Chapter 14.35
– Surface Water Management
Sections:
14.35.200 Stormwater Detention and Treatment
14.35.010 Definitions
For purposes of this chapter, the following words, terms, and phrases shall be defined as follows:
A. City Stormwater System. Those elements of the stormwater system located on city-owned property, city right-of-way, city easements and any stormwater facility the city is contractually or legally obligated to operate and maintain, including but not limited to:
1. An open drainage way, headwater stream, creek, wetland, spring, or pond, including those not maintained by the city which drain onto city-owned property or into city-maintained facilities;
2. A pipe that conveys stormwater and has been designed and constructed expressly for use by the general public and accepted by the city;
3. Streets, curbs and gutters and other surfaces in the public way which are designed to carry stormwater, roadside drainage ditches along unimproved city streets but not access drive culverts; and
4. Flood control and stormwater quality facilities (levees, dikes, overflow channels, conveyance swales, infiltration facilities, stormwater facilities, water quality facilities, detention basins, retention basins, dams, pump stations, groundwater recharge basins, sediment basins, vegetated buffers, wetlands, etc.) that have been designated and constructed expressly for use by the general public and accepted by the city.
B. Construction Activity. An activity used in the process of developing, redeveloping, enhancing, or maintaining land, including, but not limited to: land disturbance, building construction, paving and surfacing, storage and disposal of construction-related materials.
C. Construction-Related Materials. Potential water quality pollutants that are used or created during construction activities including, but not limited to, off-site deposits of sediments by vehicles (e.g., tracking, spilling); building material wastes (e.g., scrap metals, rubber, plastic, glass, masonry, wood; paints and thinners; packaging materials; insulation, plaster grout); hazardous substances (e.g., petroleum products, cleaning solvents, chemical additives, concrete curing compounds, acids for cleaning masonry surfaces, paints, thinners); and concrete washout.
D. Construction Site Management Plan (CSMP). A set of maps, data, drawings, specifications and narrative that describes expected runoff from new construction sites, and establishes best management practices or equivalent measures to be taken for preventing erosion and controlling sediments, surface runoff and other pollutants from construction activities. The CSMP serves as the city of Cottage Grove’s equivalent requirement to the erosion sediment control plan (ESCP) required by the Oregon Department of Environmental Quality and the stormwater pollution prevention plan (SWPPP) required by the United States Environmental Protection Agency.
E. Dewatering. The removal and disposal of surface water or groundwater during construction or for the purpose of facilitating construction.
F. Emergency Condition. An immediate danger to life, property, or the environment due to circumstances beyond the control of the property owner including, but not limited to, natural and human-caused disasters such as fires, floods, slides, earthquakes, sinkholes and tree blow-down.
G. Minor Recurring Activities. Repetitive minor construction, maintenance and operational activities on existing infrastructure that are performed as part of an overall work plan or program when no individual disturbance exceeds more than 500 square feet of land area and/or 20 cubic yards of fill or excavated material. Examples include, but are not limited to, connections and extensions of utility service, repair of utility and infrastructure facilities, and maintenance of stormwater facilities’ drainage capacity.
H. Open Drainage Way. A natural or manmade course, ditch or channel which has the specific function of transmitting stormwater from a point of higher elevation to a point of lower elevation.
I. Person Responsible. The owner, agent, occupant, lessee, tenant, contract purchaser or other person having possession or control of property or the supervision of a construction project on the property.
J. Related Natural Resource Area. Streams, ditches, channels, ponds, wetlands, riparian areas, or other related waterways that act as part of a natural drainage system.
K. Retention System. A stormwater facility which the city engineer has determined does not discharge or substantially reduces the discharge of stormwater into the city stormwater system. Examples include retention ponds, rain barrels, etc.
L. Runoff Control. Any measure or facility approved by the city engineer by which stormwater runoff from land surfaces on which development exists is reduced.
M. Sensitive Lands. Wetlands, significant trees, steep slopes, flood plains, Willamette River Greenway and other natural resource areas designated for protection or conservation by the Comprehensive Plan.
N. Sewer. A pipe or a conduit for carrying wastewater.
O. Sewer Service. Includes wastewater service and regional wastewater treatment service.
P. Sewerage System. The equipment, pipeline network and facilities as are needed for and are pertinent to the collection, transmission, treatment retention and disposal of wastewater.
