This section is intended to provide Dunes City impervious surface stormwater management requirements for all forms of impervious structures involving single family residences.
The city shall approve land use applications only after the requirements, standards, and processes of the Dunes City Code of Ordinances have been met including that for storm water management.
The design standard for this section shall be for proper functioning of all stormwater facilities when exposed to a rain event of 3.1 inches of rainfall within a six hour period.
Stormwater runoff from all manmade impervious surfaces is to remain on-site. If the lot being built on is capable of being redeveloped into smaller lots, the accepted stormwater management plan
shall be applicable to any later re-developments.
Any stormwater management plan prepared by a professional engineer or architect shall be based on best management practices selected from the City Of Dunes City Stormwater Management Manual of the
issue in effect at the time of initial application submittal.
The stormwater management plan provided by the land use applicant for a land use permit shall list all BMPs to be utilized which pertain to the proposed construction.
1.2 Specific Design Requirements
A. The City of Dunes City holds that any proposed construction that increases impervious surfaces by less than 500 square feet, except driveways, requires only a plot plan be submitted showing the
new impervious area & including the septic tank and drain field locations along with the normal building permit application.
B. For new impervious areas totaling in excess of 500 square feet, the City of Dunes City will require a stormwater management plan and design drawings. The stormwater management plan shall be
approved by an architect or engineer licensed in the State of Oregon. Approval by the City Engineer is also required before any land use application is accepted. The stormwater management plan will
show that runoff can be infiltrated by surfaces on the site. A designed surface infiltration facility(s), approved by the City Engineer, may be used.
C. Drainage from driveways shall be controlled by the stormwater management plan. Where water drainage from the first twenty feet of a sloping driveway connected to the street cannot be contained
on the property, the water shall be directed to the street drainage ditch. Where there is no existing ditch, one shall be designed and installed to contain the runoff. The design and location shall
require the approval of the City Engineer.
A driveway permit is required for any driveway. This includes the paving of an existing gravel driveway.
D. The design and location of all stormwater drainage paths and infiltration points shall direct water away from septic tank and drain field areas and protect these sensitive areas.
E. Any stormwater management facility utilized shall be accessible to and allow inspection on a cycle of no more than four years.
1.3 List of Stormwater Management Documents Required Prior to Final Land Use Application Approval
Prior to final approval of the land use application the applicant shall provide the city with:
a) Facility design data which permits an inspection cycle to verify function every four years.
b) A Plot Plan showing the final location of all impervious surfaces and control facility locations.
c) A maintenance plan, schedules, and instructions for all control facilities.
d) The final design of the facility & the calculations used to determine that the flow & volume requirements are met.
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