(a) A 50-foot right-of-way is required on a normal roadway; 50-foot right-of-way radius for cul-de-sacs. Cul-de-sacs are required on all dead-end roads. Twenty-five-foot sight triangles are required at all intersections.
(b) Stream buffers:
(1) A 15-foot drainage easement is required on normally dry waterways. A 15-foot drainage easement is required from the top of the stream bank on each side of live streams draining less than 50 acres.
(2) A 35-foot wide stream buffer is required on each side of all stream banks for live streams draining 50 acres or more.
a. Stream buffers are defined as strips of land located on each side of perennial and ephemeral streams which are intended to allow floodplains and stream side riparian zones to function naturally to buffer flooding, reduce sedimentation, filter non-point source pollution, and to provide protection from flood and drainage hazards.
b. The purpose of stream buffers is to protect these floodplain lands from development and land disturbing activities. No removal of trees and natural vegetation will be allowed within these streamside zones except the following:
(i) Lots created prior to the adoption of this article, except for lots subsequently subdivided in which case the entirety of the subdivision shall comply.
(ii) The creation of recreational facilities.
(iii) Roads and utilities.
(iv) Engineer/architectural designed structures where it can be demonstrated that the facility will not impair stream function, cause flooding hazards and that are compatible with the spirit of the buffers program where these exceptions are necessary, these facilities should be sited and constructed so as to minimize encroachment into the streamside zone, and landscaped so as to minimize fragmentation of the buffer system through replanting of native riparian species.
(v) In subdivisions where existing vegetation in these zones are not suitable to perform the functions of a stream buffer, a buffer must be created. A landscape plan using native riparian vegetation designed by an engineer or landscape architect must be submitted to and approved by the Greenville County Soil and Water Conservation District office.
c. The location and width of all stream buffers shall be shown on the final plat along with a statement saying “No disturbance of vegetation allowed within stream buffer area.”
(c) Drainage design storms: Proposed drainage improvements shall be designed to convey maximum flows without roadway overtopping according to the following criteria:
(1) Interior roadway pipe systems and crosslines: Ten-year design storm.
(2) Culverts on live streams and all structures which convey offsite flows in excess of 15 CCFS (25-year storm,) through the site: Twenty-five-year design storm.
(3) Small bridges: Fifty-year design storm.
(4) River crossings: One hundred-year design storm.
(d) Drainage design methods must conform to current engineering standards.
(e) All concrete pipe must be Class III or better and meet the requirements of SCDOT’s latest edition of the manual entitled “Standard Specifications for Highway Construction.” Aluminum or aluminized steel corrugated metal pipe may be used upon approval of the county engineer. Minimal pipe size is 15 inches in diameter.
(f) Roads must be centered within the 50-foot right-of-way.
(g) Side slopes must be no greater than 2 to 1; except that where cut slopes would extend more than 100 feet beyond the center line, a 1-to-1 slope may be used with proper stabilization.
(h) Standard cross-section:
(1) Thirty-six feet from center of ditch to center of ditch or top of fill to top of fill.
(2) A paved roadway width of 20 feet shall be provided. The pavement section shall consist of 4 inches of stone and 1-1/2 inches of asphalt surface or a 2-inch asphalt base course and 1-1/2 inches of asphaltic surface. All thicknesses refer to the full in-place compacted thickness. All materials and methods of construction shall meet the requirement of SCDOT’s latest edition of the manual entitled “Standard Specifications for Highway Construction.”
(3) Five-foot minimum shoulders with no less than 2% and no greater than 5% grade sloping away from the roadway.
(4) Roadway crown 1/4 inch to 1/2 inch per foot from the center of the road to the edge of pavement.
(i) Minimum horizontal curve radius is 165 feet without superelevation. Horizontal curves with lesser radii are allowed with superelevation as follows:
Superelevation | Min. Radius
|
0.04 ft/ft | 145 ft |
0.06 ft/ft | 135 ft |
(j) Reverse curves must be separated by a minimum tangent of 100 feet.
(k) Intersection approaches must be no greater than 5% grade within feet of the edge of the intersecting road’s traveled way.
(l) Intersections must be as close as possible to 90 degrees but in no case less than 60 degrees.
(m) If intersecting streets are offset, the minimum center line offset must be 125 feet.
(n) Maximum grade is 10% unless immediate surrounding terrain averages 20% or more, in which case a 15% maximum grade may be used for limited distances. Minimal grade is 1%.
(o) Minimal lengths of vertical curves shall be based on the AASHTO formula, K=L/a, where “L” equals the minimum length of the vertical curve in feet and “a” equals the algebraic difference between the incoming and outgoing tangent grades in percent, accordingly:
(1) Use K>9 (crest) and K>15 (sag) for the following:
*Residential access streets
All Streets, *mountainous classification
All Streets where “a”>15
(2) Use K>17 (crest) and K>24 (sag) for the following:
*Residential collector and *subcollector streets where “a”<10
*Residential collector and *subcollector streets, **non-mountainous
Definitions for roadway classifications:
(*Residential collector provides access to 50 or more lots)
(*Residential subcollector provides access to between 50 and 15 lots)
(*Residential access street provides access to less than 15 lots)
(**Mountainous classification denotes that immediate surrounding terrain has an average slope of 20% or greater)
(3) For criteria not covered in (1) or (2) above, minimum K factors ranging between 9 to 17 (crest) and 15 to 24 (sag) shall be determined by the county engineer on a case by case basis.
(p) Design for roadway ditches shall comply with standard engineering design methods as detailed in the latest edition of the Greenville County Stormwater Management Design Manual.
(q) All items shown as design standards must be shown on the plans in sufficient detail to assure compliance.
(r) A variance to any requirement may be granted upon approval by the Greenville County planning commission. A developer requesting a variance is to submit a plan showing all details of the request to the planning commission. Upon completion of the county planning commission staff’s review, the request will be submitted to the Greenville County planning commission for consideration. The requestor will be notified of the time and location of the planning commission meeting.
(1976 Code, § 18-24) (Ord. 3342, § 1, passed 3-7-2000)