Page 213 - _ 180314 Special Yucaipa GSA Packet

From: Edwin Lin
To: Aaron Jones
Cc: David Drewelow
Subject: Follow-up to questions concerning Yucaipa Recharge Testing Implementation
Date: Thursday, February 8, 2018 5:19:05 PM
Attachments: Todd Groundwater Yucaipa Recahrge Testing - Table 2 Project Budget and Schedule of Fees (revised February 8,
2018).pdf

Hi Aaron,
I’m writing to follow up our discussion on Monday. Specifically, you had questions about the
following items:

1. The data collection process, frequency of data recording, and overall field supervision
2. the feasibility of breaking down one test site and setting up at the new test site on the same
day

1. With respect to data collection system and frequency, the proposed infiltration system includes
flowmeter readings tied to the telemetry system, so that real-time instantaneous and totalized
flowmeter readings are accessible 24/7. However, the system does not include real-time test
basin water levels tied to the telemetry system. While the water levels in the test basins will be
controlled within a relatively tight range (+/- 2 feet), we do see a value in having real-time and
recorded measurements of water levels to confirm system functionality and to allow for more
precise calculation of vertical infiltration rates on a daily basis. David Drewelow has reviewed the
changes needed to upgrade the telemetry system to incorporate flowmeter and water level
readings and recording of data with a datalogger. The increase in costs for the telemetry upgrade
is $780 per test site (or $10,647 for thirteen sites with Todd Groundwater 5% markup) and is
recommended for addition to the field program.

2. With respect to site-to-site mobilization/demobilization days, I spoke with David Drewelow, and
we are comfortable with the proposed costs to perform the earthwork and moving of equipment
in one work day. Our costs include field crews being onsite as long as needed to ensure the
infiltration system is properly functioning (even if that goes into Tuesday). Using two field crews,
the work flow on Mondays would be as follows (1) in the morning, excavate the test basin at the
new site and de-mobe equipment at the completed site (and move equipment to the new site
with timing it to coincide with completion of excavation at new site), and (2) in the afternoon, fill
in test basin at completed site and return site to pre-disturbed grade, and start the test at the
new site.
We acknowledge that unforeseen conditions/delays could occur at a particular site that could
lead to additional work. This could be due to one of the following reasons: (1) difficult excavating
conditions, (2) site access issues, (3) increased traffic control measures/requirements, or (4)
significant increased hose length from preferred water source to recharge site. For these
reasons, I propose to add 10 hours of labor (and travel costs) for Todd Groundwater under Task
2: Intra-Site Demobe/Mobe and Testing (Sites 3-13; 11 times). This covers an additional site visit
to supervise the first site-to-site mobilization/demobilization. Additionally, we recommend
increasing the overall project contingency from the currently proposed 3 percent up to 5
percent.
I’ve attached a revised cost table that incorporates the items above. As you can see, total estimated

Yucaipa Groundwater Sustainability Agency - March 14, 2018 - Page 188 of 226