Chapter 13.16
CONSTRUCTION AND POST-CONSTRUCTION STORMWATER
Sections:
13.16.040 Responsibility for administration.
13.16.050 Ultimate responsibility.
13.16.060 General requirements for all drainage improvements.
13.16.070 Specific requirements.
13.16.080 Review and approval of plans.
13.16.090 Inspection of permanent stormwater facilities.
13.16.100 Inspections – Construction.
13.16.120 Adoption by reference.
13.16.130 Inspection, enforcement and penalties.
13.16.010 Purpose.
The purpose of this chapter is to comply with the Eastern Washington Phase II municipal stormwater permit, protect ground and surface water quality, safeguard persons, protect property and prevent damage to the environment caused by stormwater runoff from new development and redevelopment projects and land-disturbing activities. This chapter seeks to meet that purpose through the following specific objectives:
A. Prevent accelerated soil erosion and control stormwater runoff both during and after construction through the use of best management practices.
B. Eliminate the need for costly maintenance and repairs to roads, embankments, ditches, streams, wetlands, and stormwater control facilities due to inadequate soil erosion and stormwater runoff control.
C. Reduce stormwater runoff rates and volumes, soil erosion and nonpoint source pollution, wherever possible, through stormwater management controls and to ensure that these management controls are properly maintained and pose no threat to public safety. (Ord. 2017-45 § 39, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.020 Definitions.
For the purpose of this chapter, the definitions provided in the glossary of the Stormwater Management Manual for Eastern Washington shall apply. In addition, the following shall mean:
A. “Best management practices” (“BMPs”) has the same meaning as defined in Section 13.15.020.
B. “Clean Water Act” has the same meaning as defined in Section 13.15.020.
C. “Common plan of development or sale” means a site where multiple separate and distinct construction activities may take place at different times on different schedules and/or by different contractors, but still under a single plan. Examples include, but are not limited to:
1. Phased projects and projects with multiple filings or lots, even if the separate phases, or filings/lots, will be constructed under separate contracts or by separate owners (e.g., a development where lots are sold to separate builders);
2. A development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; and
3. Projects in a contiguous area that may be unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility. If the project is part of a common plan of development or sale, the disturbed area of the entire plan shall be used in determining permit requirements.
D. “Hazardous materials” means any material, including any substance, waste, or combination thereof, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may cause, or significantly contribute to, a substantial present or potential hazard to human health, safety, property or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.
E. “Land-disturbing activity” means any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and nonvegetative) and/or the existing soil topography. Land-disturbing activities include, but are not limited to, clearing, grading, filling, and excavating. Compaction associated with stabilization of structures and road construction shall also be considered land-disturbing activity. Vegetation maintenance practices are not considered land-disturbing activity.
F. “Municipal stormwater drainage system” has the same meaning as defined in Section 13.06.010.
G. “New development” means the conversion of previously undeveloped or pervious surfaces to impervious surfaces and managed landscape areas provided the conversion is not specifically exempt in the City of Walla Walla Stormwater Design Standards Handbook.
H. “Nonstormwater discharge” means any discharge to the stormwater drainage system that is not composed entirely of stormwater.
I. “Person” has the same meaning as defined in Section 13.15.020.
J. “Pollutant” has the same meaning as defined in Section 13.15.020.
K. “Pollution-generating land use activities” has the same meaning as defined in Section 13.15.020.
L. “Premises” has the same meaning as defined in Section 13.15.020.
M. “Redevelopment” means the replacement or improvement of impervious surfaces on a developed site not specifically exempt in the City of Walla Walla Stormwater Design Standards Handbook.
N. “Start of construction” shall mean the first land-disturbing activity associated with a development, including land preparation such as clearing, grading, and filling; installation of streets and walkways; excavation for basements, footings, piers, or foundations; erection of temporary forms; and installation of accessory buildings such as garages.
O. “Stormwater drainage system” has the same meaning as defined in Section 13.06.010.
P. “Stormwater facility” has the same meaning as defined in Section 13.06.010.
Q. “Stormwater pollution prevention plan (SWPPP)” means a document which describes the best management practices and activities to be implemented by a person to identify sources of pollution or contamination at a premises and the actions to eliminate or reduce pollutant discharges to stormwater, stormwater drainage systems, and/or receiving waters to the maximum extent practicable. (Ord. 2017-45 § 40, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.030 Applicability.
A. This chapter shall be applicable to all applications for new development and redevelopment projects and land-disturbing activities within the city limits. Projects are classified in one of the following three tiers which have different requirements related to stormwater management outlined in the City of Walla Walla Stormwater Design Standards Handbook:
1. Small. New development and redevelopment projects that add and/or replace less than five thousand square feet of impervious surface and land-disturbing activities of less than five thousand square feet.
