(a) 
It shall be unlawful and an offense for any person or entity to do work or cause work to be accomplished that diverts, impounds, or otherwise alters the natural flow of surface water drainage in such a manner that prevents natural drainage across an existing property, increases runoff to adjacent properties, causes damage to property, creates an attractive nuisance, or causes an unreasonable risk to the public health, safety, or general welfare.
(b) 
Any proposed project which may affect the adopted floodplain or floodway must meet all requirements as identified in chapter 7 flood damage, prevention and control.
(Ordinance 1860 adopted 4/12/2010)
(a) 
No person, firm, or corporation shall do, cause or permit to be done, the alteration of property to prevent existing drainage run-off, or patterns from entering the property in the natural course of drainage.
(b) 
No person, firm, or corporation shall do, cause or permit to be done, the installation, modification, or relocation of any construction improvement where the improvement, when completed, will impact other property. The other property may be either upstream or downstream from the property on which the improvement is to be made. The impact is primarily related to flooding of a building structure. No permit shall be issued where engineering data from a qualified professional engineer or the opinion of the city reveals that such improvement would worsen any known drainage or flooding problem.
(c) 
Any person or entity applying for a permit which alters natural grade through coverage, fill, or excavation shall be required to meet the requirements within this section. In order to provide adequate drainage away from foundations as well as minimize run-off rate to adjacent properties, the following standards shall apply to all properties which propose alteration of grade whether by an increase to structural footprint or roof cover, an increase in impervious surface coverage, or any work which alters existing grade conditions. No increase of rate flow shall be permitted onto adjacent properties.
(1) 
The slope of any altered final grading of soils around the foundation of any structure or improvement shall not be less than five (5) percent when measured from grade to any point ten (10) feet from grade elevation at the foundation wall of the structure.
a. 
Exception: Existing natural grades less than five (5) percent may be maintained.
(2) 
Diversion of surface water shall be contained within the limits of the owner's contiguous property, shall be conveyed by a free, positive, and uninterrupted means, and shall be designated as the following:
a. 
Type A drainage, or
b. 
Type B drainage, or
c. 
Type C drainage.
(3) 
All site plans submitted for projects where natural grade is altered, or covered must indicate the following:
a. 
Drainage type as listed above,
b. 
Drainage flow arrows indicating direction of proposed runoff, and
c. 
All proposed berms, swales, or drains.
(4) 
A storm water management and drainage plan (SDP) shall be required for the following projects:
a. 
New single-family residential, commercial, multi-family residential, industrial, institutional, utility developments, or any new developments including additions when the proposed property being developed exceeds five (5) percent slope from property line to property line, and
b. 
Propose an increase in lot coverage greater than twenty-five (25) percent above existing lot coverage, and
c. 
Propose an increase in the total impervious surface on a property by twenty-five (25) percent of the existing impervious surface coverage.
(5) 
The director shall require a storm water management and drainage plan (SDP), designed and sealed by a registered professional engineer, which demonstrates that a proposed construction plan or recently permitted construction meets all of the provisions of this article and does not increase the rate or direction of flow of run-off from an existing property and does not prevent natural drainage from entering an existing property.
(6) 
The director's office shall review each SDP to verify whether an increase in the rate or direction of flow of run-off from an existing property is created by the proposed project or whether the proposed project prevents natural drainage. In cases where prevention or an increase is determined, the city reserves the right to submit the SDP to the city's engineer for additional review. Any outside review is subject to fees according to the adopted schedule of development fees.
(7) 
If irregular site topography, use of landscaping, or architectural features such as raised planting beds, retaining walls, fences, or sidewalks prevent compliance with provisions of this section, the designer shall provide alternate methods and means as may be approved by the director to assure that the requirements of this Code are met. The drainage plan must be submitted, reviewed, and approved prior to issuance of a permit and the work must be approved prior to final inspection and occupancy of the structure.
(Ordinance 1860 adopted 4/12/2010)