§ 5.2. Street construction standards.

All proposed street and roadways shall be designed, constructed and surfaced in accordance with the following requirements; provided, however, no street or roadway shall have a right-of-way width of less than 66 feet, unless the street or roadway is designed with paved valley gutters, as shown in Appendix D.

If subsequent phases of a previously approved subdivision are within 1,000 feet of a paved road, the developer shall be required to pave the entrances from the paved road to the proposed phase. To be eligible to construct additional dirt roads in a subsequent phase of a dirt road subdivision, that phase must have been presented and approved as part of the original subdivision application as reflected in the official files and meeting records of the planning commission and must be located more than 1,000 feet from a paved road and must be built to roadway standards in effect in March 1996. To be eligible to construct a dirt road on a right-of-way recorded in the office of the clerk of court prior to April 15, 1985, that right-of-way must be located more than 1,000 feet from a paved road and must be built to roadway standards in effect in March 1996, except for the requirement of a minimum right-of-way exceeding 40 feet.

In the event abnormal conditions occur to which such standards and specifications do not apply, the affected property owner(s) may petition for a waiver of such standards and specifications. The absolute minimum standards and conditions for such a waiver is provided in Appendix F "Orphan Roads Program."

(A)

Construction materials. For a standard paved road:

(1)

Typical cross section. The roadbed shall be 22 feet wide, crowned at the centerline with slope of 48:1 for 11 feet from the centerline to the shoulder. The shoulder shall be six feet with a slope no greater than 12:1 to the ditchbank or setback. The ditch centerline or setback line shall not be less than 44 feet from the centerline of the opposite ditch. See typical road cross section, Appendix D.

(2)

Subgrade and base course preparation. All materials used in the base and surface courses must meet all SCDOT Standard Specifications as amended, for quality and gradation. Traffic surface is to be prepared by stripping off top soil, compacting subgrade on site to a depth of six inches (minimum), providing an eight-inch depth (minimum) of macadam base course, or SCDOT acceptable crushed rock substitute, rolled to a compaction of 97 percent Standard Proctor at optimum moisture. Unsuitable or boggy conditions will require additional removal of unacceptable material, backfilling, and placing a compacted, acceptable base on the road in accordance with SCDOT Standard Specifications, as amended. All new material shall be placed in eight-inch layers.

(3)

Surfacing. One and one-half inches (minimum) paved surface shall be constructed upon a primed base course of macadam, crushed rock, sand clay or SCDOT acceptable base course and shall be a minimum of 150 lbs. of asphalt per square yard of base course surface in accordance with SCDOT Standard Specifications, as amended. If there is any question about the actual thickness of the pavement placed, the contractor shall provide up to three corings per development and/or one per 500 feet of road, whichever is greater. If the thickness is less than required, the contractor shall overlay the substandard area(s) with the greater of either one inch thickness of plant mix or the thickness shortfall plus one-half inches.

(4)

Ground water. The ground water table must be at least 36 inches below the base course. Subsurface drainage is to be provided in areas having a high water table (particularly in cut areas) to intercept seepage that could affect slope stability, bearing strength or create undesirable wetness.

(5)

Driveways. In a new subdivision with paved roads under county maintenance, a property owner will be responsible for a paved driveway apron which meets SCDOT specifications as amended.

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(B)

Street design standards. Design standards shall meet the requirements as outlined in Table 1:

TABLE 1.
DESIGN STANDARDS FOR ROADS

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	Development Density
	Residential		Nonresidential
Improvement	Low	Medium	High	Business—Industrial
Lot size in acres:	≥2.0	>.5 to <2.0	≤.5
_____
Minimum width right-of-way (in feet)
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Local road	66	66	66	66
Collector road	66	66	80	66
Secondary arterial	66	80	80	80
Primary arterial	80	80	100	100
Minimum width traveled route (in feet)
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Local road	22 W/S*	30 W/C**	32 W/C**	30 W/C**
Collector road	22 W/S	32 W/C	32 W/C	40 W/C
Secondary arterial	24 W/S	40 W/C	44 W/C	44 W/C
Primary arterial	44 W/S	48 W/C	48 W/C	48 W/C

 

 * With shoulders (roll type curb)

** With curbs (concrete vertical firm curbs) If W/S, minimum width remains 20 ft. for local road.

	Residential		Nonresidential Business—Industrial
Maximum grade (per cost)
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Improvement:	Low	Medium	High	Industrial
Local road	10	10	8	6
Collector road	8	8	8	6
Secondary arterial	6	6	6	5
Primary arterial	6	6	6	5
Minimum grade	1	1	1	1
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	Residential		Nonresidential
Improvement	Low	Medium	High
Lot size in acres:	≥2.0	>.5 to <2.0	≤.5
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Minimum radius of curve (in feet)
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	Low	Medium	High	Industrial
Local road	100	100	100	200
Collector road	100	100	100	200
Secondary arterial	300	300	300	400
Primary arterial	500	500	500	500
Minimum length of vertical curves
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Local road Collector road Second arterial Primary arterial	100 feet, but not less than 20 feet for each algebraic difference in grade; 200 feet, but not less than 50 feet for each 1 percent; 300 feet, but not less than 50 feet for each algebraic difference in grade