2. Medium. New development and redevelopment projects that add and/or replace five thousand square feet or more of impervious surface and disturb less than one acre and land-disturbing activities of five thousand square feet or more, but less than one acre.
3. Large. All projects and activities that disturb one acre or more or are part of a common plan of development or sale that disturbs one acre or more.
B. All new and existing stormwater facilities shall be subject to the maintenance and inspection requirements of this chapter.
C. Alterations including new additions to existing stormwater drainage systems and stormwater facilities must comply with the standards and requirements set forth by this chapter, the City of Walla Walla Stormwater Design Standards Handbook, and the Stormwater Management Manual for Eastern Washington (SWMMEW).
D. Exemptions and partial exemptions to stormwater requirements for new development and redevelopment projects may be granted in accordance with the SWMMEW. In addition to those exemptions, the following activities are also exempt from stormwater requirements of this chapter subject to the approval of the city engineer which may include conditions deemed necessary to mitigate potential adverse impacts:
1. Activities by a public utility or any government agency to alleviate an emergency condition, which presents an imminent threat to life, property, public safety, or the environment.
2. Operation, maintenance, or repair of existing facilities. (Ord. 2017-45 § 41, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.040 Responsibility for administration.
Administration, implementation, interpretation and enforcement of this chapter shall be the responsibility of the city engineer or the city engineer’s designated representative. The city engineer may develop such instructions, policies and forms as are necessary to carry out the provisions of this chapter. Any powers granted or duties imposed upon the city may be delegated by the city engineer to persons or entities acting in the beneficial interest of or in the employ of the city. (Ord. 2010-25 § 2 (part), 2010).
13.16.050 Ultimate responsibility.
A. New Development and Redevelopment Projects. Any person who undertakes or causes to be undertaken any new development or redevelopment project or land-disturbing activities shall ensure that soil erosion, sedimentation and increased pollutant loads and changed water flow characteristics resulting from the activity are controlled so as to minimize pollution and avoid impacts to adjacent properties. The standards set forth herein and promulgated in accordance with this chapter are minimum standards and compliance with the same shall not relieve a person from the duty of enacting all measures necessary to minimize pollution of receiving waters. By approving a plan under this regulation, the city does not accept responsibility for the design, installation, and operation and maintenance of stormwater BMPs and facilities.
B. Long-Term Maintenance of Stormwater Facilities.
1. City-Owned Stormwater Facilities Serving the Public Right-of-Way. The city is responsible for maintenance.
2. Privately Owned Stormwater Facility Serving Private Property. Private property owner is responsible for maintenance.
3. Privately Owned Stormwater Facility Serving the Public Right-of-Way.
a. The city will accept responsibility for maintaining the structural elements (e.g., pipes, catch basins, and other drainage structures) as specified in the operations and maintenance (O&M) plan approved by the city provided a maintenance agreement and maintenance access easement are in place.
b. Private property owner(s) is/are responsible for vegetation management (e.g., pruning, mulching, mowing, weed control, and irrigation) and aesthetics as specified in the operations and maintenance (O&M) plan approved by the city. (Ord. 2017-45 § 42, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.060 General requirements for all drainage improvements.
A. All new development and redevelopment projects and land-disturbing activities, unless otherwise exempted, shall be required to comply with the standards and requirements set forth by this chapter, the City of Walla Walla Stormwater Design Standards Handbook, and the SWMMEW.
B. Stormwater facilities must be designed and constructed in accordance with the design and sizing criteria and operated and maintained in accordance with the maintenance criteria specified in the SWMMEW and the City of Walla Walla Stormwater Design Standards Handbook and operated as designed to protect water quality. An O&M plan, maintenance agreement, and maintenance access easement may also be required for certain stormwater facilities as specified in the City of Walla Walla Stormwater Design Standards Handbook.
C. Construction sites disturbing greater than or equal to one acre, including construction sites of less than one acre that are part of a common plan of development or sale that is greater than or equal to one acre, that have the potential to discharge stormwater to the municipal stormwater drainage system or surface water, shall obtain coverage under the construction stormwater general permit as required by the State of Washington Department of Ecology. Coverage must be obtained prior to any land-disturbing activity.
D. Connections of stormwater drainage systems to the sanitary sewer system are not allowed. (Ord. 2017-45 § 43, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.070 Specific requirements.
Specific requirements for small, medium, and large projects (as defined in Section 13.16.030) are summarized below. Refer to the City of Walla Walla Stormwater Design Standards Handbook for additional detail.
