Page 191 - _ 180314 Special Yucaipa GSA Packet

Project Understanding

The San Bernardino Valley Municipal Water District (Valley District) and its partner agencies and
water retailers are preparing to manage its groundwater resources conjunctively with State
Water Project (SWP) water, and increase basin recharge with enhanced natural storm runoff
and recycled water to meet future demands while maintaining independence during periods of
water shortages. To‐date, Valley District has completed preliminary subsurface investigations
and prepared a Work Plan to conduct field‐scale infiltration testing at thirteen potential
recharge sites across the Yucaipa Basin Area (Basin).

The Work Plan was developed to determine the infiltration capacity of vadose zone sediments
underlying the proposed recharge areas. Infiltration testing is a critical step in evaluation of site
recharge feasibility. Specifically, field‐scale infiltration testing will help determine whether a
proposed area can accommodate recharged water at a sufficient rate to provide measurable
benefits to groundwater levels and water quality. Estimated infiltration rates can be combined
with other hydrogeologic information (e.g., subsurface stratigraphy, fault mapping,
groundwater levels, and water quality data) to prioritize potential sites, estimate long‐term
groundwater banking potential, and support preliminary design of recharge facilities.
Additionally, infiltration rates can be used to evaluate the impacts (benefits) of various MAR
projects scenarios on groundwater storage and basin perennial yield (using the basin‐wide
USGS MODFLOW model) and estimate subsurface recharge flowpaths to assess groundwater
quality changes and recovery efficiency.

Project Approach

The proposed scope of work to implement the Work Plan has been divided into four tasks,
details of which are presented below.

Task 1 – Pre‐Field Planning

Task 1.1. Schedule and Attend Pre‐Construction Meeting

Following receipt of notice‐to‐proceed and prior to mobilization of equipment for infiltration
testing, we will schedule and participate in a pre‐construction meeting with Valley District and
SBCFCD staff and other project team members. During the pre‐construction meeting, we will (1)
confirm site access for heavy machinery, (2) delineate test basin excavation limits and
dimensions, (3) confirm preferred water source, pressure, and anticipated delivery rates, and
(4) review procedures for test basin construction, soils management requirements, conveyance
and instrument setup, and site security fencing and traffic control.

Task 1.2. Refine Site‐Specific Work Plans

Key findings from the pre‐construction meeting will be used to refine the approach and
procedures identified in the Work Plan to accommodate site‐specific conditions prior to field

Proposal – SBVMWD Yucaipa Basin Area 1 TODD GROUNDWATER
Infiltration Testing of Thirteen Sites January 2018
Yucaipa Groundwater Sustainability Agency - March 14, 2018 - Page 168 of 226