Chapter 18.250 STORMWATER CONTROL AND DRAINAGE

A. Minimize surface and groundwater quality degradation and prevent erosion and sedimentation of creeks, streams, ponds, lakes, wetlands, and other water bodies;

B. Minimize damage to property from increased runoff rates and volumes;

C. Protect the quality of waters for drinking water supply, contact recreation, fishing and other beneficial uses;

D. Establish sound developmental policies which protect and preserve the city’s water resources;

E. Protect city roads and rights-of-way from damage due to inadequately controlled runoff and erosion;

F. Preserve and enhance the aesthetic quality of the city’s water resources;

G. Protect the health, safety and welfare of the inhabitants of the city;

H. Maintain existing groundwater levels, instream flows and available water supply volumes; and

I. Further the goals of no net negative impact caused by quantity of runoff entering streams and no net negative change in the quality of runoff entering streams through the implementation of best management practices. (Ord. 09-16 (part), 2010; Ord. 96-802 § 1, 1996)

18.250.015 Adoption statement.

The city hereby adopts the thresholds, definitions, minimum requirements and exceptions, adjustment and variance criteria found in Appendix I of the NPDES Phase II Municipal Stormwater Permit, including the mandatory incorporated provisions of the current Ecology Stormwater Management Manual for Western Washington, hereafter referred to as the Western Washington Manual, or Department of Ecology approved equivalent. Where provisions of this chapter conflict with the Western Washington Manual or other cited design guidance, the more stringent requirements as determined by the director shall take precedence. (Ord. 20-10 § 1, 2020: Ord. 16-16 § 1 (part), 2016: Ord. 14-07 § 10 (part), 2014: Ord. 09-16 (part), 2010)

18.250.020 Applicability and thresholds.

The applicability of this chapter is based on the thresholds listed in Volume I, Section 2.4, Applicability of the Minimum Requirements, of the Western Washington Manual. (Ord. 16-16 § 1 (part), 2016: Ord. 11-06 § 4, 2011; Ord. 09-16 (part), 2010; Ord. 96-802 § 2, 1996)

18.250.025 Exemptions.

A. The following types of projects are exempt from this chapter:

1. Forest practices regulated under WAC Title 222, except for Class IV general forest practices that are conversions from timberland to other uses, are exempt from the provisions of the minimum requirements.

2. Commercial agriculture practices involving working the land for production are generally exempt. However, the conversion from timberland to agriculture, and the construction of impervious surfaces are not exempt.

3. The following pavement maintenance practices are exempt: pothole and square cut patching, overlaying existing asphalt or concrete pavement with asphalt or concrete without expanding the area of coverage, shoulder grading, reshaping/regrading drainage systems, crack

sealing, resurfacing with in-kind material without expanding the road prism, pavement preservation activities that do not expand the road prism, and vegetation maintenance.

The following pavement maintenance practices are not categorically exempt. The extent to which the manual applies is explained for each circumstance.

a. Removing and replacing a paved surface to base course or lower, or repairing the pavement base: If impervious surfaces are not expanded, Minimum Requirements Nos. 1 through 5 apply.

b. Extending the pavement edge without increasing the size of the road prism, or paving graveled shoulders: These are considered new impervious surfaces and are subject to the minimum requirements that are triggered when the thresholds identified for new or redevelopment projects are met.

c. Resurfacing by upgrading from dirt to gravel, asphalt, or concrete; upgrading from gravel to asphalt, or concrete; or upgrading from a bituminous surface treatment (“chip seal”) to asphalt or concrete: These are considered new impervious surfaces and are subject to the minimum requirements that are triggered when the thresholds identified for new or redevelopment projects are met.

B. The following types of projects are exempt from this chapter except as described:

1. Underground utility projects that replace the ground surface with in-kind material or materials with similar runoff characteristics are only subject to Minimum Requirement No. 2, Construction Stormwater Pollution Prevention.

