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Dunes City Draft Chapter 99  Stormwater Pollution Reduction  a/o 7/2/07

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99.05     PURPOSE. The purpose of this chapter is to establish requirements for protecting and safeguarding the general health and safety of the public by reducing stormwater-related impacts on the quality of the city’s water resources including drinking water.  Standards are provided for the capture and treatment of stormwater runoff from impervious surface areas and for reducing the introduction of pollutants into stormwater.

99.10     APPLICABILITY. The improvement of both public and private stormwater management facilities through or adjacent to a new development shall be the responsibility of the developer. Said improvements shall comply with all applicable city ordinances, policies and standards.  Except as exempt under DCC 99.15, the standards in this chapter apply to all applications for development submitted after the effective date of this ordinance requesting approval of one or more of the following:

A).            Land use application: Partition tentative plan; subdivision tentative plan; planned unit development tentative plan; or site review. 

B).            Development/Building Permit Application. 

C).            Excavation, Grading, Driveway, or Access Permit Applications.

99.15     EXEMPTIONS. The requirements and standards of this chapter do not apply to: 

A).            An application that will result in the construction or creation of less than five-hundred square feet of new or replaced impervious surface area at full buildout of the development.  

B).            A development/building permit application for any of the following: 

1)   Development of a lot or parcel included in a land use application that was determined by the city to comply with the standards in DCC 99.25, Pollution Reduction Standards.  The approved land use application shall control development.  

2)   Development of a lot or parcel that was not included in an application that was determined by the city to comply with the standards in DCC 99.25 and will result in less than five-hundred square feet of new or replaced impervious surface within a 12 month period. 

99.20     STORMWATER CONTAINMENT AND DESTINATION STANDARDS.  The purpose of these standards is to protect life and property from flood and drainage hazards through the establishment of containment and destination regulations for stormwater runoff from development. 

A).            Stormwater Containment and Destination requirements apply to all new development, except as exempted under 99.15. 

B).            All Stormwater facilities shall be designed and constructed in accordance with the flood control design standards of this code and the facility design requirements set forth in the Stormwater Management Manual. 

C).            An applicant proposing new development must submit documentation to the City showing stormwater runoff generated by the new development at the flood control design storm level will be either: 

1)    Contained on-site in accordance with the flood control design storm and Stormwater Management Manual, or 

2)    Discharged off-site in accordance with the flood control design storm and Stormwater Management Manual into an existing stormwater drainage facility that has the capacity to accommodate the runoff from the proposed development. In demonstrating facility capacity, the evaluation shall include the runoff from all current uses to the stormwater facility and runoff from new development proposals that have already been approved by the City as of the date the applicant submits a complete application. Prior approvals shall include, but are not limited to, tentative plans and final plats. Where off-site destination includes the direct discharge of runoff into an open  waterway, the proposal must comply with the Flow Control     requirements of DCC 99.30. 

3)    If the applicant cannot demonstrate that existing stormwater drainage facilities have adequate capacity to accommodate the proposed runoff from the new development, the applicant must construct storm drainage facilities with adequate capacity to accommodate the runoff from the proposed development, or construct on-site containment facilities per (A) above. 

D).           Stormwater runoff disposed of in underground systems may also be regulated through the federal Underground Injection Control (UIC) program under Part C of the Safe Drinking Water Act (42 U.S.C 300, Chapter 6A, Subchapter XII) and Oregon Administrative Rule Chapter 340, Section 044. 

99.25     POLLUTION REDUCTION STANDARDS.    The purpose of DCC 99.25 is to protect public health by reducing the introduction of pollution into the waters of the city. 

A).            Land use and development applications shall include pollution  reduction facilities selected from the Stormwater Management  Manual as follows: 

1)    For undeveloped land applications listed in DCC 99.10(A), the selected pollution reduction facilities shall treat all the stormwater runoff from the development site that will result from the water quality design storm. 

2)    For applications listed in DCC 99.10(A) or DCC 99.10(B) that change or add development, the selected pollution reduction facilities shall treat the stormwater runoff from all added and replaced impervious surfaces that will result from the water quality design storm. 

