The Colorado Department of Transportation (CDOT) Peak Period Shoulder Lane (PPSL) project encompasses 10 miles of a new third travel lane for eastbound I-70 between the US 40/I-70 interchange at Empire Junction and east Idaho Springs in Clear Creek County, Colorado.

Matrix Design Group, as a subcontractor to HDR, is responsible for:

• Drainage hydrology and hydraulics

• Water quality

• Floodplains

• Stormwater management plan

Matrix worked with CDOT’s David Singer, Andria Schmid, and Neil Ogden—and the HDR design and environmental team—to integrate storm drainage improvements into the project.

The project included the following stormwater objectives:

• Integration of the sediment control action plan into the site design for water quality improvements

• Replacement or lining of critical culverts

• Existing culvert capacity analysis

• Floodplain encroachment analysis and HEC-RAS modeling

• Scour analysis at proposed retaining walls

• Hydraulic performance of proposed water quality features

• Drainage design for proposed bridges

• Flow spread at proposed retaining walls

• Construction activities erosion control plan

Throughout the project, Matrix participated in technical team meetings and presented the project to local community officials.

Services included:

  • Hydrologic Modeling and Analysis
  • Stormwater Infrastructure Design
  • Water Quality Analysis
  • Floodplain Map Revisions (CLOMR, LOMR)
  • Construction Documents