Loading...
HomeMy WebLinkAbout2130ORDINANCE NO. 1130 AN ORDINANCE of the City of Kent, Washington, adopting by reference the "CITY OF KENT SURFACE WATER AND DRAINAGE CODE" and providing for future amendments to the Code. THE CITY COUNCIL OF THE CITY OF KENT, WASHINGTON, DO HEREBY ORDAIN AS FOLLOWS: Section 1. There is hereby adopted by reference, as if fully set forth herein, that certain Code approved by the Kent i City Council at a regular meeting December 4, 1978 and known as the "CITY OF KENT SURFACE WATER AND DRAINAGE CODE." 4 Section 2. Future changes, additions or amendments to the Code may be made by motion duly seconded and passed at any regular or special meeting of the Kent City Council. Section 3. This Ordinance shall take effect and be in force five (5) days from and after its passage, approval and publication as provided by law and upon the filing of three copies of the Code with th)v Kent City Clerk. ISABEL HOGIAN, ATTEST: MARIE JEN, CITY CLERK A�PROVED AS TO FORN�i: tJ DONALD E. MIRK, CITY ATTORNEY PASSED the day of December, 1978. APPROVED the day of December, 1978. PUBLISHED the ? day of December, 1978. I hereby certify that this is a true copy of Ordinance No. P/3C' , passed by the City Council of the City of Kent, Washington, and approved by the Mayor of the City of Kent as hereon indicated. (SEAL) MAR" JENSEN, CITY CLERK M1` CITY OF KENT SURFACE WATER AND DRAINAGE CODE WHEREAS, an expending population and increased de- velopment of land in the City of Kent, coupled with inade- quate drainage controls, has lead to drainage and runoff problems, and WHEREAS, these drainage and runoff problems contrib- ute to increased sedimentation in ponds, creeks, and streams, thereby degrading water quality, and WHEREAS, these drainage and runoff problems also con- tribute to water quality degradation through excessive dis- charge of nutrients, metals, oil and grease, toxic materials, and other detrimental substances, and WHEREAS, inadequate surface and subsurface drainage planning and practices lead to erosion and property damage, and risk to life, and WHEREAS, excessive water runoff on streets and high- ways poses a safety hazard to both lives and property, and WHEREAS, the Kent City Council finds that future prob- lems could be avoided if developers, both private and public, provide for adequate drainage of their property, NOW, THEREFORE, THERE IS HEREBY created a new City Code entitled, "SURFACE WATER AND DRAINAGE CODE". SECTION I PURPOSES. The City Council finds that this Code is necessary in order_ to promote sound development policies and CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 2 construction procedures which respect and preserve the City's water courses; to minimize water quality degradation and con- trol the sedimentation of creeks, streams, ponds, lakes and other water bodies; to protect property owners adjacent to developing and developed land from increased runoff rates which could cause erosion of abutting property; to protect downstream owners; to preserve and enhance the suitability of waters for contact recreation and fishing; to preserve and enhance the aesthetic quality of the waters; to maintain and protect valuable groundwater resources; to minimize adverse effects of alterations in groundwater quantities, locations, and flow patterns; to ensure the safety of City/County roads and rights-of-way; and to decrease drainage related damage to public and private property. SECTION II DEFINITIONS. 1. "Procedures Manual" shall mean the manual of technical and administrative procedures established by the Public Works Department which delineates methods to be used, the level of detail of analysis required, and other details for implementation of the provisions of this Code. 2. "Comprehensive Drainage Plan" refers to a detailed analysis for each drainage basin which compares the capabilities and needs for runoff accommodation due to various combinations of development, land use, structural and non-structural management alternatives. The plan recommends the form, CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 3 location and extent of quantity and quality control measures which optimally would meet the legal constraints, water quality stand- ards, and community standards, as well as identifying the institutional and funding requirements for plan implementation. NOTE: Analysis of each drainage basin will depend upon specific criteria set forth by King County in order to identify critical drainage areas. 3. "Computations" shall mean calculations, in- cluding coefficients and other pertinent data, made to determine the drainage pian with rates of flow of water given in cubic feet per sec- ond (cfs) and cubic meters per second (cros). 4. "Design Storm" shall refer to that rainfall event which is selected by the Public Works Department for purposes of design, specifying both the return period in years and the dura- tion in hours. 