3)    Development/building permit applications shall select pollution reduction facilities that treat all stormwater runoff from all new or replaced impervious surface area, or an equivalent on-site area, that will result from the water quality design storm.  

B).            All pollution reduction facilities shall be sited, designed, constructed, and maintained according to the pollution reduction provisions and the facility design requirements set forth in the  Stormwater Management Manual. 

C).            The standards in DCC 99.25 may be adjusted pursuant to the Stormwater Management Manual.

99.30     FLOW CONTROL STANDARDS.   The purpose of DCC 99.30 is to protect waterways from the erosive affects of increases in stormwater runoff peak flow rates and volumes that result from the effects of impervious surfaces and land disturbances. 

A).            All proposed improvements that may create stormwater flows which  drain into a stream, pipe, or conduit shall demonstrate using methodology  in the Stormwater Management Manual that peak rates of flow delivered to an existing open waterway will not increase during storms larger than the water quality design storm and smaller than the flood control design storm as a result of the proposed development. 

B).            For purposes of designing the system as required by the standards in this section the amount of impervious surface per lot is assumed to be the maximum allowed lot coverage by structures plus all additional impervious surface coverage. 

C).            All facilities to control the rate of stormwater runoff shall be sited,  designed and constructed according to the flow control provisions and the facility design requirements set forth in the Stormwater Management  Manual.  Flow control facilities must be designed using one of the methodologies outlined in the Stormwater Management Manual. 

D).           The standards in DCC 99.30 may be adjusted pursuant to the Stormwater Management Manual. 

99.35     STORMWATER SOURCE CONTROLS.   All source controls shall be designed and constructed according to the source control provisions set forth in the Stormwater Management Manual, except when the source control would duplicate controls required by a state or federal permit obtained by the applicant. Source control standards set forth in DCC 99.35 apply to all improvements that result in any of the defined site uses or characteristics listed in DCC 99.40 (A) - (D). 

A).            Fuel dispensing facilities and surrounding traffic areas where vehicles, equipment or tanks are refueled on the premises.  A fuel dispensing facility is the area where fuel is transferred from bulk storage tanks to vehicles, equipment, and/or mobile containers.  Exempt from these controls are propane tanks. 

B).            Exterior storage of liquid materials, for example chemicals, food products, waste oils, solvents or petroleum products in above ground containers, in quantities of fifty gallons or more, including permanent and temporary storage areas.  Exempt from this subsection are underground storage tanks or installations requiring a Water Pollution Control Facility (WPCF) permit and containers with internal protections. 

C).            All facilities that store solid waste.  A solid waste storage area is a place where solid waste containers, including compactors, dumpsters, and garbage cans, are collectively stored.  Solid waste storage areas include areas used to collect and store refuse or recyclable materials collection areas. 

D).           All development that stockpiles or stores high-risk or low-risk bulk materials in outdoor containers, as the terms “high-risk” and “low-risk” are used in the Stormwater Management Manual.  Exempt from this subsection are: 

1)   Materials that have no measurable solubility or mobility in water and no hazardous, toxic or flammable properties; 

2)   Materials that exist in gaseous form at ambient temperature; 

3)   Materials, except for pesticides and fertilizers, which are contained in a manner that prevents contact with stormwater. 

E).            All development with a designated equipment or vehicle washing or steam cleaning area. 

F).             All development projects that disturb property suspected or known to contain contaminants in the soil or groundwater. 

99.40     STORMWATER OPERATIONS AND MAINTENANCE STANDARDS. The purpose of this section is to ensure that through adequate operation and maintenance, stormwater facilities protect life and property from flood and drainage hazards and provide protection for waterways from the erosive effects of runoff. 

A).            Operation and maintenance standards apply to all facilities designed and constructed in accordance with this Section and the Stormwater Management Manual. 

B).            Unless otherwise agreed, stormwater management facilities shall be privately owned and shall be operated and maintained in accordance with this ordinance and the Stormwater Management Manual. 