2. Drainage projects are exempt from the water quality treatment provisions of this chapter as described in BGMC 18.250.130 provided they do not meet the thresholds in Volume I, Section 2.4, Applicability of the Minimum Requirements, of the Western Washington Manual. The director may also waive all or parts of the submittal requirements required by BGMC 18.250.100, ownership and maintenance requirements required by BGMC 18.250.300 and 18.250.310, and bonding requirements required by BGMC 18.250.380 if the project meets the other appropriate parts of this chapter.

3. Redevelopment projects in which the value of the proposed improvements, including interior improvements, does not exceed fifty percent of the assessed or replacement value of the existing structures on the site are exempt from Minimum Requirements Nos. 6 through 9 on replaced impervious surfaces.

4. Road redevelopment projects that increase the impervious surface area by less than five thousand square feet are exempt from Minimum Requirements Nos. 6 through 9. Road redevelopment projects that increase the impervious surface area by less than fifty percent within the project limits are required to apply Minimum Requirements Nos. 6 through 9 to the new impervious surfaces only. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010)

18.250.030 Definitions.

For the purposes of this chapter, the following definitions shall apply:

“Basin” means a topographic region in which all water drains to a common point.

“Basin plan” means a management plan for a basin identified in the most current version of the city of Battle Ground stormwater management plan.

“Best management practices” or “BMPs” means those physical, structural and managerial practices, and prohibitions of practices, that, when used singly or in combination, control stormwater runoff peak flow rates and volumes and prevent or reduce pollution of surface water or groundwater.

“City” means the city of Battle Ground, Washington.

“Construction” means any site-altering activity, including but not limited to grading, utility construction and building construction.

“Continuous runoff model” means the most current version of the Western Washington Hydrology Model (WWHM) or any other equivalent model approved by the Department of Ecology.

“Contributing drainage area” means the subject property together with the basin contributing water runoff to the subject property.

“Council” means the city council of Battle Ground, Washington.

“Department” means the city of Battle Ground public works department.

“Design storm” means the rainfall from a storm of twenty-four-hour duration. For example, “two-year storm” means the two-year, twenty-four-hour storm event.

“Development” means land-disturbing activities, construction, installation or expansion of a building or other structure, creation or replacement of impervious surfaces, and subdivision of properties.

“Director” means the director of the city of Battle Ground public works department.

“Discharge point” means the location where a discharge leaves the permittee’s MS4 through the permittee’s MS4 facilities/BMPs designed to infiltrate.

“Downstream analysis” means an analysis of the stormwater impacts of proposed development activity including the effects on existing upstream and downstream drainage systems and property, and the ability of the natural drainage ways to pass additional flow created by the development.

“Drainage project” means the excavation or construction of pipes, culverts, channels, embankments or other flow altering structures in any stream, stormwater facility, or wetland.

“Effective impervious surface” means those impervious surfaces that are connected via sheet flow or discrete conveyance to a drainage system. Impervious surfaces on residential project sites are considered ineffective if the runoff is dispersed through at least one hundred feet of native vegetation in accordance with BMP T5.30, “Full Dispersion,” as described in Chapter 5 of Volume V of the Western Washington Manual.

“Engineering acceptance” means having received completion of construction and all required paperwork has been approved by the engineering division and recorded by the applicant as required.

“Groundwater” means water in a saturated zone or stratum beneath the surface of land or below a surface water body.

“Impervious surface” means a hard surface area which either prevents or retards the entry of water into the soil. Examples include, but are not limited to, structures, walkways, patios, driveways, carports, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, haul roads and soil surface areas compacted by construction operations, and oiled or macadam surfaces.

“Land-disturbing activity” means any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and nonvegetative) and/or the existing soil topography. Land-disturbing activities include but are not limited to clearing, grading, filling, and excavation. Compaction that is associated with stabilization of structures and road construction shall also be considered a land-disturbing activity. Vegetation maintenance practices are not considered land-disturbing activity.

“Low impact development (LID)” means a stormwater and land use management strategy that strives to mimic pre-disturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on-site natural features, site planning, and distributed stormwater management practices that are integrated into a project design.

“Low Impact Development Manual” means the Low Impact Development Technical Guidance Manual for Puget Sound dated January 2012 and updated errata sheets issued or approved by the director as may be necessary to correct clear and obvious mathematical and technical errors in manual criteria.

