Chapter 16.25 APPROVAL STANDARDS

Chapter 16.25
APPROVAL STANDARDS¹

Sections:

16.25.010 Core and special requirements.

Depending on the type of drainage review required, as described in FWRC 16.25.020, one or more core or special requirements shall be met. The core and special requirements, described below, are also described in detail in the KCSWDM and Federal Way Addendum adopted by reference in FWRC 16.20.010.

(1) Core requirements.

(a) Core requirement No. 1 – Discharge at the natural location. All surface and stormwater runoff from a project must be discharged at the natural location so as not to be diverted onto or away from downstream properties. The manner in which runoff is discharged from the project site must not create a significant adverse impact to downhill properties or drainage systems.

(b) Core requirement No. 2 – Off-site analysis. All proposed projects must submit an off-site analysis report that assesses potential off-site drainage impacts associated with development of the project site and proposes appropriate mitigations of those impacts. The initial permit submittal shall meet the requirements outlined in the KCSWDM and the Federal Way Addendum.

(c) Core requirement No. 3 – Flow control. All proposed projects, including redevelopment projects, must provide on-site flow control facilities to mitigate the impacts of increased storm and surface water runoff generated by the addition of new impervious surfaces, new pervious surfaces and replacement impervious surfaces. These facilities shall, at a minimum, meet the performance criteria for one of the area-specific flow control standards and be implemented according to the applicable flow control implementation requirements described in the KCSWDM. Flow control BMPs must be provided as directed in the KCSWDM.

(d) Core requirement No. 4 – Conveyance system. All engineered conveyance system elements for proposed projects must be analyzed, designed, and constructed to provide a minimum level of protection against overtopping, flooding, erosion, and structural failure as specified in the KCSWDM.

(e) Core requirement No. 5 – Erosion and sediment control. All proposed projects that will clear, grade, or otherwise disturb the site must provide erosion and sediment controls to prevent, to the maximum extent possible, the transport of sediment from the project site to downstream drainage facilities, water resources, and adjacent properties. To prevent sediment transport, erosion and sediment control (ESC) measures that are appropriate to the project site must be applied and performed as described in the KCSWDM. Both temporary and permanent erosion and sediment controls shall be implemented as described in the KCSWDM.

(f) Core requirement No. 6 – Maintenance and operation. Maintenance and operation of all drainage facilities is the responsibility of the applicant or property owner, except those facilities for which Federal Way is granted an easement, tract, or right-of-way and officially assumes maintenance and operation as described in the KCSWDM. Drainage facilities must be maintained and operated in compliance with Federal Way maintenance standards.

(g) Core requirement No. 7 – Financial guarantees and liability. All drainage facilities constructed or modified for projects (except downspout infiltration and dispersion systems), and any work performed in the right-of-way, must comply with the financial guarantee requirements in FWRC Title 19.

(h) Core requirement No. 8 – Water quality. All proposed projects, including redevelopment projects, must provide water quality (WQ) facilities to treat the runoff from new and/or replaced pollution-generating impervious surfaces and pollution-generating pervious surfaces. Redevelopment projects may also be required to provide WQ facilities to treat existing pollution-generating impervious surfaces. WQ facilities shall be selected and implemented according to the KCSWDM.

(i) Core requirement No. 9 – Flow control BMPs. All proposed projects, including redevelopment projects, must provide on-site flow control BMPs to mitigate the impacts of storm and surface water runoff generated by new impervious surfaces, new pervious surfaces, existing impervious surfaces, and replaced impervious surfaces targeted for mitigation as specified in the following sections. Flow control BMPs must be selected and applied according to the KCSWDM.

(2) Special requirements.

(a) Special requirement No. 1 – Other adopted area-specific requirements. King County has developed several types of area-specific plans and regulations that contain requirements for drainage design. These regulations include critical drainage areas, master drainage plans, basin plans, lake management plans, and shared facility drainage plans. In some cases, these plans and regulations could overlap with the city of Federal Way’s jurisdictional area.

The Hylebos Creek and lower Puget Sound basin plan is the only one of these area-specific regulations that currently affects Federal Way. King County developed this basin plan which recommends specific land uses, regional capital projects, and special drainage requirements for future development within the Hylebos and lower Puget Sound basin.

The drainage requirements of adopted area-specific regulations such as basin plans shall be applied in addition to the drainage requirements of the KCSWDM and Federal Way Addendum unless otherwise specified in the adopted regulation. Where conflicts occur between the two, the drainage requirements of the adopted area-specific regulation shall supersede those in the KCSWDM and Federal Way Addendum.

(b) Special requirement No. 2 – Floodplain/floodway delineation. Floodplains and floodways are subject to inundation during extreme events. The 100-year floodplains are delineated in order to minimize flooding impacts to new development and to prevent aggravation of existing flooding problems by new development. Regulations and restrictions concerning development within a 100-year floodplain are found in Federal Way’s environmentally sensitive areas and flood hazard regulations.

If an approved flood hazard study exists, then it may be used as the basis for delineating the floodplain and floodway boundaries provided the study was prepared in a manner consistent with the KCSWDM and other Federal Way flood hazard regulations. If an approved flood hazard study does not exist, then one shall be prepared based on the requirements described in Chapter 4.4.2 of the KCSWDM, “Floodplain/Floodway Analysis.”

(c) Special requirement No. 3 – Flood protection facilities. Developing sites protected by levees, revetments, or berms require a high level of confidence in their structural integrity and performance. Proper analysis, design, and construction are necessary to protect against the potentially catastrophic consequences if such facilities should fail.

The applicant is required to demonstrate conformance with FEMA regulations using the methods specified in Chapter 4.4.2 of the KCSWDM. In addition, certain easement requirements (outlined in Chapter 4.1 of the KCSWDM) must be met in order to allow city access for maintenance of the facility.

(d) Special requirement No. 4 – Source control. Water quality source controls, many of which are listed in the KCSPPM and the LID Manual, prevent rainfall and runoff water from coming into contact with pollutants, thereby reducing the likelihood that pollutants will enter public waterways and violate water quality standards. When applicable, structural source control measures, such as car wash pads or dumpster area roofing, shall be shown on the site improvement plans submitted for engineering review and approval. Other nonstructural source control measures, such as covering storage piles with plastic or isolating areas where pollutants are used or stored, are to be implemented after occupancy and need not be addressed during the plan review process. All commercial and industrial projects (irrespective of size) undergoing drainage review are required to implement applicable source controls.

(e) Special requirement No. 5 – Oil control. Projects proposing to develop or redevelop a high-use site must provide oil controls in addition to any other water quality controls required by this manual. Such sites typically generate high concentrations of oil due to high traffic turnover or the frequent transfer of oil.

(Ord. No. 21-922, § 2, 11-16-21; Ord. No. 09-630, § 11, 10-20-09; Ord. No. 99-352, § 3, 11-16-99. Code 2001 § 21-12.)

16.25.020 Drainage review.

(1) When required. Drainage review is required for any proposed project, including new development and redevelopment (except for those proposing only routine maintenance, repair, or emergency modifications) which is or includes a regulated activity under FWRC 16.15.010, and for which city approval, including but not limited to any approval listed in FWRC 16.15.030, is required.

(2) Type of drainage review required. One of the following four types of drainage review will be required, depending on the project; provided, however, that a project which qualifies for small site drainage review may also require targeted drainage review if the requirements for targeted drainage review are met:

(a) Small site drainage review. Small site drainage review is required for single-family residential or subdivision projects that will result in 2,000 square feet or more of new impervious surface, replaced surface or new plus replaced impervious surface or 7,000 square feet or more of land disturbing activity, and that meet one of the following criteria:

(i) The project will result in no more than 10,000 square feet of total impervious surface added on or after January 8, 2001, no more than 5,000 square feet of new impervious surface, and no more than 35,000 square feet of new pervious surface; or

(ii) The project will result in no more than 10,000 square feet of total impervious surface added on or after January 8, 2001, and its new pervious surface area will be no more than 35,000 square feet minus 3.25 times the area of new impervious surface being proposed by the project (for sites larger than 22,000 square feet, a factor of 2.25 may be used instead of 3.25).

Compliance shall be demonstrated through the implementation of an approved small site drainage plan and a small site erosion and sediment control plan. Detailed design specifications and submittal requirements are presented in Appendix C of the KCSWDM, titled: “Small Site Drainage Requirements.”

(b) Full drainage review. Full drainage review is required for any proposed project, including a redevelopment project as determined in FWRC 16.15.010, that meets one or more of the following criteria:

(i) The project will result in 2,000 square feet or more of new impervious surface, replaced impervious surface or new plus replaced impervious surface, but is not subject to small project drainage review as determined in this section.

(ii) The project will result in 7,000 square feet or more of land disturbing activity but is not subject to small project drainage review per this section.

(iii) The project is a redevelopment project on a parcel or combination of parcels in which the total of new plus replaced impervious surface is 5,000 square feet or more and whose valuation of proposed improvements (including interior improvements and excluding required mitigation and frontage improvements) exceeds 50 percent of the assessed value of the existing parcel improvements.

If full drainage review is required, then the applicant must demonstrate that the proposed project complies with the following requirements:

(i) All core requirements specified in FWRC 16.25.010.

(ii) All special requirements specified in FWRC 16.25.010.

(c) Large project drainage review. Large project drainage review is applied to development proposals that are large and/or involve resources or problems of a special sensitivity or complexity. Large project drainage review is required for any proposed project that is subject to drainage review as determined in FWRC 16.15.010 and that meets any one of the following criteria:

(i) The project would, at full build-out, result in 50 acres or more of new impervious surface within a single subbasin or multiple subbasins that are hydraulically connected across subbasin boundaries; or

(ii) The project site is 50 acres or more (including growth reserve areas) within a critical aquifer recharge area.

