ARCHIVED REPORTS_2013 - Laserfiche WebLink

Home Browse Search

DER People.\\ Bright People.Right Solutions. 2.3 SEEPAGE MONITORING Seepage is water that enters the soil profile and generally moves downward. Seepage from the Test Pad was measured using a tipping bucket that receives liquid collected from a synthetic liner/drainage layer (pan lysimeter) that is beneath the Test Pad. iRecorded data suggests that there was 0.4656 cubic feet of seepage during the 2012/2013 water year (Table 1). Chart 1 shows the rainfall vs. seepage volume with actual and modeled data. Data indicate that the test pad showed very little seepage (<1%) for the 2012/2013 water year which was similar to the results recorded for the 2011/2012 water year. This may have been due to maturing vegetative growth on the test pad exerting an increasingly effective evapotranspiration barrier thereby reducing seepage. 2.4 MODELING OF SEEPAGE THROUGH PRESCRIPTIVE CAP Performance of the Title 27 Prescriptive Cap was modeled using HELP and Test Pad precipitation data collected so far during the 2012/2013 water year. The Prescriptive Cap was setup in HELP using the following values: • Layer 1 (vegetative cover), 12 inches thick, sandy silt (HELP soil texture#7) • Layer 2 (barrier layer), 12 inches thick, clay (HELP soil texture 16, hydraulic conductivity adjusted to 1x10-6 cm/sec) • Layer 3 (foundation layer), 24 inches thick, sandy silt (HELP soil texture#7) The modeled results showed 937.56 cu ft seepage. Results of the HELP modeling are summarized in Table 1. The HELP modeling printout can be found in Appendix B. Chart 1 shows the rainfall vs. seepage volume with actual and modeled data. Performance of the ET Test Pad (using seepage out of the bottom of the cap) was compared directly to the modeled performance of the Title 27 Prescriptive Cap. r 47717.11/ST013RO532 Page 5 of 10 August 30, 2013 Copyright 2013 Kleinfelder