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Stockton Propeller Sampling and Analysis Plan To allow for subsequent assessment of the physical condition of the tank(s), inflow into the tank(s) will be minimized to the extent possible by a combination of regular pumping and/or use of portable latrines. 3.2 Septic Tank The presence of at least one septic tank to the south of the SPI facility is apparent based on the presence of 2 manholes and observations made by SPI staff.The existence of other septic tanks on the property has been suggested, but not verified. For example,the Board Order(refer to Attachment 6) includes a map with six(6) boxed "S" symbols indicating the presence of"septic system access locations". During an initial site reconnaissance by Blankinship staff on April 22, 2022,the "S" location depicted south of the Formurex pharmaceutical manufacturing facility could not be located. Contributions to the SPI septic tank(s), if any, from Formurex are unknown at this time. The interconnectivity of the SPI septic tank(s) with the Formurex facility will be assessed by examining available records at the City of Stockton and San Joaquin County. As necessary,geophysical, camera or the use of tracer dye or other means may be used to assess this connectivity. An Underground Service Alert (USA) survey will also be done. Maps will be prepared that show the approximate lateral and vertical location of tank features and photographs will be taken of the inside of the tank(s)to preliminarily aid in assessment of its condition. Other tools such as hydrostatic testing may also be used to aid in tank assessment. Depending on the results of this task, an addendum to this workplan may be prepared. 3.3 Leach Field The existence of a leach field, if any, is not known at this time. Similarly,the connection of the SPI septic tank(s)to a leach field and/or to municipal sewer service is not known. The SPI septic tank(s) plumbing and associated leach field, if any, will be assessed by examining available records at the City of Stockton and San Joaquin County. Records include but may not be limited to design documents as part of permit applications, or as-builts submitted after construction. As necessary, geophysical, camera or the use of tracer dye or other means may be used to assess the leach field and the connectivity of the SPI tanks and other tanks. A USA survey will also be done. Maps will be prepared that show the approximate lateral and vertical location of tank and leach field features. Depending on the results of this task, an addendum to this workplan may be prepared. For example,the locations, depths and number of borings described in Tasks 3.4 and 3.5 may be altered to assess the septic tank and leach field. 3.4 Subsurface Soil Borings Upon completion of Tasks 3.1, 3.2, and 3.3 and their associated addenda workplans, subsurface soil in the vicinity of the septic tank and leach field will be assessed using direct-push sampling probe technology. If this proves difficult, a hollow stem auger approach will be used. If Tasks 3.1, 3.2 and 3.3 suggest that the septic tank is damaged or compromised, an angle boring may be placed under the septic tank. It is important to recognize that the results of Tasks 3.1, 3.2 and 3.3 may influence the location of borings and monitoring wells. If alternative locations are being considered, Board staff will be consulted prior to use of alternative locations. Prior to initiating boring advancement, an additional USA survey will be completed no less than 48 hours prior to the start of work. Hand augering and/or an air knife may be used prior to placement of borings to reduce potential damage to subsurface features. Appropriate permits will be obtained from San Joaquin County Environmental Health Department (SJCEHD). Encroachment permits, if needed, will also be obtained. Blankinship&Associates, Inc. Page 13 of 20 September 23, 2022 NES, Inc.