5. "Detention Facilities" shall mean facilities designed to hold runoff while gradually re- leasing it at a predetermined maximum rate. 6. "Developer" shall mean the individual(s) or corporation(s) applying for the permits or approvals described in Section III of this Code. 7. "Developmental coverage" shall mean all devel- oped surface areas within the subject property including, but not limited to, rooftops, drive- ways, carports, accessory buildings, parking areas, and any other impervious surfaces. CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 4 During construction, "developmental coverage" shall include the above in addition to the full extent of any alteration of previously occur- ing soils, slope or vegetation due to grading, temporary storage, access areas, or any other short-term causes. 8. "Drainage area" shall mean the watershed con- tributing water runoff to and including the subject property. 9. "Drainage plan" shall mean a plan for col- lection, transport, treatment, and discharge or recycling of water within the subject prop- erty. 10. "Drainage treatment/abatement facilities" shall mean anv facilities installed or con- structed in conjunction with a drainage plan for the purpose of treatment or abatement of urban runoff, excluding retention or deten- tion facilities. 11. "Natural location" of drainage systems shall refer to the location of those channels, swales, and other natural conveyance systems as defined by the first documented topographic contours existing for the subject property, either from maps or photographs, or such other means as appropriate. 12. "Peak discharge" shall mean the maximum surface water runoff rate (cfs and cros) determined for the design storm. 13. "Planned development" shall refer to resident- ial developments which are planned and/or dev- CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 5 eloped in several stages but submitted together for approvals, and which typically consist of clusters of multi -unit structures interspersed with areas of common open space. 14. "Receiving bodies of water" shall mean creeks, streams, lakes and other bodies of water into which waters are directed, either naturally, in manmade ditches, or in closed conduit systems. 15. "Retention facilities" shall mean facilities designed to hold water for a considerable length of time and then consume it by evaporation, plant transpiration, or infiltration into the soil. 16. "Subject property" shall mean the tract of land which is the subject of a permit and/or ap- proval action. 17. "Planning Department" shall refer to the City of Kent Planning Department. 18. "Public Works Department" shall refer to the City of Kent Public Works Department. 19. "City Engineer" shall refer to the City of Kent City Engineer. SECTION III SUBMISSION OF A DRAINAGE PLAN. 1. All developers applying for any of the follow- ing permits and/or approvals shall submit for approval a drainage plan with their application and/or request: a) Grading permit b) Substantial development permit required under RCW 90.58(Shoreline Management Act) CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 6 c) Subdivision approval d) Short subdivision approval e) Rezones f) Conditional Use Permits g) Building permits where the permit relates to 5,000 or more square feet of development coverage within the property, or where de- velopment is in a critical area as determin- ed by the Public Works Department. h) Planned (unit) development. 2. Commencement of construction work under any of the above permits or applications shall not begin until such time as final approval of the drainage plan is obtained in accord- ance with Section VII of this Code. 3. The same plan submitted during one permit/ approval process may be subsequently submitted with further required applications. The plan shall be supplemented with such additional information as may be requested by the Public Works Department or required by the provisions of the Procedures Manual. 4. The plan requirement established in this sec- tion will apply except when the developer dem- onstrates to the satisfaction of the Public Works and Planning Departments that the pro- posed activity or development: a) Will neither seriously nor adversly im- pact the water quality conditions of any affected receiving bodies of water, and b) Will not alter the surface discharge lo- CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 7 cation, alter the drainage pattern or ad- joining properties, alter drainage patterns, increase the discharge, nor cause any other adverse effects in the drainage area, and c) Will not alter the subsurface drainage pat- terns, flowrates, and discharge points, nor result in any significant adverse effects to property or residents. SECTION IV CONTENTS OF A DRAINAGE PLAN All persons applying for any of the permits and/or_ approvals contained in Section II of this Code shall provide a drainage plan for surface and perti- nent subsurface water flows entering, flowing within, and leav- ing the subject property both during and after construction. The detailed form and contents of the drainage plan shall be described in procedures established by the Public Works and Planning Departments, or in the Procedures Manual. The Proce- dures Manual will set forth the manner of presenting the follow- ing required information: 1. Background computations for sizing drainage facilities: a) Depiction of the drainage area on a topo- graphical map of approved scale and contour interval, with acreage of the site, devel- opment, and developmental coverage indicated. b) Indication of the peak discharge and volume of runoff which will be generated due to the design storm within the subject property un- der_ its current use. c) Indication of the peak discharge and volume CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 8 of runoff which will be generated due to the design storm within the subject property if the development or proposed activity is al- lowed to proceed. d) Determination of the peak discharge and vol- ume of water that will be generated by the design storm at various points on the subject property. 2. Proposed measures for handling the computed run- off at the detail level specified in the Procedures Manual. 3. Proposed measures for controlling runoff during construction. The requirements of this section may be modified at the discretion of the Public Works Department in special cases requiring more information, with the concurrence of the Plan- ning Department. SECTION V MANDATORY REQUIREMENTS FOR DRAINAGE IMPROVEMENTS. 1. a) Surface water entering the subject property shall be received at the naturally occurring locations and surface water exiting the sub- ject property shall be discharged at the nat- ural locations with adequate energy dissipa- tors within the subject property to minimize downstreams damage and with no division at any of these points. b) The design storm peak discharge from the sub- ject property may not be increased by the proposed development. CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 9 c) Retention/detention facilities must be pro- vided in order to maintain surface water discharge rates at or below the existing de- sign storm peak discharge. d) Where open channel construction is used to handle drainage within the subject property, a minimum of fifteen (15) feet will be pro- vided between any structures and the top of the bank of the defined channel. (1) In open channel work the water surface elevation will be indicated on the plan and profile drawings. The configuration of the finished grades constituting the banks of the open channel will also be shown on the drawings. (2) Proposed cross section of the channel will be shown with stable side slopes as approved by the Public Works Depart- ment. (3) The water surface elevation of the flow for the design storm will be indicated on the cross section. e) When a closed system is used to handle drain- age within the subject property, the system will be a minimum of ten (10) feet from all structures. 2. To the extent possible, approved measures for controlling runoff during construction should comply with the above provisions. 3. Variances from the requirements of Section V(1) may be permitted only after a determination by CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 10 the Public Works and Planning Departments, using the Comprehensive Drainage Plan (if available) and/or employing the following criteria: a) Sufficient capacity of downstream facilities under design conditions; b) Maintenance of the integrity of the receiving waters; c) Possibility of adverse effects of retention/ detention; d) Utility of regional retention/detention facilities; e) Capability of maintenance of the system; and f) Structural integrity of abutting foundations and structures. Request for variances shall be filed in writing with the Public Works Department and shall adequately detail the basis for requesting the variance. SECTION VI DEVELOPMENT IN CRITICAL AREAS.* Development which would increase the volume or rate of discharge due to any storm from the subject property shall not be permitted in ares disignated as critical areas by the Kent City Council. Criti- cal areas are those in which existing flooding, drainage, ero- sion, and/or instability conditions present an imminent likeli- hood of harm to the welfare and safety of the surrounding com- munity, or to the integrity of the surface or groundwater sys- tem. Development shall not be Permitted in these critical areas until such time as the existing community hazard is al- leviated and it is adequately demonstrated that the proposed development will not cause a recurrence of the problem nor the CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 11 occurrence of any new drainage -related problem. The Public Works and Planning Departments may also designate as critical any area in which comparable problems would occur in the future due to any increase in volume or peak discharge. The require- ments of this section shall apply regardless of any exemption under Section III, Item (4). Where applications of the pro- visions of this section will deny all reasonable uses of the property, the restrictions on development contained in this section may be waived for the subject property, provided that the resulting development shall be subject to all the remain- ing terms and conditions of the Code. All decisions based on the provision of this section shall be compatible with the Comprehensive Drainage Plan (if available) for the basin in which the subject property is located. For development in areas designated as critical, the developer shall provide in- formation regarding volume and rate of discharge for a range of storms as specified in the Procedures Manual. *The designation of critical drainage areas within Kent city limits will depend upon criteria set forth by King County. SECTION VII REVIEW AND APPROVAL OF THE PLAN. All storm drainage plans prepared in connection with any of the permits and/or ap- provals listed in Section III shall be submitted for review by and approval of the Public Works and Planning Departments, in accordance with the procedures established in the Procedures Manual. At the time of approval of the drainage plan for the subject property, a schedule for inspection of construction and facilities will be established by the Public Works Depart- ment. CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 12 SECTION VIII ESTABLISHMENT OF REGIONAL FACILITIES. In the event that public benefits would accrue due to modification of the drainage plan for the subject property to better implement the recommendations of the Comprehensive Drainage Plan, the Public Works Department or the Planning Department may recommend that the City should assume responsibility for the further design, construction, operation, and maintenance of drainage facilities on the subject property. Such decision shall be made concur- rently with review and approval of the plan as specified in Section VII. In the event that the City decides to assume re- sponsibility for design, construction, operation and maintenance of the facilities, the developer will be required to contribute a prorata share to the construction cost of the facilities. The developer may be required to supply additional information at the request of the Public Works Department to aid in the deter- mination by the City. Guidelines for implementing this section will be defined in the Procedures Manual or by the Public Works and Planning Department. SECTION IX BONDS AND LIABILITY INSURANCE REQUIRED. The Public Works Department is authorized to require all persons construct- ing retention/detention or other drainage treatment/abatement facilities to post surety and cash bonds. Where such persons have previously posted, or are re- quired to post, other such bonds on the facility itself or on other construction related to the facility, such person may, with the permission of. the Public Works Department and to the extent allowable by law, combine all such bonds into a single bond, provided that at no time shall the amount thus bonded be CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 13 less than the total amount which would have been required in the form of separate bonds, and provided further that such a bond shall on its face clearly delineate those separate bonds which it is intended to replace. 1. Construction Bond. Prior to commencing con- struction, the person constructing the fa- cility shall post a construction bond in an amount sufficient to cover the cost of con- forming said construction with the approved drainage plans. The amount of the bond shall be increased at one (1) year intervals in a proportion equivalent to the prevailing rate of inflation in construction costs as speci- fied in the Procedures Manual. After deter- mination by the Public Works Department that all facilities are constructed in compliance with the approved plans, the construction bond shall be released. At the City's option, an assignment of savings, letter of credit, or some other form of guarantee acceptable to the City may be substituted for the bond requirement. 2. Maintenance Bond. After satisfactory completion of the facilities and release of the construction bond by the City, the person constructing the facility shall commence a two(2) year period of satisfactory maintenance of the facility. A cash bond to be used at the discretion of the Public Works Department to correct deficiencies in said maintenance affecting public health, safety and welfare must be posted and maintained throughout the two year maintenance period. The amount of CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 14 the cash bond shall be determined by the Public Works Department but shall not be in excess of ten percent nor less than five percent of the construction cost of the drainage facilities. In addition, a surety bond or cash bond to cover the cost of design defects or failures in work- manship of the facilities shall also be posted and maintained throughout the two year maint- enance period. The amount of the bonds shall be increased at one(1) year intervals in a pro- portion equivalent to the prevailing rate of inflation. At the City's option, an assignment of savings, letter of credit, or some other form of quarantee acceptable to the City may be sub- stituted for the bond requirement. 3. The person constructing the facility shall pro- vide liability insurance in the amount of one hundred thousand dollars per individual, three hundred thousand dollars per occurrence, and fifty thousand dollars property damage, which shall name the City as an additional insured and which shall protect the City from any liability up to those amounts for any accident, negligence, failure of the facility, or any other liability whatsoever, relating to the construction or main- tenance of the facility. Said liability insurance shall be provided during construction and for the required period of maintenance following construc- tion, provided that in the case of facilities assumed by the City for maintenance pursuant to Section X of this Code the requirement to provide CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 15 insurance shall terminate when the City as- sumes maintenance responsibility. SECTION X CITY ASSUMPTION OF OPERATION AND MAINTENANCE. The City may assume the operation and maintenance responsibility of retention/detention or other drainage treatment abatement facilities after the expiration of the two (2) year operation and maintenance period in connection with the subdivision of land if: 1. All of the requirements of Section IX of this Code have been fully complied with; and 2. The facilities have been inspected and ap- proved by the Public Works Department after two (2) years of operation in accordance with the Procedures Manual; and 3. All necessary easements entitling the City to properly operate and maintain the fa- cility have been conveyed to the City and recorded with the King County Auditor; and 4. The surety bond or other security in Section IX(b) has been extended for one year, cov- ering the City's first year of operation and maintenance; and 5. The developer has supplied to the City an accounting of capital, construction, and operation and maintenance expenses or other items, for the drainage facilities up to the end of the two year period, for the purpose of establishing the basis for future bonding CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 16 requirements for other developments. In the event that the City elects not to assume operation and maintenance responsibility for the facilities it will be the responsibility of the developer to make ar- rangements with the occupants or owners of the subject prop- erty for assumption of operation and maintenance in a manner subject to the approval of the Public Works Department or in accordance with the Procedures Manual. Such arrangements shall be completed and approved prior to the end of the two year per- iod of developer responsibility. If the City elects not to assume operation and maint- enance responsibility, the drainage facilities shall be operat- ed and maintained in accordance with the arrangements as approv- ed by the Public Works Department. The City may inspect the facilities in order to ensure continued use of the facilities for the purposes for which they were built and in accordance with these arrangements. SECTION XI RETROACTIVITY RELATING TO CITY MAINTENANCE OF DRAIN- AGE FACILITIES. If any person constructing retention/detention or other drainage treatment/abatement facilities and/or receiv- ing approval of drainage plans prior to the effective date of this Code reevaluates according to the requirements of this Code the facilities and/or plans so constructed and/or approved and demonstrates, to the Public Works Department's satisfac- tion, acceptable compliance with its requirements, the City may, after inspection, approval, and acknowledgment of the prop- er posting of the required bonds or other security as specified in Section X, assume operation and maintenance responsibility of the facilities. CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 17 In cases in which all or part of the drainage fa- cilities are not accessible for operation or maintenance pur- poses due to overlying structures or other causes the City shall be held harmless for damages which might occur due to failure of design or workmanship of those segments, and fur- ther will not be responsible for their maintenance, replace- ment or rehabilitation. In such cases, responsibility shall revert to the existing owner of such facilities. SECTION XII APPLICABILITY TO GOVERNMENTAL ENTITIES. All munic- ipal corporations and governmental entities shall be required to submit a drainage plan and comply with the terms of this Code when developing and/or improving land including, but not limited to, road building and widening, within the City. It is recognized that many other city, county, state and federal permit conditions may apply to the proposed ac- tion and that compliance with the provisions of this Code does not constitute compliance with such other requirements. SECTION XIII VIOLATIONS - _PENALTIES. Violations of this Code shall subject the violator to a fine in any sum not to exceed five hundred dollars, or imprisonment in the City jail for a period not to exceed thirty days, or both such fine and imprisonment. As an alternative method of enforcement the City may initiate an action to enjoin any development under- taken in violation of this Code by making application for an injunction in any court of competent jurisdiction, and may also commence a civil action in any court of competent jurisdiction to recover any penalty provided for herein. CITY OF KENT SURFACE WATER AND DRAINAGE CODE - 18 SECTION XIV PROTECTION OF PUBLIC/PRIVATE RIGHTS. Implementa- tion of any provision of this Code shall not cause nor be con- strued as an infringement of the rights of individuals, mu- nicipalities, or corporations other than the developer seek- ing a permit or approval as described in Section III SECTION XV EFFECTIVE DATE. The requirements of this Code shall apply to all plats receiving preliminary approval subsequent to December 10, 1978. In the case of all additional actions enumerated in Section III of this Code, the terms of this Code shall apply where final action by the City has not been taken prior to the effective date of this Code. SECTION XVI SEVERABILITY. If any provision of this Code or its application to any person or property is held invalid the remainder of the Code or the application of the provision to other persons or circumstances shall not be affected.