If large project drainage review is required, compliance shall be achieved through the implementation of the scope of requirements as specified in Section 1.1.2.4, Large Project Drainage Review, of the KCSWDM.

(d) Targeted drainage review. Targeted drainage review is required for any proposed projects, including redevelopment projects, that are subject to drainage review but are not subject to full drainage review, and which fall into one or more of the following project categories:

TDR Category #1:	Projects that contain or are adjacent to floodplains or environmentally sensitive areas; or projects that propose 7,000 square feet (one acre if in small project drainage review) or more of land disturbing activity.
TDR Category #2:	Projects proposing to construct or modify a drainage pipe/ditch that is 12 inches or larger in size/depth or receives runoff from a drainage pipe/ditch that is 12 inches or more in size/depth.
TDR Category #3:	Redevelopment projects as defined in FWRC 19.30.120.

If targeted drainage review is required, then the applicant must demonstrate that the proposed project complies with the selected core and special requirements corresponding to the appropriate category or categories of project that best match the proposed project. The specific requirements for each TDR category are as follows:

(i) TDR Project Category #1.

(A) The following requirements apply to TDR Category #1 projects, but may have exemptions or thresholds that preclude or limit their application to a specific project:

(I) Core Requirement #5 – Erosion and Sediment Control.

(II) Special Requirement #1 – Other Adopted Area-Specific Requirements.

(III) Special Requirement #2 – Floodplain/Floodway Analysis.

(IV) Special Requirement #3 – Flood Protection Facilities.

(V) Special Requirement #4 – Source Control.

(B) The following requirements may be applied to projects in TDR Category #1 at the discretion of public works based on site-specific conditions:

(I) Core Requirement #1 – Discharge at the Natural Location.

(II) Core Requirement #2 – Off-Site Analysis.

(III) Core Requirement #3 – Flow Control.

(IV) Core Requirement #4 – Conveyance System.

(V) Core Requirement #6 – Maintenance and Operations.

(VI) Core Requirement #7 – Financial Guarantees and Liability.

(VII) Core Requirement #8 – Water Quality.

(ii) TDR Project Category #2.

(A) The following requirements apply to projects in TDR Category #2:

(I) Core Requirement #1 – Discharge at the Natural Location.

(II) Core Requirement #2 – Off-Site Analysis.

(III) Core Requirement #4 – Conveyance System.

(IV) Core Requirement #5 – Erosion and Sediment Control.

(V) Core Requirement #6 – Maintenance and Operations.

(B) The following requirements apply to projects in TDR Category #2, but have exemptions or thresholds that may preclude or limit their application to a specific project:

(I) Core Requirement #7 – Financial Guarantees and Liability.

(II) Special Requirement #4 – Source Control.

(iii) TDR Project Category #3.

(A) The following requirements apply to the projects in TDR Category #3:

(I) Core Requirement #1 – Discharge at the Natural Location.

(II) Core Requirement #5 – Erosion and Sediment Control.

(III) Core Requirement #6 – Maintenance and Operations.

(B) The following requirements apply to projects in TDR Category #3, but have exemptions or thresholds that may preclude or limit their application to a specific project:

(I) Core Requirement #7 – Financial Guarantees and Liability.

(II) Core Requirement #8 – Water Quality.

(III) Special Requirement #4 – Source Control.

(IV) Special Requirement #5 – Oil Control.

(Ord. No. 09-630, § 12, 10-20-09; Ord. No. 99-352, § 3, 11-16-99. Code 2001 § 21-13.)

16.25.030 Liability insurance.

The person required to construct any storm drainage facility required herein shall maintain a liability policy in the amount of $500,000 per individual, $500,000 per occurrence and $100,000 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 maintenance of the facility. Proof of such liability policy shall be provided to the public works director prior to commencing construction of any drainage facility; provided, that in the case of facilities dedicated to and accepted by the city for maintenance pursuant to FWRC 16.35.010 and 16.35.020, such liability policy shall be terminated when the city maintenance responsibility commences.

(Ord. No. 99-352, § 3, 11-16-99. Code 2001 § 21-13.5.)

Cross references: Requirements for street right-of-way use plans, FWRC 4.25.050; shoreline management regulations, FWRC Title 15; subdivisions, FWRC Title 18; zoning variance procedure, Chapter 19.45 FWRC; site plan review, Chapter 19.60 FWRC; process III review requirements, Chapter 19.65 FWRC; process IV review requirements, Chapter 19.70 FWRC; process VI review requirements, Chapter 19.80 FWRC; land modifications under the zoning regulations, Chapter 19.120 FWRC; planned unit developments, Chapter 19.250 FWRC.