What Happens to Our Coastside Sewer System When There is Less Water Being Used?

VIDEO. From the Montara Water and Sewer District (MWSD) board meeting July 1st, 2021 at 7:30pm by Zoom.

Full Agenda

[pdf-embedder url=”https://www.coastsidebuzz.com/wp-content/uploads/2021/07/Agenda-30.pdf” title=”Agenda (30)”]

Discussion of Effects of Drought on Sewer Operation, Treatment and Collection System Management Challenges

The three communities on the Coastside Granada Community Services District, Half Moon Bay and Montara Water and Sanitary District share a sewer transport and treatment system owned and operated by a Joint Powers Authority (JPA) since the 1970s. In addition to gravity and collection systems owned and managed by each agency, all the sewage for these communities is treated in a centralized treatment plant facility last upgraded in the mid 1990’s and owned and operated by SAM.

Low flows in the sewer systems as a result drought and water conservation efforts has caused many changes to the O&M of the Coastside sewer systems including increased root growth requiring extra cleaning. Low flows are also causing debris build-up requiring extra flushing, increased percentage of BOD per gallon of sewage treated which caused more corrosion and negatively affects treatment bacteria.

SAM is studying how more concentrated sewage needs a higher level of treatment, and the plant can benefit of more equalization and equipment redundancy to ensure sewage is treated to a save level and can even retreat sewage which may not meet discharge requirements after a first pass through the plant. This increase in BOD ratio is likely be a contributing factor to why SAM is seeing inflow spikes at the plant have been much higher than seasonal spikes observed 5 years ago and has resulted in some discharge violations and potential fines from the State. Recently SAM has hired aspecial consultants to assistem them with researching options and possible different methods to try to manages these issues, and provide recommendations for short term and long term solutions.

The impacts to MWSD are significant. The extra cleaning efforts (as much as doubling the time and frequency of cleaning required) because of the increased time and costs to clean out the roots and solid debris and wipes from the system which can cause more SSO (sewer system overflows). Additionally, the sewer flow is more sluggish and becomes septic which causes increase odors (rotten egg smells) and hydrogen sulfide gas production which leads to sulfuric acid attack on sewer pumps wet wells, maintenance ports and pipes which fail sooner due to corrosion, rust and deterioration.

One significant action MWSD can take is to help in this problem is to promote composting and worm bins for food waste, increase restaurant grease trap inspections, and encourage people not put food down their garbage disposal or into dish washers drains. Also Strongly discouraging flushing so-called “flushable wipes”. These do not break down in the sewer system and hang up on any sharp surface or turn and is a leading cause of sewer spills and damage to our environment.

Additionally, the District’s budget is reduced is by the decrease in Sewer Service Charge revenues due to the mainly flow based assessment system.

More Drought Posts on Coastside Buzz

High and Dry in Pacifica

Lacking Water, Growth Must Stop

Gregg Dieguez’s InPerspective on Coastside Buzz

Montara Water and Sanitary District (MWSD) Meetings ~ 1st & 3rd Thursdays @ 7:30pm

Author: Coastside Buzz

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