The North Diversion Channel collects and conveys over 50 square miles of rural and urban watershed in Albuquerque and discharges a design peak flow of 44,000 cubic feet per second to the Rio Grande through three water quality structures referred to as the bathtub, stilling basin, and embayment. Between the stilling basin and embayment was an earthen weir referred to as the equipment crossing. Weston was retained by the Albuquerque Metropolitan Arroyo Flood Control Authority (AMAFCA) to complete the construction documents for reconfiguration of the North Diversion Channel Bathtub.
The bathtub is a lowered portion of the channel constructed to convey flows beneath an existing railroad bridge. This 5-foot deep dip in the channel consistently fills with nuisance flows, does not evacuate, becomes anoxic, and concentrates pollutants. Plug flow displacement of this volume has produced fish kills and contaminated the Rio Grande. The river supplies both drinking water for over 6 million people and irrigation use of 2 million acres of land. Our work included the design of structural concrete modifications to the existing channel, geotechnical analysis of the underlying soils, and overall design of site grading, erosion control, and water quality system improvements.
A physical modeling effort by the University of New Mexico (UNM) determined the overall dimensions of improvements to the bathtub and equipment crossing. The EPA has specifically identified this portion of the channel as requiring modification. The UNM modeling report was used to create a set of construction drawings, specifications, and bidding documents. In addition, a Stormwater Pollution Prevention Plan (SWPPP) was also prepared. Weston subcontracted several firms to provide geotechnical, structural engineering, SWPPP preparation, and daily construction observation services.
Weston performed the high-level construction oversight services for AMAFCA: review of submittals, requests for information, change orders, and pay applications. Responsibilities also included conducting weekly on-site progress meetings, reviewing daily inspection reports by a subcontractor, and tracking project budget.