170.21 STORM DRAINS.

   1.   The subdivider shall, at the subdivider’s expense, provide the subdivision with adequate drains, ditches, culverts, complete bridges, storm sewers, intakes and manholes to provide the collection and removal of all surface waters. These improvements shall extend to the boundaries of the subdivision so as to provide for extension by adjoining properties. Where oversize storm sewers or drainage structures are required to serve other areas of the watershed, the additional cost shall be borne by the developer.

   2.   The subdivider shall, at the subdivider’s expense, provide the subdivision with a storm sewer system to adequately handle a five-year rain storm. The system shall include culverts, ditches, intakes, manholes, or any structure deemed necessary. All such structures shall meet the City of Indianola Standard Specifications. In addition, the subdivider shall, at the subdivider’s expense, provide the subdivision with overland drainage courses and easements to adequately handle storm water in excess of a five-year rain storm and up to a 100-year rain storm. For any subdivision containing new streets, the system shall be designed by a licensed engineer registered to practice in the State of Iowa.

      A.   Each lot shall be provided with minimum six-inch diameter storm sewer service line that is a minimum of four feet below ground level, stubbed to the property line, unless the Director of Community Development determines that sump lines can be taken to an existing overland drainage area. The sump pump line shall be a minimum of one and one-half inches in diameter.

      B.   The storm sewer system line shall be made of reinforced concrete pipe or polyvinyl chloride (PVC) pipe. The sump pump lines shall be made of PVC, PVC Truss, or PVC corrugated pipe. All structures shall be built in accordance with City of Indianola Standard Construction Specifications for Subdivisions.

      C.   The storm sewer system shall be large enough to provide for anticipated extension of use to serve additional areas, as set out in Indianola Comprehensive Plan.

      D.   Storm sewer service lines shall be connected to the City storm sewer system at intakes, manholes, or directly into the City storm sewer pipe. Tapping storm sewer service lines into the City storm sewers shall be by using approved methods.

Should it not be possible to install a storm sewer service, as described above, alternate plans may be submitted for review by the City’s consulting engineer and City staff.