C).            The city shall maintain public stormwater management facilities located on city-owned property, city rights-of-way and city easements. 

D).           To ensure that any city maintained stormwater management facility can be accessed by the city for routine and/or emergency maintenance the applicant of an applicable land use request or development permit must dedicate easements approved by and to the city. 

99.45     INSPECTION.  The City Council shall designate a Health and Safety Inspector qualified in stormwater control measures with responsibility for evaluating proposed and completed stormwater measures and facilities. This includes evaluation and approval of all stormwater standards and controls required by this ordinance at stages of completion as specified in the Stormwater Manual. The Inspector shall report to the City Council on the implementation of the requirements of this ordinance. 

99.50     ADJUSTMENT REVIEW – APPROVAL CRITERIA.  The Health and Safety Inspector shall approve, conditionally approve, or deny an adjustment review application for Stormwater Containment and Destination, Pollution Reduction, Flow Control and Source Control Standards.  Approval or conditional approval shall be based on compliance with the following applicable criteria. 

A).            The requirement in DCC 99.25 (A)(1) - (3) that selected pollution reduction facilities shall treat all the stormwater runoff that will result from the water quality design storm may be adjusted upon a finding that the selected pollution reduction facility will treat as much of the runoff as possible and one of the following applies: 

1)    The area generating untreated runoff is less than five-hundred square feet of impervious surface and is isolated from the pollution reduction facility; 

2)    The area generating untreated runoff is less than five-hundred square feet of impervious surface and it is not technically feasible to drain the untreated runoff to the pollution reduction facility; 

3)    Constructing pollution reduction facilities to treat the runoff from the area at issue would require removal of trees or damage to other natural resources; 

4)    The area generating untreated runoff is less than five-hundred square feet of impervious surface and limited access to the area would prevent regular maintenance of the pollution reduction facility. 

B).            The requirement in DCC 99.25 (B) that all pollution reduction facilities be sited, designed, and constructed according to the pollution reduction provisions and the facility design requirements set for in the Stormwater Management Manual and that pollution reduction facilities must be designed using one of the methodologies outlined in the Stormwater Management Manual may be adjusted upon finding that all of the following requirements are met: 

1)    The proposed alternative design will achieve equal, or superior, results for pollution reduction function, maintainability and safety, and the proposed siting does not adversely affect structures or other properties. 

2)    The applicant’s written description of the proposed alternative design has been reviewed and approved the City Engineer. The description of the proposed design submitted for review must include all of the following information for each component of the proposed alternative design: 

a)    Size, technical description, capacity, capital cost, design  life, construction process and costs, consequences of improper construction, operation and maintenance requirements and costs; 

b)    Data on the effectiveness of proposed alternative technologies, if available, including data from laboratory testing and pilot / full-scale operations, and information regarding the operations of any full-scale installations; 

c)     Any other available information about the proposed design, including peer reviewed articles, scientific or engineering journals, and approvals from other jurisdictions. 

3)    The applicant has submitted a method and schedule for monitoring the effectiveness of the proposed design once constructed, and a schedule for its maintenance. 

4)    The applicant has submitted a signed statement that the applicant will replace the alternative pollution reduction facility if it does not function as proposed. 

C).            The requirements in DCC 99.30 that Flow Control Standards and in DCC 99.35 Source Control Standards be sited, designed and constructed according to the provisions and the facility design requirements set forth in the Stormwater Management Manual may be adjusted if the applicant can demonstrate that the selected flow control facility will achieve the same result as those listed in the Stormwater Management Manual. 

D).           The requirement in DCC 99.40 that source controls be sited, designed and constructed according to source control provisions set forth in the Stormwater Management Manual may be adjusted if the applicant can demonstrate that the selected source control will achieve the same result as those listed in the Stormwater Management Manual.  

99.55     STORMWATER MANAGEMENT MANUAL. In order to implement DCC 99.05 through 99.50, the City Council shall adopt a Stormwater Management Manual that is consistent with  the following goals: 

A).            Reduce runoff pollution from development by reducing the overall amount of impervious surface area and extent of connectedness to downstream drainages. 

