(A) General design requirements.
(1) Required right-of-way: The minimum right-of-way width is 50'.
(2) Required minimum street section: Streets shall have a minimum travel way width of 20'. The travel surface shall be at least equal to the type of surface with which it is being connected (pavement, rock, or earth). If development characteristics warrant, the Public Works Director can approve a reduction in the surface type. Written requests for a reduction in surface type shall be directed to the Public Works Director with an accompanying justification statement.
(3) Required minimum street elevations: The minimum street centerline elevation at finish grade shall be 6.5' above mean sea level.
(4) Required minimum profile gradient: The minimum street profile centerline gradient shall be 0.4% except for causeways where land areas adjacent to the road embankment are jurisdictional wetlands or critical areas.
(5) Street centerline minimum curve radius criteria: Street centerline curve radii shall meet AASHTO guidelines for the design speed limit.
(6) Where streets are designed for less than a 30 mph speed limit, the design professional shall provide supporting design data, including traffic control signage.
(7) All roads shall be designed with a minimum road centerline radius of 125'.
(8) Horizontal sight distances shall be considered in the design process. Vertical curves shall have a minimum length of 100'.
(B) Roadway drainage design. For roadways with open roadside swale ditches, the swale ditches shall be graded as shown on details in Article A.6. The drainage plan shall show how the roadway drainage will be conveyed to an outfall or wetland. Roadside swale drainage ditches and driveway pipes shall be designed for a five (5) year average return frequency storm (minimum driveway pipe size shall be 15" in diameter). Cross drains, outfall ditches and piped systems shall be designed for a 10 year average return frequency storm. Average return frequencies are defined in § A.4.2(D). Roadside ditch inverts shall parallel the finished road longitudinal gradient except as otherwise approved by the Public Works Director. Drainage shall not be carried in roadside ditches for a distance exceeding 700' (accumulated distance) except as otherwise approved by the Public Works Director.
(C) Construction plans and specifications.
(1) The construction plans shall clearly show all work to be performed in plan view, profile, cross section, details, and specifications. Specifications providing written descriptions of the work, workmanship, appearance, materials, etc., and/or special provisions may either be shown on the drawings or presented in booklet form separate from the drawings. Specifications shall comply with the CTC (SS) or SCDOT (SS), unless otherwise directed by the Public Works Director.
(2) The following standards shall be observed and the information listed below shall be provided in the design and preparation of plans, profiles, details, drainage plans, and written specifications for construction:
(a) Include a copy of the approved preliminary plat.
(b) Plans and profiles shall be prepared on 24" x 36" or 22" x 34" sheets, having a profile at the bottom and a plan view at the top, with both the plan and profile stationing oriented in the same direction.
(c) All elevations shall be referenced to the mean sea level datum for NGVD 29.
(d) Scales shall be: vertical 1" = 2' and horizontal 1" = 50' or larger.
(3) The following shall be shown in the plan view:
(a) Stations along the centerline of the proposed road with appropriate ties at intersecting streets.
(b) The width of the right-of-way and names of proposed roads and existing roads.
(c) Alignment information, curve data with P.C., P.T., and P.I. angle points, as well as angles at intersections.
(d) Arrows indicating the direction of drainage flow within the right-of-way.
(e) Size, type, and location of trees proposed to remain within a road right-of-way or drainage easement.
(f) Existing and proposed drainage structures and drainage easements along with rights-of-way and drainage way cross sections.
(g) DHEC/OCRM Critical Line and USACOE jurisdictional wetland delineations which relate to the right-of-way or easements.
(h) Benchmarks with locations, descriptions, coordinates, datum, etc.
(i) Details shall show pond outfall structures, sight distances, traffic control devices, design speeds for roads, and other related information.
(j) Other general construction details required to define the scope of work.
(4) Profiles shall show:
(a) Existing street centerline elevations showing all breaks in grade, but in no case more than 100' apart. Profiles shall include existing streets to which ties are being made with elevations extending approximately 200' from intersections.
(b) Proposed street centerline profile with centerline elevations every 50' on vertical curves and at every 100' along tangents and at intersections.
(c) Vertical curve data.
(d) Proposed and existing storm drains, sanitary sewers, water mains, pipe under drains, and cross line pipes.
(e) Statement to be placed by design professionals on road and drainage plans: "ALL MATERIALS AND WORKMANSHIP SHALL BE IN ACCORDANCE WITH REQUIREMENTS OF THE TOWN OF JAMES ISLAND ZONING AND LAND DEVELOPMENT REGULATIONS."
(f) Statement to be signed by the owner or the authorized agent of the owner: "I certify as an agent for or as a record owner, lessee, or record easement holder, I have, or will have prior to undertaking the work the necessary approval or permission from all other persons with a legal interest in said property to conduct the work proposed in the approved subdivision construction plans."
(D) Clearing and grubbing. Except as otherwise stated herein, all primary rural road rights-of-way shall be cleared and grubbed for a minimum width of 50'. Any/all tree canopies shall be pruned to a minimum height of 15'. This work shall include the removal and disposal of trees, stumps, brush, rubbish, roots, and other objectionable materials.
(E) Clearing of drainage easements. The full width of all drainage easements shall be cleared of trees, buildings, fences, stumps, brush, logs, rubbish, roots, overhanging tree limbs, overhanging utility wires or cables, or any other item that may, in the judgment of the Public Works Director, interfere with the drainage facility or the maintenance of the facility. Existing obstacles may be left in place upon approval of the Public Works Director provided that all of the following criteria are met: a) the drainage system or the obstacle cannot be easily relocated; b) adequate and safe operational easement space for maintenance by mechanized equipment is provided; c) the drainage way is not obstructed; and d) the drainage easement width is increased to accommodate the obstructions.