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2. INVESTIGATION SITES AND TEST METHODOLOGY

2.1. INVESTIGATION SITES

Figure 1 show the locations of the eleven investigation sites in the Yucaipa Basin for which
infiltration testing was completed. Site information is summarized in Table 1, including the
assessor’s parcel number, test basin location relative to previously‐established Yucaipa
Subbasin boundaries (Geoscience 2014a), regulatory jurisdiction, geographic coordinates,
water source, and site directions.

The eleven investigation sites include undeveloped parcels and storm detention
basins/channel reaches along Oak Glen Creek, Wilson Creek, and Wildwood Creek. Sites are
owned by the San Bernardino County Flood Control District (5 sites), City of Yucaipa (5 sites),
and South Mountain Water Company (1 site). All sites are located within an approximately
3‐mile radius of downtown Yucaipa, California.

Six investigation sites (“SBCFCD Permit Sites” in Table 1) are located within stream channels
(Wilson Creek, Oak Glen Creek, and Wildwood Creek) or existing storm detention basin
facilities under jurisdiction of SBCFCD. All six sites are located on parcels owned by SBCFCD
except for the Wildwood Creek Basins, which are owned by the City of Yucaipa.

Of the five sites not under the jurisdiction of SBCFCD, four investigation sites are owned by
the City of Yucaipa (Tennessee Street Basins, Chapman Heights Basins, Dunlap Channel, and
a parcel south of Wildwood Creek near California Street adjacent to EX‐5). One site is owned
by the South Mountain Water Company (adjacent to exploratory borehole EX‐7).

2.2. INFILTRATION TEST METHODOLOGY

Infiltration tests involved the temporary construction of an approximately 1,000‐square‐foot
2
(ft ) test infiltration basin, installation and connection of a flow control system (skid) to a
local fire hydrant to automate filling and maintenance of a constant ponded water level, and
monitoring of added water volumes over an approximate 2‐week testing period.

Testing was conducted at two investigation sites at a time, with site setup and test initiation
staggered one week apart. This process was repeated as needed to complete twelve
infiltration tests at the eleven investigation sites. The field program design provided the
following advantages: (1) the contractor was on a fixed weekly schedule for test basin
excavation, equipment mobilization/demobilization and monitoring activities, and (2)
materials and labor (including fire hose, manifolds, basin trees, and traffic ramps/signage)
were required for exactly two sites for the duration of the project.

Infiltration Testing at Eleven
Investigation Sites in the Yucaipa
Basin, Yucaipa Valley, CA 4 TODD GROUNDWATER

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