Reedley, CA Environmental Rules: Grading & Drainage (2026)

Grading and drainage in Reedley are governed by the 2022 California Building Code Appendix J (Grading) as adopted under RMC Title 9, Chapter 1, and the storm drainage provisions in Title 12, Chapter 2. Grading permits are required from the Building Division for any excavation or fill that exceeds the thresholds established by the California Building Code. Generally, a grading permit is needed when the work involves more than 50 cubic yards of material, cuts deeper than 5 feet, or fill higher than 3 feet. Grading plans submitted with the permit application must show existing topographic contours, proposed finished contours, drainage patterns, calculated earthwork volumes, soil erosion and sediment control measures, and the location of all existing and proposed structures, utilities, and easements. All finished grades adjacent to buildings must direct surface drainage away from foundations with a minimum 2 percent slope (approximately 2.5 inches over 10 feet) for the first 10 feet from the building, or to the property line if the distance is less than 10 feet. This foundation drainage requirement is critical in Reedley's expansive clay soils, which are common in the San Joaquin Valley and can cause significant foundation movement when soil moisture levels fluctuate. Drainage must be conveyed to approved public storm drainage facilities, street gutters, or other approved outlets and must not be concentrated onto adjacent private property in a manner that differs from historic pre-development drainage patterns. Development projects must demonstrate through engineering analysis that post-construction stormwater runoff does not exceed pre-development conditions in volume or flow rate, or alternatively provide on-site detention or retention facilities to mitigate any increase. The city may require on-site retention basins, underground storage chambers, or other stormwater management facilities for larger developments where connection to adequate public storm drainage is not feasible. Retaining walls over 4 feet in exposed height require a separate building permit and must be designed by a California-licensed professional engineer, with plans stamped and signed by the engineer showing structural calculations, drainage provisions, and foundation details. All retaining walls must include drainage behind the wall to prevent hydrostatic pressure buildup, typically through a gravel backfill with perforated drain pipe connected to an approved outlet. The flat terrain of the San Joaquin Valley, with typical gradients of less than 1 percent across large areas, makes proper site grading especially important in Reedley. Small grading errors can result in persistent ponding, saturated soils, and drainage flowing toward rather than away from structures. Property owners contemplating any site grading should contact the Building Division at (559) 637-4200 to determine permit requirements, and the Public Works Department for questions about connecting to public drainage infrastructure.