Chapter 13.20
SURFACE WATER RUNOFF REGULATIONS

Sections:

13.20.010    Purpose.

13.20.020    Drainage review – When required – Type.

13.20.030    Drainage review – Requirements.

13.20.040    Critical drainage and/or critical erosion areas.

13.20.050    Engineering plans for the purposes of drainage review.

13.20.060    Construction timing and final approval.

13.20.070    Liability insurance required.

13.20.080    Financial guarantees authorized.

13.20.090    Drainage facilities accepted by Sammamish for maintenance.

13.20.100    Drainage facilities not accepted by Sammamish for maintenance.

13.20.110    Hazards.

13.20.120    Administration.

13.20.130    Enforcement.

13.20.140    Implementation, review and revision.

13.20.150    Severability.

13.20.010 Purpose.

The purpose of this chapter is to promote the public health, safety and welfare by providing for the comprehensive management of surface and stormwaters and erosion control, especially that which preserves and utilizes the many values of the City’s natural drainage system including open space, fish and wildlife habitat, recreation, and education. By conducting programs to reduce flooding, erosion, and sedimentation; prevent and mitigate habitat loss; enhance groundwater recharge; and prevent water quality degradation through the implementation of comprehensive and thorough permit review, construction inspection, enforcement, and maintenance, the effectiveness of the requirements contained in this chapter will be promoted. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.020 Drainage review – When required – Type.

(1) Drainage review is required when any proposed project is subject to a City of Sammamish development permit or approval and:

(a) Would result in 2,000 square feet or more of new impervious surface, replaced impervious surface or new plus replaced impervious surface; or:

(i) Would result in 500 square feet or more of new impervious surface, replaced impervious surface or new plus replaced impervious surface within an historic plat as defined and mapped in Attachment B at the end of this section; or

(ii) Would result in 500 square feet or more of new impervious surface within a landslide hazard drainage area as defined in the adopted Sammamish Addendum to the Surface Water Design Manual; or

(b) Would involve 7,000 square feet or more of land disturbing activity; or

(c) Would construct or modify a drainage pipe or ditch that is 12 inches or more in size or depth or receives surface and stormwater runoff from a drainage pipe or ditch that is 12 inches or more in size or depth; or

(d) Contains or is adjacent to a flood hazard area as defined in SMC Title 15 or 21A; or

(e) Is located within a critical drainage area; or

(f) Is a redevelopment project proposing $100,000 or more of improvements to an existing high-use site.

(2) The drainage review for any proposed project shall be scaled to the scope of the project’s size, type of development and potential for impacts to the regional surface water system to facilitate preparation and review of project applications. If drainage review for a proposed project is required under subsection (1) of this section, the City shall determine which of the following drainage reviews apply as specified in the Surface Water Design Manual:

(a) Simplified drainage review;

(b) Targeted drainage review;

(c) Directed drainage review;

(d) Full drainage review; or

(e) Large project drainage review.

(Ord. O2016-428 § 5 (Att. C); Ord. O2015-389 § 1 (Att. A); Ord. O2011-304 § 1 (Att. A))

13.20.030 Drainage review – Requirements.

(1) A proposed project required to have drainage review by this chapter must meet each of the core requirements which are described in detail in the Surface Water Design Manual and as amended by the Sammamish Addendum to the Surface Water Design Manual.

(2) A proposed project required by this chapter to have drainage review shall meet each of the special requirements which apply to the site and which are described in detail in the Surface Water Design Manual.

(3) An adjustment to the core requirements or special requirements contained in the Surface Water Design Manual may be proposed pursuant to the terms and conditions for drainage adjustment in the Surface Water Design Manual.

(4) Proposed subdivision and short plat projects shall include outreach and education materials to support the continued maintenance and operation of low impact development best management practices. Such materials shall include an on-site educational kiosk located in a high foot traffic area of the development, educational brochures and handouts, noticing on title, noticing on the final plat of maintenance and operations responsibility, and noticing in the covenants, conditions, and restrictions, when any are applicable. Educational kiosks shall only be required for subdivision plats. (Ord. O2018-459 § 1 (Att. A); Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.040 Critical drainage and/or critical erosion areas.

Development in areas where the department has determined that the existing flooding, drainage and/or erosion conditions present an imminent likelihood of harm to the welfare and safety of the surrounding community shall meet special drainage requirements set by the director until such time as the community hazard is alleviated. Such conditions may include the limitation of the volume of discharge from the subject property to predevelopment levels, preservation of wetlands or other natural drainage features or other controls necessary to protect against community hazard. Development proposed in critical drainage areas requiring drainage review shall not qualify for any exemptions or exceptions from core or special requirements in the Surface Water Design Manual unless approved by the director. Where alternate facility designs or methods will produce a compensating or comparable result in the public interest and which will meet this section’s objectives of safety, function, appearance, environmental protection and maintainability, based upon sound engineering judgment, an adjustment to the special drainage requirements promulgated under this section may be proposed; provided, that the resulting development shall be subject to all of the remaining terms and conditions of this chapter. Where application of this section will deny all reasonable use of a property and a facility or design that produces a compensating or comparable result cannot be obtained, then a best practicable alternative may be approved by the director according to the adjustment process defined in the Surface Water Design Manual. These standards are in addition to the applicable standards of Chapter 21A.50 SMC. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.050 Engineering plans for the purposes of drainage review.

