Siena Reservoir Pump Station and Pipeline

The Late Work Package (LWP) for the remaining construction was presented to Council at the April 25, 2023 meeting and approved. The contractor moved on-site in late May and began site grading work.  The excavation for the intake and wet well are to an elevation for the drilled pier work to begin.  Shoring has been installed to allow the work for the drilled piers.  Construction is expected to take 18-24 months from May 2023 (finishing between January 2025 and May 2025).

The fenced construction area and trailer at the northwest corner of Sheridan and Lowell are associated with the Siena Project and not related to oil and gas operations.  

Additional information regarding oil and gas in Broomfield can be found on the oil and gas dashboard

The Water Resources division of Public Works is responsible for maintaining and monitoring Siena Reservoir. Siena had never been drained since it was constructed and after consulting with a dam and reservoir specialist, it was determined Siena would need to be drained in a slower manner over a longer time period than was initially expected.  The draining process began in early March and is completed to a level (approximately 12 inches remaining) to allow for construction.    It is not impeding construction at this time and will remain.  Staff has met with the Colorado Parks and Wildlife (CPW).  CPW agreed to attempt to salvage fish in late April when the water level had receded to a manageable level and when water temperatures were warmer.  Unfortunately due to the steep and wet slopes, CPW could not safely attempt a fish salvage. 

If you have any questions about the project please contact Broomfield’s CIP Project Manager Ronda Jo Ackerman Alford at

Siena September 2023


The Siena Reservoir Pump Station and Pipeline Project includes a new pump station and pipeline to convey water from Siena Reservoir to Broomfield's water treatment plant in order to assist in meeting water demands during peak summer months.

Moltz Construction was selected in early 2022 as the Construction Manager/General Contractor (CM/GC).  The CM/GC assisted with reviewing constructability, analyzing potential cost savings, and scheduling of the project.  Council approved an early work package (EWP) with Moltz at the December 13, 2022 council meeting.  The work includes procurement of long lead items (pumps and controllers), tree mitigation and trail improvements to allow for trail detours.  The early work on-site began in March 2022.  The Late Work Package (LWP) was presented to Council at the April 25, 2023 meeting and approved.

Since the size of the pump station building exceeds ten percent from the original Site Development Plan (SDP), the project required an SDP amendment.  The Amendment was completed and approved by Broomfield's Planning Department in February 2023.

The Siena Pump Station and Pipeline Project will transfer raw water from Siena Reservoir to Glasser Reservoir (raw water storage) or directly to Broomfield’s Water Treatment Facility on 144th Avenue.  Broomfield’s water demands continue to increase with growth and Broomfield needs additional raw water storage to feed into the treatment facility.  Council approved a design consulting agreement with Muller Engineering for design and construction documents on May 11, 2021.

The City and County of Broomfield (Broomfield) at the November 10, 2020 Council Meeting retained Muller Engineering Company to complete a Preliminary Design Report for the design of a pump station and associated pipeline from Siena Reservoir (Siena) to the Broomfield Water Treatment Facility (WTF). Siena is located northeast of the intersection of Lowell Boulevard and Sheridan Parkway and south of the Northwest Parkway in Broomfield with a normal storage capacity of 450 acre-feet.  The WTF is located at 4395 west 144th Avenue, Broomfield, Colorado.  

A pumping station at Siena and a pipeline will deliver water to the WTF.  The facilities would assist in meeting peak summer demands for potable water.  The anticipated capacity of the facility would be 10 to 15 cubic feet per second (CFS) and 14,200 feet of pipeline expected to be 20 to 30 inches in diameter.

Broomfield has two major water supply sources: treated water purchased from Denver Water, and raw water from both the Colorado-Big Thompson (C-BT) and Windy Gap Projects. One of the City Council’s ongoing priorities is water resource acquisition and development. This includes efforts to continue moving the Windy Gap Firming Project (WGFP) forward, acquiring water rights, and constructing new capital facilities. 

Broomfield’s Water Treatment Facility (WTF), located at 4395 West 144th Avenue, treats the raw water supplies from the C-BT and Windy Gap Projects. A CIP project to expand the WTF by 6 MGD to its current 26 MGD was completed fall 2020.  

To provide a sufficient water supply to the Water Treatment Plant (WTP) during summer when water demands are highest, additional raw water storage is needed in Broomfield. Siena Reservoir is an asset of the Water Fund and is filled by a connection to the Carter Lake pipeline. Stored water cannot be drained except through the spillway and a new pump station and pipeline is required to deliver the water from Siena Reservoir to Glasser Reservoir or directly to the WTP. The improvements will provide seasonal summer storage for the next 10 to 15 years years until the Broomfield Reservoir is needed. A map showing the location of Siena Reservoir and proposed pipeline alignment is shown here:

Siena Oct. 2022

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Siena Fence Oct. 2022

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