Chapter 15.18
SURFACE WATER AND STORMWATER MANAGEMENT

Sections:

15.18.010    Legislative findings.

15.18.020    Purposes.

15.18.030    Intent and priority of applicable documents.

15.18.040    Definitions.

15.18.050    When drainage review required.

15.18.060    Prerequisites to commencement of construction.

15.18.070    City costs for drainage review.

15.18.080    Responsibility for construction of drainage facilities.

15.18.090    Completion of permanent drainage facilities required before final approval.

15.18.100    Requirements for all drainage facilities.

15.18.110    Requirements for drainage facilities to be conveyed to the city of Snoqualmie.

15.18.120    Maintenance of drainage facilities not conveyed to the city of Snoqualmie.

15.18.130    Water quality standards adopted by reference.

15.18.140    Stormwater Pollution Prevention Manual adopted by reference.

15.18.150    Illicit discharges to storm drain system or water prohibited.

15.18.160    Establishing or maintaining unauthorized connection to the municipal storm drain system.

15.18.170    Liability insurance required.

15.18.180    Use of wetlands for stormwater management prohibited.

15.18.190    Administration.

15.18.200    Enforcement.

15.18.210    Severability.

15.18.010 Legislative findings.

A. Building and development projects including redevelopment which create or increase impervious surfaces may cause stormwater runoff in greater quantities or at an increased rate of flow compared to existing conditions before development.

B. The potential adverse consequences of such increased stormwater runoff may include increased likelihood of urban flooding, degradation of water quality, and damage from erosion and sedimentation to the natural drainage system, public and private property and fish and wildlife habitat.

C. It would promote the public health, safety and welfare to require proposed development to evaluate its impacts to the storm drain system and to provide appropriate measures when determined necessary to control probable adverse consequences. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.020 Purposes.

The purposes of this chapter are to:

A. Provide for a comprehensive review process to evaluate stormwater runoff from building and development projects including redevelopment in the city and provide appropriate controls when necessary;

B. Minimize water quality degradation from pollutants and siltation from stormwater runoff;

C. Control erosion and sedimentation of creeks, streams, rivers, ponds and other water bodies from stormwater runoff;

D. Decrease damages to public and private property caused by stormwater runoff; and

E. Ensure that LID is the preferred and commonly used approach to site development with the goals of minimizing impervious surfaces, minimizing native vegetation loss, and minimizing stormwater runoff in all types of development. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.030 Intent and priority of applicable documents.

A. It is the intent of this chapter that all projects meet or exceed the thresholds, definitions, minimum requirements and exceptions/variance criteria of the following documents, all of which are hereby incorporated in this chapter as if set forth at length, in descending order of priority:

1. Appendix I of the Western Washington Phase II Municipal Stormwater Permit;

2. Appendix I-E, Flow Control Exempt Surface Waters, of the Washington State Department of Ecology Stormwater Management Manual for Western Washington, 2012, amended in 2014;

3. The City of Snoqualmie Addendum to the 2016 King County Surface Water Design Manual; and

4. The 2016 King County Surface Water Design Manual.

B. If a project meets the thresholds, definitions, minimum requirements and variance/exception criteria of a higher priority document under subsection A of this section, any conflicting thresholds, definitions, minimum requirements and variance/exception criteria of a lower priority document shall not apply. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.040 Definitions.

In addition to the definitions contained in the documents incorporated by reference in this chapter, the words set out in this section shall have the following meanings as used in this chapter:

A. “Bioretention” means a shallow depression landscaped with plantings designed to temporarily store and promote infiltration of stormwater runoff.

B. “Best management practices (BMPs)” means schedules of activities, prohibitions of practices, general good housekeeping practices, pollution prevention and educational practices, maintenance procedures, and structural or managerial practices to prevent or reduce the discharge of pollutants directly or indirectly to stormwater, receiving waters, or stormwater conveyance systems. BMPs also include treatment practices, operating procedures, and practices to control site runoff, spillage or leaks, sludge or water disposal, or drainage from raw materials storage.

C. “Clean Water Act” means the Federal Water Pollution Control Act (33 USC Section 1251 et seq.), and any subsequent amendments thereto.

D. Unless otherwise specified, “department” means the community development department of the city of Snoqualmie.

E. Unless otherwise specified, “director” means the director of the community development department of the city of Snoqualmie.

