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4. The system has built‐in telemetry to provide real‐time notifications of (a) low‐water
pressure from the water source or (b) exceedances of low‐water and high‐water
level thresholds in the test basin.
5. The system precludes the need for Valley District or the contractor to provide daily
monitoring of flow volume and pond height.
6. Redundancy of flow meters at the hydrant connection and on the 1‐inch and 2‐inch
final discharge piping ensures that volumes entering the pit are reliably tracked.

As shown on Figure 3, the conveyance system includes a totalizing flow meter, backflow
prevention device, and hand valve (to be supplied by the water agency that owns the
hydrant). Water would be conveyed from the hydrant by a combination of 3‐inch diameter
fire hose to an engineered manifold made with rigid steel or PVC pipe. A 3‐inch diameter
flexible fire hose is needed to maintain water pressure over the distances (generally several
hundred feet up to 1,000 feet or more) and head differences to be encountered from the
nearest hydrant to the test basin. General water conveyance routes from the nearest
hydrant (if available) to each site are shown on Figures 1 and 2. The 4‐inch manifold
separates the flow into three individual pipes (one 2‐inch diameter pipe and two 1‐inch
diameter pipes) set at varying depths. The setup shown on Figure 3 allows for flow into the
test basin to be automatically controlled to maintain ponded water depths between 2 and 3
feet. A totalizing flowmeter, hand valve, and float valve would be installed on each 1‐inch or
2‐inch pipe to track and control flows to the test basin. The three individual flowmeters can
be used to verify flows from the single fire hydrant flowmeter.

The three end pipes would be tied together in a “basin tree” with a steel gravity base that
sits on the bottom of the test basin. As shown on the diagram, the test basin area covered
by the basin tree is only 180 square inches (or less than 0.1 percent of the total infiltrating
area of a 30‐foot by 30‐foot basin). The system would also be equipped with high and low
water level sensors and telemetry to communicate if water levels fell below 1 feet or
exceeded 4 feet. Additionally, a low‐pressure sensor upstream of the pressure regulator on
the 4‐inch manifold would provide an automated warning if pressure from the fire hose
dropped below a certain threshold, indicating that the water source itself or the fire hose
was compromised and not able to provide water to the test basin.

1.7. INFILTRATION SYSTEM MONITORING ACTIVITIES

The telemetry built in to the engineered water conveyance and flow control system
minimizes the need for onsite monitoring. Nevertheless, documentation of flowmeter
readings for each test basin and maintenance of the systems will be needed. We understand
that staff from Valley District and its partner agencies would be able to conduct daily site
visits to record flowmeter readings and basin water levels. An example field data worksheet
(and associated chart showing vertical infiltration rate calculated over time) is provided in
Appendix E. Under such a scenario, monitoring by the contractor of the flow control system
at a given investigation site would occur only once during the two‐week test.

Final Infiltration Test Work Plan for
Thirteen Investigation Sites
Yucaipa Valley, CA 6 TODD GROUNDWATER

Yucaipa Groundwater Sustainability Agency - March 14, 2018 - Page 58 of 226