Page 58 - Yucaipa Sustainable Groundwater Management Agency - Yucaipa SGMA
P. 58

Infiltration Test Results









 Note: Flow rates into the basin averaged 18.16 to 18.31 gpm
 (below minimum threshold of digital paddle meter);
 thus infiltration rates were calculated based on
 meter readings approximately every two to three days.
        A                                          B






                                                                                                              E






                                                            A. Initial excavation of test infiltration basin
                                                            B. Flow control skid and temporary fencing
                                                            C. Post-infiltration potholing to evaluate
        C                                                        subsurface moisture conditions
                                                            D. Dry soil conditions below shallow silt layer
                                                                 occuring at 10-12 feet below the channel
                                                            E. Test in progress (Day 1)



                    DRY SOIL (SILT)
                10-12 FEET BELOW
                CHANNEL BOTTOM


        C                                         D




                       Conclusions:
 Test Start  Aug-06-2018
                       - Results of infiltration testing indicate that the site (within the channel) is not suitable for recharge.
 Test End  Aug-20-2018  - Full-scale basin initial infiltration rates (based on 50% of measured field-scale testing infiltration
 Basin Dimensions (L x W) (ft)  41 x 21  10th Street and Avenue E  rates) are estimated at 1.7 feet/day. Long-term infiltration rates (based on 50% of full-scale basin initial
 Test Site             infiltration rates) are estimated at 0.9 feet/day.
 Average Water Height (ft)  2.5
 " )                   - Low infiltration rates appear to be due to low-permeability clayey silt layer, the top of which occurs
 2
 Infiltrating Area Basin Bottom (ft )  960  at 10-12 feet depth. Dry soil conditions were observed below the clayey silt layer at end of testing.
 2
 Infiltrating Area Basin Bottom + Walls (ft )  1,270  Hydrant  - No fine-grained deposits were identified in EX-5 above 94 feet-bgs; fine-grained material appears
 Total Water Added (gallons)  270,060  to be associated with sediment load from natural stormflows.
 Boring
 Total Water Added (acre-feet)  0.8  EX-5  Recommendations:
  High (ft/d)  4  X Y  - Near-surface coarse-grained sediments found in Wildwood Creek at California Street, appear to have
 Infiltration Rate                limited thickness and are underlain by a fine-grained matrix associated with natural stormflows,
 Low (ft/d)  2.94
 (Constant-Head)       which limit infiltration significantly.
 Average (ft/d)  3.5   - No additional actions are recommended at this site.
 Infiltration Rate                    High (ft/d)  3.07
 (Falling-Head)   Low (ft/d)  2.4  ยด                                                             Figure 6
 Full-Scale Basin Est. Initial Infiltration Rate (ft/d)  1.7  0  400 Feet                    Wildwood Creek
 Full-Scale Basin Est. Long-Term Infiltration Rate (ft/d)  0.9                             at California Street

 Yucaipa Sustainable Groundwater Management Agency - January 23, 2019 - Page 50 of 137
   53   54   55   56   57   58   59   60   61   62   63