NorthStar was hired to determine flow capacity and storage volumes for approximately three miles of the Arkansas Valley Conduit south of State Highway 78 and north of the St. Charles Reservoirs. The AVC Ditch provides the only storm water outlet as well as the majority of stormwater detention for approximately 1,000 lots in the El Camino neighborhood of Pueblo. The AVC Ditch was originally constructed (and subsequently abandoned) by CF&I to divert raw water from the Arkansas River to the St. Charles Reservoirs. The ditch has very flat slopes (approximately 0.1%) and therefore low capacity but yet has a very high storage volume due to its overall length and cross-section.

During development of the initial phases of El Camino (mid 1970’s), the AVC Ditch was modified adjacent to development areas to provide an on-line storm water detention facility. The flat slopes in the ditch cause significant ponding of nuisance flows. This has resulted in considerable vegetation, including large trees establishing themselves in the ditch over the last thirty years. One phase of this project included an analysis by NorthStar of alternatives to improve the ditch to eliminate or control ponding and water quality while minimizing impact to existing vegetation and storage volumes.

NorthStar also studied the undeveloped portions of the AVC Ditch downstream from El Camino to determine cost effective methods for increasing storage volumes while maintaining, as a minimum, historic flow rates. NorthStar then completed detailed design of staged on-line detention facilities that maximized the storage volume in the AVC Ditch and actually increased ditch capacity.