B).            Emphasize stormwater management facilities that, to the maximum extent practicable, retain and treat stormwater utilizing on-site controls. 

C).            Emphasize stormwater management facilities that incorporate vegetation as key element, and include design and construction requirements that ensure landscape plant survival and overall stormwater facility function success. 

D).           Operate and maintain stormwater management facilities in accordance with facility-specific Operation and Maintenance Plans. 

E).            Reduce pollutants of concern that are generated by identified site uses and site characteristics that are not addressed solely through the pollution reduction measure by implementing additional specific source control methods including reducing or eliminating pathways that may introduce pollutants into stormwater and avoiding preventable discharges to surface waters or groundwater. 

99.60     DEFINITIONS. As used in this Chapter, unless the context requires otherwise, the following words and phrases mean: 

Development: All improvements on a site, including buildings, other structures, parking and loading areas, landscaping, paved or graveled areas, grading and areas devoted to exterior display, storage, or activities, Development includes improved open areas such as plazas and walkways, but does not include natural geologic forms or landscapes. 

Flow control facility.  Any structure or drainage device that is designed, constructed, and maintained to collect, retain, infiltrate, or detain surface water runoff during and after a storm event for the purpose of controlling flow rate and volume leaving the site. 

Impervious Surface / Area.  Any surface area that causes water to runoff the surface in greater quantities or at an increase rate of flow from conditions preexisting to development.  Types of impervious surface include, but are not limited to, rooftops, asphalt and concrete parking lots, driveways, roads, and sidewalks.  

Note: Slatted decks are considered pervious surface.  Gravel surfaces are considered pervious surfaces unless they cover impervious surfaces or are compacted to a degree that causes their runoff coefficient to exceed eighty percent.   

Nonpoint Source Pollution: Discharge from a diffuse pollution source, that is without a single point of origin. 

Pollution Reduction Facility.  Any structure or drainage device that is designed, constructed, and maintained to collect and filter, retain, or detain surface water runoff during and after a storm event for the purpose of maintaining or improving surface and/or groundwater quality. 

Property suspected or known to contain contaminants in the soil or groundwater.  Any real property where the presence of any hazardous substance or petroleum product indicates an existing release, past release, or  threatened release of a hazardous substance or petroleum product into the ground, groundwater, or surface water of the property. 

Runoff. Water from rainfall, snow melt, or otherwise discharged that flows across the ground surface instead of infiltrating the ground. 

Source Control.  Any structure, device, or design that is used to eliminate or reduce stormwater pollution from a known source. 

Stormwater. Water derived from a storm event. 

Stormwater Management Manual.  The Dunes City Stormwater Management Manual as adopted by the city. 

Stormwater Management Facility.  Any structure or configuration of the ground that is used or, by its location, becomes a place where stormwater flows or is accumulated, including but not limited to pipes, curbs, gutters, catch basins, ponds, open drainage ways, runoff control facilities, wetlands and their accessories. 

Water Quality Design Storm.  A theoretical storm for estimating the amount of stormwater runoff to be treated.  Facilities designed to store and treat a volume of stormwater shall be sized in accordance with the Stormwater Management Manual. 

99.65     ENFORCEMENT. Failure to construct, operate and maintain source controls as set forth in this Chapter shall be unlawful and a civil infraction subject to the enforcement provisions of Chapter 36 of the Dunes City Code.  

A).            If Dunes City determines that maintenance or repair work is required to be done to stormwater management facilities located in the development, the city shall give the owner notice of the specific maintenance and / or repair required.  The city shall set a reasonable time in which such work is to be completed by the persons who were given notice. If the above required maintenance and / or repair is not completed within the time set by the city, written notice will be sent to the owner stating that the city’s intention is to perform such maintenance and bill the owner for all incurred expenses. 

B).            If, at any time Dunes City determines that the existing facility creates any imminent threat to public health, safety, or welfare, Dunes City may take immediate measures to remedy said threat. No notice to the persons as listed in (A) above shall be required under such circumstances. All other owner responsibilities remain in effect.