Groundwater Collection Via Subsurface Drains

Location

Entiat, Washington

Client

Inter-Fluve, Inc. (Prime)
Yakima Indian Nation (Ultimate Client)

Project Description

GSA conducted shallow aquifer saturated hydraulic conductivity testing and saturated and unsaturated flow modeling to evaluate groundwater capture volumes via a shallow collection drain. Shallow groundwater collected by the proposed drain would be directed to back-channel salmon spawning habitat along the Entiat River.

The water flow modeling was used to evaluate potential drain collection volumes as a function of subsurface hydraulic conductivity, drain line depth and diameter, and drain line distance from the main river channel. Model results indicated that the groundwater collection line should capture 0.05 to 0.5 gallons/minute per foot of drain, depending on subsurface conditions and design. Recommendations were made for optimizing groundwater collection volume with modification of drain line placement and size.

Project Highlights