Improving ditches & maintenance

Roadside ditches are prevalent and required maintenance is expensive which leads to delays and potential build-up of water quality contaminants. This project will evaluate maintenance and retrofit techniques such as reshaping and planting plans to reduce long-term costs and optimally improve stormwater quality. In this project, the Washington State University – Puyallup (WSU-P) will test retrofitted ditch shapes and plant palettes for improved pollutant removal, conveyance of higher storm flows, and lower long-term maintenance effort. 


Study questions

  • Can alternative retrofit strategies mitigate pollutant loads and peak flows in roadside ditches?
  • Can alternative plant palettes mitigate pollutant loads and peak flows in roadside ditches?

Study findings

This study is on-going until April 2024.

Project tasks and deliverables

Scope of Work

Task 1: Project management

  • 1.1: Semi-annual Project Report
  • 1.2: Semi-annual Project Report 
  • 1.3: Semi-annual Project Report
  • 1.4: Semi-annual Project Report 
  • 1.5: Semi-annual Project Report

Task 2: Quality Assurance Project Plan (QAPP)

  • 2.1 Draft QAPP
  • 2.2 Final QAPP

Task 3: Site instrumentation

  • 3.1: Instrumentation installation memo

Task 4.0: Evaluating alternative planting palettes  

  • 4.1: Draft report including total effort associated with the successes and failures of the vegetation plantings.
  • 4.2: Final Report

Task 5.0: Quantifying effects ditch maintenance and retrofit on water quality and quantity  

  • 5.1: Six months raw data with semi-monthly report 
  • 5.2: Six more months raw data with semi-monthly report 
  • 5.3: Draft water quality report and presentation that includes effort associated with water quality remediation by ditch treatment a total of 12 ditch sections. 
  • 5.4: Final water quality report

Task 6.0: Communication of findings

  • 6.1: Draft report of complete study findings 
  • 6.2: Final study report with complete appendices and Excel file of all QA/QC'd data collected over the project 
  • 6.3: Stormwater Work Group presentation and a regional stormwater related conference or workshop 
  • 6.4: Draft SAM fact sheet