Littleton preservation panel presses to stabilize Slaughterhouse Gulch flume as Englewood moves forward with City Ditch piping

City and Englewood utilities staff told the Littleton Historic Preservation Commission at a study session that the City Ditch piping project will place a new pipeline beneath Slaughterhouse Gulch and that a steel flume there, built in the 1940s, is structurally degraded and faces safety risks.

The presentation, given by Stephanie Ellis, an engineer with Englewood Utilities and project manager, and by Littleton public‑works staff including Ryan Grimroth, deputy director of Littleton Public Works, described project goals, schedule and a consultant condition assessment of the Slaughterhouse Gulch flume. "Our goal is to have a fully piped system between Chatfield Reservoir and the Allen Water Treatment Plant," Ellis said, describing benefits that Englewood expects from piping the ditch: better source water quality, reduced pumping and chemical treatment, and fewer stormwater inflows into drinking‑water supply.

The nut of the commission's concern is the future of the Slaughterhouse Gulch flume and adjacent, now‑abandoned sections of City Ditch. Staff presented three broad options and a lower‑cost stabilization alternative: (1) remove the flume as part of Englewood's project (Englewood would cover most removal costs under the current intergovernmental authorization); (2) repair and maintain the flume so it can remain functional; (2a) stabilize the existing structure in place (a lower‑cost preservation‑minded option); and (3) dismantle and relocate sections for display or museum conservation. Roy (city staff presenter) summarized the consultant's repair estimate: "the work ... $640,000 over 10 years was to get the flume back into full working order. So water flowing through it, not leaking, structurally sound, all those kinds of things." The lower‑cost stabilization option was presented as about $153,000 over 10 years.

Project context and timeline

Staff said the City Ditch is one of Colorado's earliest irrigation canals and that Englewood owns and operates the ditch between Chatfield Reservoir and Harvard Gulch Park in Denver. The City Ditch piping project seeks a continuous, piped conveyance from Chatfield to Englewood's Allen Water Treatment Plant; piping would replace mixed open channel and pipe reaches and reduce the utility's need to pump and treat lower‑quality South Platte River water. The project was included in Englewood's water master plan in 2020; preliminary and final design steps occurred in 2022–2024, and Englewood issued an RFP for construction in February 2024. Staff said construction is planned to begin in summer 2025 and the contract shows a project completion window in 2026. Several easements and agreements must be finalized before construction proceeds in the Slaughterhouse Gulch area.

Staff outlined four legal/parcel instruments for Littleton to consider: (a) an Intergovernmental Agreement (IGA) with Englewood covering responsibilities during construction and preservation commitments; (b) a temporary construction easement granting Englewood contractor access for staging and trenching; (c) a permanent easement that would establish the new pipeline corridor and describe allowed activities; and (d) a quitclaim deed that, once recorded, would transfer ownership and maintenance responsibility for the abandoned ditch “dog‑leg” area (the purple area shown in staff maps) to the City of Littleton. Staff said Littleton City Council was scheduled to consider some or all of those agreements on July 15 to allow work to begin this summer.

Condition, costs and safety

Presentations and photos from the consultant assessment showed rust, missing anchor bolts in abutment concrete, and footing piers with undermined concrete at Slaughterhouse Gulch. Staff noted Englewood has already stabilized at least one footing after the assessment. Staff said removal costs would be covered largely by Englewood under the currently authorized plan, while repair to return the flume to full functioning condition was estimated in the consultant report at roughly $640,000 over a 10‑year window. The staff‑added stabilization‑only alternative (option 2a) was roughly $153,000 over 10 years. Costs to dismantle and relocate portions of the flume rose with the size of the section moved.

Staff also identified a tree mitigation payment (about $216,000) that Englewood would pay Littleton under the proposed agreements to offset removal of park trees affected by the new alignment and bank stabilization work. Staff said the State Historical Fund (History Colorado) offers preservation grants (the larger grant program can award up to about $250,000) but that such grants are competitive and typically require local historic designation to qualify.

Commission discussion and recommendation

Commissioners raised safety concerns if the flume is left dry and accessible to children, asked whether the structure has a documented history of incidents (staff said none were known), and debated preservation philosophy. Commissioners and staff agreed a preserved flume has stronger interpretive value when left in place with the adjacent ditch, rather than being removed and installed as an isolated museum trophy. Commissioners said they had not been given sufficient lead time on the item in prior Council presentations and requested earlier consultation in the future.

After discussion the Historic Preservation Commission signaled a clear preference for option 2a (stabilize the structure in place and defer major investment) as the interim recommendation and said it was strongly opposed to outright removal (option 1) and to wholesale relocation of the flume without further study (option 3). Commissioners asked staff to return with more detailed preservation, security and funding options before Littleton executes final agreements that would relinquish ownership or allow permanent removal.

Next steps

Staff said Littleton staff will bring the necessary easements and agreements to City Council on the schedule discussed so Englewood can begin construction; areas where the new pipe ties into the existing ditch will have to wait until the annual ditch season ends (water use typically runs April–October) and staff projected flume removal, if it occurs as part of the construction, to happen in late 2025 or early 2026. Historic Preservation Commission members asked to be consulted early on any commemoration or interpretation plans and for at least 60 days' notice before final council action affecting preservation options.

The commission's interim advice to staff: do not agree to the removal option as currently authorized; pursue stabilization in place (option 2a) while staff and preservation planners investigate grants and interpretive approaches and return to the commission and council with refined cost, scope and security proposals.