Skip to page body Home About Us What's New City Government City Services Community Visitors Business How Do I...

City News

News Review
City Council to Review Proposal to Require Sewer Lateral Inspections
Posted Date: 8/26/2014

Private Lateral v250

Sewer Lateral Ordinance
City Council Meeting
Monday, September 2, 2014
City Hall
26 Corte Madera Ave
Mill Valley CA, 94941

Looking to protect the long-term integrity and safety of the sewer system in the City of Mill Valley, the Mill Valley City Council is set to review a proposed ordinance at its Sept. 2 meeting that would require an inspection of private sewer laterals, which connect individual properties to the main sewer system, in four instances:

  • When a property owner submits a building permit application for improvements valued at $50,000 or more over a three-year period. The City currently requires a sewer lateral inspection when a property owner submits a permit application that involves new plumbing – a new sink or toilet, for example.
  • When a property is sold.
  • When a sewage overflow, malfunction or another public health threat occurs at a property as determined by the City Engineer.
  • When the City is doing a road or sewer main improvement on a resident’s street. For instance, the City is in the midst of an estimated $13 million, five-year upgrade of its sewer system.

The Sewerage Agency of Southern Marin (SASM) board approved a model ordinance earlier this year and is encouraging all of its member agencies to adopt it. For the ordinance to become law in each sewer district, 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 introduce the ordinance on September 2, and would potentially adopt it at the October 6 meeting. The SASM board itself already approved a model ordinance and is encouraging all of its member agencies to adopt it.

In a report issued in June, the Marin County 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.”

Protecting Sewer System

inflitration + h2OCity Manager Jim McCann said the ordinance has two critical goals:

  1. To improve efficiency and operational integrity of the SASM-wide sewer system and the wastewater treatment plant, which is operated under contract by the City and is located on Sycamore Avenue
  2. To enhance environmental quality, specific water quality of groundwater, creeks and the Bay.

During rainy winter months in particular, a significant amount of rainwater seeps into cracks in privately owned laterals, increasing the load placed on public sewer pipes and making it more likely that the larger system will fail.

Groundwater and stormwater flowing into the sewer system is called "infiltration and inflow" (I&I) in sewer parlance. The flow from private sewer laterals accounted for as much as 36 percent of the groundwater and stormwater seeping into the overall sewer system, McCann said.

The normal quantity of sewage that flows to the wastewater treatment plant is approximately 2.3 million gallons per day. This volume increases more than 10 fold to almost 30 million gallons per day during peak storm events.

“The system is perforated,” McCann told the Council in an introductory discussion about the ordinance at its August 4 meeting. “We’ve got a significant desire to reduce that INI volume. This has been a priority of the Council and SASM for quite some time.”

Public Works Director Jill Barnes said that I&I from private sewer laterals has a huge economic impact on the overall sewer system as the additional flows must be collected and then run through a costly treatment process before being pumped and discharged to the Bay.

“This huge amount of I&I also puts us at risk for overflows,” she added.

Mayor Stephanie Moulton-Peters noted that the City paid as much $1.6 million in fines in the wake of a sewage overflow in 2008 caused in part by extreme flow volume to the treatment plant.

“The costs of not addressing this are significant in terms of dollars, risk and environmental quality – this is great that this ordinance has come to us,” she said.

McCann added that the Public Works department continues its extensive overhaul of streets and sewer pipes throughout the City, noting that there are many different avenues being taken to significantly reduce I&I and that the proposed ordinance will add new tools in this ongoing effort.

“The main sewer pipes are certainly a part of I&I but without addressing the private laterals, we’ll never get a significant reduction,” he said.

What Other Agencies Are Doing

The proposed ordinance is in line with what has been approved by a number of agencies in the Bay Area. Most recently, the Ross Valley Sanitary District unanimously approved 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 so-called “point of sale” ordinances that require lateral inspections when a property is sold, as do a number of East Bay agencies and municipalities, including those in Albany, Berkeley, Piedmont, Oakland and Emeryville.

