Page 56 - Yucaipa Sustainable Groundwater Management Agency - Yucaipa SGMA

Infiltration Test Results

A B

F

A. Initial excavation of test infiltration basin
B. Setting up flow control skid
C. Temporary fencing and 4" fire hose from
YVWD hydrant on 10th Street
C D D. Initial test basin filling (Day 1)
E. Testing in progress (Day 2)
Note abandoned pipes unearthed
during excacation in background
F. Test in progress view from north (Day 2)

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 6.4 feet/day.
- Long-term infiltration rates (based on 50% of full-scale basin initial infiltration rates) are estimated
at 3.2 feet/day.
- Relatively high infiltration rates are representative of the generally permeable vadose zone
E sediments (sand, gravel) encountered from 25 to 200 feet in adjacent exploratory boring EX-7
(located oustide of the channel south of Avenue E)
- Fine-grained silt/clay deposits encountered in the upper 25 feet of EX-7, were not encountered
Test Start Jul-30-2018 during excavation. It is possible that upper clay deposits are only located outside of
the drainage channel.
Test End Aug-13-2018 - Depth to water in EX-7 was 115 ft-bgs in 2014, similar to water levels east of the fault,
Basin Dimensions (L x W) (ft) 39 x 36 Chicken Hill Fault indicating that the Chicken Hill Fault is a partial barrier to subsurface flow at this location.
Average Water Height (ft) 2.1 - Due to its downgradient location in the Calimesa Basin, The value of this site for recharge is
contingent on potential benefits this site can provide to the Western Heights Subbasin.
2
Infiltrating Area Basin Bottom (ft ) 960 - Water level differences of approximately 300 feet across the Chicken Hill Fault indicate
2
Infiltrating Area Basin Bottom + Walls (ft ) 1,270 Hydrant the that the hydraulic connection between the site and Western Heights Subbasin is
Total Water Added (gallons) 1,451,335 10th Street and Avenue E expected to be poor. However, further investigation and/or evaluation is needed
to confirm this interpretation.
Total Water Added (acre-feet) 4.5 Chicken Hill Fault Test Site
High (ft/d) 13.44 " ) Recommendations:
Infiltration Rate - Pilot scale infiltration test with monitoring wells west/northwest of the Western Heights Fault
Low (ft/d) 12.04 Boring
(Constant-Head) EX-7 would be needed to identify potential site vadose zone storage capacity constraints due to recharge
Average (ft/d) 12.7 X Y mounding and to confirm if recharge can benefit the Western Heights Subbasin.
Infiltration Rate High (ft/d) 11.54 Chicken Hill Fault
(Falling-Head) Low (ft/d) 9.75 ´ Figure 5
Full-Scale Basin Est. Initial Infiltration Rate (ft/d) 6.4 0 400 Feet 10th Street
Full-Scale Basin Est. Long-Term Infiltration Rate (ft/d) 3.2 and Avenue E

Yucaipa Sustainable Groundwater Management Agency - January 23, 2019 - Page 49 of 137