9-5A-9: GENERAL REQUIREMENTS:
   A.   Stormwater Management Manual Adopted: The Department of Ecology 2019 “Stormwater Management Manual for Western Washington”, together with the 2019 City of Orting Stormwater Management Manual Amendment, are hereby adopted by reference, as though fully set forth herein, as the Stormwater Management Manual for the City of Orting and is hereinafter referred to as the “manual” or the “Stormwater Management Manual”.
   B.   Low Impact Development Manual Adopted: The Volume 5 of the Ecology 2019 (Stormwater Management Manual for Western Washington” is hereby adopted by reference as though fully set forth herein as the Low Impact Development Manual for the City of Orting and is hereinafter referred to as the “LID Manual”.
   C.   Rain Garden Handbook: The June 2013 “Rain Garden Handbook for Western Washington” as published by the Washington State Department of Ecology is hereby adopted by reference as though fully set forth herein as the Rain Garden Handbook for the City of Orting and is hereinafter referred to as the “Rain Garden Handbook”.
   D.   The following hierarchy shall be used in the order listed to determine applicable requirements:
      1.   The 2019 City of Orting Stormwater Management Manual Amendment;
      2.   The 2019 “Stormwater Management Manual for Western Washington”;
      3.   The currently adopted City of Orting Development Standards;
      4.   The 2012 “Low Impact Development Technical Guidance Manual for Puget Sound”;
      5.   The 2013 “Rain Garden Handbook for Western Washington”.
   E.   Low Impact Development (LID) Practices:
      1.   Projects shall implement LID BMPs and on-site stormwater management
BMPs where such projects exceed the thresholds identified in the Stormwater Management Manual and Minimum Requirement 5 must be addressed. Constraints that make LID BMPs or on-site stormwater management BMPs infeasible must be documented in the project’s Permanent Stormwater Site Plan. The Permanent Stormwater Site Plan, including constraints to the implementation of LID BMPs or on-site stormwater management BMPs, are required to be submitted for review for approval by the City in accordance with applicable submittals required under OMC Titles 10, 12, 13 and 15.
      2.   Constructed LID BMPs: Constructed LID BMPs for stormwater management shall be considered based on the order of preference identified in the Stomwater Management Manual.
      3.   Stormwater BMPs: If LID BMPs are infeasible as documented in the Permanent Stormwater Site Plan approved by the City, BMPs in subsection D of this section shall be used.
      4.   Underground Injection Control (UIC): Projects that implement LID BMPs or permanent Stormwater BMPs that result in a facility considered an underground injection control well based on 173-218 WAC shall be registered by the project applicant with the Washington State Department of Ecology. The Permanent Stormwater Site Plan shall document, based on the requirements of the Stormwater Management Manual, whether or not LID BMPs or permanent Stormwater BMPs are UIC wells and documentation that UIC wells have been registered.
   F.   Stormwater Best Management Practices (BMPs):
      1.   General: Where LID practices are not feasible or approved, BMPs shall be used to control stormwater pollution and/or flow rates and volumes. BMPs shall be used to comply with the standards in this article. BMPs are in the manual.
      2.   Experimental BMPs: In those instances where appropriate BMPs are not in the manual, experimental BMPs should be considered. Experimental BMPs are encouraged as a means of solving problems in a manner not addressed by the manual in an effort to improve stormwater quality technology. Experimental BMPs must be approved in accordance with the approval process outlined in the manual.
   G.   Flow Control: Flow control, where required, shall provide the following control:
      1.   Flow rates and durations for fifty percent (50%) of the 2-year through the 50-year flow frequency event for the following conditions:
         a.   Direct connection or connection through a series of stormwater facilities or natural conveyance systems that discharge to the City stormwater drainage system that has existing capacity limitations; and
         b.   There are no existing flooding problems between the project site and the discharge point of the existing City stormwater drainage system.
      2.   Flow rates and durations for fifty percent (50%) of the 2-year through the 50-year frequency event, flow rates for the 100-year frequency event, and provide a twenty percent (20%) safety factor for the following conditions:
         a.   Direct connection or connection through a series of natural conveyance systems or stormwater facilities that discharge to the City stormwater drainage system that has existing capacity limitations; and
         b.   There are existing flooding problems between the project site and the discharge point of the existing City stormwater drainage system that may be aggravated by the proposed project.
