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McGregor Square Passive Groundwater Management System

Location: Denver, CO

Overview:  McGregor Square is located in an older industrial area across from Coors Field in Downtown Denver. The offsite-sourced metal and petroleum-contaminated groundwater flowed below McGregor Square towards the Platte River. The contaminated water would require treatment prior to discharge into the storm system with a fee estimate of about $2 Mil for initial installation and a maintenance fee of about $20K per month, which posed a significant cost to the client. A failure of the system would result in flooding with contaminated water resulting in major cleanup and public health impacts. 


CTL|Thompson’s solution was to design a system of piping, gravel, and a vault increasing the permeability and allowing the water to flow. We worked with the client, design team, and contractor to design and implement the system. The design of the system was complex; avoiding proposed foundation elements and below slab utilities. CTL|T elicited support from state and federal regulators which received approval. The system has been operational since 2018 without issue. We have used this approach on two other projects in the area with success and consider this a possibility on other projects with groundwater issues. We believe it is beneficial to the public, clients, and infrastructure not to rely on permanent dewatering if possible, allowing the water to flow and “Let Groundwater Be Groundwater.”  The project was awarded an American Council of Engineering Companies (ACEC) Colorado Honor Award.

Services: Environmental

Other related projects:

Boulder County Justice Center

CTL|Thompson provided extensive asbestos consulting services to Boulder County related to construction projects at the Boulder County Justice Center. We performed air monitoring and in-house sample analysis by Phase Contrast Microscopy (PCM) methodology. Prior to beginning construction, we performed air sampling throughout the building and settled dust sampling within the HVAC system.  

Meow Wolf

A popular attraction in Denver that immerses visitors in other worldly art exhibits, Meow Wolf is located near I-25 and Colfax. CTL|T performed the environmental assessment, geotechnical investigation and construction observations, which included observing the installation of the aggregate piers, caissons, and structural steel framing among many other things.

Pikes Peak Heights

The property that was once designated as a construction and demolition landfill is now being developed into a new neighborhood called Pikes Peak Heights at Sand Creek. Working with Pinyon Environmental, Inc., CTL|Thompson was able to help transform this blighted property into an environmentally cleared property for almost 200 housing units. The effort earned both companies an American Council of Engineering Companies (ACEC) Colorado Honor Award.

Bel Mar Shopping Mall

CTL|Thompson played a key role in characterizing the Bel Mar Plaza site. Our Phase I Environmental Site Assessment (ESA) identified potential environmental concerns through the use of historical city directories.​ The concerns included on-site automobile maintenance facilities, underground storage tank releases, and two dry cleaners. Bel Mar, which opened in 1966 as the Villa Italia Mall, represented a major Brownfield project due to historic use. Our Phase II ESA included the installation of 15 monitoring wells in an effort to define the extent of hydrocarbon and PCE and TCE solvent contamination beneath this Brownfield site. Bel Mar now serves as a City Center for the City of Lakewood. This mixed-use redevelopment makes use of recycled building materials, green building technology and existing and recycled landscape vegetation including mature trees.

The Regency Athletic Complex at MSU Denver

The project site is a redevelopment of a major Brownfield, with both surface and groundwater contaminants. CTL|Thompson provided on-site environmental inspection services, testing, and management of both asbestos and chemical contaminants unearthed during excavation, and also successfully entered the client into the State of Colorado Voluntary Cleanup Program. The American Council of Engineering Companies (ACEC/CO) awarded CTL|Thompson the ‘Grand Conceptor’ Award at the 2016 Engineering Excellence Awards for the highly successful outcome of this project. This award is the highest engineering honor in the State of Colorado.

Metropolitan State University, Center for Student Success

CTL|T performed the environmental consulting services on this project. Our services have included a Phase I ESA and an extensive Phase II ESA consisting of environmental boreholes, test pits, and a geophysical survey in the center of the site. This means that as the contractor digs up the parking lot and starts moving earth, there are former industrial uses, and (chiefly) asbestos in the soil, which necessitate air monitoring, soil management and oversight.

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