27th Street Storm Interceptor Project

Web banner for 27th Street Storm Interceptor project

27th Street Storm Interceptor Project will improve public infrastructure and safety, relieving drainage and flooding issues in Five Points, the Curtis Park neighborhood and the RiNo Art District.

Banner for Phase 3 of the 27th Street Storm Interceptor project 

PHASE 3: In addition to providing flood relief in the immediate area, the new, enlarged 27th Street stormwater system will work in concert with stormwater systems along 33rd and 36th Streets to provide greater flood protection to the larger area.

This project will employ both open trench construction and tunneling methods. Tunneling will occur for the portion beneath Welton and the RTD Light Rail tracks, allowing Welton to stay open for the duration of the work.

In addition to installing a new large diameter pipe, this project will also include:

  • new ADA ramps
  • sidewalk
  • curb / gutter
  • tree planters
  • large inlets constructed on Washington between 25th and Welton to alleviate flooding in the immediate area 

Project Map

Map of 27th Street Storm Interceptor Project area

Current Impacts

Upcoming Impacts map for 27th Street Storm Interceptor projects

Crews are working on laying 84" stormwater pipe

Photo of crews working on laying 84

A stockpile of the 84" stormwater pipe being laid

A stockpile of the 84

Crews pour concrete at manhole #17

Crews pour concrete at manhole #17.

A view into the pipe installation on California

A view into the pipe installation on California.

Drone shot of project work currently occurring

A drone shot of the pipe installation on California, and the tunneling operation at 26th and Welton.

A view into the pit on California

A view into the pit on California — crews have continued pipe install, moving towards 26th & California.

Phase 3 Construction Update - 10/21/21

Status: The installation of the 84” stormwater pipe — moving from Welton to California – is going well. At the end of next week we expect curb and gutter work along California to begin, with paving to follow. During the week of November 1st some preliminary work begins across the street as crews start inlet construction along Washington Street.

Current Impacts: The intersection of 26th and California will remain closed until late November or early December. California has a soft closure (open to local traffic) from 27th to mid-block, and a hard closure from mid-block to the intersection of 26th & California. There is a soft closure on California between 26th & 25th, a soft closure on 26th (open to local traffic) between Stout and California, and a hard closure between the intersection of 26th & California to Welton. Construction closures will be limited two blocks with only one intersection closed at a time.

Unless we encounter an unforeseen safety issue causing a temporary closure, Welton will remain open at all times during construction. RTD’s Light Rail will remain open at all times during construction. Business access remains open. Please follow all suggested detour routes.

Questions?: It’s easy to reach us. Email us, text or call the hotline to get your questions or concerns addressed quickly!


The project team plans to start the open cut for pipe installation and tunnel excavation at the same time during the first or second week of August.  The open cut for the pipe installation will require the full closure of California—and then 26th—with tunnel excavation operations occurring within the same full closure on 26th. The tunneling method under Welton enables us to keep the RTD Light Rail and Welton open at all times during the construction.

During the construction, walk-up access to businesses and residences will remain open. There will be some temporary water and sewer interruptions during the work. Affected businesses and residences will be notified in advance.

Signage will clearly define and direct detour routes, and we will be sending out weekly impact / detour maps in our email updates — so be sure to sign up for these crucial emails.

Phase 2 Archive

Status: Construction was completed in Fall 2020

Sod Watering: The contractor initially watered the new sod, and now it becomes the responsibility of the property owner.

During this project we have appreciated your patience with closures, water service interruptions and all of the inconveniences projects of this type bring. Thank you for working with us along the way.

Project Map

Phase 2 map for 27th Street Storm Interceptor project

Construction Impacts

27th Street will be closed to traffic in sections up to two blocks at a time, between Arapahoe and California Streets. Traffic will be detoured onto adjacent streets as needed, but residential, business and pedestrian access will be maintained via secondary access points or through the construction zone.

Existing water lines and sanitary sewer lines will need to be relocated to accommodate the new storm sewer pipe.  Businesses and residences along 27th Street (between Arapahoe and California Streets) will have temporary water and sewer disruptions to complete the relocation work. Advance notice will be provided to those who will be impacted.

Construction Methods

Storm drainage systems are far beneath the surface of city streets, and thus require shoring of the excavation sites to ensure the safety of the workers below. There are many types and methods of shoring that have been used on previous stormwater projects — some of these methods are more invasive than others. Sheet piling and beam and lagging shoring systems are examples of shoring methods that are more invasive. Slide rail and trench boxes are examples of the less invasive shoring systems. 

This phase of the 27th St. Storm Interceptor project is far less complicated than Phase 1, thus it is likely that the contractor will be using minimally invasive shoring methods combining the use of slide rail systems and trench boxes. We do not anticipate that the contractor will need to use sheet piling or beam and lagging to complete this project, and therefore we do not anticipate any vibration issues on Phase 2.

There will be a monitoring system in place, similar to what was in place on Phase 1. Anyone with questions or concerns about vibration issues can contact the CCD project manager, Aaron McMichael, to resolve the issue.


The 27th Street Storm Interceptor project is one of several large-diameter storm drain projects to relieve drainage and flooding issues in the Five Points and Curtis Park neighborhoods and the RiNo Art District. Currently in this area, stormwater runoff drains to the South Platte River at the over-burdened 36th Street Outfall, leading to flooding during storms. When complete, the new storm drain system will connect to an existing 108-inch storm drain at Coors Field Parking Garage at Blake Street, balancing water flow between multiple systems and resulting in less flooding along the 27th and Washington Street corridors.

Phase 3 and additional future phases of the project are still in design, but the alignment is expected to run from the end of Phase 2 down California Street to 26th Ave, southeast along 26th Ave to Washington Street and continue south down Washington Street toward 20th Ave. These future phases are still seeking funding approval. 

The 27th Street Storm Drain project was first identified in the 2005 Stormwater Master Plan. This project is a high priority focus stormwater basin and was included in the 2016-2021 Six-Year Capital Improvement program.

Phase 1 Archive

Phase 1 construction began at the Coors Field Parking Garage in October 2018 and continued upstream (eastward) along 27th Street to Arapahoe. This phase was completed in June 2019.

Meeting Materials