Why a construction crew is back in the Soapstone Valley

by Marlene Berlin

Construction work is under way in the Soapstone Valley for the first time since DC Water wrapped up the bulk of its sewer rehabilitation project in 2024.

This time, it’s for a different project. It’s happening here, between Linnean Avenue north of the park and Soapstone Creek:

And the reason it’s been an active construction zone since February is the DC Department of Energy and Environment’s Linnean outfall and gully restoration project.

DOEE wants to steer stormwater down a preset path engineered to slow the water’s flow and resist erosion. The water is coming from a 20-acre drainage area, some of which ends up in storm sewers and pours from an outfall at the top of the gully. The other source is surface water, which follows the street before it is dumped into the valley below.

The red arrow on the DOEE site plan indicates stormwater flow from the surface. The green arrow is pointing to a stormwater outfall toward the valley.

DOEE completed a similar project at the same site in 2015, but it was compromised when a giant tulip poplar fell and redirected much of the stormwater. Lessons learned from that project are being applied to this one. The replacement structure is more substantial in the use of boulders and stepping pools.

DOEE’s Matt English invited me to visit him at the site on Wednesday. Watching the backhoes work to place the boulders and tree materials was quite enthralling.

The structure is a series of pools with cascade rock banks to prevent erosion of the steep terrain. At the bottom of the largest cascade structure is a tangle of tree trunks. That, officially, is called “wood toe protection.”

Matt English explained in an email that its purpose is “to replicate logjams in nature” and further prevent erosion. His email included this photo as an example:

A naturally occurring logjam

Most stormwater will flow down one channel (the blue arrow in the site plan above). The channel marked in purple is for overflow, and English said it will be of use only when the rainfall is in excess of a 100-year storm event. In the mid-Atlantic and factoring in climate change, that would be more than 9.8 inches in 24 hours.

At the site, English told me that while the project is scheduled to end in July, it could be finished in June and perhaps even sooner. Much depends on the weather.

In the meantime, a good spot to watch the crew at work is from the Soapstone Trail near the Audubon Terrace dead-end. The project is federal EPA money being put to good use and managed well by our local government.