If you need French drain installation in Longview, WA, ask where the water will go before you ask how long the trench will be. Most of the city is flat, diked and pumped, so there is often no natural downhill for a pipe to run to.
We make the 25-minute trip up I-5 from Woodland and look at the lot in the wet season whenever we can, since January shows what August hides.
Landscape Drainage in Longview, WA: Flat Ground, Shared Ditches and Runoff From Above
Longview's lowland is a drainage problem with a ceiling. The soil is mostly Caples silty clay loam, which puts the winter water table 1.5 to 2.5 feet from the surface, and NOAA's normals give Longview about 21 inches of rain in November, December and January alone. A French drain there is limited by its outlet, not the shovel: the trench can only run as deep as the point it drains to.
That outlet is often shared. Consolidated Diking Improvement District No. 1 runs 35 miles of ditches and 7 pump stations for the city, and its FAQ says discharges must meet City of Longview or Cowlitz County stormwater rules. We confirm what is allowed with the city and the district before we design to a ditch or street drain.
Columbia Heights has the opposite trouble: water arrives from above. The district's interior levee along Pacific Way catches hillside runoff and pumps it to the Columbia, so what a hillside lot sheds ends up in the same system. Curtain drains and swales above the house matter more there than a deep pipe.
On the older streets we also look at what is already buried: original downspouts that may still empty at the foundation, and street-tree roots, which find perforated pipe. We route lines away from big trees where we can.
What Our French Drain Installation in Longview, WA Includes
The build follows the method on our landscape drainage and French drain page: a locate call, the outlet picked first, perforated pipe in fabric-wrapped drain rock, and a test before backfill. Roof water goes in its own line through downspout drainage. When the trench is closed we restore the lawn with new sod, and on hillside lots the drain behind a retaining wall is part of the same plan.
When the Rivers Run High: Designing for Longview Winters
In December 2025, floodwater closed Longview streets including Ohio Street and 46th Avenue, and FEMA's data lists Cowlitz County in the declaration for those storms. In a flood no yard outlet drains freely, and no French drain changes that. Ours are built for ordinary heavy winter rain, and we say plainly where a lot's elevation limits what a drain can do.
What Changes the Price of Drainage in Longview
A ditch outlet at the property line costs less than a long run to a street connection. Hillside lots add trench depth and slope access, and hand digging near street-tree roots takes longer than machine work. Sod and bed restoration is a separate line on your written estimate.
