WORK PLANS - Laserfiche WebLink

Home Browse Search

APPENDIX A PROTOCOLS FOR INSTALLATION, SAMPLING ,AND ABANDONMENT OF SITE ASSESSMENT BORINGS SOIL CORING PROCEDURES Prior to drilling, all boreholes will be cleared by hand auger, shovel, or posthole digger to 5 feet below ground surface. Soil and groundwater samples will be collected for lithologic and chemical analysis using a direct driven dual tube soil coring system. A hydraulic hammer will drive sampling rods into the ground to collect continuous soil cores. Two nested sampling rods are driven simultaneously: small-diameter inner sampling rods are used to obtain and retrieve the soil cores; the larger diameter(approximately 2-inch OD) outer rods serve as temporary drive casing. As the rods are advanced, soil is driven into an approximately 1.5-inch-diameter sample barrel that is attached to the end of the inner rods. Soil samples are collected in sleeves inside the sample barrel as both rods are advanced. After being driven 3 feet, the inner rods are removed from the borehole. The sleeves containing the soil samples are removed from the inner sample barrel, and can then be preserved for chemical analyses or used for lithologic identification. After adding new sleeves,the drive sampler and inner rods are then lowered back into the borehole to the previous depth, an additional casing is attached, and the process is repeated until the desired depth is reached. The use of outer rods prevents sloughing of the formation while the inner rods are withdrawn from the hole. This ensures that the drive sampler will always be sampling soil from the desired interval, rather than potentially contaminated soil that has sloughed in from higher up in the hole. All drive casing, inner sample barrels, inner rods, and tools will be cleaned with Alconox or — equivalent detergent and deionized water. All rinsate from the cleaning will be contained in 55- gallon drums at the project site. — GROUNDWATER SAMPLING PROCEDURES After the targeted water-bearing zone has been penetrated, the sample barrel and inner rods will be removed from the borehole. Small-diameter well casing with 0.010-inch slotted well screen or equivalent may be installed in the borehole to facilitate the collection of groundwater samples. Threaded sections of PVC are lowered into the borehole inside the drive casing. The drive casing is then pulled up to expose the slotted interval of the PVC. Groundwater samples may then be collected from within the PVC casing with a bailer,peristaltic pump, bladder pump, or inertial pump until adequate sample volume is obtained. BOREHOLE GROUTING On completion of soil and water sampling,boreholes will be abandoned with a cement grout containing up to 5 percent pure sodium bentonite. The grout will be pumped through a grouting tube positioned at the bottom of the boreholes, prior to withdrawing the outer rods. e\p,oiav\70137\master\.rok„P998\appmmxa.,pd