The purpose of this chapter is to implement requirements to: (1/23)

A.

Provide for the management and control of stormwater runoff from all new development and redevelopment areas; (1/23)

B.

Minimize erosion and sediment transport; (1/23)

C.

Minimize degradation of water quality due to sediments and pollutants in stormwater runoff; and (1/23)

D.

Reduce downstream flooding. (1/23)

The provisions of this chapter shall apply to all new and redevelopment projects within the incorporated boundary of the City of Keizer, including, but not limited to, all land partitions and subdivisions, planned unit developments, multifamily developments, single-family developments, commercial developments, industrial development, and manufactured home parks. Redevelopment includes reconstruction and/or expansion of structures and/or impervious surfaces. The requirements of this chapter apply regardless of whether a permit is required. (1/23)

Any new development or redevelopment listed in subsection 2.306.02 shall conform to the requirements listed herein, as follows: (1/23)

A.

The requirements will be applied to projects proposed within the city's jurisdiction at land use, design review, and/or the building permit stages of the project. (1/23)

B.

The stormwater management system plan shall be submitted to and approved by the public works director before construction of any new or redevelopment project, regardless of the size of project. (1/23)

C.

A design by an Oregon-registered professional engineer is required for stormwater facilities on any projects that create or replace 5,000 square feet or more of impervious surface. (1/23)

D.

Sites creating or replacing less than 5,000 square feet of impervious surface are generally not required to provide an engineered design unless required by the city due to site-specific conditions. (1/23)

E.

Plans for the construction of stormwater conveyance, flow control, retention, and treatment facilities for the project shall be designed in accordance with city standards and specifications. The plans shall include all information as necessary for the city to review the adequacy of the storm drainage system design. The criteria and all other requirements for the design of both public and private stormwater flow control, retention, treatment, and conveyance facilities are set forth in the city's design standards. (1/23)

F.

Stormwater facilities on private property and owned by a private entity shall be required to complete and submit to the city an executed private stormwater maintenance agreement before the facilities are put into operation and the release of any occupancy permits. (1/23)

G.

In the event any part of a development is traversed by any watercourse, channel, stream or creek, gulch or other natural drainage channel, or public stormwater conveyance system, adequate easements for public stormwater conveyance purposes shall be provided to the city. Acceptance of the easement shall not imply maintenance by the city unless maintenance is expressly accepted by the city in the easement. (1/23)

H.

Channel obstructions are not allowed except as approved for the creation of detention or retention facilities approved under the provisions of the design standards. Fences with swing gates may be utilized as approved by the city. (1/23)

I.

For projects requiring an improvement agreement for issuance of a public works construction permit, the developer shall certify in writing that the site is built according to the submitted site drainage and grading plan prior to release of the improvement agreement. The developer shall provide certified elevations to the city. (1/23)

J.

For partitions and other developments not requiring a public works construction permit, any site grading and drainage requirements shall be completed and approved prior to issuance of any building permits. (1/23)

K.

Prior to acceptance of a public storm drainage system by the city, the system shall be inspected by the city. All costs for city inspection shall be borne by the developer. (1/23)

L.

Prior to the city supporting final plat approval for land divisions or building occupancy for site development, the storm drainage system shall be inspected by the city. All costs for city inspection shall be borne by the developer. (1/23)

A preliminary description of the proposed stormwater management system is required to be submitted with the land use application for all developments listed in section 2.306.02. The preliminary description shall include, at a minimum, the following information: (1/23)

A.

A cover sheet, listing the project name and owner, contact information including phone numbers and email address, and the project site address. For projects requiring an Oregon-registered professional engineer, the name of the engineer of record and the engineer's seal and certification shall also be provided. (1/23)

B.

A site map of the project site and areas directly adjacent to the site, including: (1/23)

1.

Existing topographic contours, at one-foot intervals or smaller; (1/23)

2.

Existing structures and other features on the site, with indications of proposed demolition, removal, or reconfiguration; (1/23)

3.

Description of the existing site conditions, sensitive areas, and waterways affecting or affected by the project; (1/23)

4.

Description and size of the watershed containing the site, including identification of existing stormwater runoff onto and across the property; (1/23)

5.

Existing, pre-developed stormwater flow patterns on the site and crossing the site boundaries; (1/23)

6.

Description of the existing downstream point of disposal for the project, indicating the type and size of the conveyance. (1/23)

C.

An overview of the project and stormwater management system, including: (1/23)

1.

Brief description of the project size, project scope, and proposed improvements; (1/23)

2.

Proposed project configuration, including proposed flow patterns on the site and crossing the site boundaries; (1/23)

3.

Location of proposed stormwater facilities, noting estimated type and size; (1/23)

4.

Proposed point(s) of disposal for stormwater. (1/23)

D.

A conceptual storm design report for the project, including: (1/23)

1.

Preliminary estimate of new and replaced impervious area; (1/23)

2.

Preliminary soil infiltration rate estimates, based on preliminary tests and/or soil data determinations; (1/23)

3.

Preliminary storm runoff calculations, noting the methodology used in calculation; (1/23)

4.

Preliminary evaluation conveyance capacity of the downstream point of disposal. (1/23)

All activities within the city limits that disturb more than 2,000 square feet of area are subject to the requirements of the current city erosion control ordinance. Any such activity that disturbs less than five acres, either singly or cumulatively as part of a common plan of development or sale, shall be required to submit an erosion and sediment control plan (ESCP) and obtain an erosion control permit from the city.

Projects that disturb five acres or more shall be required to obtain both a city erosion control permit and an NPDES 1200-C General Construction permit from the department of environmental quality. (1/23)

The criteria and all other requirements for the ESCP are provided in the city's design standards. (1/23)