Mountlake Terrace public works officials on April 24 outlined results from a multi-year, data-driven inspection campaign for the city’s wastewater pipes and described next steps for repairs and targeted maintenance.

The city has used a Sewer Line Rapid Assessment Tool (SLRAT) to score pipe segments from 0 (worst) to 10 (best) and to prioritize cleaning and further inspection. Public Works Director Gary Shymek and maintenance staff presented an overview of about 3,249 SLRAT inspections covering roughly 144 miles of sewer and reported that 94% of measurements returned fair-to-good scores (7–10) while 6% were poor or blocked.

The SL R AT results show 761,460 linear feet inspected; staff identified roughly 91,513 feet (about 12% of the system) requiring cleaning based on scores of 4 and below. Staff said targeted cleaning and follow-up video inspection (CCTV) let crews focus on problem segments rather than jetting every line on a 5–7 year cycle. Rex Fishbaugh, who leads the SLRAT inspections, told council the city’s approach concentrated jetting and CCTV work on the lowest-scoring quadrants and then scheduled repairs by risk and consequence.

Why it matters: staff said the assessment-guided approach reduces wasted effort, lowers the chance of missed blockages and reduces the risk of overflows to creeks. Based on staff estimates presented to council, cleaning only the recommended trouble segments over the last three years would cost roughly $92,000–$183,000 compared with $761,000–$1.5 million for jetting the entire system, yielding an estimated assessment-driven savings of $669,000–$1.3 million. Staff also estimated the focused program conserved roughly 2.7–4.0 million gallons of water versus citywide blind jetting.

What staff will do next: Shymek and Rex said crews will continue to prioritize “red” (0–3) scores immediately for jetting, follow with CCTV to document structural condition, and then recommend lining or replacement where necessary. The presentation said pipe lining is used where feasible to extend life and avoid full excavation, but full replacement is still required where pipe condition precludes lining.

Council questions focused on the practical impacts for neighborhoods, how the quadrant-average method addresses isolated poor segments, and whether the city can require or educate homeowners about items that cause blockages. Staff said red-score segments are generally addressed within days because of the risk of backups. They also described outreach and inspection practice that often lets staff determine whether a backup is a homeowner-side issue or a public-main issue before homeowners pay for private repairs.

Staff emphasized several implementation points: continued SLRAT scoring and CCTV to generate a data baseline for an asset-management software system; coupling scores with consequence-of-failure to set repair priorities; and returning to council with methodology and cost estimates for lining versus replacement when particular pipe segments are flagged for structural repair.

Ending: Councilmembers thanked staff for the briefing and asked for future reporting that shows the repair methodology, timing, and how lining decisions will be made once CCTV documentation is complete.