Cottonwood Drive Stormwater Improvements Project

Construction on this project is scheduled to begin in September 2017. Contact Kraig Olason, Senior Planner at Whatcom County Public Works with questions at (360) 778-6301.
Project Update (9/15/17): The Cottonwood Drive Stormwater Improvements project is underway and on schedule. Iverson Earthworks, LLC has been hard at work excavating the area for the new stream channel, which meets up with the existing channel, and grading the surrounding slopes. Geotextile fabric was placed within the channel and topped with streambed gravel.  An area was excavated and prepared for the placement of the inlet pipe and catch basin structure. Next week, we will be placing the catch basin and inlet pipe. The next step will be to remove a section of the existing pipe and add a new section for the outlet that will tie into the catch basin.


Problem Statement:

Regular flooding occurs throughout the wet season.The existing drainage inlet into the marine outfall at Cottonwood Drive is easily clogged with debris. Flooding occurs when flow entering the outfall is restricted during large rainfall events. Drainage is poor between Birch Bay Drive and the escarpment located just water-ward of Morgan Drive. Floodwater collects in this area and sits for much of the winter. Frequent flooding from the poorly-designed inlet creates ponding and hardship for some landowners.

Project Goals:
 
The following elements were considered when developing the proposed project:
  1. Minimize flooding in the Cottonwood South Neighborhood by improving inlet performance
  2. Realign current stream channel to limit bank erosion and provide improved entry into the inlet
  3. Acquire drainage easement and improve access to new inlet for maintenance needs
Project Description:

The current inlet alignment is not optimal for efficient flow, and erosion of the east bank is undermining the steep slope and overlying vegetation. A new stormwater inlet will be installed just upstream of the current inlet, which includes an emergency overflow. Drainage water will be conveyed into the outfall pipe if the main inlet becomes plugged or congested. Additional improvements include re-aligning the stream and providing rock armoring on the east bank to improve its stability. Native plantings will be installed following the construction project and maintained by Whatcom County until fully established.

Project Duration and Schedule: 

This project is scheduled for September of 2017 and will take an estimated three weeks to complete.



Flooding problem on Birch Bay Drive

Project update postcard sent to nearby residents in July 2017


Construction Year: 2017

Engineer: Tetra Tech Inc.

Contractor: Iverson Earth Works

Construction Contract: $83,550

Documents: