Chapter 14.15 CONTROLLING STORM WATER RUNOFF FROM NEW DEVELOPMENT, REDEVELOPMENT, AND CONSTRUCTION SITES

The city council finds that this chapter is necessary to promote sound development policies and construction procedures which respect the city’s watercourses; to minimize water quality degradation and control of sedimentation of creeks, streams, ponds, lakes, and other water bodies; to protect the life, health, and property of the general public; to preserve and enhance the suitability of waters for contact recreation and fish habitat; to preserve and enhance the aesthetic quality of the waters; to maintain and protect valuable ground water quantities, locations, and flow patterns; to ensure the safety of city roads and rights-of-way; and to decrease drainage-related damages to public and private property. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.015 Stormwater management manual adopted.

The 2005 State Department of Ecology Storm Water Management Manual for Western Washington, as amended by this code, is hereby adopted as the city’s minimum storm water regulations and as a technical reference manual and maintenance standard and is hereinafter referred to as the “Stormwater Manual.” (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.020 Definitions.

For the purpose of this chapter and other provisions in this title related to storm water, certain terms, phrases, words and their derivatives shall be defined and construed as specified in the Stormwater Manual and in this title. Words used in the singular include the plural, and the plural the singular. The words “shall,” “will” and “must” are mandatory; the words “should” and “may” are permissive. When any definition in this title conflicts with definitions in the Stormwater Manual or any other ordinance of the city, that which provides more environmental protection shall apply unless specifically provided otherwise in this title.

(1) “Applicant” means any person who has applied for a development permit or approval.

(2) “Certified Erosion and Sediment Control Lead (CESCL)” means an individual who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by the Department of Ecology (see BMP C160 in the Stormwater Manual). A CESCL is knowledgeable in the principles and practices of erosion and sediment control. The CESCL must have the skills to assess site conditions and construction activities that could impact the quality of storm water and the effectiveness of erosion and sediment control measures used to control the quality of storm water discharges.

(3) “City planner” also means community development director.

(4) “Comprehensive drainage plan” means a detailed analysis adopted by the city which compares the capabilities and needs for runoff accommodation due to various combinations of development, land use, structural and nonstructural management alternatives. The plan recommends the form, location, and extent of quantity and quality control measures which would satisfy legal constraints, water quality standards and community standards and identifies the institutional and funding requirements for plan implementation.

(5) “Conveyance system” means the drainage facilities, both natural and manmade, which collect, contain, and provide for the flow of surface and storm water from the highest points on the land down to a receiving water. The natural elements of the conveyance system include swales and small drainage courses, streams, rivers, lakes, and wetlands. The human-made elements of the conveyance system include gutters, ditches, pipes, channels, and most retention/detention facilities.

(6) “Department” means the public works or community development department of the city of Marysville, as appropriate for capital or private development projects.

(7) “Developer” means the individual(s) or corporation(s) or governmental agency(ies) applying for permits or approvals.

(8) “Director of public works” or “director” means the director of the public works department or his/her designee.

(9) Discharge Storm Water Directly or Indirectly to the Marysville Small Municipal Separate Storm Sewer System (MS4). A project discharges storm water directly or indirectly to the MS4 if:

(a) The drainage system installed is in right-of-way or an area that will become right-of-way after construction and final site approval;

(b) The drainage system installed will become publicly owned after construction and final site approval;

(d) The drainage system installed is intended to outfall into a portion of the existing MS4 or public right-of-way.

(10) “Drainage system” or “storm drainage system” or “storm water system” means the same as the Stormwater Manual definition for “storm water drainage system.”

(11) “Engineer” means the city engineer or development services manager, as designated for enforcement of capital or private development activities, of Marysville.

(12) “Existing grade” means the grade prior to grading.

(13) “Finish grade” means the final grade of the site, which conforms to the approved plan.

(14) “Grading” or “grading activity” means any excavating, filling, or grading or combination thereof.

(15) “Ground water” means water in a saturated zone or stratum beneath the surface of land or a surface water body.

(16) “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):

(a) Owned or operated by a state, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to state law) having jurisdiction over disposal of wastes, storm water, or other wastes, including special districts under state law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under Section 208 of the CWA that discharges to waters of the United States;

(b) Designed or used for collecting or conveying storm water;

(d) Which is not part of a publicly owned treatment works (POTW) as defined in the Code of Federal Regulations at 40 CFR 122.2.

(17) “Parcel” means a tract or plot of land of any size, which may or may not be subdivided or improved.

(18) “Planned residential developments” refers to residential developments which are planned and/or developed in several stages but submitted together for approvals, and which typically consist of clusters of structures interspersed with areas of common open spaces (refer to Chapter 22G.080 MMC).

(19) “Private drainage system” or “private storm water disposal systems” means drainage systems located on private property that may or may not discharge directly as through pipes, channels, etc., or indirectly as sheet flow, subsurface flow, etc., into the city’s drainage system.

(20) “Public storm drainage system” means that portion of the drainage system of the city located on public right-of-way, easements or other property owned by the city.

(21) “Rough grade” means the stage at which the grade approximately conforms to the approved plan.

(22) “Site plan” means a plan which indicates the character of the existing site, topography, natural drainage features on or adjacent to the site, the location and dimensions of all impervious surfaces, flow arrows indicating the direction of storm water flows on-site and any off-site flows entering the site, and the proposed method of utilizing the existing drainage system.

(23) “Small municipal separate storm sewer system” or “small MS4” means a conveyance or system of conveyances including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels and/or storm drains which is:

(a) Owned or operated by a city, town, county, district, association or other public body created pursuant to state law having jurisdiction over disposal of sewage, industrial wastes, storm water, or other wastes, including special districts under state law such as a sewer district, flood control district or drainage district, or similar entity.

(b) Designed or used for collecting or conveying storm water.

(d) Not part of a publicly owned treatment works (POTW) as defined at 40 CFR 122.2.

(e) Not defined as “large” or “medium” pursuant to 40 CFR 122.26(b)(4) and (7) or designated under 40 CFR 122.26(a)(1)(v).

Small MS4s include systems similar to separate storm sewer systems in municipalities such as: universities, large publicly owned hospitals, prison complexes, highways and other thoroughfares.

Small MS4s do not include storm drain systems operated by nongovernmental entities such as: individual buildings, private schools, private colleges, private universities, and industrial and commercial entities.

(24) “Storm water site plan” means the comprehensive report containing all of the technical information and analysis necessary to evaluate a proposed new development or redevelopment project for compliance with storm water requirements. Contents of the storm water site plan will vary with the type and size of the project, and individual site characteristics. See the Stormwater Manual for details.

(25) “Subject property” means the tract of land which is the subject of the permit and/or approval action.

(26) “Undeveloped conditions” means the state, status, or condition of the subject property prior to any development of the property that has occurred, which may include trees, pastures, meadows, or native features. (Ord. 2857 § 3, 2011; Ord. 2816 § 1 (Exh. A), 2010; Ord. 2694 § 2, 2007; Ord. 2476 § 2, 2003).

14.15.030 Applicability.

(1) Storm water management review and approval by the city is required when any new development, redevelopment, or proposed construction site project meets or exceeds the threshold conditions defined in MMC 14.15.040 (e.g., new impervious area, drainage system modifications, redevelopments, etc.) and/or is subject to a city development permit or approval requirement. All the provisions of this title are applicable to any project requiring storm water management review and approval.

(2) Commencement of construction work under any of the nonexempt actions, permits, or applications shall not begin until the department approves a storm water pollution prevention plan (SWPPP) pursuant to the requirements of MMC 14.15.050.

(3) Whenever a minimum area or quantity requirement is set forth in this chapter, such requirement shall be met if any activity or development occurs on the subject property within a continuous 18-month period.

(4) Unless otherwise specified in this chapter, all standards, definitions, and requirements shall be in accordance with the Stormwater Manual.

(5) The following activities are exempt from the minimum requirements set forth in MMC 14.15.050:

(a) Forest Practices. 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.

(b) Commercial Agriculture. 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.

(c) Oil and Gas Field Activities or Operations. Construction of drilling sites, waste management pits, and access roads, as well as construction of transportation and treatment infrastructure such as pipelines, natural gas treatment plants, natural gas pipeline compressor stations, and crude oil pumping stations are exempt. Operators are encouraged to implement and maintain best management practices to minimize erosion and control sediment during and after construction activities to help ensure protection of surface water quality during storm events.

(d) Road Maintenance.

(i) The following road 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, and vegetation maintenance.

(ii) The following road maintenance practices are considered redevelopment, and therefore are not categorically exempt. The extent to which the minimum requirements in MMC 14.15.050 apply is explained for each circumstance.

(A) Removing and replacing a paved surface to base course or lower, or repairing the roadway base. If impervious surfaces are not expanded, MMC 14.15.050 minimum requirements Nos. (1) through (5) apply. However, in most cases, only MMC 14.15.050 minimum requirement No. (2), Construction Storm Water Pollution Prevention Plan (SWPPP), will be germane. Where appropriate, project proponents are encouraged to look for opportunities to use permeable and porous pavements.

(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 in MMC 14.15.050 that are triggered when the thresholds identified for 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 in MMC 14.15.050 that are triggered when the thresholds identified for redevelopment projects are met.

(e) Underground Utility Projects. Underground utility projects that replace the ground surface with in-kind material or materials with similar runoff characteristics are only subject to MMC 14.15.050(2), Minimum Requirement No. 2, Construction Storm Water Pollution Prevention Plan (SWPPP). (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.040 Minimum requirement thresholds.

Not all of the minimum requirements in MMC 14.15.050 apply to every development or redevelopment project. The applicability varies depending on the type and size of the project. This section identifies thresholds that determine the applicability of the minimum requirements in MMC 14.15.050 to different projects. The flow charts in Figures 14.15.040(1) and 14.15.040(2) must be used to determine which of the minimum requirements in MMC 14.15.050 apply. The minimum requirements themselves are presented in MMC 14.15.050.

(1) New Development. All new development shall be required to comply with MMC 14.15.050(2), Minimum Requirement No. 2.

(a) The following new development shall comply with MMC 14.15.050 minimum requirements Nos. 1 through 5 for the new and replaced impervious surfaces and the land disturbed:

(i) Creates or adds 2,000 square feet, or greater, of new, replaced, or new plus replaced impervious surface area; or

(ii) Has land disturbing activity of 7,000 square feet or greater.

(b) The following new development shall comply with MMC 14.15.050 minimum requirements Nos. 1 through 9 for the new impervious surfaces and the converted pervious surfaces:

(i) Creates or adds 5,000 square feet, or more, of new impervious surface area; or

(ii) Converts three-quarters acres, or more, of native vegetation to lawn or landscaped areas; or

(iii) Converts 2.5 acres, or more, of native vegetation to pasture.

(2) Redevelopment. All redevelopment shall be required to comply with MMC 14.15.050(2), minimum requirement No. 2. In addition, all redevelopment that exceeds certain thresholds shall be required to comply with additional minimum requirements in MMC 14.15.050 as follows.

(a) The following redevelopment shall comply with MMC 14.15.050, minimum requirements Nos. 1 through 5 for the new and replaced impervious surfaces and the land disturbed:

(i) The new, replaced, or total of new plus replaced impervious surfaces is 2,000 square feet or more; or

(ii) Seven thousand square feet or more of land disturbing activities.

(b) The following redevelopment shall comply with MMC 14.15.050 minimum requirements Nos. 1 through 9 for the new impervious surfaces and converted pervious areas:

(i) Adds 5,000 square feet or more of new impervious surfaces; or

(ii) Converts three-quarters acres, or more, of native vegetation to lawn or landscaped areas; or

(iii) Converts 2.5 acres, or more, of native vegetation to pasture.

(c) If the runoff from the new impervious surfaces and converted pervious surfaces is not separated from runoff from other surfaces on the project site, the storm water treatment facilities must be sized for the entire flow that is directed to them.

(d) The director may allow the minimum requirements in MMC 14.15.050 to be met for an equivalent (flow and pollution characteristics) area within the same site. For public roads projects, the equivalent area does not have to be within the project limits, but must drain to the same receiving water.

(3) Additional Requirements for Redevelopment Project Sites.

(a) For road-related projects, runoff from the replaced and new impervious surfaces (including pavement, shoulders, curbs, and sidewalks) shall meet all the minimum requirements in MMC 14.15.050 if the new impervious surfaces total 5,000 square feet or more and total 50 percent or more of the existing impervious surfaces within the project limits. The project limits shall be defined by the length of the project and the width of the right-of-way.

(b) Other types of redevelopment projects shall comply with all the minimum requirements in MMC 14.15.050 for the new and replaced impervious surfaces if the total of new plus replaced impervious surfaces is 5,000 square feet or more, and the valuation of proposed improvements – including interior improvements – exceeds 50 percent of the assessed value of the existing site improvements.

(c) The director may exempt or institute a stop-loss provision for redevelopment projects from compliance with minimum requirements for treatment, flow control, and wetlands protection as applied to the replaced impervious surfaces if the director has adopted a plan and a schedule that fulfills those requirements in regional facilities. See also MMC 14.15.175 and 14.15.180 and Chapter 14.18 MMC.

(d) The director may grant a variance/exception to the application of the flow control requirements to replaced impervious surfaces if such application imposes a severe economic hardship. See MMC 14.15.175 and 14.15.180. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.050 Minimum requirements.

This section describes the minimum requirements for storm water management at development and redevelopment sites. MMC 14.15.040 should be consulted to determine which of the minimum requirements below apply to any given project. Figures 14.15.040(1) and 14.15.040(2) should be consulted to determine whether the minimum requirements apply to new surfaces, replaced surfaces or new and replaced surfaces.

(1) Minimum Requirement No. 1: Preparation of Storm Water Site Plans. All projects meeting the thresholds in MMC 14.15.040 shall submit a storm water site plan. Storm water site plans shall be prepared in accordance with Chapter 3 of Volume I of the Stormwater Manual.

(2) Minimum Requirement No. 2: Construction Storm Water Pollution Prevention Plan (SWPPP).

(a) The city may choose to allow compliance with this minimum requirement to be achieved for an individual site if the site is covered under Ecology’s General NPDES Permit for Storm Water Discharges Associated with Construction Activities and fully implementing the requirements of that permit.

(b) The city may choose to allow site operators to apply an “erosivity waiver” to projects disturbing less than five acres that meet the requirements in subsection (2)(j) of this section; such projects would be waived from the requirement that the city review site plans for construction phase storm water pollution prevention.

(c) The city may develop an abbreviated SWPPP format to meet the SWPPP requirement under the NPDES Phase II Municipal Storm Water Permit for sites that are less than 5,000 square feet of new impervious surface; or new, replaced, or new plus replaced is less than 2,000 square feet.

(d) All new development and redevelopment projects are responsible for preventing erosion and discharge of sediment and other pollutants into receiving waters. All projects must submit a construction storm water pollution prevention plan (SWPPP) as part of the storm water site plan (see subsection (1) of this section, Minimum Requirement No. 1: Preparation of Storm Water Site Plans) for all projects which meet the thresholds in MMC 14.15.040. The SWPPP shall be implemented beginning with initial soil disturbance and until final stabilization.

(e) Sediment and erosion control BMPs shall be consistent with the BMPs contained in Chapters 3 and 4 of Volume II of the Stormwater Manual, and/or other equivalent BMPs contained in technical storm water manuals approved by the Department of Ecology.

(f) The SWPPP shall include a narrative and drawings. All BMPs shall be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative shall include documentation to explain and justify the pollution prevention decisions made for the project. Clearing and grading activities for developments shall be permitted only if conducted pursuant to an approved site development plan (e.g., subdivision approval) that establishes permitted areas of clearing, grading, cutting, and filling. When establishing these permitted clearing and grading areas, consideration should be given to minimizing removal of existing trees and minimizing disturbance/compaction of native soils except as needed for building purposes. These permitted clearing and grading areas and any other areas required to preserve critical or sensitive areas, buffers, native growth protection easements, or tree retention areas as may be required by Chapter 22E.010 MMC, Critical Areas Management, or Chapter 22D.050 MMC, Clearing, Grading, Filling and Erosion Control, shall be delineated on the site plans and the development site.

(g) Seasonal Work Limitations. From October 1st through April 30th, clearing, grading, and other soil disturbing activities are only authorized if silt-laden runoff will be prevented from leaving the site through a combination of the following:

(i) Site conditions including existing vegetative coverage, slope, soil type and proximity to receiving waters; and

(ii) Limitations on activities and the extent of disturbed areas; and

(iii) Proposed erosion and sediment control measures.

(h) Based on the information provided and/or local weather conditions, the director may expand or restrict the seasonal limitation on site disturbance. The following activities are exempt from the seasonal clearing and grading limitations:

(i) Routine maintenance and necessary repair of erosion and sediment control BMPs;

(ii) Routine maintenance of public facilities or existing utility structures that does not expose the soil or result in the removal of the vegetative cover to soil; and

(iii) Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities.

(i) Construction Storm Water Pollution Prevention Plan (SWPPP) Elements. The construction site operator shall include each of the 12 elements below in the SWPPP and ensure that they are implemented unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the SWPPP. The SWPPP shall include both narrative and drawings. All BMPs shall be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative shall include documentation to explain and justify the pollution prevention decisions made for the project.

(i) Element 1 – Preserve Vegetation/Mark Clearing Limits.

(A) Prior to beginning land disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area.

(B) Plastic, metal, or stake wire fencing may be used to mark the clearing limits.

(C) The duff layer, native top soil, and natural vegetation shall be retained in an undisturbed state to the maximum degree practicable.

(ii) Element 2 – Establish Construction Access.

(A) Construction vehicle access and exit shall be limited to one route, if possible, or two routes for linear projects such as roadways where more than one access is necessary for large equipment maneuvering.

(B) Access points shall be stabilized with quarry spalls, crushed rock or other equivalent BMP to minimize the tracking of sediment onto public roads.

(C) Wheel wash or tire baths shall be located on site, if the stabilized construction entrance is not effective in preventing sediment from being tracked onto public roads.

(D) If sediment is tracked off site, roads shall be cleaned thoroughly at the end of each day, or more frequently during wet weather. Sediment shall be removed from roads by shoveling or pickup sweeping and shall be transported to a controlled sediment disposal area.

(E) Street washing is allowed only after sediment is removed in accordance with subsection (2)(i)(ii)(D) of this section. Street wash wastewater shall be controlled by pumping back on site or otherwise be prevented from discharging into systems tributary to waters of the state.

(iii) Element 3 – Control Flow Rates.

(A) Properties and waterways downstream from development sites shall be protected from erosion due to increases in the velocity and peak volumetric flow rate of storm water runoff from the project site.

(B) Downstream analysis is required. See Chapter 3 of the Stormwater Manual for off-site analysis guidance.

(C) Where necessary to comply with subsection (2)(i)(iii)(A) of this section, storm water retention or detention facilities shall be constructed as one of the first steps in grading. Detention facilities shall be functional prior to construction of site improvements (e.g., impervious surfaces).

(D) The director may require pond designs that provide additional or different storm water flow control, if necessary to address local conditions or to protect properties and waterways downstream from erosion due to increases in the volume, velocity, and peak flow rate of storm water runoff from the project site.

(E) If permanent infiltration ponds are used for flow control during construction, these facilities should be protected from siltation during the construction phase.

(iv) Element 4 – Install Sediment Controls.

(A) Storm water runoff from disturbed areas shall pass through a sediment pond, or other appropriate sediment removal BMP, prior to leaving a construction site or prior to discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but shall meet the flow control performance standard of subsection (2)(i)(iii)(A) of this section.

(B) Sediment control BMPs (sediment ponds, traps, filters, etc.) shall be constructed as one of the first steps in grading. These BMPs shall be functional before other land disturbing activities take place.

(C) BMPs intended to trap sediment on site shall be located in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages.

(v) Element 5 – Stabilize Soils.

(A) Exposed and unworked soils shall be stabilized by application of effective BMPs that prevent erosion.

(B) No soils should remain exposed and unworked for more than the time periods set forth below to prevent erosion:

• During the dry season (May 1st through September 30th): seven days.

• During the wet season (October 1st through April 30th): two days.

(C) The time period may be adjusted by the director, if the director determines that local precipitation data justify a different standard.

(D) Soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast.

(E) Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and, where possible, be located away from storm drain inlets, waterways and drainage channels.

(F) Applicable practices include, but are not limited to, temporary and permanent seeding, sodding, mulching, plastic covering, soil application of polyacrylamide (PAM), the early application of gravel base on areas to be paved, and dust control.

(G) Soil stabilization measures selected should be appropriate for the time of year, site conditions, estimated duration of use, and potential water quality impacts that stabilization agents may have on downstream waters or ground water.

(H) Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and, where possible, be located away from storm drain inlets, waterways and drainage channels.

(vi) Element 6 – Protect Slopes.

(A) Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion.

(B) Soil type and its potential for erosion shall be considered.

(C) Slope runoff velocities shall be reduced by reducing the continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surface.

(D) Off-site storm water (run-on) or groundwater shall be diverted away from slopes and undisturbed areas with interceptor dikes, pipes and/or swales. Off-site storm water should be managed separately from storm water generated on the site.

(E) At the top of slopes, drainage shall be collected in pipe slope drains or channels shall be protected to prevent erosion. Temporary pipe slope drains shall handle the expected peak 10-minute flow velocity from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, one-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis shall use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis shall use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model to predict flows, bare soil areas should be modeled as “landscaped area.”

(F) Drainage shall be provided to remove ground water intersecting the slope surface of exposed soil areas.

(G) Excavated material shall be placed on the uphill side of trenches, consistent with safety and space considerations.

(H) Check dams shall be placed at regular intervals within constructed channels that are cut down a slope.

(vii) Element 7 – Protect Drain Inlets.

(A) Storm drain inlets made operable during construction shall be protected so that storm water runoff does not enter the conveyance system without first being filtered or treated to remove sediment.

(B) All approach roads shall be kept clean. All sediment and street wash water shall not be allowed to enter storm drains without prior and adequate treatment unless treatment is provided before the storm drain discharges to waters of the state.

(C) Inlet protection devices shall be cleaned or removed and replaced when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer).

(viii) Element 8 – Stabilize Channels and Outlets.

(A) All temporary on-site conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the following expected peak flows. Channels shall handle the expected peak 10-minute flow velocity from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, one-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis shall use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis shall use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model to predict flows, bare soil areas should be modeled as “landscaped area.”

(B) Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches shall be provided at the outlets of all conveyance systems.

(ix) Element 9 – Control Pollutants.

(A) All pollutants, including waste materials and demolition debris, that occur on site shall be handled and disposed of in a manner that does not cause contamination of storm water.

(B) Cover, containment, and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks shall include secondary containment.

(C) Maintenance, fueling and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident.

(D) Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system or to the sanitary sewer with local sewer district approval.

(E) Application of fertilizers and pesticides shall be conducted in a manner and at application rates that will not result in loss of chemical to storm water runoff. Manufacturers’ label requirements for application rates and procedures shall be followed.

(F) BMPs shall be used to prevent or treat contamination of storm water runoff by pH modifying sources. These sources include, but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete pumping and mixer washout waters. Construction site operators shall adjust the pH of storm water if necessary to prevent violations of water quality standards.

(G) Construction site operators shall obtain written approval from the Department of Ecology prior to using chemical treatment other than CO2 or dry ice to adjust pH.

(x) Element 10 – Control Dewatering.

(A) Foundation, vault, and trench dewatering water, which have similar characteristics to storm water runoff at the site, shall be discharged into a controlled conveyance system prior to discharge to a sediment trap or sediment pond.

(B) Clean, nonturbid dewatering water, such as well-point ground water, can be discharged to systems tributary to or directly into surface waters of the state, as specified in subsection (2)(i)(viii) of this section, Element 8 – Stabilize Channels and Outlets, provided the dewatering flow does not cause erosion or flooding of receiving waters. Clean dewatering water should not be routed through storm water sediment ponds.

(C) Other dewatering disposal options may include: (1) infiltration; (2) transport off site in vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters; (3) on-site chemical treatment or other suitable treatment technologies approved by the director; (4) sanitary sewer discharge with local sewer district approval, if there is no other option; or (5) use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized dewatering.

(D) Highly turbid or contaminated dewatering water shall be handled separately from storm water.

(xi) Element 11 – Maintain BMPs.

(A) All temporary and permanent erosion and sediment control BMPs shall be inspected, maintained and repaired as needed to assure continued performance of their intended function in accordance with BMP specifications.

(B) All temporary erosion and sediment control BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Disturbed soil areas resulting from removal of BMPs or vegetation shall be permanently stabilized.

(xii) Element 12 – Manage the Project.

(A) Development projects shall be phased to the maximum degree practicable and shall take into account seasonal work limitations.

(B) The construction site operator shall maintain, and repair as needed, all sediment and erosion control BMPs to assure continued performance of their intended function.

(C) The construction site operator shall periodically inspect its sites. For projects that disturb one or more acres, site inspections shall be conducted by a certified erosion and sediment control lead, who shall be identified in the SWPPP and shall be present on site or on call at all times.

(D) Construction site operators shall maintain, update and implement their SWPPP. Construction site operators shall modify their SWPPP whenever there is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state.

(j) Erosivity Waiver. The city may allow construction site operators to qualify for a waiver from the requirement to submit an SWPPP for review by the city provided the following conditions are met:

(i) The site will result in the disturbance of less than five acres; and the site is not a portion of a common plan of development or sale that will disturb five acres or greater; and

(ii) The project’s rainfall erosivity factor (“R” Factor) is less than five during the period of construction activity, as calculated using the Texas A&M University online rainfall erosivity calculator at: http://ei.tamu.edu/. The period of construction activity begins at initial earth disturbance and ends with final stabilization; and

(iii) The entire period of construction activity falls between June 15th and September 15th; and

(iv) The site or facility has not been declared a significant contributor of pollutants; and

(v) There are no planned construction activities at the site that will result in non-storm water discharges; and

(vi) A waiver is allowed by the city; and

(vii) The construction site operators notify the city of the intention to apply this waiver at least one week prior to commencing land disturbing activities. The notification must include a summary of the project information used in calculating the project’s rainfall erosivity factor (see subsection (2)(j)(ii) of this section) and a certified statement that:

(A) The operator will comply with applicable local storm water requirements; and

(B) The operator will implement appropriate erosion and sediment control BMPs to prevent violations of water quality standards.

(3) Minimum Requirement No. 3: Source Control of Pollution. All known, available and reasonable source control BMPs are required for all projects approved in the city. Source control BMPs must be selected, designed, and maintained in accordance with Volume IV of the Stormwater Manual or an approved equivalent manual approved by the Department of Ecology.

(4) Minimum Requirement No. 4: Preservation of Natural Drainage Systems and Outfalls. Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down-gradient properties. All outfalls require energy dissipation.

(5) Minimum Requirement No. 5: On-Site Storm Water Management. The project site must provide on-site storm water management BMPs to infiltrate, disperse, and retain storm water runoff on site to the maximum extent feasible without causing flooding or erosion impacts. Roof downspout control BMPs, functionally equivalent to those described in Chapter 3 of Volume III of the Stormwater Manual, and dispersion and soil quality BMPs, functionally equivalent to those in Chapter 5 of Volume V of the Stormwater Manual, shall be required to reduce the hydrologic disruption of developed sites.

(6) Minimum Requirement No. 6: Runoff Treatment.

(a) Project Thresholds. The following require construction of storm water treatment facilities (see Table 14.15.050(6) below):

(i) Projects in which the total of effective, pollution-generating impervious surface (PGIS) is 5,000 square feet or more in a threshold discharge area of the project; or

(ii) Projects in which the total of pollution-generating pervious surfaces (PGPS) is three-quarters of an acre or more in a threshold discharge area, and from which there is a surface discharge in a natural or manmade conveyance system from the site.

Table 14.15.050(6) Treatment Requirements by Threshold Discharge Area
	< 3/4 acres of PGPS	> 3/4 acres PGPS	< 5,000 sf PGIS	> 5,000 sf PGIS
Treatment Facilities		X		X
On-Site Storm Water BMPs	X	X	X	X

PGPS = pollution-generating pervious surfaces

PGIS = pollution-generating impervious surfaces

sf = square feet

(b) Treatment Type Thresholds. If the construction project requires storm water treatment, the following treatment type thresholds shall be used to determine applicable treatment options:

(i) Oil Control. Treatment to achieve oil control applies to projects that have “high-use sites.” High-use sites are those that typically generate high concentrations of oil due to high traffic turnover or the frequent transfer of oil. High-use sites include:

(A) An area of a commercial or industrial site subject to an expected average daily traffic (ADT) count equal to or greater than 100 vehicles per 1,000 square feet of gross building area;

(B) An area of a commercial or industrial site subject to petroleum storage and transfer in excess of 1,500 gallons per year, not including routinely delivered heating oil;

(C) An area of a commercial or industrial site subject to parking, storage or maintenance of 25 or more vehicles that are over 10 tons gross weight (trucks, buses, trains, heavy equipment, etc.);

(D) A road intersection with a measured ADT count of 25,000 vehicles or more on the main roadway and 15,000 vehicles or more on any intersecting roadway, excluding projects proposing primarily pedestrian or bicycle use improvements.

(ii) Enhanced Treatment. Enhanced treatment for reduction in dissolved metals is required for the following project sites that discharge to fish-bearing streams, lakes, or to waters or conveyance systems tributary to fish-bearing streams or lakes:

(A) Industrial project sites;

(B) Commercial project sites;

(D) High AADT roads as follows:

• Fully controlled and partially controlled limited access highways with Annual Average Daily Traffic (AADT) counts of 15,000 or more;

• All other roads with an AADT of 7,500 or greater.

However, such sites listed above that discharge directly (or indirectly through a municipal storm sewer system) to Basic Treatment Receiving Waters (Appendix I-C of the Stormwater Manual), and areas of the above-listed project sites that are identified as subject to basic treatment requirements, are also not subject to enhanced treatment requirements. For developments with a mix of land use types, the enhanced treatment requirement shall apply when the runoff from the areas subject to the enhanced treatment requirement comprise 50 percent or more of the total runoff within a threshold discharge area.

(iii) Basic Treatment. Basic treatment generally applies to:

(A) Project sites that discharge to the ground, unless:

• The soil suitability criteria for infiltration treatment are met (see Chapter 3 of Volume III of the Stormwater Manual for soil suitability criteria); or

• The project uses infiltration strictly for flow control – not treatment – and the discharge is within one-quarter mile of a phosphorus-sensitive lake (use a phosphorus treatment facility), or within one-quarter mile of a fish-bearing stream or a lake (use an enhanced treatment facility).

(B) Residential projects not otherwise needing phosphorus control as designated by U.S. EPA, the Department of Ecology, or by the city.

(C) Project sites discharging directly to salt waters, river segments, and lakes listed in Appendix I-C of the Stormwater Manual.

(D) Project sites that drain to streams that are not fish-bearing, or to waters not tributary to fish-bearing streams.

(E) Landscaped areas of industrial, commercial, and multifamily project sites, and parking lots of industrial and commercial project sites that do not involve pollution-generating sources (e.g., industrial activities, customer parking, storage of erodible or leachable material, wastes or chemicals) other than parking of employees’ private vehicles. For developments with a mix of land use types, the basic treatment requirement shall apply when the runoff from the areas subject to the basic treatment requirement comprises 50 percent or more of the total runoff within a threshold discharge area.

(c) Treatment Facility Sizing – Water Quality Design Storm Volume. The volume of runoff predicted from a 24-hour storm with a six-month return frequency (a.k.a., six-month, 24-hour storm). Wetpool facilities are sized based upon the volume of runoff predicted through use of the Natural Resource Conservation Service curve number equations in Chapter 2 of Volume III of the Stormwater Manual, for the six-month, 24-hour storm. Alternatively, the ninety-first percentile, 24-hour runoff volume indicated by an approved continuous runoff model may be used.

(d) Water Quality Design Flow Rate.

(i) Preceding Detention Facilities or When Detention Facilities Are Not Required. The flow rate at or below which 91 percent of the runoff volume, as estimated by an approved continuous runoff model, will be treated. Design criteria for treatment facilities are assigned to achieve the applicable performance goal at the water quality design flow rate (e.g., 80 percent TSS removal).

(ii) Downstream of Detention Facilities. The water quality design flow rate must be the full two-year release rate from the detention facility.

(A) Alternative methods may be used if they identify volumes and flow rates that are at least equivalent.

(B) That portion of any development project in which the above PGIS or PGPS thresholds are not exceeded in a threshold discharge area shall apply on-site storm water management BMPs in accordance with subsection (5) of this section, Minimum Requirement No. 5: On-Site Storm Water Management.

(e) Treatment Facility Selection, Design, and Maintenance. Storm water treatment facilities shall be:

(i) Selected in accordance with the process identified in Chapter 4 of Volume I of the Stormwater Manual;

(ii) Designed in accordance with the design criteria in Volume V of the Stormwater Manual; and

(iii) Maintained in accordance with the maintenance schedule in Volume V of the Stormwater Manual.

(f) Additional Requirements. The discharge of untreated storm water from pollution-generating impervious surfaces to ground water is prohibited, except for the discharge achieved by infiltration or dispersion of runoff from residential sites through use of on-site storm water management BMPs.

(7) Minimum Requirement No. 7: Flow Control.

(a) Applicability. Except as provided below, all projects shall provide flow control to reduce the impacts of storm water runoff from impervious surfaces and land cover conversions. The requirement below applies to projects that discharge storm water directly, or indirectly through a conveyance system, into a fresh water.

(i) Flow control is not required for projects that discharge directly to, or indirectly through an MS4 to a water listed in Appendix I-E of the Stormwater Manual subject to the following restrictions:

(A) Direct discharge to the exempt receiving water does not result in the diversion of drainage from any perennial stream classified as Types 1, 2, 3, or 4 in the State of Washington Interim Water Typing System, or Types “S,” “F,” or “Np” in the Permanent Water Typing System, or from any category I, II, or III wetland; and

(B) Flow splitting devices or drainage BMPs are applied to route natural runoff volumes from the project site to any downstream Type 5 stream or category IV wetland:

• Design of flow splitting devices or drainage BMPs will be based on continuous hydrologic modeling analysis. The design will assure that flows delivered to Type 5 stream reaches will approximate, but in no case exceed, durations ranging from 50 percent of the two-year to the 50-year peak flow.

• Flow splitting devices or drainage BMPs that deliver flow to category IV wetlands will also be designed using continuous hydrologic modeling to preserve pre-project wetland hydrologic conditions unless specifically waived or exempted; and

(C) The project site must be drained by a conveyance system that is comprised entirely of manmade conveyance elements (e.g., pipes, ditches, outfall protection, etc.) and extends to the ordinary high water line of the exempt receiving water; and

(D) The conveyance system between the project site and the exempt receiving water shall have sufficient hydraulic capacity to convey discharges from future build-out conditions (under current zoning) of the site, and the existing condition from nonproject areas from which runoff is or will be collected; and

(E) Any erodible elements of the manmade conveyance system must be adequately stabilized to prevent erosion under the conditions noted above.

(ii) If the discharge is to a stream that leads to a wetland, or to a wetland that has an outflow to a stream, both this minimum requirement (Minimum Requirement No. 7) and subsection (8) of this section, minimum requirement No. 8, apply.

(b) Thresholds. That portion of any development project in which the below thresholds are not exceeded in a threshold discharge area shall apply on-site storm water management BMPs in accordance with subsection (5) of this section, Minimum Requirement No. 5: On-Site Storm Water Management. The following require construction of flow control facilities and/or land use management BMPs that will achieve the standard flow control requirement for western Washington (see Table 14.15.050(7)):

(i) Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area; or

(ii) Projects that convert three-quarters acres or more of native vegetation to lawn or landscape, or convert 2.5 acres or more of native vegetation to pasture in a threshold discharge area, and from which there is a surface discharge in a natural or manmade conveyance system from the site; or

(iii) Projects that through a combination of effective impervious surfaces and converted pervious surfaces cause a 0.1 cubic feet per second increase in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other model approved in the Stormwater Manual.

Table 14.15.050(7) Flow Control Requirements by Threshold Discharge Area
	Flow Control Facilities	On-Site Storm Water Management BMPs
< 3/4 acres conversion to lawn/landscape, or < 2.5 acres to pasture		X
> 3/4 acres conversion to lawn/landscape, or > 2.5 acres to pasture	X	X
< 10,000 square feet of effective impervious area		X
> 10,000 square feet of effective impervious area	X	X
> 0.1 cubic feet per second increase in the 100-year flood frequency	X	X

(c) Standard Flow Control Requirement. Storm water discharges shall match developed discharge durations to pre-developed durations for the range of pre-developed discharge rates from 50 percent of the two-year peak flow up to the full 50-year peak flow. This standard requirement is waived for sites that will reliably infiltrate all the runoff from impervious surfaces and converted pervious surfaces. The pre-developed condition to be matched shall be a forested land cover unless:

(i) Reasonable, historic information is available that indicates the site was prairie prior to settlement (modeled as “pasture” in the Western Washington Hydrology Model); or

(ii) The drainage area of the immediate stream and all subsequent downstream basins have had at least 40 percent total impervious area since 1985. In this case, the pre-developed condition to be matched shall be the existing land cover condition. Where basin-specific studies determine a stream channel to be unstable, even though the above criterion is met, the pre-developed condition assumption shall be the “historic” land cover condition, or a land cover condition commensurate with achieving a target flow regime identified by an approved basin study.

(d) Additional Requirement. Flow control BMPs shall be selected, designed, and maintained in accordance with Volume III of the Stormwater Manual or an approved equivalent.

(8) Minimum Requirement No. 8: Wetlands Protection.

(a) Applicability. The requirements below apply only to projects whose storm water discharges into a wetland, either directly or indirectly through a conveyance system. These requirements must be met in addition to meeting subsection (6) of this section, Minimum Requirement No. 6: Runoff Treatment.

(b) Thresholds. The thresholds identified in subsection (6) of this section, Minimum Requirement No. 6: Runoff Treatment, and subsection (7) of this section, Minimum Requirement No. 7: Flow Control, shall also be applied for discharges to wetlands.

(c) Standard Requirement. Discharges to wetlands shall maintain the hydrologic conditions, hydrophytic vegetation, and substrate characteristics necessary to support existing and designated uses. The hydrologic analysis shall use the existing land cover condition to determine the existing hydrologic conditions unless directed otherwise. A wetland can be considered for hydrologic modification and/or storm water treatment in accordance with Guide Sheet 1B in Appendix I-D on the Stormwater Manual.

(d) Additional Requirements. Storm water treatment and flow control facilities shall not be built within a natural vegetated buffer, except for:

(i) As necessary, conveyance systems as approved by the director; or

(ii) As allowed in wetlands approved for hydrologic modification and/or treatment in accordance with Guide Sheet 1B in Appendix I-D of the Stormwater Manual.

(9) Minimum Requirement No. 9: Operation and Maintenance. All project submittals must include an operation and maintenance manual that is consistent with the provisions in Volume V of the Stormwater Manual for all proposed storm water facilities and BMPs. The party (or parties) responsible for maintenance and operation shall be identified in the operation and maintenance manual. For private facilities approved by the city, a copy of the manual shall be retained on site or within reasonable access to the site, and shall be transferred with the property to the new owner. For public facilities, a copy of the manual shall be retained in the appropriate department. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection by the city. (Ord. 2857 § 3, 2011; Ord. 2816 § 1 (Exh. A), 2010; Ord. 2694 § 2, 2007; Ord. 2476 § 2, 2003).

14.15.062 Low impact development (LID) – Alternative drainage standards.

Low impact BMPs are an alternative to conventional storm water management systems that rely on detention ponds and closed conveyance. Instead, low impact development is intended to manage runoff close to the source of generation and to mimic the predeveloped hydrologic condition of a site. This is accomplished first through minimizing the impervious surface coverage and second by managing runoff through dispersion, infiltration, evapotranspiration, or a combination of these approaches. Use of LID BMPs may reduce or eliminate the need for conventional detention facilities but does not remove the obligation to comply with the minimum requirements in MMC 14.15.050. A variety of BMPs to minimize impervious surfaces and to manage storm water have been developed and tested for use in western Washington. These BMPs and the overall LID approach are described in the LID Technical Guidance Manual for Puget Sound.

The menu of LID BMPs identified in the LID Technical Guidance Manual for Puget Sound are accepted for use in storm water site plans to address the minimum requirements for flow control and runoff treatment in MMC 14.15.050, subject to the specifications, performance standards, and design criteria in the LID Technical Guidance Manual for Puget Sound, review and approval under this chapter, Chapter 22C.260 MMC, as applicable, and the requirements and limitations below.

(1) The city engineer may approve the following LID BMPs to meet water quality treatment requirements:

(a) Full Dispersion. Sites that are approved for full dispersion, consistent with the standards in the LID Technical Guidance Manual for Puget Sound, are not required to provide water quality treatment.

(b) Bioretention. Any storm water runoff that infiltrates through the imported soil mix in an approved bioretention facility will have received the equivalent of enhanced treatment. Where bioretention is intended to fully meet treatment requirements, facilities shall be designed, using an approved continuous runoff model, to infiltrate 60 percent of the developed two-year peak flow.

(2) In addition to the requirements in MMC 14.15.065, applicants for LID BMPs shall provide a site assessment. The site assessment shall include the following, unless waived or modified by the city engineer:

(a) A mapped inventory of existing vegetation and description of tree cover and understory;

(b) A mapped inventory of wetlands and streams and required buffers under Chapter 22E.010 MMC on the site;

(c) A survey prepared by a registered land surveyor or other licensed professional to conduct surveys showing existing development, including utility infrastructure, on and adjacent to the site, major and minor hydrologic features, including seeps, springs, closed depression areas, drainage swales, and topographic relief at two-foot contours;

(d) The location of all existing and proposed lot lines and easements;

(e) A soils report by a licensed geotechnical engineer or licensed engineering geologist. The report shall identify:

(i) Underlying soils on the site, utilizing soil pits and soil grain analysis to assess infiltration capability. The frequency and distribution of test pits shall be adequate to direct placement of the roads and structures away from soils that can most effectively infiltrate storm water;

(ii) Topographic features that may act as natural storm water storage or conveyance and underlying soils that provide opportunities for storage and partial infiltration;

(iii) Depth to ground water;

(iv) Landslide hazard areas on the site and the distance to slopes over 25 percent or landslide hazard areas within 500 feet of the site;

(f) Flood hazard areas on or adjacent to the site;

(g) SEPA environmental checklist.

(3) Additional studies may be required to address potential impacts to down-slope properties.

(4) Restrictions on conversion of drainage facilities shall be recorded on the face of the plat.

(5) A covenant shall be recorded with the Snohomish County auditor’s office for each lot containing or served by bioretention facilities in a form approved by the city attorney. The covenant shall identify requirements and liability for preservation and maintenance of low impact development facilities approved under this chapter and privately held in individual or undivided ownership or intended for public ownership.

(6) An easement shall be granted for city access to low impact development facilities on private property to allow inspection, maintenance, and repair. (Ord. 2857 § 3, 2011; Ord. 2816 § 1 (Exh. A), 2010; Ord. 2694 § 2, 2007).

14.15.065 Contents of a storm water site plan.

(1) Storm Water Site Plan Required. New development and redevelopment projects must submit a storm water site plan for approval by the department as set forth in MMC 14.15.040.

(2) Contents of Plan. In addition to the requirements described in MMC 14.15.050 and the Stormwater Manual, an off-site analysis report shall be required. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.066 Determining construction site sediment damage potential.

Any person submitting a storm water site plan must also determine the construction site sediment damage potential. Qualified personnel must use the rating system described in Appendix 7 of the NPDES Phase II Municipal Storm Water Permit to determine the site’s potential to discharge sediment. The damage potential rating must be submitted and approved to receive final civil plan review approval. (Ord. 2816 § 1, 2010).

14.15.070 Development in critical flood, drainage and/or erosion areas.

Development which would increase the volume of discharge from the subject property shall not be permitted in areas where existing flooding, drainage, and/or erosion conditions present an imminent likelihood of harm to the welfare and safety of the surrounding community or property, until such time as the community hazard is alleviated. Where application of the provisions of this section will deny all reasonable use of the property, the director or designee may waive the restrictions on development contained in this section; provided, that the resulting development shall be subject to all of the remaining terms and conditions of this chapter and Chapter 22E.010 MMC, Critical Areas Management. (Ord. 2857 § 3, 2011; Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.080 Establishment of regional facilities.

(1) Public Benefit. 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 director or designee may recommend that the city should assume responsibility for the further design, construction, operation, and maintenance of the drainage facilities, or any increment thereof, on the subject property. Such decision shall be made concurrently with review and approval of the plan.

(2) Applicant’s Responsibility. In the event that the city decides to assume responsibility for all or any portion of the design, construction, operation, and maintenance of the facilities, the applicant shall be required to contribute a prorated share to the estimated cost of the facilities; provided, that such share shall not exceed the estimated costs of improvements the applicant would otherwise have been required to install. The applicant may be required to supply additional information at the request of the director or designee to aid in such determination by the city. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.090 Fees.

Fees shall be charged for preliminary review, construction plan review, inspection, and final plan review done upon completion of all civil work and approval of the final plat map. The city shall have the option of sending plans out for review, in which case fees will also include consultant rates. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.100 Construction standards and specifications.

The director shall approve, prepare, administer, and enforce detailed construction standards and specifications for all storm drainage lines, on-site storm water and erosion control facilities. The city shall not accept ownership or maintenance responsibility for any lines or facilities which are constructed in violation of said standards and specifications. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.110 Review and approval of plans.

All storm water site plans and any other documents required by or prepared in connection with this chapter shall be submitted for review and approval by the director or designee.

The applicant shall keep two sets of plans on site at all times for recording as-built information; one set shall be submitted to the project engineer, and one set shall be submitted to the director at completion of construction and prior to final acceptance of work. The owner and/or contractor shall notify the project engineer and the director when conflicts exist between the plans and field conditions. Conflicts shall be resolved (including plan and profile revisions) and resubmitted for approval prior to proceeding with construction. For further plan retention and revision requirements for storm water site plans and construction storm water pollution prevention plans see the Stormwater Manual and MMC 14.15.050(2), Minimum Requirement No. 2: Construction Storm Water Pollution Prevention Plan (SWPPP). (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.120 Inspections – Construction.

All activities regulated by this chapter shall be inspected by the engineer and/or public works department. Projects shall be inspected at various stages of the work to determine that adequate control is being exercised. Stages of work requiring inspection include, but are not limited to, preconstruction; installation of BMPs; land-disturbing activities; installation of utilities, landscaping, retaining walls; and completion of project. When required by the director or designee, a special inspection and/or testing shall be performed.

The holder of any permit or approval issued subject to a detailed drainage plan shall arrange with the engineer for scheduling the following inspections:

(1) Initial Inspection. Inspection prior to clearing and construction will apply to sites with a high potential for sediment damage, as identified by the applicant during civil review based on definitions and requirements of Appendix 7 of the Western Washington Phase II Municipal Storm Water Permit;

(2) Grading Preparation. Whenever work on the site preparation, grading, excavations, or fill is ready to be commenced, but in all cases prior thereto subject also to provisions of MMC 22D.050.070;

(3) Rough Grading. When all rough grading has been completed;

(4) Bury Inspection. Prior to burial of any underground drainage structure;

(5) Finish Grading. When all work including installation of all drainage structures and other protective devices has been completed;

(6) Planting. When erosion control planting shows active growth;

(7) System-wide inspections for residential developments will take place after all flow control and water quality treatment facilities are completed during the period of heaviest house construction to identify maintenance needs and enforce compliance with maintenance standards as needed.

In some circumstances not all of the above inspections may be necessary. It shall be the discretion of the public works director or designee to waive or combine any of the above inspections as dictated by conditions.

The public works director or designee shall inspect the work and shall either approve the same or notify the applicant in writing in what respects there has been failure to comply with the requirements of the approved plan. Any portion of the work which does not comply shall be promptly corrected by the applicant. The public works director or designee may make unscheduled site inspections to ensure compliance. Uncorrected violations will be subject to the provisions of MMC 14.15.190. (Ord. 2857 § 3, 2011; Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.130 Bonds and liability insurance required.

The department is authorized to require all persons constructing retention/detention or other drainage system features to post surety or cash bonds. Where such persons have previously posted, or are required 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 director or designee, 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 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 construction, the person constructing the facility shall post a construction bond in an amount sufficient to cover the cost of performing said construction per the approved drainage plans. Alternatively, an equivalent cash deposit to an escrow account administered by a local account bank may be allowed at the city’s option.