Q. Stormwater. Water derived from a storm and conveyed as runoff, snow melt runoff, and surface runoff and drainage.
R. Stormwater Facility. A facility designed to improve the quality and manage the quantity of stormwater runoff. Stormwater facilities include vegetated swales and sand filters, wet or dry ponds, marshes, infiltration facilities, and structural storm sewer devices. Stormwater facilities do not include conveyance systems that are meant only for conveying the stormwater from one place to another and do not affect the quality or quantity of the stormwater.
S. Stormwater Service. The use of the city’s stormwater system including, but not limited to, collection of stormwater discharged from property on which development exists and its deposit directly or indirectly into the city stormwater system.
T. Suspended Solids or SS. Solids that either float on the surface or are suspended in water, wastewater or other liquids and which are removable by a laboratory filtration device.
U. Wastewater. Liquid and sewage from residential dwellings, commercial buildings, industrial and manufacturing facilities, and institutions, whether treated or untreated, which are contributed to the publicly owned sewer or sanitary sewer system.
V. Wastewater Service. The use of the city wastewater system including, but not limited to, collecting of wastewater discharged from property and its deposit directly or indirectly into the city wastewater system, and failing to connect thereto within the time prescribed. (Ord. 3138 §5, 2021)
14.35.100 Erosion Prevention
A. Purpose. The purpose of this chapter is to restrict the discharge of sediments or other construction-related materials, including hazardous substances as identified in Section 13.08.150, into the city stormwater system to:
1. Prevent or minimize, to the maximum extent practicable, negative impacts to adjacent properties, water quality, and stormwater-related natural resource areas resulting from construction activities; and
2. Maintain the capacity of the city stormwater system by minimizing sedimentation.
B. When Standards Apply.
1. When Standards Apply. Unless otherwise provided, the standards in this chapter apply to all construction activities that result in any one or all of the following:
a. Land disturbance, including, but not limited to, clearing, grading, grubbing, logging, excavating, filling, and storing of materials;
b. Structural development or demolition, including, but not limited to, buildings, bridges, roads, and other infrastructure;
c. Impervious surfaces, including, but not limited to, parking lots, driveways, walkways, and patios; or
d. Dewatering.
2. Exempt Activities. Notwithstanding the foregoing, the following activities shall be exempt from the provisions of this section:
a. Actions by a public utility, the city, or any other governmental agency to remove or alleviate an emergency condition, restore utility service, or reopen a public thoroughfare to traffic; or
b. Actions by any other person when the city determines, and documents in writing, that the actions are necessary to remove or alleviate an emergency condition, restore utility service, or reopen a public thoroughfare to traffic.
C. Compliance. Regardless of whether a permit is required under subsection E of this section, no person shall engage in any construction activity covered by subsection (B)(1) of this section in a manner that can potentially impact water quality, adjacent properties or stormwater-related natural resource areas except as allowed by this code. All persons shall implement erosion prevention and sediment control measures designed to meet the outcomes below. Failure to meet those outcomes shall subject the person to the same enforcement provisions as those applicable to a permit holder under subsection F of this section.
D. Expected Outcomes. All persons conducting construction activities covered in subsection B of this section shall employ, to the maximum extent practicable, erosion prevention and construction site management practices that will achieve during both the construction period and wet weather season the following outcomes:
1. Adjacent properties, water features, and related natural resource areas are kept free of deposits or discharges of soil, sediment or construction-related material from the site except those that would occur through natural processes from an undisturbed site;
2. Vegetation in water features, related natural resource areas, and associated bank and/or riparian areas adjacent to construction sites are preserved or protected from impacts that exceed those that occur through natural processes on an undisturbed site;
3. Public rights-of-way, the city stormwater system and related natural resource areas, private streets and private stormwater drainage systems that discharge to the city stormwater system are kept free of mud, soil, sediment, concrete washout, trash, or other similar construction-related material. Direct deposit, dropping, dumping, erosion, tracking, or other discharge by construction vehicles of materials shall not occur in excess of those that occur through natural processes from an undisturbed site. Any such discharges that occur shall be prevented from entering water features or the city stormwater system and removed not later than the end of the day in which the discharge occurred, or as directed by the city. During the wet weather season corrective action shall be taken immediately for such discharges;
4. Soils and stockpile areas shall not be exposed to precipitation or stormwater runoff without the provision of secondary containment, perimeter controls, and other approved BMPs;
5. Earth slides, mudflows, earth sloughing, or other earth movement which may leave the property shall not occur in excess of those that occur through natural processes on an undisturbed site;
6. No discharge into the city stormwater system or related natural resource areas of construction-related contaminants resulting from activities such as, but not limited to, cleaning or washing of equipment, tools, or vehicles shall occur; and
7. No hazardous substances, such as paints, thinners, fuels, and other chemicals shall be released onto the site, onto adjacent properties, or water features, the city stormwater system, or related natural resource areas.
