Laserfiche WebLink
Bentonite pellets will be emplaced above the filter pack to a thickness of about 2 feet, and <br /> charged with about 1 gallon of water per 2 pounds of pellets. Bentonite grout will be also <br /> be emplaced through the augers as they are withdrawn. This grout will consist of Type I or <br /> II portland cement with from 3 to 5 percent bentonite powder as an additive (one 94-pound <br /> sack of portland cement to 4.5 to 7.5 gallons of water). San Joaquin County will be <br /> contacted to witness the placement of the seal. <br /> Monitoring Well Development <br /> HP-5 will be developed as soon as practical after the cement grout sets. Development will <br /> be accomplished by surging along the entire screen length with a surge block and bailing <br /> using a well development rig. Development will continue for at least 2 hours, or until the <br /> produced water is free of visible turbidity and suspended sediments. The purpose of the <br /> development is to produce high-quality samples and restore the natural hydraulic properties <br /> of the aquifer near the well. Water produced during development will be directed into a <br /> nearby drainage ditch. <br /> Wellhead Survey <br /> A reference point will be located and marked at the top of the HP-5 well casing and <br /> vertically surveyed to the nearest 0.01 foot. Previously, holding pond wellhead elevations <br /> were surveyed relative to HP-1 by assuming an arbitrary elevation of 100 feet as the <br /> reference point for this well. HP-5 will also be surveyed relative to HP-1 to calculate the <br /> direction and gradient of flow of the uppermost groundwater beneath the ponds. Water <br /> levels in the wells will be measured relative to the surveyed reference point on the casing <br /> with a calibrated electric sounder to the nearest 0.01 foot. HP-5 will be located in the field <br /> on a photographic base map. <br /> Water Quality Sampling <br /> Groundwater samples will be collected from each holding pond well. However, a sample <br /> will not be collected from HP-5 until a minimum of 72 hours has elapsed following devel- <br /> opment. Surface water samples will also be collected from each holding pond and from <br /> Sugar Cut Slough. Samples from Sugar Cut Slough will be collected both upgradient and <br /> downgradient of the holding ponds. Samples will be analyzed for TDS, electrical con- <br /> ductivity (EC), pH, major cations (sodium, potassium, calcium, and magnesium), and major <br /> anions (bicarbonate, chloride, sulfate, and nitrate). These analyses will allow an evaluation <br /> of potential leakage from the ponds by comparing the concentrations of these constituents <br /> in groundwater to the concentrations of the same constituents in pond water and Sugar Cut <br /> Slough water, and by comparing the geochemical characteristics of the groundwater to that <br /> of the pond water and Sugar Cut Slough water. <br /> Analyses for TDS, EC, pH, and chloride will be performed at the City's wastewater <br />■, treatment plant laboratory. The other analyses will be performed at the CH2M HILL <br /> laboratory in Redding, California. Table 1 summarizes these analyses, together with the <br /> analytical methods, preservation methods, and sample containers. <br /> SAC/SAC36357/041.WPI 8 8/94 <br />