(1) These requirements are in addition to the submittal requirements established by Chapter 20.05 SMC.

(a) All engineering plans shall be submitted to the City for review in accordance with the Surface Water Design Manual except those drainage plans developed by, or under the review of, the City of Sammamish department of public works for either surface and stormwater capital improvement, repair, maintenance or restoration projects or other linear government agency projects, such as roadways, railways, pipelines, utility lines and trails.

(b) If engineering plans are returned for any reason, they shall be returned to the applicant.

(c) All master drainage plans, if required, shall be submitted to the City for review in accordance with the specifications in the Surface Water Design Manual. The master drainage plan process should commence at the same time as the State Environmental Policy Act (SEPA) process.

(d) Drainage plans not subject to review by the City under subsection (1)(a) of this section shall be reviewed by the department of public works in accordance with this chapter. Project applicability and compliance with this chapter shall be documented in writing and available for review.

(2) The expiration time frames as specified in the Surface Water Design Manual shall apply to all permit and approval applications.

(3) All plans shall be processed in accordance with the review procedures specified in the Surface Water Design Manual.

(4) Submittal procedures, definitions and specifications for the required contents of engineering plans are presented in the Surface Water Design Manual. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.060 Construction timing and final approval.

(1) No work related to permanent or temporary storm drainage control for a permitted development may proceed without the approval of the director.

(2) Erosion and sediment control measures associated with both the interim and permanent drainage systems shall be:

(a) 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

(b) 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.

(3) The applicant shall have constructed and have in operation those portions of the drainage facilities necessary to accommodate the control of surface and stormwater runoff discharging from the site before the construction of any other improvements or buildings on the site, or in accordance with SMC Title 19A. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.070 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, which shall name City as an additional insured and protect the City from liability relating to the construction or maintenance of the facility until construction approval or acceptance 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 may initiate enforcement action pursuant to SMC Title 23. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.080 Financial guarantees authorized.

The City is authorized to require all applicants issued permits or approvals under the provisions of this title to post financial guarantees consistent with the provisions of SMC Title 27A. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.090 Drainage facilities accepted by Sammamish for maintenance.

(1) The City is responsible for the maintenance, including performance and operation, of drainage facilities which have formally been accepted for maintenance by the director.

(2) The City may assume maintenance of privately maintained drainage facilities only if (a) the City first determines that a clear public benefit will result, greater in scope than the public cost, from the use of public resources to participate wholly or partially in the maintenance of a private storm or surface water drainage system component, and (b) all of the following conditions have been met:

(a) All necessary easements or dedications entitling the City to properly maintain the drainage facility have been conveyed to the City;

(b) The director has determined that the facility is in the dedicated public road right-of-way or that maintenance of the facility will contribute to protecting or improving the health, safety and welfare of the community based upon review of the existence of or potential for:

(i) Flooding,

(ii) Downstream erosion,

(iii) Property damage due to improper function of the facility,

(iv) Safety hazard associated with the facility,

(v) Degradation of water quality or in-stream resources, or

(vi) Degradation to the general welfare of the community; and

(c) The director has declared in writing acceptance of maintenance responsibility by the City. Copies of this document will be kept on file in the department of public works.

(3) The director may terminate the department’s assumption of maintenance responsibilities in writing after determining that continued maintenance will not significantly contribute to protecting or improving the health, safety and welfare of the community based upon review of the existence of or potential for:

(a) Flooding;

(b) Downstream erosion;

(c) Property damage due to improper function of the facility;

(d) Safety hazard associated with the facility;

(e) Degradation of water quality or in-stream resources; or

(f) Degradation to the general welfare of the community.

Copies of this document will be kept on file in the department of public works.

(4) A drainage facility which does not meet the criteria of this section shall remain the responsibility of the applicant required to construct the facility and persons holding title to the property for which the facility was required. (Ord. O2017-432 § 1 (Att. A); Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.100 Drainage facilities not accepted by Sammamish for maintenance.

