FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Piemmeter Installation and Destruction Report City of Stockton RWCF Page 2 Permitting and Site Preparation Condor submitted a boring permit application to the SJCEHD and received the permit prior to initiating any fieldwork. A copy of the piezometer installation permit issued by SJCEHD is included in Attachment D. L The piezometer installation locations were marked with white paint and Underground Service Alert (USA) was notified 72 hours in advance of the fieldwork to locate and identify underground utilities in and near the work area. The SJCEHD was notified of the fieldwork schedule at least 72 hours in advance of the fieldwork. Prior to conducting drilling activities, an on-site tailgate meeting was held with all personnel and Condor representatives in attendance. A site-specific Health and Safety Plan was discussed with, and presented to, all personnel for their signatures. r Piezometer Installation A Condor representative supervised the completion of the four borings using hollow-stem auger drilling ` methods on August 17, 2007. The borings were advanced by V & W Drilling, Ina (V & W), of Lodi, California (C-57#720904). The borings were subsequently completed as temporary piezometers. Piezometer locations are shown in Figure 2(Attachment A). 6. The temporary piezometers were constructed with five (5) feet of two-inch outside diameter (O.D.), Schedule 40, flush-threaded, machine-slotted poly vinyl chloride (PVC) screen (slot size 0.010). A PVC ` slip cap was placed at the bottom of the piezometer screens. Blank PVC casing was installed above the screen to the ground surface. No glue or solvents were used in the construction of the temporary piezometers; piezometer construction details are provided in Table 1,below. 6. Table 1-Temporary Piezometer Construction Details Casing Borehole Screen Filter Bentonite Grout Piezometer Date Depth Diameter Diameter Interval Pack Seal Seal D) Installed (ft.) (in) (in) (ft) Interval Interval Interval (ft.) (ft.) (ft.) r. PZ•1 8/17/2007 16 2 8 11 - 16 9- 16 6-9 2-6 PZ-2 8/17/2007 16 2 8 11 - 16 9-16 6-9 2-6 PZ-3 1 8/17/2007 20 1 2 1 8 1 15-20 1 13-20 10-13 1- 10 PZ-4 8/17/2007 20 2 8 15-20 1 13-20 t110-13 Note: All measurements are is fed(ft)below ground surface(bgs)udess otherwise noted;(in)=inches A filter pack of clean Monterey sand was placed in the annular space to approximately two feet above the screens while the augers were in place. Following placement of the filter pack each boring was surged, if field conditions allowed, prior to placement of the bentonite seal to settle the sand pack. Approximately three feet of bentonite pellets were placed above the sand to form a protective seal. During placement of the sand and bentonite pellets in the piezometer annulus, the depth was monitored with a weighted tape measure while the augers were retracted to minimize potential bridging. The bentonite chips were activated with potable water and allowed to hydrate at least 30 minutes prior to placement of the grout seal. A SJCEHD approved Volclay® bentonite grout seal (mixed according to manufacturer's specifications) was pumped over the bentonite pellets to approximately one - two feet below ground surface (bgs). Native fill was used to complete the temporary piezometers to the surface. Locking monuments were placed over the temporary piezometers casings for protection. Mr. Frank Girardi of the SJCEHD observed the piezometer completions. w lk-W 'i 41 CONDOR