A. 
To the extent practicable, all development must conform to the natural contours of the land and natural and pre-existing man-made drainage ways must remain undisturbed.
B. 
To the extent practicable, lot boundaries created by partition or subdivision must coincide with natural and pre-existing man-made drainage ways to avoid the creation of lots that can be built upon only by altering such drainage ways.
A. 
All developments must provide an adequate drainage system to prevent the undue detention or retention of stormwater or surface water on the development site. Stormwater or surface water will not be regarded as unduly detained or retained if:
1. 
The detention or retention results from a technique, practice or device deliberately installed as part of an approved sedimentation or stormwater runoff control plan prepared by an engineer; or
2. 
The detention or retention is not substantially different in location or degree than that experienced by the development site in its predevelopment state, unless such detention or retention presents a danger to health or safety.
B. 
No stormwater may be channeled and directed into a sewer line.
C. 
Whenever practicable, the drainage system of a development must coordinate with and connect to the drainage systems or drainage ways on surrounding properties or streets.
D. 
All developments must be constructed and maintained so that adjacent properties are not unreasonably burdened with stormwater runoff as a result of the developments.
All developments must be constructed and maintained so that impacts to natural and man-made drainage ways do not unreasonably burdened upstream or downstream properties with surface water flooding as a result of the developments. More specifically:
A. 
No development may be constructed or maintained so that the development unreasonably impedes the natural flow of water from higher adjacent properties across the development, resulting in substantial damage to the higher adjacent properties; and
B. 
No development may be constructed or maintained so that stormwater from the development is collected and channeled into natural or man-made drainage ways, such that the volume and/or rate of flow is substantially greater than the pre-development volume and/or rate.
C. 
No development may be constructed such that the flow of water through natural or existing man-made drainage ways is obstructed. Bridges and culverts constructed to allow the flow of water through a development must be designed to pass flow during a 100-year storm event.
A. 
For projects that disturb over one acre, applicants must apply to Oregon Department of Environmental Quality (DEQ) for a National Pollutant Discharge Elimination Control System (NPDES) 1200(C) permit.
B. 
Erosion and sediment control plans are required by the City as a component of the site plan for all plats and all projects which require site plan review. Erosion control plans must be designed to the specifications as outlined in this chapter.
C. 
Development of the land may not begin (and no building permits may be issued) until the City-appointed engineer approves the erosion control plan.
D. 
For purposes of this section, "disturb" means any use of the land by any person in any development, and/or road construction and maintenance that results in a change in the natural cover or topography that may cause or contribute to sedimentation. Sedimentation occurs whenever solid particulate matter, mineral or organic, is transported by water, air, gravity or ice from the site of its origin.
A. 
Storm sewers constructed within the street will be sized by the developer's engineer and will consider all potential runoff requirements within the site and upstream of the site.
1. 
The storm sewer will be sized for a 100-year design recurrence criteria for storm drainage facilities.
2. 
The minimum size of storm sewers is eight inches in diameter.
3. 
Spacing of catch basins along the street must conform to published engineering recommendations, which consider profile of the street and street width.
B. 
On-site detention shall be required for new development where downstream deficiencies exist or are anticipated to exist. The square footage considers the total development of the property including the future potential impervious surface. Required design recurrence criteria for a commercial or residential storm drainage detention facility is a 10-year interval. Development that has less than 5,000 square feet of impervious surface is exempt from detention requirements.
C. 
Pervious pavement, and pavement and roofs that drain to an infiltration facility will not be counted when sizing a detention facility to handle the stormwater design.
The discharge of any material other than stormwater into the stormwater system is prohibited. The placement of materials in a location where they are likely to be carried into the stormwater system by any means is also prohibited.