      3.   Complete on site stormwater management must be provided for the following:
         a.   Infiltration of all stormwater if there is no existing City stormwater drainage system to connect to and if the site does not currently drain to the existing City stormwater drainage system.
         b.   An outfall into a flow control exempt waterbody may be constructed by the project proponent subject to the following requirements:
            (1)   A hydraulic project approval (HPA), if required, is applied for by the project proponent and is issued by Washington Department of Fish and Wildlife;
            (2)   The outfall does not violate any stormwater diversions as documented in appendix 1E of volume I of the manual;
            (3)   The project proponent obtains all other permits required by Federal, State and local laws and regulations; and
            (4)   The project proponent enters into an operations and maintenance agreement with the City. The operations and maintenance agreement will be waived provided that the outfall is permitted under the Department of Ecology’s industrial stormwater general permit or other individual permit that requires the ongoing maintenance and monitoring of the outfall.
      4.   Projects are exempt from flow control, if the flow control thresholds for new or redevelopment projects are exceeded; provided that:
         a.   The project has a direct connection or connection through a series of manmade conveyance systems or stormwater facilities that discharge to the City stormwater drainage system that has adequate capacity, i.e., does not exceed the then existing limitations upon capacity as determined by the City; and
         b.   There are no existing flooding problems between the project site and the discharge point of the existing City stormwater drainage system.
      5.   Project sites that are located in areas regulated under the flood control ordinance (codified at title 14 of this Code) and for which flow control is provided shall set the regulated structure elevations based on the higher of:
         a.   The elevation required by title 14 of this code, or
         b.   The backwater elevation at the flow control facility caused by the receiving water. The backwater elevation in the flow control facility shall be based on:
            (1)   The tailwater elevation based on the 100-year floodplain elevation in the receiving water floodway published by the federal emergency management agency for an unbreached levee;
            (2)   Flow rate for the 100-year frequency event through the stormwater drainage system from the site point of connection to the discharge location. The flow rate shall include the site and any other contributing areas; and
            (3)   Flow rate for the 100-year frequency event from the site point of connection back through the flow control riser.
   H.   Illicit Discharges: Illicit discharges to stormwater drainage systems, surface water or groundwater are prohibited. “Permitted discharges” are defined in section 9-5A-4 of this article. Sites are subject to inspection for illicit discharges in accordance with section 9-5B-10 of this chapter. The following are prohibited discharges to any public or private stormwater drainage system or natural conveyance system that discharge to surface or ground waters of the state:
      1.   Discharges from potable water sources, including water line flushing, hyperchlorinated water line flushing, fire hydrant system flushing, and pipeline hydrostatic test water that are not dechlorinated to the limits identified herein. Planned discharges shall be dechlorinated to a concentration of 0.1 ppm or less, pH adjusted, if necessary, and volumetrically and velocity controlled to prevent resuspension of sediments in the stormwater drainage system.
      2.   Discharges from lawn watering and other irrigation runoff that are not minimized.
      3.   Swimming pool discharges that are not dechlorinated to the limits identified herein. The discharges shall be dechlorinated to a concentration of 0.1 ppm or less, pH adjusted and reoxygenized if necessary, volumetrically and velocity controlled to prevent resuspension of sediments in the stormwater drainage system. Swimming pool cleaning wastewater and filter backwash shall discharge to sanitary sewer system.
      4.   Street and sidewalk wash water, water used to control dust, and routine external building wash down that does not use detergents that are not minimized. At active construction sites, street sweeping must be performed prior to washing the street.
      5.   Nonstormwater discharges covered by another NPDES permit unless the permittee is in full compliance with all permit requirements, waiver or order and other applicable laws and regulations, and that written approval by the director has been granted for the discharge into the city’s stormwater drainage system.
      6.   Other nonstormwater discharges. The discharges shall be in compliance with the requirements of the stormwater pollution prevention plan approved by the director, which addresses control of construction site dewatering discharges by applying AKART to prevent contaminants from entering surface water or groundwaters.
   I.   Prohibition Of Illicit Connections:
      1.   The construction, use, maintenance, or continued existence of illicit connections to a stormwater drainage system is prohibited.
      2.   This prohibition expressly includes, without limitation, illicit connections made in the past, regardless of whether the connection was permissible under law or practices applicable or prevailing at the time of connection.
      3.   In addition to violations resulting from other illicit connections, a person is considered to be in violation of this article if the person connects a line conveying sewage to a stormwater drainage system, or allows such a connection to continue.
   J.   Stormwater Source Control:
      1.   The businesses or activities Listed in Table 1, when permitted by the City, shall implement stormwater source control Best Management Practices (BMPs) when such business or activities are performed outdoors subject to rainfall and runoff of pollutants.
