Stormwater Trunkline Condition Assessment
Project Status
To help keep area residents informed of our construction progress, we will post project updates to this site on a regular basis. Click here to see status updates.
Project Details/Neighborhood
The stormwater conveyance system includes a network of pipes (mains and laterals), culverts, ditches, and outfalls. The goal of this project is to inspect the mains including verifying pipe diameter, material, and condition. Inspections will be performed using closed circuit television (CCTV) cameras inserted into the pipes.
CCTV is a common method of inspecting and assessing the condition of pipes. A remote-controlled crawler mounted camera moves along the inside of pipes to provide an image for assessment. The CCTV results will be used to evaluate the overall stormwater pipeline condition to identify and prioritize system improvement needs.
This is the first year of a multi-year program to collect data on the condition of the stormwater system. The Initial three inspection locations include:
- Location 1 - Basin 29 – 12” to 24” diameter stormwater pipe running north/south in residential backyards (in easements) between 80th Ave SE and 81st Ave SE
- Location 2 - Basin 38 - 30” diameter stormwater pipe in residential yards (in easements) along 86th Ave SE and SE 74th Place, continuing across West Mercer Way and into Clarke Beach Park
- Location 3 - Basin 10 - 24” to 48” diameter stormwater pipes along SE 34th St, through Mercerdale Park, and along 77th Ave SE in the Town Center
- Location 4 - Basin 27 - primarily 12” diameter crossings and stormwater pipe along West Mercer Way from 4800 block south to the 5200 block
- Location 5 - Basin 28b - 24” diameter stormwater pipes along 84th Ave SE, down SE 59th Street, then paralleling a watercourse along the backsides of residents (in easements) to the SE 56th Street Landing.
- Location 6 - Basin 42 – 12 to 36” diameter pipes in 3 different segments. The first segment runs along 89th Ave SE, through side yards of residents (in easements) to SE 60th Street, then parallels a watercourse to Pioneer Park (in easements). The second segment runs along East Mercer Way next to Engstrom Open Space and Pioneer Park. The final segment is taking flow from a watercourse and routing the storm flow through side yards (with easements) to Lake Washington.
Additional sites will be added once the work at these locations is complete.
Project Timeline
Q4 2023 to Q3 2024
Estimated Budget
$190,00 for inspection
$60,000 for analysis
Contact
Elayne Grueber,P.E., Capital Project Manager, elayne.grueber@mercerisland.gov cell:206-549-1036
Status Updates
June 2024
During the first year of this program, the City has inspected and cleaned approximately 24,000 feet (nearly 5 miles) of trunkline stormwater pipes. City staff are utilizing inspection videos to document pipe conditions and pinpoint pipes requiring repairs. A majority of the pipes inspected in the first year were found to be in good condition, with only a few repair projects identified. This is an on-going program with the goal of continuing to inspect and assess 2-5 miles of pipe each year.
May 2024
Additional assessments are planned for fall of 2024.
March 2024
Photos:
1. CCTV- Video equipment in use
2. CCTV- lowering crawler camera into catch basin
The City has inspected approximately 15,000 feet (nearly 3 miles) of trunkline stormwater pipes. City staff are using the inspection videos to evaluate pipe condition and determine repair needs. Overall, the inspected storm pipes have been in good condition with minimal defects observed.
December 2023
Photo 1: Looking into a deep catch basin. Contractor setting up CCTV camera on remote control crawler to inspect the storm sewer.
Photo 2: Set up at a catch basin for CCTV inspection work.
Photo 3: Image from work van during CCTV inspection showing large roots inside of a 36-inch pipe.
CCTV inspection work has been completed on the initial three locations. Inspection results being reviewed and pipes being rated based on condition.
Additional sites are being considered for another round of inspection.
October 2023
In October, letters were sent to residents in locations 1 and 2 who have catch basins in their back yards, to notify them of the project and schedule.
Crews were out the week of October 16 to locate catch basins in Location 2.
Late in October or in November, crews will locate catch basins in Location 1.
ProVac (the contractor) will be out late October or in November to start the CCTV inspection work. This work is weather dependent and cannot be done when storm pipes are carrying a significant amount of flow. Work will continue until all locations are inspected. The schedule will depend on weather.
SW0127 location 1,2,&3 (763 KB) Location 1 Basin 29 (978 KB) Location 2 Basin 38 (1020 KB) Location 3 Basin 10 (1 MB) SW0127 location 4,5,&6 (1 MB)