F. “Drainage facility” means a constructed or engineered feature that collects, conveys, stores, treats, or otherwise manages stormwater runoff or surface water. Drainage facilities include, but are not limited to, a constructed or engineered stream, lake, wetland, or closed depression, or a pipe, channel, ditch, gutter, flow control facility, flow control BMP, water quality facility, erosion and sediment control facility, or any other structure and appurtenance that provides for drainage.

G. “Drainage review” means an evaluation by the department of a proposed project’s compliance with the drainage requirements of this chapter.

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

I. “Hazardous materials” means any material, including any substance, waste, or combination thereof, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may cause, or significantly contribute to, a substantial present or potential hazard to human health, safety, property or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.

J. “Hyperchlorinated” means water that contains more than 10 milligrams per liter chlorine.

K. “Illicit discharge” means any direct or indirect nonstormwater discharge to the city’s storm drain system, except as expressly allowed by this chapter.

L. “Illicit connection” means any man-made conveyance that is connected to a municipal separate storm sewer without a permit, excluding roof drains and other similar type connections. Examples include sanitary sewer connections, floor drains, channels, pipelines, conduits, inlets, or outlets that are connected directly to the municipal separate storm sewer system.

M. “Low impact development (LID)” means a stormwater and land use management strategy that strives to mimic predisturbance 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.

N. “Low impact development best management practices (LID BMPs)” means distributed stormwater management practices, integrated into a project design, that emphasize predisturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration. LID BMPs are referred to as flow control BMPs in the King County Surface Water Design Manual and include, but are not limited to, bioretention, permeable pavements, roof downspout controls, dispersion, soil quality and depth, and minimal excavation foundations.

O. “Municipal separate storm sewer system” (MS4) means a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains):

1. Owned or operated by the city of Snoqualmie;

2. Designed or used for collecting or conveying stormwater;

3. Which is not part of a publicly owned treatment works (POTW). “POTW” means any device or system used in treatment of municipal sewage or industrial wastes of a liquid nature which is publicly owned; and

4. Which is not a combined sewer. “Combined sewer” means a system that collects sanitary sewage and stormwater in a single sewer system.

P. “National Pollutant Discharge Elimination System (NPDES) stormwater discharge permit” means a permit issued by the Environmental Protection Agency (EPA) (or by the Washington Department of Ecology under authority delegated pursuant to 33 USC Section 1342(b)) that authorizes the discharge of pollutants to waters of the United States, whether the permit is applicable on an individual, group, or general area-wide basis.

Q. “Nonstormwater discharge” means any discharge to the storm drain system that is not composed entirely of stormwater.

R. “Permeable pavement” means pervious concrete, porous asphalt, permeable pavers or other forms of pervious or porous paving material intended to allow passage of water through the pavement section. It often includes an aggregate base that provides structural support and acts as a stormwater reservoir.

S. “Person” means any individual, association, organization, partnership, firm, corporation or other entity recognized by law and acting as either the owner of a premises or as the owner’s agent.

T. “Pollutant” means anything which causes or contributes to pollution. Pollutants may include, but are not limited to: paints, varnishes, and solvents; oil and other automotive fluids; nonhazardous liquid and solid wastes and yard wastes; refuse, rubbish, garbage, litter, or other discarded or abandoned objects and accumulations, so that the same may cause or contribute to pollution; floatables; pesticides, herbicides, and fertilizers; hazardous substances and wastes; sewage, fecal coliform and pathogens; dissolved and particulate metals; animal wastes; wastes and residues that result from constructing a building or structure; and noxious or offensive matter of any kind.

U. “Premises” means any building, lot, parcel of land, or portion of land, whether improved or unimproved, including adjacent sidewalks and parking strips.

V. “Project” means a building or development project, including redevelopment, that requires a city permit or approval and will result in the construction of new or a combination of new and replaced impervious surface.

W. “Storm drain system” means the system of gutters, pipes, streams, or ditches used to carry surface water and stormwater runoff from surrounding lands to streams, lakes, or engineered treatment facilities.

X. “Stormwater” means runoff during and following precipitation and snowmelt events, including surface runoff and drainage.

Y. “Stormwater pollution prevention plan (SWPPP)” means a document which describes the best management practices and activities to be implemented by a person to identify sources of pollution or contamination at a premises and the actions to eliminate or reduce pollutant discharges to stormwater, stormwater conveyance systems, and/or receiving waters to the maximum extent practicable.

Z. “Surface Water Design Manual” means the 2016 King County Surface Water Design Manual and the City of Snoqualmie Addendum to the 2016 King County Surface Water Design Manual. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.050 When drainage review required.

