D. General Standards
(1) Grading and Slope Protection
In addition to the grading standards in the Engineering Standards Manual, the following general standards shall apply:
a. All buildings, structures, driveways, and roads shall, to the maximum extent practicable, follow the natural contours of the land to minimize disturbed area.
b. Grading and cut-and-fill practices shall be minimized and shall blend scale, form, and visual character into the natural landforms and minimize exposed scars. Level grading of entire lots without respect for existing landforms or neighboring development is prohibited.
c. Sharp angles shall be rounded off, in a natural manner, at the top and ends of cut and fill slopes (within approximately five feet of the sharp angle) unless steep angles are a natural character of the site. Where this would damage tree root systems, the amount of rounding off may be reduced and shrubs used instead to hide the transition.
d. Except for driveways, cut-and-fill slopes shall be entirely contained within a lot and natural grade at the lot lines shall be maintained.
e. Where the existing terrain is generally level, slopes greater than 1:3 are prohibited within five feet of property lines.
f. Finished floor elevations of buildings and parking areas shall transition with the grades of the site.
g. On sloped properties, structures shall be designed to step down with the existing topography. Building placement on slopes shall incorporate stepped vertical massing and plan view offsets to save existing vegetation and landforms.
(2) Storm Drainage Facilities
In addition to the storm water management standards in the Engineering Standards Manual, the following general standards shall apply:
a. Generally
1. All developments shall be designed with considerations for existing, temporary, and post-development drainage impacts and flows. These considerations shall include quantity, quality, and method of delivery of drainage flows.
2. Project designs shall provide drainage or storm water capture/low-impact development measures on the project site so that off-site storm drainage flows do not increase, are not more polluted, or differently delivered than existing flows, unless adequate provisions satisfactory to the City Engineer are made to accommodate the flow off site.
b. Design measures shall be implemented to prevent nonstorm drainage flows from flowing between or off of properties.
c. All development proposals shall, to the maximum extent feasible, preserve existing drainage courses in as natural a manner as possible. Storm water may be directed into natural or landscaped areas where infiltration can occur (bio-retention basins, swales, rain gardens).
d. No obstruction, including walls and fences, shall be placed within a drainage facility, roadside ditch, wash, or drainage easement, unless authorized by the City Engineer.
e. Maintain existing riparian areas in undisturbed form unless authorized by the City Engineer.
(3) Detention Basins
Detention basins can serve multiple purposes, including removing sediment from storm water runoff and reducing runoff. Detention basins shall be designed as natural-looking and usable resources and shall:
a. Be designed in free-form shapes to blend with the natural landscape. They may be integrated into a park or recreation area with controlled access and signage that provides for the safe public use of such areas.
b. Be landscaped to serve as areas of visual interest, and to soften their appearance.
c. Incorporate landscape materials that are consistent with the overall landscape palette of the project and that comply with the standards in Section 5.6, Landscaping, Buffering, and Screening.