“Native vegetation” means vegetation comprised of plant species, other than noxious weeds, that are indigenous to the Pacific Northwest and which reasonably could have been expected to naturally occur on the site. Examples include trees such as Douglas fir, western hemlock, western red cedar, alder, big-leaf maple, and vine maple; shrubs such as willow, elderberry, salmonberry, and salal; and herbaceous plants such as sword fern, foam flower, and fireweed.

“Natural location” means the location and elevation of those channels, swales, and other nonmanmade conveyance systems as defined by the first documented topographic contours existing for the site, either from maps or photographs.

“NPDES” means the National Pollutant Discharge Elimination System.

“Outfall” means a point source as defined by 40 CFR 122.2 at the point where a discharge leaves the permittee’s MS4 and enters a surface receiving waterbody or surface receiving waters. Outfall does not include pipes, tunnels, or other conveyances which connect segments of the same stream or other surface waters and are used to convey primarily surface waters (i.e., culverts).

“Peak discharge” means the maximum stormwater runoff rate in cubic feet per second determined for the design storm.

“Pollution-generating impervious surface” or “PGIS” means those impervious surfaces considered to be a significant source of pollutants in stormwater runoff. Such surfaces include those which are subject to: vehicular use, industrial activities or storage of erodible or leachable materials, wastes, or chemicals, and which receive direct rainfall or the run-on or blow-in of rainfall. Metal roofs are also considered to be pollution-generating unless they are coated with an inert, nonleachable material (e.g., baked-on enamel coating).

“Pollution-generating pervious surface” or “PGPS” means any nonimpervious surface subject to use of pesticides and fertilizers or loss of soil.

“Predeveloped condition” means the land cover that existed at a site prior to development or redevelopment. For projects required to comply with Minimum Requirement No. 7 for flow control, the predeveloped condition shall be assumed to be a forested land cover unless reasonable, historic information is provided that indicates the site was prairie prior to settlement.

“Project engineer” means a registered professional engineer, licensed in the state of Washington, experienced and knowledgeable in the practice of civil engineering related to stormwater runoff control and treatment and who is responsible for design and the preparation of stormwater plans and hydrology report.

“Project site” means that portion of a property, properties, or right-of-way subject to land-disturbing activities, new impervious surfaces or replaced impervious surfaces.

“Redevelopment” means development activity on sites that have thirty-five percent or more impervious surface coverage at the time of the project.

“Regional facility” means a facility designed to treat and control stormwater runoff from multiple project sites.

“Registered soil scientist” means a professional soil scientist certified by the Soil Science Society of America, experienced and knowledgeable in the practice of pedology related to soil survey, who is responsible for design and preparation of soils maps, related soil groups, and identifying soil factors for construction engineering.

“Replaced impervious surface” means the removal and replacement of any exterior impervious surfaces or foundation for structures, or the removal down to bare soil or base course and replacement for other impervious surfaces.

“Road redevelopment project” means any work, whether publicly or privately funded, on an existing roadway.

“Roof downspout system” means infiltration or dispersion systems that meet the requirements stated in Chapter 3 of Volume III of the Western Washington Manual.

“Severe and unexpected economic hardship” means site specific constraints that make the strict application of any or all of the minimum requirements economically infeasible and prevent reasonable development of a property to its designated use as defined by the city comprehensive plan.

“Site” means the area defined by the legal boundaries of a parcel or parcels of land that is (are) subject to development. For road projects, the length of the project site and the right-of-way boundaries defining the site.

“Steep slopes” means slopes greater than fifteen percent.

“Stormwater facility” means the natural or constructed components of a stormwater drainage system, designed and constructed to perform a particular function, or multiple functions. Stormwater facilities include, but are not limited to: pipes, swales, ditches, open channels, culverts, stormwater ponds, catch basins, manholes, oil/water separators and sedimentation basins.

“Stormwater utility” means a publicly owned utility responsible for stormwater control.

“Stream” means those areas where surface waters produce a defined channel or bed. For the purposes of this chapter, streams shall include both natural channels and manmade channels which were constructed to replace a natural stream.