Drainage review shall be required when any project meets or exceeds the threshold conditions defined in the City of Snoqualmie Addendum to the Surface Water Design Manual or a city of Snoqualmie permit or approval is required for the project. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.060 Prerequisites to commencement of construction.

No project shall be permitted to commence construction until either the director has determined in writing that the project is exempt from drainage review or the drainage review determined to be necessary for the project has been completed, including approval of a stormwater plan for the project, approval of engineering plans for any required drainage facilities, and delivery to the director of a consent in writing signed by the owner of the property upon which the drainage facilities are to be located to enter upon real property for the purposes of inspection and enforcement of the provisions of this chapter. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.070 City costs for drainage review.

All city costs incurred for drainage review, engineering plan review, and construction inspection, and all costs associated with conveyance of those drainage facilities to be conveyed to the city of Snoqualmie, shall be the responsibility of the developer according to the procedures set forth in Chapter 14.20 SMC. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.080 Responsibility for construction of drainage facilities.

A. Unless otherwise provided, it shall be the responsibility of the developer or property owner of a project to design, construct and maintain drainage facilities that comply with the standards and minimum requirements of this chapter.

B. No work related to permanent or temporary stormwater control for a permitted development may proceed without the approval of the director.

C. Erosion and sediment control measures associated with both the temporary and permanent storm drain systems shall be:

1. Constructed in accordance with the approved plan prior to any grading or land clearing other than that associated with an approved erosion and sediment control plan; and

2. Satisfactorily sequenced and maintained until all improvements, restoration, and landscaping associated with the permit and approvals for the project are completed and the potential for on-site erosion has passed.

D. The applicant shall have constructed and have in operation those portions of the drainage facilities necessary to accommodate the control of stormwater runoff discharging from the site before the construction of any other improvements or buildings on the site, or before final recording of a plat or short plat, unless, upon written request of the applicant, the city engineer authorizes recording before construction of drainage facilities in order to minimize impacts that may result from construction of drainage facilities during inappropriate times of the year, with a bond sufficient to ensure timely completion. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.090 Completion of permanent drainage facilities required before final approval.

All permanent drainage facilities shall be inspected by the city and must be clean and fully operational prior to the final city approval allowing occupancy, use or sale of the project. No performance bond shall be permitted to obtain such final project approval prior to completion and approval of any required permanent drainage facilities, except pursuant to SMC 15.18.080(D). (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.100 Requirements for all drainage facilities.

A. A performance bond shall be posted in the amount of 150 percent of the estimated cost of construction of the drainage facilities to ensure completion of the drainage facility within the time specified for completion.

B. Upon release of the performance bond, a maintenance/guarantee bond shall be posted for 10 percent of the cost of construction to ensure that any defects in material or workmanship are repaired and that the drainage facility functions in accordance with its design specifications for a period of two years.

C. The developer shall grant the city of Snoqualmie an easement permitting access for inspection and performance of any required maintenance or repair required to protect the public health and welfare prior to conveyance to the city. Any costs expended by the city shall be an obligation of the developer. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.110 Requirements for drainage facilities to be conveyed to the city of Snoqualmie.

If permanent drainage facilities are to be conveyed to the city of Snoqualmie, the following additional requirements shall be met:

A. A developer extension agreement shall be entered prior to commencement of construction, describing specifically the facilities conveyed by reference to approved engineering plans, and the conditions under which the city shall accept the drainage facilities.

B. The drainage facilities shall be operated and maintained by the developer for a period of at least two years before conveyance to the city.

C. A complete and accurate set of as-builts in high-quality, searchable PDF and AutoCAD format must be provided to and approved by the city.

D. Electronic files meeting all city standards for electronic files, including file format and GIS standards, have been provided to and approved by the city. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.120 Maintenance of drainage facilities not conveyed to the city of Snoqualmie.

A. The person holding title to the property and the developer required to construct a drainage facility shall remain responsible for the drainage facility’s ongoing performance, operation and maintenance.

B. Maintenance of drainage facilities shall conform to the operation and maintenance plan approved as part of the stormwater plan.

C. It shall be a gross misdemeanor for any person responsible for maintenance of a drainage facility to refuse or fail to perform required maintenance after written notice from the director to perform required maintenance. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.130 Water quality standards adopted by reference.

