ARCHIVED REPORTS_XR0006202 - Laserfiche WebLink

Home Browse Search

A negative pressure of 50 mbar at the UVB wellhead was maintained by adjusting the height of the bubble tray and the opening of the UVB blower butterfly valve The desired negative ' pressure at the UVB wellhead should be in the range 45 to 65 millibar While the UVB blower was running, the flow rate of the air intake stream and the UVB off-gas stream were measured (mean flow rate for 30 seconds) to verify that air was being pulled in through the air intake pipe and through groundwater Air flow through the water was indicated by vibration of the air intake pipe, and by the sound of vigorous bubbling heard by placing the ' ear against the air intake pipe Proper operation of the UVB system without any blockage in air pathways was ensured by a UVB off-gas stream flow rate greater than the air intake stream flow ' rate (175 versus 155 cfm, respectively) In order to check that the seal of the UVB well flange is good, the negative pressure at the UVB ' well head was measured with the air intake stream unobstructed and then blocked It was verified that the seal of the UVB well flange is good, because the negative pressure increased when the air intake stream was blocked ' Proper functioning of the support pump was checked by stopping and starting the pump and verifying by placing the ear to the intake pipe and hearing when the pump was turned on and off ' Water level measurements during general operation were taken when both the UVB system support pump and blower were off and when both were on Following start-up troubleshooting, the UVB system was started on 6 February 1997 and 736 hours of operation were accrued as of 14 March 1997 The UVB system was shut down briefly for the installation and development of the UVB monitoring wells from 11 to 14 February and from 25 to 27 February 1997, respectively Tedlar bag air samples of the UVB off-gas were collected at a sampling port on the pressure side ' of the UVB blower on 6, 17, and 20 February 1997, and 7 and 14 March 1997 The air samples were submitted to a laboratory for TPH-g and BTEX analysis The chain of custody and laboratory analytical results are provided in Appendix C On 28 February 1997, groundwater samples were collected from UVB-MWI and UVB-MW2 ' and submitted to a laboratory for TPH-g and BTEX analysis Groundwater sampling procedures are described in Appendix B, and the groundwater purge and sample forms are provided in Appendix D The chain of custody and laboratory analytical results are provided in Appendix C ' UVB system performance parameters are shown in Table 3 3.9 SURVEY OF NEWLY INSTALLED WELLS ' The ground surface elevations and the top-of-casing elevations of all of the onsite and offsite wells, except for MW 11 and the air sparge wells, were surveyed on 24 and 25 February 1997 by ' Cooper, Thorne, and Associates, a state licensed land surveyor The well survey report is provided in Appendix E The benchmark used is the city of Stockton Benchmark number 265, a chiseled mark on the sidewalk on the eastern side of Pershing Avenue, south of March Lane Elevations are listed in Table 4 ' WP61 73942 R01397 3 10