“Subregional facility” means a facility designed to treat and control stormwater runoff from more than one development in a contributing drainage area of less than forty acres.

“Temporary building” means buildings that will be in place for one year or less.

“Threshold discharge area” means an on-site area draining to a single natural discharge location or multiple natural discharge locations that combine within one-quarter mile downstream as determined by the shortest flow path.

“Western Washington Manual” means the current State of Washington Department of Ecology’s “Stormwater Management Manual for Western Washington,” and updated errata sheets issued or approved by the director as may be necessary to correct clear and obvious mathematical and technical errors in manual criteria.

“Wetlands” means those areas defined as wetlands under Chapter 18.270 BGMC.

Any terms not defined in this chapter shall be as defined in Appendix One of the city’s NPDES Phase II permit. (Ord. 21-36 § 1, 2021; Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 3, 1996)

18.250.035 Construction details.

The city of Battle Ground standard construction details for stormwater are kept on file at the city and maintained by the city engineer. (Ord. 09-16 (part), 2010)

18.250.040 Enforcement.

The director is authorized to enforce the provisions of this chapter utilizing the remedies and procedures under BGMC Title 20. (Ord. 09-16 (part), 2010; Ord. 96-802 § 4, 1996)

18.250.100 Submittal requirements.

Preliminary and final submittals of the stormwater plans and hydrology report shall conform to the requirements of the latest edition of the city of Battle Ground’s stormwater design and construction requirements. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 5, 1996)

18.250.120 Record drawings.

Record drawings will be provided consistent with the standards maintained by the city engineer. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 7, 1996)

18.250.130 General standards for water quality treatment.

A. All projects, as applicable or unless otherwise exempted by this chapter, shall provide treatment of stormwater runoff through the use of BMPs specified in the Western Washington Manual or LID BMPs as specified in BGMC 18.250.170. Alternatively, experimental BMPs meeting the requirements of BGMC 18.250.180 may be utilized if approved by the director.

B. For vegetated wet facilities including, but not limited to, wet biofiltration swales, stormwater treatment wetlands, wet ponds and wetpools, plantings are required to be plugs, rootstock or nursery stock. Seeding of wet facilities is not allowed unless it can be demonstrated to the satisfaction of the director that facility vegetation will be fully established before the facility receives stormwater. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 8, 1996)

18.250.160 Oil/water separators.

A. The following development activities require American Petroleum Institute (API) or Coalescing Plate Separator (CPS)-type oil/water separators:

1. Commercial or industrial sites with an expected average daily traffic count greater than or equal to one hundred vehicles per one thousand square feet of gross building area;

2. Commercial or industrial sites subject to petroleum storage and transfer in excess of one thousand five hundred gallons per year, not including routinely delivered heating oil;

3. Commercial or industrial sites subject to parking, storage or maintenance of twenty-five or more vehicles over ten tons gross weight;

4. Roadway intersections with a measured average daily traffic count of twenty-five thousand vehicles or more on the main roadway and fifteen thousand vehicles or more on any intersecting roadway, excluding projects proposing primarily pedestrian or bicycle improvements;

5. Log storage and sorting yards;

6. Airfields and aircraft maintenance;

7. Industrial machinery and equipment maintenance;

8. Railroad yards;

9. Fueling stations;

10. Vehicle maintenance and repair;

11. Construction businesses including paving, heavy equipment storage and maintenance, storage of petroleum products (this does not include construction sites); or

12. Other activities that exhibit a significant risk of high oil loading in runoff.

B. The following development activities shall require spill control (SC) type oil/water separators:

1. Restaurants;

2. Multifamily residential projects creating parking spaces for twenty-five or more vehicles;

3. Fleet vehicle yards which have more than twenty-five vehicles parked overnight;

4. Retail/wholesale vehicle and equipment dealers; or

5. Other activities where the risk of oil spills or illegal dumping of oil or grease is significant as determined by the director.

C. For development activities cited in subsections A and B of this section, oil/water separators shall not be required on portions of a site where the risk of oil or grease spills or dumping is minimal.

