Denver Water is looking into moving some of our operations buildings to the corner of 40th Avenue and Clayton Street. As part of this project, we are taking important steps to responsibly manage the vegetation on and around the property. 

Denver Water, working in coordination with the city forester, recently completed a detailed assessment of the trees inside the site and along the surrounding rights of way. This review found that many of the trees are in poor condition, are potentially affected by the emerald ash borer beetle or have become unsafe due to years of neglect. For these reasons, some trees must be removed to protect public safety and to meet city requirements. 

During this work, you may see temporary sidewalk closures while an arborist completes heavy pruning of the trees outside the fenceline along Clayton Street. At this time, there are no plans to remove healthy trees in the public right of way. Only trees that are clearly dead or hazardous will be removed. 

You will also see tree removal activities inside the property. Many of these trees are in poor health and need to be removed for safety or because they conflict with the proposed site plan. Once construction is complete and irrigation is restored, Denver Water plans to replant more trees than are being removed, creating a healthier, more resilient ecosystem for the community. 

We expect to begin tree pruning and removal in the next week, and the work will last approximately one week. 

Denver Water will make every attempt to complete this project as quickly as possible; however, as with any construction project, unforeseen circumstances, such as weather conditions, material shortages and crew availability, may extend the completion of work.   

For more information, contact Denver Water Customer Care at 303-893-2444, Monday through Friday, from 7:30 a.m. to 5:30 p.m.  

If you have questions about the emerald ash borer beetle, or the City of Denver’s “Be A Smart Ash” program, call the city forester’s office at 720-913-065, or visit BeASmartAsh.org.  
 

During our initial assessment of the property, we discovered small pieces of old concrete debris on the grounds that contain traces of paint with asbestos. This material appears to be left behind from past activity on the site, long before our ownership. Although we did not cause this condition, we want to assure you that we are taking full responsibility for addressing it safely, carefully and transparently.

In December 2025 and through February 2026, you may notice workers on the property conducting a controlled removal and cleanup of these materials. This work will be performed by licensed environmental professionals who follow all state and federal health and safety regulations.

We want to be absolutely clear: there is no risk of asbestos exposure to neighbors or the surrounding community during this activity. The material will be handled in a manner that prevents it from becoming airborne. Protective measures will be in place throughout the entire process to ensure everyone’s safety.

This is the first step in the process to prepare the site for potential future construction. As new members of this community, transparency, safety and respect are our top priorities. We are committed to being good neighbors and to ensuring that all work on the site is conducted responsibly and in partnership with the people who live closest to it.

In addition to a pre-demolition study, Denver Water hired consultants to conduct two environmental site assessments (ESAs). Previous owners also conducted ESAs, which Denver Water’s consultants used to help develop the current ESAs.

A Phase I ESA is a research-based environmental investigation used to determine whether a property has potential contamination from past or present uses. This typically includes historical research into previous property uses; site visits; interviews with owners, operators or occupants of the site; and a regulatory review (e.g., existing local, state or federal agency records). 

A Phase II ESA is conducted only if the Phase I ESA finds potential environmental concerns. It includes physical sampling (e.g., soil, groundwater and soil-vapor samples) and laboratory analysis to determine whether contamination is actually present. A Phase II ESA can also identify next steps, such as remediation, voluntary cleanup or no action.

Environmental Impact Studies are required by the National Environmental Policy Act (NEPA) when a project involves federal action, such as funding, permits or the use of federal land. They typically focus on the broad future impacts of a project (e.g., wildlife, air quality, traffic, noise), whereas Phase I and II ESAs look for existing contamination. 

Denver Water hired Olsson Inc. to perform a Phase I Environmental Site Assessment (ESA) for the proposed Denver Water operations complex located at 525 E. 40th Ave. Based on the findings in the Phase I assessment, Denver Water retained Olsson to conduct a Phase II ESA at the site. 

In October 2025, a team from Atlas Technical Consultants, a subcontractor for Olsson, specializing in asbestos, inspected the building that is currently on the property. During that inspection, they found asbestos-containing materials and lead paint that were left behind from past activity on the site.

The Phase I ESA identified the following:

• The property is located inside the Vasquez Boulevard/1-70 Superfund area. 
• It also has an unverified underground storage tank (UST) and another UST that is listed as “still in use” due to a lack of records related to the UST. 
• In the past, the site was used by Western Electric, which may have handled equipment with polychlorinated biphenyls (PCBs). These chemicals were used in electrical equipment, hydraulic fluids and other industrial products. 
• Old homes were also once on part of the property, so things like buried debris or asbestos-containing building materials could still be in the ground. Even if they are not currently visible, asbestos-containing materials may present health risks. Consequently, as an added precaution, our demolition contractor will excavate up to 3 feet below the surface to verify that any remnants from previously demolished structures do not contain materials of concern.
• Earlier testing found some chemicals in the soil and groundwater — detailed in the Phase II ESA bullets below— that were within approved levels. 
• The findings in the Phase I ESA prompted Denver Water to conduct a Phase II ESA to identify if any remediation of voluntary action was necessary. 

The Phase II ESA identified the following:

• Soil sampling indicated the presence of metals, including arsenic, barium, chromium and lead. None of the compounds detected in soil exceed applicable standards.
• Of the soil samples taken, only one area showed any signs of petroleum-related chemicals (called TPH-DRO and TPH-ORO). These chemicals come from things like diesel, oil or other fuels. Concentrations of these chemicals were below the required cleanup limit.
• Groundwater samples detected the presence of five metals. Of these, only the concentrations for arsenic and lead were slightly above the respective EPA maximum contaminant levels. Neither of these metals require action. 
• Note: While identified arsenic levels in both soil and groundwater exceed EPA standards, Colorado has naturally occurring high levels of arsenic. As such, Colorado Department of Public Health and Environment has issued state-specific guidance. Arsenic levels detected at the site do not exceed this state-specific guidance and do not require remediation
  
   

The pre-demolition site assessment identified small pieces of concrete debris that contained traces of paint with asbestos, left behind from previous site activities. Beginning in December 2025 and continuing through March 2026, Denver Water’s contractor, Hillen Corporation, conducted remediation activities, which included safely removing and disposing of these materials. Our contractors completed this work March 10, 2026.

• The asbestos remediation plan was approved by the Colorado Department of Public Health and the Environment. The agency is also responsible for ensuring the asbestos removal work is complete and meets all applicable local, state and federal health safety standards. 
• The underground storage tanks that were abandoned in place are being remediated and removed, with oversight from the Colorado Department of Oil and Public Safety.
   

Denver Water is committed to being a good neighbor before, during and after construction, which includes completing projects quickly and efficiently, while working with the surrounding community. 

This includes:

• Sharing project updates via our e-newsletter, mailers, website and social media channels.
• Providing updates at neighborhood meetings as needed or requested.
   

Please reach out to Denver Water Customer Care (303-893-2444) or email our community relations team (WaterUDoing@denverwater.org) with any questions, feedback or concerns.