French Drains & Drainage Systems in Tumwater, WA

Drainage & French drains in Tumwater: what to know

Tumwater’s 2022 drainage manual is built on Ecology’s 2019 stormwater manual for Western Washington, and it carries the thresholds that trigger review. We have not pinned down the figure a yard drain triggers, so we measure the soil each run would disturb and bring that number to the city as a question rather than a claim.

A drain that changes how water leaves the parcel is a grading and runoff question first. TMC 17.16.010(D) points to the stormwater standards that apply to the parcel, and those standards are read against each outlet before it is built. Runoff should never be pointed at a neighbor’s lot, and an outlet the parcel cannot hold is redrawn before the trench is dug.

Permits and rules in Tumwater

Spoil volumes come first: each run’s excavation is totaled and compared with the city’s manual. The outlet then goes to the city as a written question, and we verify whether any line reaches street right-of-way, asking whether that work needs city review. The answers and the totals stay in the job file.

Rules change and vary by parcel, so we confirm the current requirements with the city before we start.

How we approach it

Measure the soil each run would disturb before layout
Locate every roof downspout and grade low spot first
Pick an outlet the parcel holds, not a neighbor’s lot
Put any street-edge connection to the city before digging

For the full process, see our Drainage Systems & French Drains page.

Questions from Tumwater homeowners

What sets the stormwater review for a Tumwater yard drain?

The manual’s thresholds are not in our reading, so the figure a yard drain triggers is still open. We total the soil moved and any new surface, and we send both numbers to the city before digging starts.

Where may a Tumwater drain empty its water?

Onto ground on your own parcel that can take it, or to a point the city accepts in writing. A neighbor’s lot is never the planned outlet, and the choice is drawn on the site plan before the first cut.

Does a Tumwater line that ends at the curb count as right-of-way work?

A line that reaches the street edge may sit in city right-of-way, so we ask the city to confirm it in writing. The route is drawn on the plan first, and the reply is kept with the job.