Portland City Code ch. 14 (Land Use Code)

Citation: Portland City Code ch. 14 (Land Use Code)
Jurisdiction: Portland (municipal)
Source: Official source
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TABLE 11-B: DRAINAGE SPACING edge of a wetland. Surface drainage which is
Grade (%) Spacing directed to an unscarified buffer strip shall be
0-2 250 ft. diffused or spread out to promote infiltration
3-5 200-135 ft. of the runoff and to minimize channelized flow
6-10 100-80 ft. of the drainage through the buffer strip.
11-15 80-60 ft. G. Ditch relief (cross drainage) culverts, drainage
16-20 60-45 ft. dips, and water turnout shall be installed in a
21+ 40 ft. manner effective in directing drainage onto
unscarified buffer strips before the flow gains
to permitted uses within the district. A road or sufficient volume or head to erode the road,
driveway may also be approved by the review driveway, or ditch. To accomplish this, the
authority in a Resource Protection subdistrict, following shall apply:
upon a finding that no reasonable alternative 1. Ditch relief culverts, drainage dips, and
route or location is available outside the associated water turnouts shall be spaced
district. When a roadway or driveway is along the road or driveway at intervals no
permitted in a Resource Protection subdistrict, greater than indicated in Table 11-B.
the road and/or driveway shall be setback as far 2. Drainage dips may be used in place of ditch
as practicable from the normal high-water line relief culverts only where the grade is 10%
of a water body, tributary stream, or upland or less.
edge of wetland. 3. On sections having slopes greater than ten
D. Road and driveways banks shall be no steeper 10%, ditch relief culverts shall be placed at
than slope of two horizontal to one vertical and approximately a 30 degree angle
shall be graded and stabilized in accordance downslope from a line perpendicular to
with the provisions for erosion and the centerline of the road or driveway.