(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-year period of satisfactory maintenance of the facility. A cash bond to be used at the discretion of the city, 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 the cash bond shall be determined by the public works director or designee. In addition, at the discretion of the city, a surety bond or cash bond to cover the cost of design defects or failures in workmanship shall also be posted and maintained through the two-year maintenance period. Alternatively, an equivalent cash deposit to an escrow account administered by a local account bank may be allowed, at the city’s option.

(3) Liability Policy. The person constructing the facility shall maintain a liability policy in an amount to be determined by the city which shall name the city of Marysville as an additional insured and which shall protect the city from any liability for any accident, negligence, failure of the facility, or any other liability whatsoever, relating to the construction or maintenance of the facility. The liability policy shall be maintained for the duration of the facility by the owner of the facility; provided, that in the case of facilities assumed by the city for maintenance pursuant to MMC 14.15.140, the liability policy shall be terminated when the city maintenance responsibility commences. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.140 City assumption of maintenance.

The city may assume the maintenance of storm water drainage system facilities after the expiration of the two-year maintenance period if:

(1) Conveyance to the city occurred per MMC 14.03.420;

(2) All of the requirements of this chapter have been fully complied with;

(3) The facilities have been inspected and approved by the department after two years of operation;

(4) All necessary easements entitling the city to properly maintain the facility have been conveyed to the city. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.150 Retroactivity relating to city maintenance of drainage facilities.

If any person constructing retention/detention facilities and/or receiving approval of drainage plans prior to the effective date of this chapter demonstrates, to the city’s satisfaction, total compliance with the requirements of this chapter, the city may, after inspection, approval, and acknowledgment of the proper posting of the required bonds as specified in MMC 14.15.130, assume maintenance of the facilities. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.160 Maintenance of drainage facilities by owner.

In the event that the city elects not to assume the operation and maintenance responsibility for the facilities, it shall be the responsibility of the owner of the property, or persons with a shared ownership interest in the property, or their heirs, successors and assigns, to operate, maintain, repair and replace the facilities in continuous compliance with the standards and specifications of Chapter 14.17 MMC. The director or designee shall have authority to periodically enter upon the property and inspect the facilities to ensure such compliance. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.170 Applicability to governmental entities.

All municipal corporations and governmental entities shall be required to submit a storm water site plan and comply with the terms of this chapter when developing and/or improving land within the incorporated areas of the city of Marysville or within adjacent areas which may affect the city. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.175 Adjustments.

All adjustments to the minimum requirements in MMC 14.15.050 may be granted prior to permit approval and construction. Adjustments must be reviewed in the context of each application, site and potential impacts. Approval does not establish precedent for subsequent applications that may reflect different scale, complexity and site conditions. Adjustments to the minimum requirements may be granted by the director; provided, that a written finding of fact is prepared, that addresses the following:

(1) The adjustment provides substantially equivalent environmental protection.

(2) Based on sound engineering practices, the objectives of safety, function, environmental protection and facility maintenance are met. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.180 Exceptions.

(1) Exceptions to the minimum requirements in MMC 14.15.050 may be granted prior to permit approval and construction. Exceptions must be reviewed in the context of each application, site and potential impacts. Approval does not establish precedent for subsequent applications that may reflect different scale, complexity and site conditions. Application for an exception shall be filed in writing with the director and shall adequately detail the reason for an exception.

(2) Exceptions/variances (exceptions) to the minimum requirements in MMC 14.15.050 may be granted by the director following legal public notice of an application for an exception or variance, legal public notice of the director’s decision on the application, and written findings of fact that document the director’s determination to grant an exception. The city will keep records, including the written findings of fact, of all exceptions to the minimum requirements in MMC 14.15.050.

(3) Project-specific design exceptions based on site-specific conditions do not require prior approval of the Department of Ecology. The city will seek prior approval by the Department of Ecology for any jurisdiction-wide exception.

(4) The director may grant an exception to the minimum requirements in MMC 14.15.050 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 director must consider and document with written findings of fact the following:

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

(b) How the application of the minimum requirement(s) in MMC 14.15.050 restricts the proposed use of the site compared to the restrictions that existed prior to the adoption of the minimum requirements; and

(d) The uses of the site that would have been allowed prior to the adoption of the minimum requirements in MMC 14.15.050; and

(e) A comparison of the estimated amount and percentage of value loss as a result of the minimum requirements in MMC 14.15.050 versus the estimated amount and percentage of value loss as a result of requirements that existed prior to adoption of the minimum requirements in MMC 14.15.050; and

(f) The feasibility for the owner to alter the project to apply the minimum requirements in MMC 14.15.050.

(5) In addition, any exception must meet the following criteria:

(a) The exception 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 exception is the least possible exception that could be granted to comply with the intent of the minimum requirements in MMC 14.15.050. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.185 Additional procedures and review.

In various sections of this chapter, the public works director or designee, the city engineer, and/or the city planner may be empowered to impose requirements, give approvals, make determinations and the like (hereinafter in this section “administrative determination(s)”). This section sets out procedures for administrative determination(s). All administrative determination(s) shall be made in a timely manner to satisfy all requirements of state law. All administrative determination(s) shall be in writing and shall set out facts and conclusions to support the decision made. All administrative determination(s) shall be made to achieve the purposes of this chapter as set forth in MMC 14.15.010. All administrative determination(s) may be appealed to the hearing examiner by filing written notice of appeal with the city clerk within 10 days of service of the administrative determination. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.190 Enforcement.

Enforcement of the provisions of this chapter shall be pursuant to MMC Title 4. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.200 No special duty created.

(1) It is the purpose of this chapter to provide for the health, welfare, and safety of the general public, and not to create or otherwise establish or designate any particular class or group of persons who will or should be especially protected or benefitted by the terms of this chapter. No provision or term used in this chapter is intended to impose any duty whatsoever upon the city or any of its officers, agents, or employees for whom the implementation or enforcement of this chapter shall be discretionary and not mandatory.

(2) Nothing contained in this chapter is intended to be, nor shall be, construed to create or form the basis for any liability on the part of the city or its officers, agents, and employees for any injury or damage resulting from the failure of any premises to abate a nuisance or to comply with the provisions of this chapter or by reason or as a consequence of any inspection, notice, or order, in connection with the implementation or enforcement of this chapter, or by reason of any action of the city related in any manner to enforcement of this chapter by its officers, agents, or employees. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.210 Severability.

If any section, subsection, sentence, clause, phrase, or word of this chapter should be held to be invalid or unconstitutional by a court of competent jurisdiction, such invalidity or unconstitutionality thereof shall not affect the validity or constitutionality of any other section, subsection, sentence, clause, phrase, or word of this chapter. (Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).

14.15.220 Appeals.

The decision of the director may be appealed by an aggrieved party pursuant to MMC 22G.010.530 to the hearing examiner by filing written notice of appeal, including an appeal fee of $500.00, with the city’s public works department or community development department, within 10 days of notice of the director’s decision. (Ord. 2857 § 3, 2011; Ord. 2816 § 1 (Exh. A), 2010; Ord. 2476 § 2, 2003).