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Infiltration Test Results

Silt/Clay

A B

E

A. 4" fire hose / YVWD fire hydrant in background
B. Post-excavation / fencing setup (Day 1)
C. Test in progress (Day 3)
D. Test in progress (Day 4)
C C D E. Post-testing - hard silt/clay layer shown in upper 3 feet

Conclusions:
- Results of infiltration testing confirm/indicate that the site is favorable for recharge.
Test Start Sep-03-2018 - Full-scale basin initial infiltration rates (based on 50% of measured field-scale testing infiltration
rates) are estimated at 10.5 feet/day. Long-term infiltration rates (based on 50% of full-scale basin
Test End Sep-17-2018
initial infiltration rates) are estimated at 5.2 feet/day.
Basin Dimensions (L x W) (ft) 32 x 32 - While long-term estimates consider expected clogging of the basin bottom from SWP water,
YVWD
Average Water Height (ft) 2.5 Hydrant actual long-term rates will be dependent on the specific site recharge goal and implementation
2
Infiltrating Area Basin Bottom (ft ) 960 of a basin maintenance plan.
- High infiltration rates are representative of almost exclusively coarse-grained deposits (sand/gravel/
Oak Glen Creek Basins
2
Infiltrating Area Basin Bottom + Walls (ft ) 1,270 Test Site (Excavated) cobbles) identified during excavating and in EX-2.
Total Water Added (gallons) 1,974,600 X Y Boring EX-2 - Infiltration test results for excavated and bermed test basins within Oak Glen Creek Basin highlight
Total Water Added (acre-feet) 6.1 " ) the importance removing the upper approximate 3 feet of fine silt/clay that has accumulated in the basin.
High (ft/d) 24.06 Recommendations:
Infiltration Rate - If site recharge goals are expected to exceed the operational capacity of the Oak Glen Creek Basins,
Low (ft/d) 17.86
(Constant-Head) the removal of the upper 3 feet of sediment in each of the Oak Glen Creek basins prior to future
Average (ft/d) 21.0 active recharge is recommended. Pilot-scale testing is not critical at this site.
Infiltration Rate High (ft/d) 19.7
(Falling-Head) Low (ft/d) 19.7 ´ 0 400 Feet Figure 10
Full-Scale Basin Est. Initial Infiltration Rate (ft/d) 10.5 Oak Glen Creek
Full-Scale Basin Est. Long-Term Infiltration Rate (ft/d) 5.2 Basins (Excavated)

Yucaipa Sustainable Groundwater Management Agency - January 23, 2019 - Page 54 of 137