The city of Snoqualmie hereby adopts by reference the water quality standards established under authority of Chapter 90.48 RCW and contained in Chapter 173-201A WAC as they now exist or may hereafter be amended. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.140 Stormwater Pollution Prevention Manual adopted by reference.

A. The King County Stormwater Pollution Prevention Manual, Best Management Practices for Commercial, Multi-Family and Residential Properties, April 2016, is hereby adopted by reference.

B. Maintenance of records documenting implementation of applicable best management practices shall be the responsibility of each property owner. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.150 Illicit discharges to storm drain system or water prohibited.

A. Prohibited Discharges – Prohibition of Illegal Discharges. No person shall throw, drain, or otherwise discharge, cause or allow others under its control to throw, drain or otherwise discharge into a drainage facility and/or surface and groundwaters any materials other than stormwater.

B. Examples of prohibited contaminants include but are not limited to the following:

1. Trash or debris.

2. Construction materials.

3. Petroleum products including but not limited to oil, gasoline, grease, fuel oil and heating oil.

4. Antifreeze and other automotive products.

5. Metals in either particulate or dissolved form.

6. Flammable or explosive materials.

7. Radioactive material.

8. Batteries.

9. Acids, alkalis, or bases.

10. Paints, stains, resins, lacquers, or varnishes.

11. Degreasers and/or solvents.

12. Drain cleaners.

13. Pesticides, herbicides, or fertilizers.

14. Steam cleaning wastes.

15. Soaps, detergents, or ammonia.

16. Swimming pool, spa, or hot tub cleaning wastewater, or filter backwash.

17. Chlorine, bromine, or other disinfectants.

18. Heated water.

19. Domestic animal wastes.

20. Sewage.

21. Recreational vehicle waste.

22. Animal carcasses.

23. Food wastes.

24. Bark and other fibrous materials.

25. Lawn clippings, leaves, or branches.

26. Silt, sediment, concrete, cement or gravel.

27. Dyes.

28. Chemicals not normally found in uncontaminated water.

29. Any other process-associated discharge except as otherwise allowed in this section.

30. Any hazardous material or waste not listed above.

C. Allowable Discharges. The following types of discharges shall not be considered illegal discharges for the purposes of this chapter unless the director of the department of parks and public works determines that the type of discharge, whether singly or in combination with others, is causing or is likely to cause pollution of surface water or groundwater:

1. Diverted stream flows.

2. Rising groundwaters.

3. Uncontaminated groundwater infiltration, as defined in 40 CFR 35.2005(20).

4. Uncontaminated pumped groundwater.

5. Foundation drains.

6. Air conditioning condensation.

7. Irrigation water from agricultural sources that is commingled with urban stormwater.

8. Springs.

9. Uncontaminated water from crawl space pumps.

10. Footing drains.

11. Flows from riparian habitats and wetlands.

12. Discharges from emergency fire fighting activities.

13. Dye testing is allowable but requires verbal notification to the director at least one day prior to the date of test.

D. Conditional Discharges. The following types of discharges shall not be considered illegal discharges for the purposes of this chapter if they meet the state’s conditions, or unless the director of the department of parks and public works determines that the type of discharge, whether singly or in combination with others, is causing or is likely to cause pollution of surface water or groundwater:

1. Potable water, including water from water line flushing, hyperchlorinated water line flushing, fire hydrant system flushing, and pipeline hydrostatic test water. Planned discharges shall be dechlorinated to a concentration of 0.1 ppm or less, pH-adjusted, if necessary and volumetrically and velocity controlled to prevent resuspension of sediments in the storm drain system;

2. Lawn watering and other irrigation runoff are permitted but shall be minimized;

3. Dechlorinated swimming pool, spa, and hot tub discharges. These discharges shall be dechlorinated to a concentration of 0.1 ppm or less, pH-adjusted and reoxygenized if necessary, volumetrically and velocity controlled to prevent resuspension of sediments in the storm drain system. Discharges shall be thermally controlled to prevent an increase in temperate of the receiving water. Swimming pool cleaning wastewater and filter backwash shall not be discharged to the storm drain system;

4. Street and sidewalk wash water, water used to control dust, and routine external building wash down that does not use detergents are permitted if the amount of street wash and dust control water used is minimized. At active construction sites, street sweeping must be performed prior to washing the street;

5. Nonstormwater discharges covered by any NPDES permit; provided, that the discharger is in full compliance with all requirements of the permit, waiver, or order and other applicable laws and regulations; and provided, that written approval has been granted for any discharge to the storm drain system;

6. Other nonstormwater discharges. The discharges shall be in compliance with the requirements of a pollution prevention plan reviewed by the city which addresses control of such discharges.