D. Oil/water separators shall be designed in accordance with Chapter 11 of Volume V of the Western Washington Manual. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 11, 1996)

18.250.170 Low impact development best management practices.

A. Refer to the Western Washington Manual and the latest edition of the Low Impact Development Technical Guidance Manual for Puget Sound for use of LID BMPs in the appropriate situation.

B. LID BMPs shall be designed as specified in the Low Impact Development Technical Guidance Manual for Puget Sound.

C. Infiltration testing must be performed if infiltration will be used to dispose of water from LID BMPs. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 12, 1996)

18.250.180 Experimental best management practices.

A. Experimental best management practices are those which have not been fully tested and evaluated by the city or the Department of Ecology and are not included as accepted practices in this code or the Western Washington Manual.

B. Experimental BMPs may be allowed upon approval by the director if the Department of Ecology Technology Assessment Protocol—Ecology (TAPE) program is followed. (Ord. 09-16 (part), 2010; Ord. 96-802 § 13, 1996)

18.250.190 Drainage structure labeling and signage.

A. All catch basins and manholes capable of accepting stormwater shall be marked as required by the city standard detail.

B. Signs shall be installed along all above ground stormwater facilities as required by the city standard detail. (Ord. 15-04 § 38 (part), 2015: Ord. 09-16 (part), 2010; Ord. 96-802 § 14, 1996)

18.250.200 General standards for runoff quantity control.

All projects, as applicable or unless otherwise exempted by this chapter, shall provide quantity control of stormwater runoff through the use of BMPs specified in the Western Washington Manual or LID BMPs as specified in BGMC 18.250.170. Alternatively, experimental BMPs meeting the requirements of BGMC 18.250.180 may be utilized if approved by the city. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 § 15, 1996)

18.250.300 Ownership of stormwater facilities.

A. Stormwater facilities located within public road rights-of-way shall be owned by the city.

B. City ownership of stormwater facilities is required where the city will assume long-term maintenance of the facilities.

C. Stormwater facilities which collect, convey, treat, and/or infiltrate runoff from public rights-of-way shall be publicly owned and maintained, unless it is demonstrated to the satisfaction of the director that the stormwater facility can be adequately maintained by private parties.

D. Stormwater facilities that treat runoff from only private property shall be owned and maintained by private parties.

E. Stormwater facilities that treat mixed runoff from public and private property shall be owned and maintained by private parties unless otherwise approved by the director.

F. Stormwater facilities that treat stormwater runoff from single-family residential subdivisions shall be publicly owned and maintained, unless it is demonstrated to the satisfaction of the director that the stormwater facility can be adequately maintained by private parties. (Ord. 09-16 (part), 2010; Ord. 96-802 § 19, 1996)

18.250.305 Ownership of roof and foundation drains.

The property owner served by roof and foundation drains is responsible for installation, maintenance, and operation of such drains that are located in the city’s right-of-way. (Ord. 19-24 § 1 (part), 2019)

18.250.310 Maintenance.

A. Initial Maintenance.

1. To ensure satisfactory operation of new public stormwater facilities, the applicant constructing the facility shall maintain it for two years after completion of the project. A maintenance agreement stating that the applicant will be responsible for the maintenance of the facility must be recorded prior to engineering acceptance.

2. The applicant shall post and maintain a maintenance bond or other security acceptable to the director during this two-year initial maintenance period. The purpose of the maintenance bond is to cover the cost of design defects or failures in workmanship of the facilities. The amount of the maintenance bond shall be twenty percent of the construction cost of the stormwater facilities.

B. Long-Term Maintenance.

1. Final plats shall include a note specifying the party(s) responsible for long-term maintenance of stormwater facilities.

2. If private parties are to provide long-term maintenance of a stormwater facility, a maintenance covenant will be required. The covenant shall include an agreement to transfer maintenance responsibilities to future occupants or owners of the property. Said covenant shall be recorded prior to engineering acceptance.

3. If the city provides long-term maintenance of a stormwater facility, all the following requirements shall be met:

a. The facilities shall be inspected and approved by the director prior to acceptance. Required remedial work to correct design, construction, and maintenance deficiencies shall be completed by the project developer prior to acceptance; and

b. All necessary ownerships and easements entitling the city to properly access and maintain the facility shall be conveyed to the city and recorded with the county auditor.

