Monthly Tech Talk Topics
What is GIS?
Geographic Information Systems. GIS is a tool used to map assets such as water and sewer lines, fire hydrants, manholes, valves, pumps, and more. Each point in a GIS database provides information regarding the size, material, maintenance history, location notes, etc. and can be used to implement an Asset Management Program. The District has used GIS for several years and staff continues its innovation to incorporate its use within our programs and operations. The CCSD recently switched GIS platforms to Diamond Maps, a tool developed especially for water and sewer utilities. Some of the ways staff utilizes GIS is to map and detail activities related to water leak repairs, manhole inspections and maintenance, and lines jetted or repaired. The Utilities Department recently purchased four refurbished Samsung tablets to enable operators to access GIS in the field, update features in the system, and track daily activities. Diamond Maps also includes a Work Order feature which can be used to assign activities to individual operators, such as valve exercising or lift station maintenance. In addition, GIS can also be used to create maps which can be provided to contractors or other agencies to assist those parties in performing work on or near CCSD infrastructure. Maps can also be created to help the community, Board, and staff visualize other data relevant to the District, as discussed in the Utilities Report presented in the January 21, 2021 regular Board agenda packet..
Dynamics of the San Simeon Wells and the Sustainable Water Facility
This month’s topic describes three scenarios of the San Simeon Creek lower watershed: a typical water year with adequate recharge, a dry year with above-normal drawdown, and a dry year with SWF operations. Currently, the CCSD is pursuing a permit to operate the SWF in dry years to prevent a reverse gradient which could result in percolated wastewater and seawater intrusion into the freshwater portion of the San Simeon Creek basin. Without the SWF, production at the San Simeon Wells would be drastically curtailed or even halted, putting undue strain on the sensitive Santa Rosa Creek basin.
Variable Frequency Drive (VFD)
Why does it seem like whenever we talk about specifying new pump equipment, we insist on considering adding a VFD controller? In a nutshell, it saves money.
Special thanks to Nikola Tesla in the late 1800’s for inventing the alternating current (AC) motor. Jump to today, the simple electrical theory for variable frequency drive in pump applications is that changing the electrical frequency will change the pump speed. The typical example is the frequency of 60 Hz can be lowered to 50 Hz. This would reduce the pump speed by 20 percent. Reducing the pump speed would reduce flow and pressure nominally but would reduce power usage by an exponential power of 3. For example, reducing the pump speed by 20 percent would reduce power usage by almost 50 percent!
In addition to energy savings, VFDs extend the life of pumps by keeping equipment running at maximum efficiency. For example, the force of torque on a pump is reduced at start-up, preventing excess wear on cold start applications. This also provides flexibility and control for operators by allowing for paced activities such as chemical dosing.
Santa Rosa Wells
The majority of the CCSD’s water is supplied by the San Simeon wells with Santa Rosa Wells (SR) 3 and 4 serving as supplemental sources to rest the San Simeon wells and aquifer during periods of peak demand, usually in the dry season. Typically, use of the Santa Rosa wells is similarly balanced to protect the integrity of the pumps and equipment at each site. However, of these two SR Wells, SR4 is used the majority of the time due to its more consistent water quality. Due to SR3’s proximity to the creek and the influence of that surface water on the quality of water extracted, this well is only brought online when Santa Rosa Creek is dry or nearly dry. Thus, it typically remains offline from about December through April of each year. While offline, the treatment plant still executes automatic backwash cycles monthly or bi-monthly to keep the filter media of the treatment plant wetted. This is why minimal water processing is recorded each month at this site.
In the late fall of 2018, SR3 was taken offline when review of operational data revealed it was not performing optimally. SR3 has remained offline since then due to borderline finished water quality. The CCSD is committed to providing the best achievable water quality to its customers, especially in light of the current pandemic. The SR3 well treatment facility consists of media filtration and disinfection and various analytical equipment. Modifications to this facility have been made in an attempt to improve water quality, such as cleaning out mixing vessels and testing/calibrating analytical equipment. These modifications have required running the well to waste to protect the quality of water sent to customers during installation and repair. SR3 serves as an important piece of the CCSD’s water supply portfolio and is needed to most effectively manage the use of other District well sites. Staff will continue to pursue bringing this plant and well site back online. Future updates regarding the status of this effort will be provided to the Board as information becomes available.