The Greens at Ventana Canyon condominium homes was experiencing a high frequency of breaks in their water distribution system.Riley conducted an assessment of the current water distribution and determined that poor initial construction practices were the reason for frequent waterline breaks throughout the property and proceeded with a full system redesign. Riley conducted hydraulic modeling of the new system using EPANET and prepared design drawings and specifications.The new system design was updated to meet current drinking water system design guidelines and best practices for operation and maintenance.
ACUITY Environmental Solutions is providing groundwater remediation services and subcontracted Riley to assist with engineering design of a new groundwater extraction well and pumping system. Riley designedthepumpand piping system (civil, mechanical, and electrical) to extract the groundwater and pipe water into the existing treatment system. The new groundwater well serves as an addition to an existing system of remediation wells. The additional groundwater well serves as an upgrade to the existing remediation system, increasing the output of treated groundwater. Riley assisted with the pump selection, pipe sizing, and appurtenance selection to safely convey the flow to the existing equalization tank.
Client:Chee Family Residence / Ranch Hands MinistryChurch
Location: Leupp, AZ
–6000+ feet of waterline
–5500+ feet of sewer line
The access to clean and reliable potable drinking water on the Navajo Nation has been a longstanding issue and has hindered development and growth. To help address these issues at the community scale, Riley is working with community members in Leupp, Arizona to upgrade an existing water well system that was primarily intended for livestock and agriculture use to also includeresidential potable uses. The new water system design will require retrofitting the existing well, integrating a treatment system and designing thewater distribution and wastewater systems.
The Town of Oro Valley stormwater utility department has been experiencing maintenance and repair issues throughout the town’s drainage infrastructure.The Town determined the need toupdate the drainage criteria manual to account for the unique desert hydrologic conditions such as flash floods and sediment transport. The Town relied up on the experience of Riley’s senior engineers who haveextensive experience in southwest desert hydrology & hydraulics and geomorphology to improve upon the currentmanual by incorporating engineering methods and practices specific to the region.
The Rosemont Project Watershed Model (RPWM) is a HEC-HMS based watershed model that was created for the Rosemont Copper project in Pima County to comply with requirements set forth by the Arizona Department of Environmental Quality. The HEC-HMS model uses data from a dense network ofsite–specific rain gages and stream gages located throughout the site. The RPWM will be used to estimate potential impacts that the project may have on downstream runoff. Riley is tasked with the calibration and implementation of the RPWM, using site-specific rain and stream gage data to estimate potential impacts and mitigation effortsthat the proposed mine development may have on downstream flows.
Barrel Canyon and Davidson Canyon are ephemeral regional watercourses in Pima County that are subject to intermittent surfacewater flows and flashy runoff events. Riley was contracted to conduct baseline surveys of various locations to characterize vegetative and geomorphologicalconditions (i.e., vegetation strata sampling, photographic record, sediment gradation analyses, LIDAR surveys) prior to the proposed construction of the Rosemont mine.The baseline conditions were assessed on an annual basis to determine if there were any naturally occurring patternswhich may be impacted by the mine.
SRK Consulting is providing mining-closure services for a confidential site in Arizona and utilized Riley for designing surface stormwater control structures (i.e., channels, spillways, culverts and stilling basins) associated with reclamation atfour sites around the mine. Multiple design options consisting of varying spillway and channel armoring typeswere evaluated at each of the four sites.The multiple design options included evaluation of a wide range design flows ranging from the 100-year flood event to the Probable Maximum Flood eventto minimize risk to the surrounding community while restoring hydrology to pre-mining conditions.Tradeoff analyses were performed,considering factors such ascapital costsand risk mitigation,allowing the client could make confident decisions moving forward into final design and construction.
An inactive large mining site has significantly altered the natural watercourse and landscape over the course of its mine life. In order to permanently close the site, it must be reclaimed in a manner that is environmentally responsible, restores surface flows to pre-mine conditions, and is safe to the public and surrounding communities. As part of the reclamation efforts, surface stormwater control structures (channels and spillway) are being designed for floods ranging from the 1,000-year event to the Probable Maximum Flood event to mitigate flood risk to neighboring communities. Of particular concern for this projectis the increasing uncertainty of climate change which is being accounted for in the design of the stormwater control structures. A multi-criteria analysis matrix was developed to evaluate the feasibility of the design options, providing the client with a safe and cost-effective approach for reclamation.
Location: San Xavier District, Tohono O’odham Nation, Arizona
(Project “stats” off to the side):
-6,000 ft of Channel and Berm
-215 acres of floodplain modeled
–24” D50Rock Riprap Armoring
The natural watercourse of several braided washes caused significant incising and erosion of theexisting containment earthworks which led to onsite waste rock stormwater comingling with offsite stormwater. Achannel and levee system was designedto contain the waste rock runoffand safely divert offsite stormwater around the waste rock dump.The levee was armored with large riprapto protect against the sediment–laden highly erosive flowsthat occur onsite. In-depth hydrologic and 2D hydraulic modeling was performed to estimate peak flows and design the levee system. The end product for the client was a cost effectivedesign using on-site materials that complied with requirements set forth in the Section 404 permit issued by the U.S. Army Corp of Engineers.