C. The city shall inspect privately maintained facilities for compliance with the requirements of this chapter. Facilities shall be maintained to the standards set forth in the city of Battle Ground stormwater facility maintenance manual, or the design engineer provided maintenance manual. If the parties responsible for long-term maintenance fail to maintain their facilities to acceptable standards, the city shall issue a written notice specifying required actions to be taken in order to bring the facilities into compliance. Following the written warning the city will enforce maintenance requirements as detailed in BGMC 18.250.040. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-802 §§ 20, 21, 1996)

18.250.320 Tracts, easements, and covenants.

A. All stormwater facilities maintained by the city shall be in a tract dedicated to the city of Battle Ground. In subdivisions and short plats the tracts are recommended, but not required, to meet minimum zoning lot size requirements.

B. Stormwater easements shall be provided to the city for access and maintenance of all conveyance systems within the site, which are to be maintained by the city. The required widths of easements shall be as follows. The director may decrease widths in special cases or require increased widths when necessary to ensure adequate area for equipment access and maintenance:

1. Pipes with inner diameter less than or equal to thirty-six inches: twenty feet.

2. Pipes with inner diameter greater than thirty-six inches: twenty feet plus pipe inner diameter.

3. Pipes shall be located with their centerline no closer than one-quarter of the easement width from an adjacent property line.

4. Streams and channels: top width of channel plus fifteen feet on one side.

C. Private stormwater facilities must have an access and inspection covenant dedicated to the city of Battle Ground encompassing the facility.

D. No buildings or other structures are permitted within easements. Fences crossing easements must cross the easement perpendicularly and shall provide gates that extend across the entire width of the easement for access by maintenance vehicles. (Ord. 09-16 (part), 2010)

18.250.330 Location of stormwater facilities.

A. Runoff treatment and control facilities shall be located prior to the point of discharge into a stream, lake, or fish-bearing water or prior to discharge to groundwater.

B. Unless otherwise approved by the director, infiltration systems shall be located as follows:

1. Fifty feet from the top of any slope greater than fifteen percent;

2. One hundred feet from municipal water supply wells; and

3. One hundred feet from existing or proposed septic drain fields.

C. Infiltration systems shall be located and designed to prevent influencing existing or proposed building foundations.

D. Swales and other stormwater treatment facilities using biofiltration shall be located outside easements and corridors used by phone, electric, water, natural gas, and other utilities unless the utilities are installed prior to construction of the biofiltration system. (Ord. 09-16 (part), 2010; Ord. 96-802 § 22, 1996)

18.250.350 Fencing of stormwater facilities.

A. Stormwater ponds dedicated to the city shall be fenced unless otherwise approved by the director.

B. Privately owned stormwater ponds shall be fenced where they abut the public right-of-way or where a pond interior side slope is steeper than 3H:1V.

C. The size and type of fence, as required by subsections A and B of this section, shall be per the city of Battle Ground standard details.

D. For private stormwater ponds that are not fenced a hold harmless agreement shall be provided to the city on the city’s standard form.

E. Fences that are privately maintained must be kept in good repair. (Ord. 19-24 § 1 (part), 2019: Ord. 15-04 § 38 (part), 2015: Ord. 09-16 (part), 2010; Ord. 96-802 § 24, 1996)

18.250.370 Recovering costs of stormwater facilities.

A. The following costs associated with stormwater facilities may be recoverable through latecomers agreements as described in Article II of Chapter 17.200 BGMC.

B. The costs for constructing a regional stormwater facility included in the approved city of Battle Ground stormwater management plan may be eligible as a credit against applicable system development charges. (Ord. 09-16 (part), 2010; Ord. 96-802 § 26, 1996)

18.250.380 Bonds and insurance.

A. Performance Security. In lieu of completing required stormwater facilities within a preliminary plat prior to recording, the applicant may post a performance bond or other security, if acceptable to the director, in the amount of one hundred twenty-five percent of the approved estimated cost (prepared by the project engineer) of completing construction per the approved stormwater plan. After determination by the director that all facilities are constructed in compliance with the approved plan, are performing their intended functions in a satisfactory manner, and that the requirements of BGMC 18.250.310(A) and subsection B of this section are met, the performance bond or security shall be released.