E. Prohibition of Illicit Connections.

1. The construction, use, maintenance, or continued existence of illicit connections to the storm drain system is prohibited.

2. This prohibition expressly includes, without limitation, illicit connections made in the past, regardless of whether the connection was permissible under law or practices applicable or prevailing at the time of connection.

3. A person is considered to be in violation of this chapter if the person connects a line conveying sewage to the MS4, or allows such a connection to continue. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.160 Establishing or maintaining unauthorized connection to the municipal storm drain system.

A. It shall be a misdemeanor to establish any unauthorized connection to the municipal storm drain system.

B. It shall be a gross misdemeanor to maintain or fail or refuse to remove any unauthorized connection to the municipal storm drain system after written notice from the director to remove such unauthorized connection to the municipal storm drain system. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.170 Liability insurance required.

The applicant required to construct the drainage facility pursuant to this chapter shall maintain a combined single limit per occurrence liability policy in the amount established annually by the city risk management program, which shall name the city of Snoqualmie as an additional insured and protect the city of Snoqualmie from liability relating to the construction or maintenance of the drainage facility until construction approval or acceptance of ownership of the drainage facility by the city of Snoqualmie for maintenance, whichever is last. Proof of this required liability policy shall be provided to the director prior to commencing construction of any drainage facility. If this liability insurance is not kept in effect as required, the city of Snoqualmie may initiate enforcement. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.180 Use of wetlands for stormwater management prohibited.

Notwithstanding any other provision of this code, drainage facilities shall not be built within a natural vegetated buffer or wetland, provided:

A. Conveyance systems may be approved by the city when there is no feasible alternative;

B. Drainage facilities may be located in the outer 15 feet of a wetland buffer when required by engineering constraints, and when such discharges are designed to be infiltrated into appropriate soils or discharged as surface sheet flow in appropriate slope conditions, pursuant to SMC 19.12.170(H)(3); and

C. Drainage facilities may be allowed in wetlands approved for hydrologic modification and/or treatment in accordance with Guidesheet 1 in Appendix I-D of the Washington State Department of Ecology Stormwater Management Manual for Western Washington (2012, amended in 2014). (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.190 Administration.

A. Administration.

1. The community development department director and the director of the parks and public works department are authorized to promulgate and adopt administrative rules under the procedures specified in Chapter 2.05 SMC for the purpose of implementing and enforcing the provisions of this chapter. Adopted administrative rules are available to the public from the department, including but not limited to the Surface Water Design Manual.

2. The community development department director is authorized to develop procedures for applying adopted rules and regulations during the review of permit applications for the development of land. These procedures may also be contained in the Surface Water Design Manual.

B. Inspections. The director or designee and/or the director of the parks and public works department is authorized to make such inspections and take such actions as may be required to enforce the provisions of this chapter.

C. Right of Entry. Whenever necessary to make an inspection to enforce any of the provisions of this chapter, monitor for proper function of drainage facilities or whenever the community development department or parks and public works department director or designee has reasonable cause to believe that violations of this chapter are present or operating on a subject property or portion thereof, the director or designee may enter such premises at all reasonable times to inspect the same or perform any duty imposed upon the director by this chapter; provided, that if such premises or portion thereof is occupied, the director or designee shall first make a reasonable effort to locate the owner or other person having charge or control of the premises or portion thereof and demand entry.

D. Access. Proper ingress and egress shall be provided to the community development department or parks and public works department director or designee to inspect, monitor or perform any duty imposed upon the director by this chapter. The director or designee shall notify the responsible party in writing of failure to comply with this access requirement. Failing to obtain a response within seven days from the receipt of notification, the director or designee may order the work required completed or otherwise address the cause of improper access. The obligation for the payment of all costs that may be incurred or expended by the city in causing such work to be done shall thereby be imposed on the person holding title to the subject property. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.200 Enforcement.

The director is authorized to enforce the provisions of this chapter, the ordinances and resolutions codified in it, and any rules and regulations promulgated thereunder pursuant to the enforcement and penalty provisions. The remedies in this chapter are in addition to any other remedy provided by law. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).

15.18.210 Severability.

If any provision of this chapter or its application to any person or property is held invalid, the remainder of the chapter or the application of the provisions to other persons or property shall not be affected. (Ord. 1198 § 19 (Exh. B), 2017; Ord. 1081 § 2, 2011).