Lemmon Valley Estates Flood Protection

Terraphase served as the prime consultant for Federal Emergency Management Agency (FEMA) map revision and Waters of the U.S. (WOUS) delineation related to a proposed 34-acre development located southeast of the Military Road and Lemmon Drive intersection in Lemmon Valley, Nevada. The property is impacted by an unchannelized portion of Golden Valley Wash and includes areas mapped within the FEMA Special Flood Hazard Areas (SFHAs). Accurate floodplain mapping was essential to assessing the development potential of the site and addressing misclassifications based on outdated FEMA data.

Scope of Services

Terraphase performed a comprehensive hydrologic evaluation using HEC-HMS to calculate site runoff and estimate retention basin requirements for the 10-day, 100-year storm event. A detailed review of FEMA SFHAs and flood profiles was conducted to identify discrepancies between outdated flood mapping and current topographic data. Our team prepared a HEC-RAS hydraulic analysis for both corrected effective and proposed conditions and coordinated with the project design team to support floodplain revision efforts.

Additional work included environmental site assessment (ESA) compliance evaluations and preparation of a FEMA Conditional Letter of Map Revision (CLOMR) report and submittal.

Notable Accomplishments