B. Maintenance Security. In cases identified in BGMC 18.250.310(A)(2), a maintenance bond or other security acceptable to the director shall be posted and maintained throughout the two-year initial maintenance period for a stormwater facility. (Ord. 09-16 (part), 2010; Ord. 96-802 § 27, 1996)

18.250.410 Regional and subregional facilities.

A. The city encourages multiple users of stormwater facilities. If regional or subregional facilities are used to meet some or all of the requirements for stormwater quality treatment and quantity control, the following conditions shall be met:

1. Stormwater runoff shall be transported from a project site to a regional/subregional facility through a pipe or manmade open channel conveyance system, or through a natural drainage way if approved by the director.

2. If the regional/subregional facility does not yet exist, interim quantity control and treatment methods shall be used to meet the requirements of this chapter. All interim methods shall be reviewed and shall require written approval by the director.

3. The facility must have sufficient capacity to provide quality treatment and/or quantity control as required by this chapter.

B. A system development charge will be assessed for use of a regional/subregional facility per the city capital plan. (Ord. 09-16 (part), 2010; Ord. 96-811 § 2, 1996: Ord. 96-802 § 29, 1996)

18.250.510 Variances.

A. Major Variances. If application of the minimum requirements will impose a severe and unexpected economic hardship, an applicant can make a written request for a waiver from some or all of the minimum requirements.

1. The public works director or designee may grant an exception to the minimum requirements if such application imposes a severe and unexpected economic hardship. To determine whether the application imposes a severe and unexpected economic hardship on the project applicant, the public works director or designee must consider and document – with written findings of fact – the following:

a. The current (pre-project) use of the site;

b. How the application of the minimum requirement(s) restricts the proposed use of the site compared to the restrictions that existed prior to the adoption of the minimum requirements; and

c. The possible remaining uses of the site if the variance were not granted; and

d. The uses of the site that would be allowed prior to the adoption of the minimum requirements; and

e. A comparison of the estimated amount and percentage of value loss as a result of the minimum requirements versus the estimated amount and percentage of value loss as a result of requirements that existed prior to adoption of the minimum requirements; and

f. The feasibility for the owner to alter the project to apply the minimum requirements.

2. Any major variances must meet the following conditions:

a. The variance will not increase risk to the public health and welfare, nor be injurious to other properties in the vicinity and/or downstream, and to the quality of waters of the state; and

b. The variance is the least possible exception that could be granted to comply with the intent of the minimum requirements.

3. Major variances may be granted by the city following legal public notice of an application for the variance, legal public notice of the city’s decision on the application, and written findings of fact that document the city’s determination to grant the variance.

4. Major variances shall be processed as a Type III land use action as set forth in BGMC 17.200.035.

B. Minor Variances. The director may grant minor variances to the numerical standards of this chapter prior to permit approval and construction. Minor variances deal with the design and construction of facilities and are not limited to any percentage change.

1. Requirements that may be changed by minor variances include, but are not limited to, the following:

a. Conveyance system analysis and design;

b. Off-site analysis;

c. Materials;

d. Facility side slopes;

e. Easements;

f. Percent of facility made up of retaining wall;

g. Fencing requirements; and

h. Varying from the standard details.

2. Minor variances shall be processed as part of engineering review which is a Type I land use action as set forth in BGMC 17.200.035. (Ord. 16-16 § 1 (part), 2016: Ord. 09-16 (part), 2010; Ord. 96-811 § 3, 1996: Ord. 96-802 § 31, 1996)

18.250.620 Severability.

The provisions of this chapter are hereby declared to be severable. If any provision, clause, sentence, or paragraph of this chapter or the application thereof to any person, establishment, or circumstances shall be held invalid, such invalidity shall not affect the other provisions or application of this chapter. (Ord. 09-16 (part), 2010)