONDENCE_FILE 1

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r '0 Occidental Chemical Company Page -2 31 April 1980 It is therefore incumbent upon us, both as the regulator and the regulated, that wells be destroyed properly, as the drilling components are withdrawn, and not at some later time. The destruction process must be inspected, and is therefore an incurred cost offset by permit fees; and also fulfills statutory requirements. Permits are required for each well boring. 2. The requirement for "neat cement" destruction of each well has been con- tested upon the basis that unspecified unconfined aquafers may be present in the substrata, thus making prescribed destruction mentods an exaggerated exercise in great expense without commensurate benefit. No data of substance has been provided to substantiate the contestation. What little data that has been provided, does indicate that momentous variations occurs in con- ductivity, ammonia content, and sulfates at variable aquafer levels. No foreknowledge of such variabilities, or their significance is possible, and until the project is completed, and scientific data is produced, protection of aquafers from consequential affects of the project remains this agency's paramount concern and statutory responsibility. Soil characteristics which are now known, in respect to previous wells which have been drilled in the project lead to a conclusion that total contiguous destruction of the nonpermanent, uncased, wells is mandatory, and the requirement remains. Slight technological modifications of the preestablished requirements, as iterated in our 15 February 1980 letter (copy enclosed) are indicated; they are in augmentation: a. All "pilot" wells shall be destroyed under permit and concurrent inspection when, and during, the drilling components are withdrawn, by way of a Tremie tube (or pipe) through which either neat cement (or nine sack mixture) which has been 1/4" - 1/2" screened (on site), isup mped from the most distal depth of the well, (without freefall) to the most proximal ground level surface. This requirement alters item (4) in the 15 February 1980 letter. b. All other cased - well grouts shall be installed as approved under permit procedures. c. The requirements of item (5) in the 15 February 1980 letter are augmented to require submission of quantified weigh or invoice manifests of materials for each well, within two calendar weeks of the use of the destruction materials.