   Table 1. Businesses or Activities Subject to Stormwater Source Control:
Business or Activity
Standard Industrial Code (SIC) Major Group
SIC Industry Group No.
North American Industry Classification System (NAICS) Major Group
Business or Activity
Standard Industrial Code (SIC) Major Group
SIC Industry Group No.
North American Industry Classification System (NAICS) Major Group
Support Activities for Animal Production
074, 075
1152xx,
Construction of Buildings
15
236
Heavy and Civil Engineering Construction
16
237
Specialty Trade Contractors
17
238
Beverage, Food, and Tobacco Manufacturing
20
311, 312
Wood Product Manufacturing
24
321
Paper Manufacturing
26
3221xx, 3222xx
Printing and Related Support Activities
27
323
Chemical Manufacturing
28
325
Petroleum and Coal Products Manufacturing
29
3241xx
Plastics and Rubber Product Manufacturing
30
326
Leather and Allied Product Manufacturing
31
316
Nonmetallic Mineral Product Manufacturing
32
327
Primary Metal Manufacturing
33
331
Fabricated Metal Product Manufacturing
34
332
Machinery, Computer, and Electronic Product manufacturing
35
333, 334
Electrical Equipment, Appliance, and Component Manufacturing
36
335
Transportation Equipment Manufacturing
37
336
Rail Transportation
40
482
Transit and Ground Passenger Transportation
41
485
Truck Transportation and Warehousing
42
484, 493
Support Activities for Transportation
473, 474, 478
4881xx, 4882xx, 4884xx, 4889xx,
Utilities
49
2211xx
Wholesale Trade - Durable Goods
501, 503, 505,506, 507, 509
423140, 423930, 423110, 4233xx, 4237xx, 4238xx,
Wholesale Trade - Nondurable Goods
514, 515, 516,517, 518, 519
424930, 4244xx, 4246xx, 4247xx, 4248xx,
Building Materials, Hardware, Garden Supplies Dealers
521, 523, 526
444
Food and Beverage Stores
54
445
Automotive Dealers and Gasoline Service Stations
55
441, 447
Food Services and Drinking Places
58
722
Rental and Leasing Services
735
5321xx, 5324xx
Repair and Maintenance
75
811192, 8111xx, 8112xx, 8113xx, 8114xx,
Ambulatory Health Care Services and Hospitals
806, 807
621910,
Educational Services
82
6111xx, 6112xx, 6113xx, 6115xx
Museums, Historical Sites, and Similar Institutions
842
712
 
   Notes:
   Listing is from Washington State Department of Ecology Western Washington Phase II Municipal Stormwater Permit, Appendix 8 - Urban Land Uses and Pollutant Generating Sources, August 2019. Listing is for consistency with NPDES Permit and does not imply the business or activity will be permitted by the City.
   2.   Source control BMPs for new businesses or activities Listed in Table 1 shall be identified in permit application packages. Source control BMPs shall be identified in the Stormwater Site Plan (SSP) for projects triggering a SSP.
   3.   No later than August 1, 2022, existing businesses or activities listed in Table 1 shall begin implementing operational source control BMPs where operational BMPs are not currently provided. The basis of operational source control BMPs shall be provided to the City if the City finds that the selected source control BMPs or their implementation are not effective in preventing or reducing pollutant runoff. Selection and implementation of structural source control BMPs may be required by the City subject to the enforcement provisions of Chapters 9-5B-11 and 9-5B-12 OMC. Source control BMPs for existing businesses or activities listed in Table 1 shall be fully compliant as required by Chapter 9-5B-11 OMC.
   4.   Source control BMPs shall be selected, implemented and maintained in accordance with the adopted stormwater manual identified in Chapter 9-5A-9.A OMC.
   5.   Source control BMPs not identified in the adopted stormwater manual but which may still be appropriate may be submitted for an adjustment or variance in accordance with Chapter 9-5A.16 OMC provided that such source control BMPs provide equivalent protection to the BMPs identified in the adopted stormwater manual. Permit applications shall document proposed source control BMPs, identify why BMPs in the adopted stormwater manual are not applicable or suitable, and state that the proposed BMPs will provide equivalent or better protection.
   6.   Structural source control BMPs, or treatment BMPs/facilities, or both, shall be required for pollutant generating sources if operational source control BMPs do not prevent illicit discharges or violations of surface water, groundwater, or sediment management standards because of inadequate stormwater controls. (Ord. 911, 8-31-2011; amd. Ord. 2017-1014, 10-11-2017; Ord. 2019-1057, 1-8-2020; Ord. 2022-1096, 6-29-2022; Ord. 2022-1098, 7-27-2022)