E. Erosion Prevention Permit.
1. Permit Required. Except as otherwise provided in subsection (E)(6) of this section, no person shall commence any construction activity without first obtaining from the city one of the erosion prevention permits listed below if the construction activity:
a. Is located in a designated sensitive land area; and/or
b. Is located within the public right-of-way and requires permits from the Cottage Grove engineering department; and/or
c. Requires a building permit or sewer/water line permit from the Cottage Grove public works and development department.
Construction activity that disturbs more than one acre of land must obtain a 1200C permit from the Department of Environmental Quality (DEQ).
2. Permit Classifications. The public works and development director or his designee may issue the following types of permits, either of which will meet the requirements of subsection (E)(1) of this section:
a. Individual Permit. A person, property owner, or easement holder of record may obtain an individual permit for each construction activity on the same development site, or for multiple construction activities proposed in connection with a development project on the same development site, including utility work, public improvements, private infrastructure, structures, and other site improvements.
b. Annual Permit. A person, property owner, or easement holder of record may obtain an annual permit for minor recurring activities occurring on one or more development sites.
3. Application. The application for an erosion prevention permit shall be accompanied by:
a. Fee. A fee established by the city council in an amount sufficient to recover the city’s administrative costs.
b. Erosion Prevention Permit Application. An application form established by the public works and development department, signed by the property owner and applicant.
c. Construction site management plan, for individual permits impacting over 4,500 square feet (or 180 cubic feet).
1. The construction site management plan shall identify: potential water quality impacts associated with the proposed construction activities; techniques and methods to be used to prevent and control erosion, sedimentation, and other pollutants associated with construction activity; and the location, design, and construction schedule for all erosion, sedimentation, and other construction site management control measures to be implemented and maintained.
2. If the development site has or will have 60 percent or more impervious lot coverage, the construction site management plan must be prepared by a certified professional(s). The construction site management plan need not be prepared by a certified professional if the development is one single-family dwelling or accessory structure, or one duplex dwelling.
3. The approved construction site management plan shall be kept at the construction site and available for on-site inspection purposes.
d. Work, scope and practices for annual permit. No construction site management plan shall be required for an annual permit. Instead, the applicant shall provide a narrative description of the scope of work to be performed and the practices employed for meeting the requirements of this chapter. A copy of the annual permit and narrative shall be kept at the site and available for on-site inspection purposes.
4. Review and Issuance.
a. The application for the erosion prevention permit shall be reviewed by the city as a Type I permit per Section 14.41.200 and approved or denied, based on compliance with the outcomes identified in this chapter, including specific erosion and sedimentation prevention measures and schedules.
b. The erosion and sediment control measures required shall be the minimum required measures needed to meet anticipated construction, site conditions, and weather during construction. During the construction period, erosion and sediment control measures may be required to be upgraded as needed based on the activity and for unexpected storm events and to ensure that sediment and sediment-laden runoff do not leave the site.
5. Permit Duration.
a. An individual erosion prevention permit shall remain in effect for the full period of the construction activity. The public works and development director may extend the duration of the permit for a period of up to, but not to exceed, two years after completion of the construction activity if the manager determines the extension is necessary to ensure that the construction activity has stabilized in accordance with the outcomes identified in the administrative rules.
b. Annual permits may be issued for a full calendar year, and shall expire on or before December 31st of the year issued. Annual permits may not be extended.
