SR0085184 (2) - Laserfiche WebLink

Home Browse Search

SHALLOW INJECTION WELL INSTALLATION WORK PLAN arcadis.com 2022.02.15 OCC Lathrop_Shallow Injection Well Installation Work Plan_final 5 4.1.2 Field Activities 4.1.2.1 Pilot Boring Installation Each pilot boring will be advanced by a C-57 licensed drilling contractor using mud rotary drilling methodology (unless an alternative method is deemed more appropriate) under supervision by Arcadis staff working under the direction of a California licensed Professional Geologist. Mechanical deviation will be recorded by the drilling contractor during drilling to ensure that the pilot hole is straight and plumb. The mechanical drift indictor shall be run in the pilot hole at intervals no greater than 90-feet. To stabilize each borehole, a temporary 10 to 20-foot outer surface casing will be installed to ensure that no washout is observed near the surface. Once the temporary outer surface casing is installed, the pilot hole will be drilled, and the borehole will be logged and sampled using a 94 mm continuous coring system to the total depth of the borehole. Soil cuttings and core samples will be described using the Unified Soil Classification System (USCS) and identify potential production intervals and confining layers/aquitards. Once the total depth of each pilot boring is reached, and the Brown Clay has been identified, the pilot hole will be reamed to a nominal 8-inch diameter to the total depth of the boring to facilitate downhole geophysical logging. Downhole geophysical logging will include spontaneous potential, resistivity, lateralog, spectral gamma ray, and natural gamma logs to confirm the lithology and to facilitate the selection of the screened interval(s). Select soil samples will be submitted to the laboratory for sieve analysis. Sieve samples will be selected from potential screen intervals based on lithological assessment and geophysical logging. Approximately, one sample representing the range of grain sizes per five feet of potential screen will be submitted for each potential screen interval to a geotechnical laboratory for sieve analyses following ASTM Method 6913. Sieve analysis results will be used to determine the optimal filter pack design and slot size for each of the potential screen sections. Following sample collection and geophysical logging, the borehole will be backfilled with clean sand until screen slot size is determined and the screen and casing are on site. A final well design will be prepared based on the sieve results and geophysical data. The drilling company will also submit their recommended well design for the final injection well. Once the design has been finalized, the well design will be submitted to the drilling contractor and used as a basis for ordering well materials. The well materials including casing will be ordered based on the final well design. It is anticipated that well materials will require approximately 2 to 4 weeks to be delivered after the order is placed. 4.1.2.2 Injection Well Installation Following acquisition of each well screen and casing, drilling will resume, and the pilot hole will be reamed to a nominal 16-inch diameter to the total depth of the well prior to installation of the well screen and casing. Mechanical deviation will be recorded by the drilling contractor during drilling to ensure that the well is straight and plumb. The mechanical drift indictor will be run in the reamed hole at intervals no greater than 90-feet. Following reaming, a caliper log will be run to determine borehole diameter and annular volumes for the screen and casing installation. The subcontractor will submit a plan on quantity