A. Small projects must:
1. Control erosion and avoid adverse impacts to adjacent properties from stormwater runoff.
B. Medium projects that add or replace impervious surfaces must:
1. Prepare and submit a stormwater report;
2. Prepare and submit an erosion and sediment control plan;
3. Control erosion and avoid adverse impacts to adjacent properties from stormwater runoff;
4. Retain the twenty-five-year, twenty-four-hour storm event on site; and
5. Address Core Element No. 3 (Source Control of Pollution), Core Element No. 5 (Runoff Treatment) and Core Element No. 7 (Operation and Maintenance) requirements at high-use sites as defined in the SWMMEW.
C. Medium projects that involve land-disturbing activities, but do not add or replace impervious surfaces, must:
1. Prepare and submit a site plan; and
2. Prepare and submit an erosion and sediment control plan.
D. Large projects that add or replace impervious surfaces must:
1. Prepare and submit a stormwater report;
2. Prepare and submit a construction SWPPP (which includes an erosion and sediment control plan);
3. Control erosion and avoid adverse impacts to adjacent properties from stormwater runoff;
4. Retain the twenty-five-year, twenty-four-hour storm event on site; and
5. Address Core Elements Nos. 1 through 8 as specified in the City of Walla Walla Stormwater Design Handbook and the SWMMEW.
E. Large projects that involve land-disturbing activities, but do not add or replace impervious surfaces, must:
1. Prepare and submit a site plan; and
2. Prepare and submit a construction SWPPP. (Ord. 2017-45 § 44, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.080 Review and approval of plans.
A stormwater report addressing all applicable core elements and all plans and other information required by the City of Walla Walla Stormwater Design Standards Handbook shall be submitted by the applicant to the city engineer for review and approval. All plans and changes in the approved plans must be approved by the city engineer or authorized representative prior to construction. The applicant shall obtain all appropriate permits for construction. (Ord. 2017-45 § 45, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.090 Inspection of permanent stormwater facilities.
Structural stormwater facilities constructed on medium projects at high-use sites and large projects shall be inspected once every five years after final installation, or more frequently if determined by the city engineer to be necessary to prevent adverse water quality impacts, to ensure adequate maintenance is being performed, or to ensure they are functioning as designed.
The city engineer or appointed designee is authorized to enter at all reasonable times in or upon any property, public or private, for the purpose of inspecting and investigating any conditions relating to the provisions of this chapter or any regulation adopted under this chapter; provided, that the city shall first give written notice to the owner or person responsible for such property at least fifteen days in advance. (Ord. 2017-45 § 46, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.100 Inspections – Construction.
Erosion control measures shall be implemented prior to the start of construction in accordance with the approved plans. The city will perform general monitoring of the construction and inspect all structural stormwater facilities on medium projects at high-use sites and large projects during installation. Connections to the existing municipal stormwater drainage system must be inspected and approved by an authorized representative of the city engineering division prior to backfilling. The developer or owner will be responsible for all engineering, testing requirements, construction staking, construction inspection and production of as-built record drawings for the stormwater drainage system. Stormwater facilities and stormwater drainage system components shall be constructed in conformance with city standards and approved plans. The engineer of record shall certify that the stormwater facilities and stormwater drainage system components are constructed in conformance with city standards and the approved plans and that the as-built record drawings for the stormwater drainage system are an accurate representation of the stormwater facilities and stormwater drainage system components along with documentation of any changes made during construction. (Ord. 2017-45 § 47, 2017: Ord. 2010-25 § 2 (part), 2010).
13.16.110 Other regulations.
This chapter is not intended to modify or repeal any other rule, regulation or provision of law. The requirements of this chapter are in addition to the requirements of any other chapter, rule, regulation or other provision of law. Where a conflict arises, whichever provision is more restrictive or imposes greater protection of health, welfare, public safety or the environment shall control. (Ord. 2010-25 § 2 (part), 2010).
13.16.120 Adoption by reference.
The city of Walla Walla adopts by this reference the most recent version of the Stormwater Management Manual for Eastern Washington as a technical guidance document.
Where any conflicts exist, this chapter of the municipal code shall prevail. (Ord. 2010-25 § 2 (part), 2010).
13.16.130 Inspection, enforcement and penalties.
Any development carried out contrary to the provisions of this chapter shall constitute a public nuisance and may be enjoined as provided by the statutes of the state of Washington or by city code, and shall be subject to the inspection, enforcement and penalty provisions set forth in Chapters 8.05 and 8.07. (Ord. 2010-25 § 2 (part), 2010).