Drainage structures and hydraulics - DS

Drainage structures and hydraulics installation requirements.

Grate Inlet on Catch Basin - Type 2 (DS-2)

This plan may be used when flows dictate a larger pipe than a normal grate inlet structure can handle. It also works well if there are a number of pipes converging at a location, or when pipes are entering at odd angles. The Unit H of a Grate Inlet Type 2 is grouted directly into a Flat Slab on top for a Catch Basin Type 2. The photo shows this application on a 48" catch basin.

Grate inlet on catch basin surrounded by dirt - DS-2

Due to this item being a hybrid of different precast units, frame and grate, a special provision is required. Description should include the diameter of the catch basin, measurement and payment shall be per each.

View Grate Inlet on Catch Basin plan sheet (PDF 54KB)

Download the Grate Inlet on Catch Basin WinZip file (ZIP 178KB)
(WinZip file contains the following file formats: .dgn, .dwg files)

Manhole Ring and Cover for Bridges (DS-6)

This drawing depicts a manhole used to gain access into a box girder bridge cell.

Manhole ring and cover on a bridge - DS-6

When developed, this former standard plan was the only source of information on the fabrication of access doors. Now, manufactured access doors are readily available and this plan is no longer needed. It is being retained, primarily to provide information when an existing bridge manhole requires repair.

View Manhole Ring and Cover for Bridges plan sheet (PDF 230KB)

Download the Manhole Ring and Cover for Bridges WinZip file (ZIP 614KB)
(WinZip file contains the following file formats: .dgn, .dwg files)

Download free Adobe Acrobat Reader
Download free evaluation version of WinZip

8,683 animals crossed the Snoqualmie Pass East Project area

as recorded by WSDOT and partners in 2020 and 2021.

46% increase in Amtrak Cascades ridership to 251,000 passengers

in 2021 compared to 172,000 in 2020.

Nine wetland and stream mitigation sites across 32.7 acres added

to our monitoring program in 2021 to help offset climate change impacts.