The SASM ordinance’s proposed 180-day “grace period” requires an inspection of the lateral before a home sale is finalized, but does not require the repairs be made prior to the transfer of property. This approach does not delay real estate transactions. Once the City or SASM member agency receives the sewer service lateral inspection report, it determines whether repairs/improvements are needed within 180 days.

“We’re not going to get in the middle of their real estate transaction,” said City Councilman John McCauley, the City’s representative on the SASM board.

In response to concerns from the Marin Association of Realtors, the proposed SASM ordinance has no requirement to complete repairs before title transfers, a key distinction from those of other agencies.

Comments, Questions & Input

There are a number of ways for 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:

  • Tuesday, September 2, 7 pm – City Hall
  • Monday, October 6, 7 pm – City Hall

Send written comments via mail: City Manager, 26 Corte Madera Ave., Mill Valley, CA 94941 or email Please write "Sewer Lateral Ordinance" in the subject line.

Proposed Private Sewer Lateral Ordinance

Frequently Asked Questions

1. What is a sewer lateral?
A privately owned pipe that conveys sewage from a building to the City’s collection system usually located beneath the roadway fronting the property. The sewer lateral includes all pipes and fittings from the outer face of the building served to the connection into the City’s sewer main, including the connection itself. The property owner is responsible for maintaining the sewer lateral.

2. What is Inflow and Infiltration (I & I)?
 INFLOW means any water other than sewage that is directed into the City’s collection system through roof drains, yard or area drains, or any other source of storm or ground water. INFILTRATION means water other than sewage that enters into the City’s collection system through cracks, breaks, open joints, or other deficiencies in laterals or in the City’s system. Inflow and Infiltration are commonly referred to as I & I in the sewer industry.

3. Why is the City proposing to adopt a sewer lateral ordinance (Ordinance)?
As a result of l & I, the sewer collection system and treatment facilities are overburdened, leading to unnecessary costs for collection, treatment and discharge of large volumes of I&I. These excessive volumes place our system at risk for sewage overflows into the creeks and the Bay. These overflows degrade the environment and pose a risk to the health and safety of the public and can lead to significant fines.

4. Who would the Ordinance impact?
The Ordinance would impact owners within the City of Mill Valley who are selling or buyers who are purchasing a property with a connection to a City sewer main. It would also impact owners at the time the street or sewer into which the lateral connects is scheduled for rehabilitation. In addition, it would impact owners who obtain a building permit for work valued at $50,000 or more. Finally, it would impact owners whose sewer lateral is overflowing or clearly deficient and otherwise causing a public health threat.

5. How would the Ordinance affect a property owner?
The City would require that the owner provide an Inspection Report when triggered by one of four events:

  • Transfer of property (point-of sale).
  • City road or sewer main capital improvement projects on a street into which the sewer lateral connects.
  • Building Permit applications for improvements valued at $50,000 or more.
  • Overflow, malfunction or other public health threat as determined by agency staff.

An owner would hire a licensed plumber to inspect the sewer and prepare an Inspection Report. Upon review of the Inspection Report, if deficiencies are found in the lateral, the City Engineer would issue the owner a Notice to Repair and establish a time period of 180 days for the owner to make the improvements.

6. What type of deficiencies will the City Engineer require an owner to repair?
Defects including displaced joints, open joints, root intrusion, substantial deterioration of the line, cracks, leaks, inflow or infiltration or extraneous water, root intrusion, grease and sediment deposits or other conditions likely to increase the chance for blockage of the sewer service. Downspouts or area drain connections that allow rainwater to groundwater to enter the sewer system are not allowed and would need to be disconnected.

7. How will the City verify that the repairs are adequately completed?
Upon completion of repairs the owner would schedule an inspection with the City. The Owner’s licensed plumber would perform a water or air pressure test of the sewer lateral observed by City staff to demonstrate its acceptable integrity.