 

	Development Density
	Residential		Nonresidential
Improvement:	Low	Medium	High	Business— Industrial
Lot size in acres:	≥2.0	>.5 to <2.0	≤.5
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Minimum length of tangents between reverse curves (in feet)
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Local road	100	100	150	200
Collector road	100	100	150	200
Secondary arterial	200	200	250	300
Primary arterial	300	300	350	400
Minimum sight distance (in feet)
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Local roads	200	200	200	250
Collector road	200	240	240	250
Secondary arterial	275	275	300	300
Primary arterial	275	300	300	400
Intersection	Across Corners—75 feet Back Intersection
Minimum turnaround (in feet)
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Local road right-of-way diameter	120	120	140	160
Pavement	100	100	120	140
Center island diameter (if required)	40	40	50	60
Design speed (miles per hour)
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Local roads	30	30	25	30
Collector roads	35	35	30	35
Secondary arterial	65	60	55	55
Primary arterial	70	65	60	55
Maximum length of cul-de-sac
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Permanent	Six times minimum lot width, serving no more than 14 families and not exceeding 500 feet in length.
Temporary	12 times minimum lot width, serving no more than 25 families and not exceeding 1,000 feet in length.
	Residential		Nonresidential Business—
Minimum radius (in feet)	Low	Medium	High	Industrial
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At right-of-way	30	30	50	50
At pavement	25	25	45	45

 

(Ord. No. 156, 4-20-87; Ord. No. 90-12, 8-20-90)

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(C)

County roads. Roads which have been dedicated the county and which are constructed to the standards outlined in this ordinance shall be accepted into the county road maintenance system. Before acceptance is approved, the following provisions must be met, as applicable:

(1)

Inspection. A registered engineer must inspect and certify satisfactory completion of the following inspection steps. In addition, once notified that an inspection step has been completed, the county will inspect the quality or construction within two working days. This inspection must be conducted before starting construction on the next step. Any corrections must be completed at the expense of the developer before approval or acceptance.

a.

At completion of clearing and grubbing operations. Right-of-ways must be clearly staked, including slope easements.

b.

At completion of rough grading.

c.

At completion of subgrade. All required compaction test results will be reviewed at this time. Utilities to be installed prior to acceptance must be present at this time.

d.

At completion of base course.

e.

Before and after all primer applications.

f.

During final pavement application. Copies of asphalt tickets must be submitted.

g.

Final acceptance inspection. Stand of grass must be present or an escrow agreement may be executed in an amount determined to be adequate to cover the cost to re-grass all county disturbed areas if the stand of grass has not taken hold within one year from the date of acceptance by the county. If an acceptable stand of grass is established within the one-year period, the escrow amount will be returned to the developer. If not, the full amount will be distributed to the county to be used to establish the required stand of grass.

(2)

Compaction and testing requirements.

a.

Compaction of embankments, subgrade and base course shall conform to requirements of the most recent edition of SCDOT Standard Specifications, as amended, except that where no percentage is stated, 97 percent of a Standard Proctor Test will be required.

b.

Compaction and/or sieve analysis tests for subgrade and base course will be at the expense of the developer and must be performed by an independent geotechnical engineering/testing firm. Where SCDOT specifications have no requirements, the frequency of density testing shall be no less than one test for every 500 linear feet of roadway centerline or fraction thereof for base courses.

c.

All fill soils deeper than 24 inches shall be tested for compaction. This includes all fill soils in a wetland area. The frequency of testing shall be at the discretion of the planning commission.

d.

Backfill material placed in eight-inch layers in all utility trenches, service lines and storm drain lines installed within the designated road right-of-way shall be compacted to a minimum of 97 percent of a Standard Proctor Test. Compaction testing shall be at the expense of the developer and performed by an independent engineering/testing firm. The frequency of testing shall be at the discretion of the planning commission.

(3)

Clearing of right-of-way. All right-of-way shall be cleared and all improvements to property such as fences, shrubs, trees, etc., removed from the right-of-way.

(4)

Maximum slope ratio. Slopes created by cut or fill operations shall be no steeper than 2:1 (two horizontal to one vertical). In cases where the toe of the slopes extend beyond the right-of-way, additional right-of-way or sloping easements to encompass all right-of-way needed to maintain the 2:1 slope must be shown on the plans.

(5)

Cul-de-sac requirement. For emergency and road maintenance purposes, all dead end streets shall be constructed with a temporary or permanent cul-de-sac or an approved turnaround.

(6)

Turn around requirements. The allowable length of a proposed dead end street and whether intermediate turnarounds are required shall be determined by the International Fire Code in effect at the time of application and the approval of the appropriate fire official with the jurisdiction of the particular site location.

(7)

Traffic control signs. To insure public safety and proper identification, all intersections shall have proper traffic flow signs, to include stop and yield signs and street name signs, provided and erected by the developer.

(8)

Flooding. No street shall be approved which is subject to frequent flooding. Positive drainage must be obtained in all cases.

(Ord. No. 91-3, §§ 3—7, 5-20-91; Ord. No. 96-12, § 6, 5-20-96; Ord. No. 07-14, § II, 8-6-07; Ord. No. 09-18, §§ I, II, 1-5-10)