(1) The person or persons holding title to the property and the applicant required to construct a drainage facility shall remain responsible for the facility’s continual performance, operation and maintenance in accordance with the standards and requirements of the department and remain responsible for any liability as a result of these duties. This responsibility includes maintenance of a drainage facility which is:

(a) Under a maintenance guarantee or defect guarantee;

(b) A private road conveyance system;

(c) Released from all required financial guarantees prior to July 7, 1980;

(d) Located within and serving only one single-family residential lot;

(e) Located within and serving a multifamily or commercial site unless the facility is part of an approved shared facility plan;

(f) Located within or associated with a short subdivision or subdivision which handles runoff from an area of which less than two-thirds is designated for detached or townhouse dwelling units located on individual lots unless the facility is part of an approved shared facility plan;

(g) Previously terminated for assumption of maintenance responsibilities by the department in accordance with this chapter; or

(h) Not otherwise accepted by the City for maintenance.

(2) Prior to the issuance of any of the permits for any multifamily or commercial project required to have a flow control or water quality treatment facility, the applicant shall record a declaration of covenant as specified in the Surface Water Design Manual. The restrictions set forth in such covenant shall include, but not be limited to, provisions for notice to the persons holding title to the property of a City determination that maintenance and/or repairs are necessary to the facility and a reasonable time limit in which such work is to be completed.

(a) In the event that the titleholders do not effect such maintenance and/or repairs, the City may perform such work upon due notice. The titleholders are required to reimburse the City for any such work. The restrictions set forth in such covenant shall be included in any instrument of conveyance of the subject property and shall be recorded with the records and licensing services division of King County.

(b) The City may enforce the restrictions set forth in the declaration of covenant provided in the Surface Water Design Manual.

(3) Prior to the issuance of any of the permits and/or approvals for the project or the release of financial guarantees posted to guarantee satisfactory completion, the person or persons holding title to the subject property for which a drainage facility was required shall pay a fee established by the director as set forth in the City resolution to reasonably compensate the City for costs relating to inspection of the facility to ensure that it has been constructed according to plan and applicable specifications and standards.

(4) The duties specified in this section with regard to payment of inspection fees and reimbursement of maintenance costs shall be enforced against the person or persons holding title to the property for which the drainage facility was required.

(5) Where not specifically defined in this section, the responsibility for performance, operation and maintenance of drainage facilities and conveyance systems, both natural and constructed, shall be determined on a case-by-case basis. In any such case-by-case analyses, the City shall only be responsible for the performance, operation and maintenance of drainage facilities and conveyance systems if a determination is first made pursuant to the criteria set forth in SMC 13.20.090(2) as now in effect or as may be subsequently amended. (Ord. O2017-432 § 1 (Att. A); Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.110 Hazards.

Whenever the director determines that any existing construction site, erosion and sedimentation problem and/or drainage facility poses a hazard to life and limb, endangers any property, and/or adversely affects the condition or capacity of other drainage facilities, the safety and operation of City right-of-way, utilities, and/or other property owned or maintained by the City, the applicant/person to whom the permit was issued pursuant to this chapter, the owner of the property within which the drainage facility is located, the applicant/person responsible for maintenance of the facility, and/or other person or agent in control of said property, upon receipt of notice in writing from the director, shall within the period specified therein repair or otherwise address the cause of the hazardous situation in conformance with the requirements of this chapter.

Should the director have reasonable cause to believe that the situation is so adverse as to preclude written notice, the director may take the measures necessary to eliminate the hazardous situation; provided, that the director shall first make a reasonable effort to locate the owner before acting. In such instances the applicant of whom a drainage plan was required pursuant to this chapter, the owner of the property and/or the person responsible for the maintenance of the facility shall be obligated for the payment of all costs incurred. If costs are incurred and a financial guarantee pursuant to this chapter or other City requirement has been posted, the director shall have the authority to collect against the financial guarantee to cover costs incurred. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.120 Administration.

(1) Administration.

(a) The director is authorized to promulgate and adopt administrative rules under the procedures specified in Chapter 2.55 SMC, for the purpose of implementing and enforcing the provisions of this chapter. Adopted administrative rules are available to the public from the department of public works. This includes, but is not limited to, the Surface Water Design Manual.

(b) The 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.

(2) Inspections. The director is authorized to make such inspections and take such actions as may be required to enforce the provisions of this chapter.

(3) 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 director has reasonable cause to believe that violations of this chapter are present or operating on a subject property or portion thereof, the director 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 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.

(4) Access. Proper ingress and egress shall be provided to the director to inspect, monitor or perform any duty imposed upon the director by this chapter. The director 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 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. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.130 Enforcement.

The City 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 of SMC Title 23. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.140 Implementation, review and revision.

The department may administer a training program for users of the Surface Water Design Manual. The department may also conduct an ongoing research program to evaluate the effectiveness of the requirements in meeting the purpose of this chapter. This research program may examine, but not be limited to, hydrologic and hydraulic analysis methods, stream geomorphologic analysis methods, water quality, best management practices and erosion and sediment control measures. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))

13.20.150 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 provision to other persons or property shall not be affected. (Ord. O2016-428 § 5 (Att. C); Ord. O2011-304 § 1 (Att. A))