Monthly Tech Talk Topics
Evapotranspiration - July 15, 2021
In general, evapotranspiration is the sum of evaporation and transpiration. Evaporation is the process of turning liquid into vapor. Heat and atmospheric conditions cause water in our creeks to turn to vapor. Transpiration is the process of water movement through vegetation mainly through its leaves, stems and flowers. Evapotranspiration is defined as the water lost to the atmosphere from the ground surface through a combination of these two processes. This factor plays a role in water conservation through irrigation practices as evapotranspiration rates vary in regions within our County. In our area, evapotranspiration rates are generally lower than in the inland areas of the County. Consider this when you adjust your irrigation controls. This and other devices such as soil moisture meters will contribute to water smart irrigation. For more information on this topic see the link to the California Irrigation Management Information System (CIMIS). https://cimis.water.ca.gov/
Modified Ludzak-Ettinger (MLE) Process - June 17, 2021
One of the major PG&E infrastructure upgrades at our wastewater treatment plant is our aeration basin, and specifically, our Modified Ludzack-Ettinger (MLE) process. In an earlier topic we discussed how microorganisms play a large role in wastewater treatment. This discussion will summarize the heart of our wastewater treatment process.
In order to maintain low nitrogen levels in our treated effluent, we use the MLE process to target nitrogen removal.
Refer to the figure below that illustrates the MLE process within our aeration basin:
- Anoxic Zone (low oxygen zone) The first step in the treatment train is an anoxic zone. The influent wastewater serves as the carbon source for bacteria. Return activated sludge from the clarifier provides microorganisms that will also facilitate the biological treatment process.
- Aeration Zone (high oxygen zone) In this zone, the addition of air helps facilitate the breakdown of the waste solids.
- Return Activated Sludge (waste solids and microorganisms) Some sludge is returned to the anoxic zone to continue the treatment cycle (Return Activated Sludge or “RAS”). The sludge not reused continues through the treatment process and is later disposed of as solid waste. Microorganisms in RAS are “hungry” and, when introduced to the low oxygen environment, will “eat” the oxygen in the nitrate and the new carbon source from the waste solids.
When first implemented at the WWTP, the MLE process resulted in a 90% reduction in nitrates. Permanent modifications to the WWTP are required to maintain these nutrient reductions and increase process and energy efficiencies in the years to come.
Water Conservation Legislation - May 20, 2021
In 2018, landmark water conservation legislation was signed into law, although the lengthy road map to implementation has largely erased it from the average citizen’s memory. You may recall the sensational headlines about the 55-gallon per person per day limit and the false claim that Californians would have to choose between taking a shower or doing laundry. In reality, these policy laws, Assembly Bill 1668 and Senate Bill 606, work together to push Californians toward a more sustainable water future by imposing water budgets on the suppliers (that’s us) not on customers like you. Individual households and businesses will not be required to meet specific indoor and outdoor standards. These water budgets will emphasize the aggregate amount of all categories of urban water use, such as indoor and outdoor residential use, Commercial, Industrial, and Institutional (CII) use, irrigation, and water loss. Some of these standards, such as outdoor residential use, are still being developed for future implementation. Once the CCSD’s standards are set, the District will decide how best to achieve the new targets as a service area. In the meantime, the District continues to offer rebates and other water conservation programs to help customers use water wisely. Learn more by visiting us at www.cambriacsd.org/water-conservation.
In response to this legislation, the State issued a primer called Making Water Conservation a California Way of Life. It’s available online at https://water.ca.gov/Programs/Water-Use-And-Efficiency/2018-Water-Conservation-Legislation.
Fats, Oils and Grease (FOG) - April 15, 2021
Now that our collection system maintenance is fully operational, we would like to remind our community to keep the FOG out! By FOG, we mean Fats, Oils, and Grease. These are some of the most common causes of sewer system blockage across the nation and it’s true for our community as well. FOGs can come from our food service establishments, but “harmless” amounts of oil washed down the sink from our residential customers can amount to an accumulation of problems to our aging sewer collection system. Even though our Code prohibits FOG discharge in our sewer system in excess of 100 mg/L (about 1/16 of a teaspoon per liter of water), we believe these simple reminders will help tremendously.
To help prevent sewer blockages, please properly dispose of fats, oils, and grease by following these simple practices:
- Do not pour cooking oil, greasy food, dairy products, or salad dressing down the drain.
- Use strainers in the sink drains to catch food scraps and other solids.
- Do not use hot water and soap to try to wash grease down the drain. It will eventually cool and harden in the sewer lines.
- Pour cooled grease into a disposable container, cover with a tight-fitting lid and place in your freezer. Once contents are frozen, toss in the garbage.
- Mix cooking oils with absorbent material such as coffee grounds or cat litter. Place in tight lidded container and dispose in garbage.
- Wipe or scrape food particles from pots, pans and dishes into the trash can prior to placing them in the dishwasher or sink. (This also saves water by skipping the rinse!)
- Wipe excess fats and grease from pans with a dry paper towel and toss it in the garbage.
These tips will prevent grease blockage that could lead to sewage spills which could harm property and the environment.
For those in the food service establishments, please follow these same guidelines and continue to maintain your grease traps. Thank you ahead of time for your cooperation.
 CCSD Municipal Code 5.04.170.B
Inflow and Infiltration (I/I) - March 18, 2021
During the recent major storm, our Wastewater Treatment Plant saw sewer flows increase to 2.7 million gallons per day (MGD); compared with 0.452 MGD the day before the rains started. Why?
These increased flows are attributed to what we call in the wastewater industry: Inflow and Infiltration (I/I).
Infiltration is groundwater that enters sewer pipes, manholes or sewer laterals through holes, breaks, joint failures, connection failures and other openings. There is a daily component of infiltration in our sewer flows which often exhibits seasonal variation in response to groundwater levels. Prolonged rainfall can trigger a rise in groundwater levels and increased infiltration flows. Infiltration is related to the total amount of piping in the ground and not any specified water-use component.
Inflow is storm surface water run-off that enters the wastewater system from yard-, roof-, and footing drains, from cross-connections with storm drains and downspouts, and through holes or joints in manhole covers.
High I/I flows are characteristic of an aging collection system. Within the last 3 years, staff replaced several manhole lids and raised the grade of some manholes. Although these improvements reduced the inflow by over 100,000 gallons per day, we acknowledge that more will need to be done. Investigating I/I are tasks that our collection system workers will continue to undertake, and we will prioritize repairs as part of our capital improvement program.
What's Bugging us Down at the WWTP - February 18, 2021
In general, both “bugs” and wastewater get a bad rap, but they both play an important role in your daily life—whether you realize it or not. By bugs, we mean microorganisms that live in the wastewater system. All of your liquid household waste ends up at the CCSD’s wastewater treatment plant (WWTP). Wastewater treatment relies, in part, on natural biological processes to help remove dissolved suspended solids from wastewater. Much like the helpful organisms living in your gut, microorganisms in the wastewater system treat contaminants as food, helping to break down and remove them. When the population of bugs at the WWTP is upset—such as recently happened with the inundation of stormwater into the collection system—it disrupts the normal process which allows the bugs to feast. This increases the time it takes to treat and dispose of the water and may result in temporary odors.
What is GIS? - January 21, 2021
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 - December 17, 2020
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) - November 19, 2020
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 - October 15, 2020
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.