Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
Geo(o icafTechnics Inc <br /> g Page 2 <br /> Groundwater Monitoring Report <br />' Project No 723 2 <br /> • September 13,2000 <br /> 1.0 GROUNDWATER MONITORING <br /> 1.1 Hydrogeology of Site <br /> A site-specific groundwater gradient and bearing was calculated from the depth to water <br /> measurements taken during the groundwater monitoring The gradient was 0 0046 ft/ft <br /> flowing N82°E This is the fifth event where a site-specific groundwater gradient was <br /> calculated by resolving a three-point problem using MW-4, MW-5 and MW-6 These wells <br />' were selected because they are constructed relatively similar in regards to depth of screen <br /> interval The average elevation of groundwater under the site was 17 34 feet below mean sea <br />' level Depths to water ranged from 27 29-28 12 feet bgs <br /> Figure 2 is a groundwater gradient map for the August 29, 2000 event <br />' This is the fourth event where the deep discretely screened well, MW-101, was monitored A <br /> shallow well was not installed next to MW-101 so a vertical gradient cannot easily be <br /> calculated The groundwater head in MW401 is nearly equal (+0 01 feet) to the head in <br /> nearby MW-3 so it appears there was not a significant vertical gradient on August 29, 2000 <br /> Table 1 in Appendix A contains the groundwater elevations and gradients for the site <br /> 12 Groundwater Sampling Procedure <br />' On August 29, 2000, Del-Tech Geotechnical Support personnel arrived on-site opened the <br /> p <br /> wells, and measured the depth to water with an electrically actuated sounding tape The <br /> water level reading was recorded to an accuracy of 0 01 foot In wells where free-floating <br /> product was suspected, a clear disposable bailer is used to gauge the interface During this <br /> monitoring no free product was noted <br /> Stagnant water in the well casing was purged using a Waterra pump as recorded in the field <br />' logs (Appendix C) The rate of well purging was monitored The wells were purged of <br /> approximately three casing volumes and until the groundwater parameters (temperature, <br /> conductivity, and pH) had stabilized (Appendix C) indicating that water, representative of <br />' actual aquifer conditions, was entering the well Groundwater parameter stabilization was <br /> characterized by three successive readings within 10% <br />' Before a sample was collected, the well's water level was allowed to recharge to at least 80% <br /> of the initial level All water removed from the monitoring well and not used as a sample, <br /> was placed in a 55-gallon DOT (Department of Transportation 17-H) approved container that <br />' is properly labeled and temporally stored on-site <br /> The dedicated Waterra pump was used to collect each sample <br />