Mile High Apartments will bring 382 new apartments units to a location in Denver just minutes from the downtown area. The new development is located next to the Rodolfo “Corky” Gonzales Branch Library off of Colfax Ave, and kitty-corner to Sports Authority Field at Mile High.
The project had a number of challenges including a limited footprint, corrosive soils, and a high degree of treatment needed to meet water quality standards from the City of Denver.
To address these issues engineers from Harris, Kocher & Smith designed a stormwater detention system consisting of 388 LF of 120” polymer coated corrugated metal pipe (CMP) in a double manifold, 3 barrel configuration. The system contains (5) 120” weir plates, (2) trackracks, (5) 36” risers, (24) 120” bands/gaskets, and (5) stubs.
To meet the treatment requirements, an 8’x11’ Stormwater Management StormFilter vault with (24) 27” cartridges was placed downstream of the detention system. The StormFilter cartridges are filled with ZPG media, a proprietary blend of zeolite, perlite, and granulated activated carbon that target organics, soluble metals, and other pollutants.
In this part of Colorado storage and treatment is typically managed using above ground ponds with biofiltration swales. The lack of space for such elements required engineers to manage these requirements below ground. Using a large diameter pipe (120”) allowed for a large volume of storage in a small footprint.
Contech designed the detention system with a series of internal orifice plates and weirs to control targeted release rates and drain down times specified by local drainage requirements. Using the detention system to control release rates in this way allowed Contech to place the StormFilter in a downstream configuration which provided the most economic treatment option.
The highly limited footprint was a unique element of this project. The detention system underwent multiple design iterations until the final layout was acceptable. Pipe material requirements were also a unique element of this project, but having a poly coated CMP option allowed Contech to provide an underground detention system in an area where soil conditions sometimes prohibits the use of aluminized pipe.
Contech also provided a long-term life cycle analysis (25 years) for the StormFilter system to give the owner a better understanding of long-term maintenance cost of the system.
AGL Construction installed this system. A Contech representative was present for the preconstruction meeting and visited the site multiple times over the course of the 4 week installation period. The installation was described as being “textbook.”