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both sides of the ramp. Signage would include, but not necessarily be limited to “Slow
Down, Speed Bump Ahead” and “Work Ahead” signs.

1.5. POTENTIAL WATER SOURCES

A direct connection to a local fire hydrant (or water from the State Water Project [SWP]
pipeline) is the preferred method to supply test water. The use of a hydrant (or SWP water)
precludes the need for onsite water storage and provides significant positive pressure in the
water conveyance system. A positive‐pressure water conveyance system is more reliable
and manageable than a gravity‐drained conveyance system using an onsite water storage
tank. Potential water retailers include YVWD, WHWC, and SMWC. Locations of the hydrant
nearest to each test infiltration basin (if applicable) are shown on Figures 1 and 2. A water
meter would be rented from the respective water company. Costs would include a
refundable meter rental deposit, meter use fee, and water use fee.

1.6. WATER CONVEYANCE AND FLOW CONTROL SYSTEM

Based on (1) review of lithologic logs for sites with existing exploratory borings, (2)
observations made during the site reconnaissance, and (3) results of historical infiltration
testing conducted by the USGS at the Wilson Creek Basins (Moreland, 1970), vertical
infiltration rates from investigation site to investigation site could range from less than 2
feet per day (feet/day) up to possibly 15 feet/day. This equates to test water needs ranging
from about 13,000 gallons per day (gpd) up to 100,000 gpd, or about 9 to 70 gallons per
minute (gpm). Higher infiltration rates are expected in basins underlain by coarser‐grained
sediments (i.e., within existing larger flood control facilities, Oak Glen Creek, and Yucaipa
Creek). Lower infiltration rates are expected in basins underlain by finer‐grained sediments
(e.g., on currently undeveloped sites and within the smaller flood control basins in the
northwest portion of the basin).

To accommodate the potentially large range in test water needs, a direct connection to
pressurized source of water for the test (i.e., fire hydrant) is preferred. Additionally, a
robust, automated engineered water conveyance and flow control system is desirable.

Figure 3 shows a process flow diagram for a recommended water conveyance and flow
control system. The system is described in further detail below and provides the following
benefits:

1. The flow rate is automatically controlled, providing a high range of discharge rates
to match variable infiltration rates during testing and from site‐to‐site.
2. The flow rate range is controlled by adjustment of the pressure regulator setting
and hand valves to accommodate variable pressure from different water sources.

3. No water storage tank is needed, except for sites with no pressurized water source;
having no onsite water storage tank results in a smaller work area footprint and less
fencing.

Final Infiltration Test Work Plan for
Thirteen Investigation Sites
Yucaipa Valley, CA 5 TODD GROUNDWATER

Yucaipa Groundwater Sustainability Agency - March 14, 2018 - Page 57 of 226