6. Waiver of Erosion Prevention Permit. Notwithstanding any other provisions of this section, the following activities shall not require an erosion prevention permit:
a. Issuance of permits and/or approvals for land divisions, interior improvements to an existing structure, or other approvals for which there is no physical disturbance to the surface of the land; and
b. Annual landscape maintenance activities on developed properties, necessary to maintain the existing developed landscape.
This waiver applies only to the requirement to obtain an erosion prevention permit and shall not be construed as an exemption from any of the erosion prevention requirements, including but not limited to erosion prevention and sediment control measures designed to meet the outcomes established in this chapter.
F. Erosion Prevention – Enforcement.
1. Enforcement Policy. The primary focus of this section is to implement measures for preventing erosion and minimizing stormwater impact that will meet the outcomes established in this chapter, and the city will use the amount of enforcement necessary to achieve compliance. Where possible the city will rely on education rather than enforcement. The public works and development director or designee may provide educational programs or other informational materials that will assist permittees in meeting the desired erosion and sedimentation controls, and other construction site management practices outcomes.
2. Inspections. The city may make periodic inspections to ensure compliance with this code, rules issued hereunder, or conditions imposed on an erosion prevention or other permit.
3. Violations. Failure to comply with the provisions of this code, rules issued hereunder, the erosion prevention permits, or conditions imposed thereon, during the period that the permit(s) remains in effect may result in:
a. The issuance of a corrective memorandum and/or an administrative compliance order by the city;
b. The issuance of a stop work order by the city;
c. The imposition of an administrative civil penalty pursuant to the provisions of Chapter 14.15; and/or
d. The issuance of a citation into municipal court for violation of this code.
Failure to comply with any stop work or compliance order issued by the city shall constitute a separate violation. Each day a violation continues also shall constitute a separate violation. (Ord. 3138 §5, 2021)
14.35.200 Stormwater Detention and Treatment
A. Purpose. As the city of Cottage Grove develops, impervious surfaces create increased amounts of stormwater runoff, disrupting the natural hydrologic cycle. Without stormwater management, these conditions decrease groundwater recharge while increasing channel erosion and the potential for localized flooding. The city continues to use swales and other more natural methods to control and convey stormwater runoff, incorporating wetlands and other natural systems into stormwater drainage plans to the greatest extent possible rather than relying exclusively on pipes. Runoff from urban areas is a major source of pollution and watershed degradation. The city is currently a designated management agency (DMA) under the Willamette Basin TMDL and as such, is responsible for reducing pollutant loads transported to surface waters from runoff. In order to protect and enhance watershed health and long-term livability, the city requires that development comply with the following stormwater management criteria.
B. When Standards Apply. For all projects that create greater than or equal to 1,000 square feet of new impervious surface, when the development site is greater than or equal to one-half acre, stormwater detention and treatment facilities shall be provided. Detention and treatment facilities shall be designed and sized according to the City of Eugene Stormwater Management Manual (2014), which is adopted as the city’s stormwater management manual. Where the manual and this section conflict, this section shall prevail.
C. Expected Outcomes. The intent of these requirements is as follows:
1. To maintain runoff peak flows at predevelopment levels.
2. To provide treatment of runoff to limit the transport of pollutants to area waterways.
3. To limit accumulation of ponded water by discouraging the use of detention ponds and other centralized stormwater facilities through the dispersal of small detention and treatment facilities throughout a development. Preference shall be given to detention and treatment systems designed to drain completely within 24 hours to limit standing water.
4. To encourage the use of vegetated treatment systems over structural pollution control devices.
5. Exceptions or alternatives to the requirements and standards of the stormwater management manual may be allowed by the city engineer based on specific site conditions; provided, that detention and treatment requirements are met in conformance with the intent as stated above. Applicants are encouraged to use either the simplified approach or presumptive approach to size facilities.
6. The following storm data shall be used in sizing facilities:
|
Recurrence Interval, Years |
2 |
5 |
10 |
25 |
100 |
|---|---|---|---|---|---|
|
Flood Control, Destination: 24-Hour Depths, Inches |
3.12 |
3.6 |
4.46 |
5.18 |
6.48 |
|
Pollution Reduction: 24-Hour Depths, 1.4 Inches |
|
|
|
|
|
(Ord. 3166 §2, 2022)