Colorado Springs, CO
Galloway is providing full planning, civil site engineering and survey services for this 153-acre residential project developed by Challenger Homes, Inc. This low-impact design (LID) subdivision will include 485 lots consisting of single-family and paired patio homes.
Galloway provided innovative design solutions for the required stormwater detention. A low impact development (LID) solution was implemented to utilize the existing sandy soils on the site and reduce the required detention volumes of the sub-regional detention pond. Small roadside bio-retention cells were utilized to capture the water quality event volume and allow it to infiltrate while larger storms were captured in a traditional storm sewer system and piped to the sub-regional detention facility. Galloway worked closely with the City of Colorado Springs from concept to full implementation of the design as the City had never permitted such a large-scale LID.
In addition to the on-site LID system, Galloway designed a 7.5-acre-foot sub-regional detention pond to implement a master planned detention facility and ensured that both the drainage criteria manual and the MS4 permit requirements were met. A master plan was prepared for the development which utilized EPA-SWMM to model the runoff for the site in multiple storm events. The model was used to show that the water quality event was accounted for and to size the sub-regional detention pond due to the complex nature of over detaining on-site ponds in series.
Engineering services were also provided to construct three collector roadways to the site as well as the internal local roads. Galloway worked with the City of Colorado Springs and El Paso County to coordinate the timing of Marksheffel Road widening improvements and the effects of the widening on the proposed roadways. Galloway was able to facilitate multi-jurisdictional solutions to multiple challenges regarding the roadway design caused by steep existing grades and existing oil pipelines within the development. Galloway provided design for the development’s water and sewer infrastructure.
Galloway worked closely with the City of Colorado Springs to design and implement the bio retention cells as LID on this scale had not previously been performed within the City. Once constructed the LID will be owned and maintained by a Metro District for the development.