A.   Best Management Practices: Building sites shall use best management practices (BMPs) to retain as much stormwater as possible on the property.
B.   Highway Drainage: Drainage to a state highway shall be subject to the regulations of the Idaho transportation department. Necessary permits shall be acquired by the developer.
C.   Road Drainage: Drainage to a road under the care, custody and control of the Jerome highway district shall be subject to their regulations. Necessary permits shall be acquired by the developer.
D.   Drainage To U.S. Waters Or Canals: No drainage shall be allowed from a building site directly to any waters of the United States or to any privately owned canal system.
E.   Residential Subdivisions:
   1.   All residential subdivisions shall design and construct stormwater retention facility or facilities to retain the 25-year, 24-hour rainstorm event.
   2.   The stormwater shall be detained and released over a forty eight (48) hour period or at a rate that is approved by the North Side Canal Company or by any other entity that may govern the waterway downstream.
   3.   The stormwater dischargers releasing water from their retention area shall use best management practices (BMPs) to reduce the amount of pollutants from the water. Discharge water quality shall comply with the most current regulations or standards that may apply.
   4.   The retention facilities shall also have an overflow device that can convey the 100-year, 24-hour rainstorm event, without damage to the retention facility. This structure should be designed to minimize any downstream safety problems.
   5.   Storm sewers shall be placed in a public right of way or minimum fifteen foot (15') wide easement. Easements shall also be required for the retention areas. The city reserves the right to modify the retention facilities to stay in compliance with any state or federal regulation.
F.   Commercial And Industrial Developments: All commercial and industrial developments shall design and construct stormwater retention facilities to retain the 50-year, 24-hour rainstorm event. Refer to subsection 16.34.020A3b of this chapter to determine the volume requirements. No discharge of stormwater will be allowed from these areas.
G.   Procedure For Review And Approval Of The Stormwater Management Plan:
Note: Review and approval by the city does not constitute an engineering review of project plans and calculations. The review is for the purpose of ensuring general conformance to city policies and requirements. The submitting engineer is solely responsible for the design. All submissions to the city shall be stamped by a professional engineer registered in the state.
The following shall be submitted to the city:
   1.   A topographic survey of the development showing all drainage and irrigation water conveyance systems within the area encompassed by a line two hundred feet (200') outside the property line.
   2.   Peak flow calculations, with peak flows delineated on the drawings.
   3.   Runoff volume calculations.
   4.   Plans and profiles of new or modified drainage and irrigation water conveyance systems.
   5.   Plans, profiles and calculations for stormwater retention or detention facilities.
   6.   Flood routing computations for the 100-year flood through any existing drainage conveyance systems.
   7.   Maintenance and operation manuals for stormwater facilities.
   8.   Infiltration rates where applicable.
   9.   Seasonal high ground water table elevations where applicable. This applies when the absorption of stormwater is used as a best management practice. Facilities using absorption designs shall not intercept the postdevelopment ground water table. The bottom of the facility shall have a minimum four foot (4') vertical separation from the seasonal high ground water elevation and bedrock. The four foot (4') separation between the bottom of the facility and the seasonal high ground water table shall contain a sandy loam material to treat the water prior to entering the ground water. If the best management practices are utilized to pretreat the water prior to discharge into the absorption facility, the requirement for four feet (4') of sandy loam will be waived.
The seasonal high ground water table elevation shall be established and used for the facility design. The elevation of the seasonal high ground water table shall be determined by a monitoring well established at the facility site and monitored during the high ground water season. If available, ground water records may be used to establish the probable highest ground water elevation. The high ground water elevation shall be shown on the plans and be referenced to a nearby bench mark; the latitude and longitude of the well shall be shown on the plans. If ground water is encountered during construction of the facility at an elevation higher than that shown on the plans, the facility shall be redesigned to account for the higher elevation.
   10.   Soil classifications where applicable.
   11.   Flood routing of the 100-year storm to the ultimate drainage system.
   12.   Copies of associated permits and discharge agreements.
   13.   Copy of the pollution prevention plan that is on file with EPA for the development. Prior to beginning of construction on any development site larger than five (5) acres, the developer or their representative must have a pollution prevention plan in place and must file a notice of intent (NOI) with the EPA, in accordance with NPDES (national pollutant discharge elimination system) requirements. The pollution prevention plan will include provisions for reducing sediment discharges from the construction site and tracking of mud onto roadways. A copy of this plan and the NOI shall be provided to the city prior to any site grading. Refer to 40 CFR chapter 1, section 122.26, stormwater discharges for NPDES requirements. (Ord. 994 §2, 2006)