East of 64th Street and south of Red Bird Road in north Scottsdale, Lomas Verdes Estates is a small single-family custom and semi-custom residential subdivision of six lots on approximately 7 acres of native desert, surrounded by established residential neighborhoods. Two natural washes cross the property, making careful drainage design central to how the lots, driveways, and entry are laid out.
Working for Lomas Verdes Estates, LLC, our team took the project forward from its earlier approvals, preparing the project plans, specifications, and contract documents in 2019 and an amendment to the approved Final Drainage Report for the City of Scottsdale. We built existing and proposed condition HEC-RAS models and delineated the floodplains of both the north and south washes, and refined the grading and drainage design: regrading the entrance drive to accommodate the future half-street build-out of 64th Street, and combining the separate driveways for two lots into a single shared drive that eliminated a wash crossing, served by a new six-barrel culvert across the north wash. Updated calculations confirmed that all four retention basins meet or exceed their required volumes, with restricted orifices and bleeder pipes sized to drain each basin within 24 to 36 hours while holding back first-flush sediment. Where the south channel's velocities rose slightly above 5 feet per second, the design adds rip-rap protection to the bank, and scour and lateral migration analyses confirmed the reach is expected to remain generally stable.
The modifications maintain the original design requirements and do not change the historical points where flows enter and leave the site, and future development within the lots is prohibited from altering the washes, protecting upstream and downstream properties. Our team also prepared the Stormwater Pollution Prevention Plan under ADEQ's AZPDES Construction General Permit, defining the erosion and sediment controls, inspections, and maintenance for the roughly 4.3 acres disturbed during construction.
