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features, such as dry sand or gravel, V.Site or on site structures, and areas of deer stressed vegetation that might be caused by landfill gas migration. (3) Monitoring well spacing shall be reduced as necessary to protect persons and structures threatened by landfill gas migration. (c) Depth (1) The depth of the wellbore of all monitoring wells shall equal the maximum depth of waste. The number and depths of monitoring probes within the wellbore shall be installed in accordance with the following criteria, except as specified in ¶(c)(2) of this section. (A) a shallow probe shall be installed 5 to 10 feet below the surface; (B) an intermediate probe shall be installed at or near half the depth of the waste; (C) a deep probe shall be set at or near the depth of the waste; (D) the specified depths of monitoring probes within the wellbore shall be adjusted based on geologic data obtained during drilling, and probes shall be placed adjacent to soils which are most conducive to gas flow; (E) All probes shall be installed above the permanent low seasonal water table, above and below perched ground water, and above bedrock; and (F) When the depth of the waste does not exceed 30 feet, the operator may reduce the number of probes to two, with one probe located in the shallow zone as indicated above and the other located adjacent to permeable soils at or near the depth of the waste. (2) Exclusions or modifications to the requirements specified in (c)(1) of this section may be requested when conditions limit the practicality or do not warrant the installation depth criteria (e.g., filled pits, cut and trench, and canyon fills). In those cases, the operator shall propose an alternate system of equivalent probe depths. The proposal must demonstrate to the satisfaction of the EA and CIWMB that probes located at these depths are sufficient to detect migrating landfill gas and provide protection to public health and safety and the environment. (3) The EA may require an increase in the number of monitoring wells or probes or the depth of the wellbore or modify the depths of monitoring probes within a wellbore to ensure compliance with Section 20921(a). The operator is not precluded from utilizing existing gas monitoring wells of an alternate design when the operator demonstrates to the satisfaction of the EA and CIWMB that such wells have been installed in a manner that ensures the detection of landfill gas migrating from the disposal site. From: Joe Brusca[mailto:jbrusca@bruscaassociates.com] Sent: Thursday, August 10, 2017 3:24 PM To: Robert McClellon [EH] Cc: 'Cybil Bryant' Subject: Murphy Parkway Lathrop Soil Gas Monitoring Workplan Robert, 10