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Infiltration Test Results

A B

E

A. Traffic control and buried hose from SMWC hydrant
B. Testing in progress (Day 1)
C. EX-4 monitoring well (151' deep)
D located ~100' east of test basin
D. Flow control skid at end of test (Day 14)
E. Test in progress view from east (Day 7)

C
Conclusions:
- Results of infiltration testing indicate that the site is suitable for recharge.
- Full-scale basin initial infiltration rates (based on 50% of measured field-scale testing infiltration
rates) are estimated at 19.5 feet/day.
- Long-term infiltration rates (based on 50% of full-scale basin initial infiltration rates) are estimated
at 9.8 feet/day.
Test Start Sep-10-2018 - Relatively high infiltration rates are representative of the permeable vadose zone sediments
(sand, gravel) encountered in adjacent exploratory boring EX-4
Test End Sep-24-2018
- No significant fine-grained silt/clay deposits were encountered in EX-4, which was drilled to
Basin Dimensions (L x W) (ft) 29 x 28 Wildwood Creek Basin 151 feet-bgs. Depth to water in MW-3 was 103 ft-bgs after 6 days of testing and rose to
Average Water Height (ft) 3.0 South Mesa Barrier Test Site within 99 ft-bgs at the end of testing (after 14 days of infiltration).
2
Infiltrating Area Basin Bottom (ft ) 960 " ) X Y Boring EX-4 - While long-term estimates consider expected clogging of the basin bottom from SWP water,
actual long-term rates will be dependent on the specific site recharge goal and implementation
2
Infiltrating Area Basin Bottom + Walls (ft ) 1,270 Peizometer PZ-3 of a basin maintenance plan.
Total Water Added (gallons) 4,040,929
Recommendations:
Total Water Added (acre-feet) 12.4
- Pilot scale infiltration test is recommended to identify potential site vadose zone storage capacity
High (ft/d) 45.8 constraints due to recharge mounding and the influence of the South Mesa Barrier.
Infiltration Rate
Low (ft/d) 32.2 - Prior to pilot testing, installation of monitoring well west of the South Mesa Barrier is recommended
(Constant-Head) to confirm groundwater storage benefits from managed aquifer recharge at this location.
Average (ft/d) 39.0
Infiltration Rate High (ft/d) 31.2
(Falling-Head) Low (ft/d) 28.3 SMWC Hydrant ´ 0 400 Feet Figure 11
Full-Scale Basin Est. Initial Infiltration Rate (ft/d) 19.5 Wildwood Creek
Full-Scale Basin Est. Long-Term Infiltration Rate (ft/d) 9.8 Basin

Yucaipa Sustainable Groundwater Management Agency - January 23, 2019 - Page 55 of 137