You are here:
Factors Affecting Exfiltration Rate from a Subsurface Infiltration Stormwater Control Measure
Citation:
Liu, J. AND Mike Borst. Factors Affecting Exfiltration Rate from a Subsurface Infiltration Stormwater Control Measure. International Low Impact Development Conference, Nashville, TN, August 12 - 15, 2018.
Impact/Purpose:
investigates the exfiltration rates from subsurface infiltration shafts along the length of the storage gallery under three permeable pavement strips in CSO-130 to 1) identify the main factors such as hydraulic head, water temperature, and cumulative rainfall depth (CRD) affecting the exfiltration rate from the shafts, as well as how edge effect influence the exfiltration rate; and 2) better understand the hydrologic process in the shafts and improve future design and installation guidance .
Description:
The Louisville and Jefferson County Metropolitan Sewer District, KY constructed a set of permeable pavement strips in the street along the curb parking lane in combined sewer overflow basin 130. The strips have a series of 0.46-m diameter subsurface infiltration shafts spaced at roughly even intervals along the length of the control. USEPA monitored each shaft in three selected strips from April 2013 through December 2015. The exfiltration rates were calculated using hydraulic head increments from 189 storm events (> 2.54 mm) during the 33-month monitoring period. The initial exfiltration rates of shafts depended on the bottom soil texture. The exfiltration rates generally 1) increased as hydraulic head increased; 2) increased as water temperature increased; and 3) decreased with cumulative rainfall (as time progressed). Water exfiltration from adjacent shafts may have inhibited water drawdown in the target shaft when the space between two shafts was less than 2-m.