ITEM:		CONSENT CALENDAR
9.	CONSIDER Expenditure of Funds to improve cooling tower and rearing channel operations at the Sleepy Hollow Steelhead Rearing Facility
Meeting Date:			April 19, 2021	Budgeted:	Yes
From:			David J. Stoldt, General Manager	Program/	Protect Environmental Quality
				Line Item No.:	2-3-1 A General Operations Maintenance
Prepared By:			Thomas Christensen	Cost Estimate:	$11,800
General Counsel Review: N/A
Committee Recommendation: The Administrative Committee reviewed this item on April 12, 2021 and recommended approval.
CEQA Compliance: Categorical Exemption, Section 15301, Existing Facilities.

SUMMARY: Staff proposes to hire Telemetrix, a communications consultant, to install a wet bulb temperature sensor to improve cooling tower operations and a magnetic flow meter to monitor flow to the rearing channel. The equipment would be integrated into the Programmable Logic Controller (PLC) that monitors and operates the Sleepy Hollow Steelhead Rearing Facility. The cost of installation and programming is estimated to be up to $11,800 (including a 15% contingency). Work should be carried out prior to the initiation of 2021 operations at the facility.

RECOMMENDATION: The Administrative Committee recommends that the Board approve the funds for installation and integration into the PLC.

DISCUSSION: After completion of a facility upgrade in the spring of 2020, operations during summer and fall 2020 revealed two significant issues: 1) the cooling tower can warm Carmel River flow used at the facility during warm periods; and 2) debris and biofilm caused the flow meter for the rearing channel to malfunction.

1) cooling tower and installation of a wet bulb sensor

A large cooling tower was installed in 2000 with the capability to circulate about 800 gallons per minute (almost 2 cubic feet per second). This tower was refurbished in 2020, but not as part of the overall facility upgrade (the tower requires periodic maintenance). The tower works as an evaporative cooler, i.e., air is drawn into the tower through media filled with river water, a part of which “evaporates” and cools the surrounding water passing through the media. The cooler generally cools outside air by 15-25 degrees; however, afternoon temperatures at Sleepy Hollow are often in the mid-to high 90’s (°F) and there are short stretches of temperatures over 100 °F, sometimes with high levels of humidity (which reduces the effectiveness of the cooling tower).

Through monitoring of temperature sensors at the cooling tower inlet and outlet installed with the facility upgrade in 2020, it was determined that running the cooling tower fan on warm afternoons resulted in heating the river water flowing to the rearing channel through the cooling tower, rather than cooling the water. Manually turning the cooling tower fan on and off (either when on site or remotely) proved to be inefficient, as there are diurnal changes in air temperatures and humidity at the site and the time of day when these changes occur constantly.

Staff asked Telemetrix (TMX) to propose a method to automate operation of the cooling tower fan. A two-phased approach is proposed: 1) install a wet bulb temperature sensor, which measures the lowest temperature that can be achieved purely by evaporative cooling; 2) tie the sensor into the PLC and reprogram the PLC to operate the cooling tower fan based on wet bulb temperature (this is a standard industry practice for cooling tower operations).

Installation of the wet bulb sensor and linking it to the PLC would allow the PLC to automatically turn on the cooling tower fan when temperature and humidity conditions allow cooling of the water and turn it off when running the fan would heat water.

2) rearing channel magnetic meter

Flow to the rearing channel is currently monitored using a “paddle wheel” style meter that has a small paddle wheel inserted into the delivery pipe to the head of the rearing channel. The paddle wheel clogged in 2020 due to debris and biofilm and had to be removed, cleaned, and reinserted (at a cost of $500). Accurate flow measurement at the head of the rearing channel is needed to determine that flow is going to the channel and is a factor used in determining steelhead density and habitat quality. A magnetic meter does not have clogging issues because a magnetic field is used to measure flow in the pipe and there is no part of the instrument in the pipe flow.

TMX was the controls subcontractor for the facility upgrade, has extensive experience with the onsite equipment, and installed and programmed the PLC for the facility.

IMPACTS ON STAFF AND RESOURCES: Funds for this work were included in the mid-year FY 2020-2021 budget adjustment under Program line item 2-3-1 A. General Operations and Maintenance.

EXHIBIT

9-A March 20, 2021 Cost Estimate from Telemetrix

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