Page 19 - Yucaipa Valley Water District

Director Memorandum No. 19-057 Page 5 of 7

a perched groundwater condition. Therefore, Geoscience deepened Location #2 to make
sure that the soil materials encountered in the upper 95 feet in Location #1 was penetrated.

Geoscience also installed a piezometer to make sure groundwater levels could be
measured to assess potential perched conditions.

Based on the lithology encountered in the unsaturated zone Geoscience thought it was
prudent to have a subsidence benchmark placed and survey to detect whether hydro-
compaction would be induced when the vadose zone was saturated during the test.

Geoscience also equipped two additional wells (Location 2 piezometer and the residential
well) from their initial quote.

The additional costs for Task 3 are detailed in the attached table and are composed of
staff time, additional subcontractor costs, and reimbursables.

The total additional cost for Task 3 is $33,244.

Task 4 - Pilot Testing - Artificial Recharge Basin Construction and Monitoring

This task includes the addition of climate equipment including an evaporation pan and rain
gauge which was not included in the original estimate. The local data was determined to
be insufficient for the precise nature of this study.

The soil types were found to be much more variable across the area than initially
determined from the two instrumentation borings. The District agreed to evacuate the
basin by pumping the water into the adjacent fields so as to dry out the basin as quick as
possible. After the basin dried, Geoscience conducted additional investigations using 12
hand drilled borings to explore the distribution of soil types beneath the bottom of the basin
across the basin. Geoscience also completed seven shallow percolation tests to assess
the percolation rates of the various shallow subsurface soil types to develop an initial
estimate of potential infiltration. Based on these investigations and shallow test pits
conducted at the site with the District staff, Geoscience recommended the depth of
removal of soils for the pilot test.

The additional new subtasks completed as a part of Task 4 to date are detailed in the
attached table. The new subtasks are described in bold font. Where additional costs were
incurred on old tasks, the explanation is in bold within the description.

The total additional cost for Task 4 is $68,220.

Financial Analysis

This project is not included in the current operating budget. Funds for this project will be split
equally between the Water Division - Depreciation Reserves (02-10310) and Sewer Division -
Depreciation Reserves (03-10310).

Yucaipa Valley Water District - June 4, 2019 - Page 19 of 237