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Proposal to Require Sewer Lateral Inspections
Posted Date: 7/24/2014

Update: At its regularly scheduled meeting on March 2, 2015, the City Council adopted Ordinance No. 1270 amending Chapter 17.04 of the Mill Valley Municipal Code regarding construction and installation of private sewer laterals. Click here to read the Staff Report and Ordinance.

In an effort to protect the integrity of the sewer system in the City of Mill Valley and throughout its surrounding areas, the Sewerage Agency of Southern Marin (SASM) approved a model ordinance to require an inspection of private sewer laterals, which connect individual properties to the main sewer system, when homes are resold, if they are remodeled at a value of at least $50,000 or during sewer rehabilitation projects on a resident’s street.

The Mill Valley City Council is set to review the proposed ordinance at its August 4 meeting. For the ordinance to become law in each of the sewer districts, the board of each of SASM’s six member agencies – the City of Mill Valley and the Alto, Almonte, Homestead Valley and Richardson Bay sanitary districts – must adopt it. In the City’s case, the Council will hear a first reading of the ordinance August 4, and would potentially adopt it after a second reading at the September 2 meeting. The SASM board itself already approved a model ordinance and is encouraging all of its member agencies to adopt it.

City of Mill Valley Public Works Director Jill Barnes said the ordinance is about protecting the SASM-wide sewer system and the wastewater treatment plant, which is operated under contract by the City and is located on Sycamore Avenue. Barnes said that during wet winter months in particular, a significant amount of rainwater seeps into cracks in privately-owned laterals, which then increases the burden placed on public sewer pipes and heightens the likelihood of failures in the system.

inflitration + h2OBarnes said groundwater and stormwater flowing into the sewer system, which is called "infiltration and inflow" (I&I) in sewer parlance, accounted for as much as a 50 percent increase on the overall system measured over a year.

“Damaged sewer laterals contribute to overburdening the capacity of the SASM wastewater treatment plant and (surrounding sewer pipes) … it is in the public’s interest that SASM address the I&I (infiltration and inflow) contributed by private laterals,” Wastewater Treatment Plant Manager Mark Grushayev wrote in a staff report.

"We know that (I&I) from private sewer laterals has a huge economic impact on the overall system," Barnes said. "It also puts us at risk for overflows."

Under the proposed ordinance, an inspection of a private sewer lateral would be required if:

  • A property owner submits a building permit application for improvements valued at $50,000 or more over a three-year period.
  • A property is sold.
    A sewage overflow, malfunction or another public health threat occurs at a property as determined by SASM staff.
  • A SASM member agency is doing a road or sewer main improvement. For instance, the City is in the midst of an estimated $13 million, five-year upgrade of its sewer system.

Based on an analysis of each of those four triggers – that is, the numbers from the City of Mill Valley of annual home sales, number of homes on 2013/14 Street and Sewer Rehabilitation Project and the number of sewer lateral repairs as reported through plumbing permits issued, City staff estimates that 40 percent of homes will be inspected under this required multi-pronged approach over five years.

The so-called “point-of-sale” requirement in the draft ordinance, a common feature in private sewer lateral inspection ordinances, authorizes a member agency to require that the seller provide an inspection report of the sewer lateral to the member agency when a property owner lists the home for sale.

Once the agency receives the sewer service lateral Inspection Report, it determines whether it indicates any deficiencies in the operation of the sewer service lateral and would then require repairs/improvements as needed to be done within 180 days.

In response to concerns from the Marin Association of Realtors, the proposed SASM ordinance has no requirement to complete repairs before title transfers. Despite substantial outreach from SASM, including a subcommittee featuring SASM board member and Mill Valley City Councilman John McCauley, the Marin Association of Realtors remains opposed to the proposed ordinance, citing the possibility that a sewer lateral inspection could slow down the buying process.

In a report issued in June, the Marin County Civil Grand Jury called on the county's 23 sewer agencies to require repair of private sewer laterals when properties are remodeled or sold. The new laws are often referred to as “point-of-sale ordinances.”

A number of agencies have approved such ordinances in 2014, including the Ross Valley Sanitary District, whose board unanimously approved in June an ordinance requiring that laterals be inspected when properties are listed for sale or prior to issuance of a permit for a remodel valued at $75,000 or more.

Belvedere and Sausalito also have point of sale ordinances in place, as do a number of East Bay agencies and municipalities, including those in Albany, Berkeley, Piedmont, Oakland and Emeryville.

Under the ordinance, each SASM member agency would be responsible to implement the proposed lateral ordinance. If approved, it is estimated that the ordinance would cost the City $65,000 a year. But City officials expect that figure to be dwarfed by the likely long-term savings that will come by reducing the level of I&I on the larger sewer system, and reducing the subsequent sewer overflows that could occur when the system is over-burdened.

The Staff Report and proposed ordinance will be available next week and will be posted hereSign up for eNews to have the City Council meeting agenda and links to supporting documents sent directly to your inbox.

The City Council values community participation and invites you to provide input into the proposed sewer lateral ordinance:

  • Attend one or more of the City Council’s public hearings on the ordinance. The hearings are set for: Monday, August 4, and Tuesday, September 2. Both meetings will take place at 7 pm at Mill Valley City Hall and will be webcast live and archived.
  • Send written comments via mail: Department of Public Works, 26 Corte Madera Ave., Mill Valley, CA 94941 or email Please write "Sewer Lateral Ordinance" in the subject line.