(A) For the purposes of this section, the following definitions shall apply:
BERM. A flood control device constructed of compacted earth, soil, or sand, which may be used independently or to cover riprap.
BULKHEAD. A vertical erosion control device intended to protect property from erosion and flooding installed on high ground within 15 feet of the critical line as defined by SCDES.
PERPETUAL EASEMENT LINE. The landward edge of the federal beach renourishment project as defined by the Army Corps of Engineers.
RETAINING WALL. A vertical erosion control or stabilization device intended to protect property from erosion and flooding installed on high ground landward of the critical line setback.
REVETMENT. Sloping material installed seaward of a seawall facing the oceanfront baseline as defined by SCDES.
RIPRAP. Sloping material installed on the side of the bulkhead facing the marsh front critical line as defined by SCDES or as the foundation of a berm.
SEAWALL. A vertical erosion control device intended to protect property from wave erosion and flooding installed on high ground which is adjacent to the oceanfront baseline as defined by SCDES.
(B) Minimum construction standards for all erosion control devices.
(1) New or substantially improved erosion control devices cannot be combined in a manner that would compound flooding, significantly impair drainage, cause adjacent shoreline impacts, or cause any negative impacts to dune or marsh growth. However, mixed use of erosion control methods dictated by site conditions on property can be permissible in the same contiguous linear plane.
(2) Any erosion control device placed wholly or in part within the Dune Management Area or the critical line setback must be maintained in an intact condition or removal may be required at the owner's expense.
(3) Construction of erosion control devices, as well as the placement of riprap and revetments, shall require a permit from the city and proof of location behind the SCDES critical line or baseline in the form of a pre-construction survey with an SCDES certified critical line or baseline location and an as-built survey showing as-built improvement and the certified baseline or critical line as applicable.
(4) No portion of an erosion control device, riprap, or revetment shall be placed seaward of the baseline or beyond the critical line.
(5) Construction or repair of erosion control devices on the beach from May 1 through October 31 is subject to the following requirements.
(a) The building permit holder must contact the Folly Beach Turtle Watch Permit Holder each day prior to the commencement of work. The Folly Beach Turtle Watch Permit Holder will provide verification that there are no active turtle nests in the work area. Verification will be provided prior to 8:00 a.m.
(b) If an active nest is in the work area, work must stop until the nest is relocated. If a turtle nest located in the work area is established before permitted work begins and can not be relocated, construction cannot begin until the nest hatches.
(c) The work area shall be defined as the area within 25 feet of the location of the seawall or the path used to access the site.
(C) Minimum construction standards for seawalls and revetments.
(1) No new or substantially improved vertical unfaced seawall shall be allowed on the ocean front.
(2) Any new or substantially improved vertical seawall surface must maintain a setback of at least 25 feet from the perpetual easement line except that a new or substantially improved vertical seawall surface located seaward of a habitable structure closer than 25 feet from the PEL shall be placed as close the structure as is feasible.
(3) New or substantially improved seawalls and associated revetments placed wholly or partly within the Dune Management Area must be constructed so that the top of the vertical seawall is at an elevation of eight feet NA VD 88.
(4) Any area with in the Dune Management Area disturbed for the construction or repair of a seawall or revetment shall be filled such that the finished grade of the area of disturbance is at an elevation of ten feet NAVD 88 and planted with appropriate vegetation as designated by the Building Official.
(5) Seawalls shall be designed by a certified design professional, registered in the state and shall meet the following minimum standards:
(a) Seawalls shall be constructed of either:
1. Reinforced concrete six inches thick designed with adequate reinforcement to achieve a 3,000 psi 28-day strength, or
2. Pressure treated wood three inches by ten inches or three inches by 12 inches tongue and groove, or a double thickness of two inches sheeting with staggered joints is acceptable for walls with a standing height of under four feet.
(b) The depth of embedment of a seawall shall be at least equal the height of the wall above the ground. An allowance should be made to account for erosion scour after construction.
(c) Tiebacks shall be located at a spacing of eight feet or less and attached to secure anchors capable of withstanding a 2,000- pound pull. Tiebacks may be deleted if a revetment is placed seaward of the seawall.
(d) Seawalls shall be backfilled with a compacted clean granular material to provide adequate support. “Clean” shall mean no metal, wood or glass.
(e) Seawalls will either tie into adjacent seawalls or will have an adequate return wall meeting the same design requirements as the seaward wall. Return walls must continue landward far enough to prevent flanking after the erosion of the dune system seaward of the wall.
(f) Any new or substantially improved vertical seawall surface must maintain a setback of at least 25 feet from the perpetual easement line except that a new or substantially improved vertical seawall surface located seaward of a habitable structure closer than 25 feet from the PEL shall be placed as close the structure as is.
(6) Any new or substantially improved vertical seawall surface must be faced with a sloping revetment. Revetments shall be designed by a certified design professional, registered in the state and shall meet the following minimum standards:
(a) The outside of a revetment shall consist of at least two layers of armor stones whose pieces shall range in weight from a minimum of 50 pounds to a maximum of 250 pounds; at least 60% shall weigh more than 150 pounds. Broken pavement, blocks or bricks are not acceptable materials for the outer layer of a revetment. However, they may be used for under layers.
(b) Revetments shall be underlain with a commercial grade porous filter cloth designed for ocean erosion control and approved by the Building Official (e.g. Phillips 66 stock or equal) and placed on a slope no steeper than one vertical to two horizontal.
(c) The toe of the revetment shall extend at least two feet below the existing beach elevation.
(d) In no case shall the toe of the revetment be located closer than 5 feet from the perpetual easement line.
(D) Minimum construction standards for bulkheads, retaining walls, and riprap.
(1) New or substantially improved bulkheads or associated riprap located wholly or partly with in the required setback from the critical line must be constructed so that the top of the vertical structure is no higher than the highest average grade on the property.
(2) Bulkheads and retaining walls shall be designed by a certified design professional, registered in the state.
(a) Bulkheads and retaining walls shall be backfilled with a compacted clean soil to provide adequate support. “Clean” shall mean no metal, wood or glass.
(b) Bulkheads shall either tie into adjacent bulkheads or will have an adequate return wall.
(3) Broken pavement, blocks or bricks are not acceptable materials for riprap.
(4) Riprap used as the foundation of a berm must be designed by a certified designed professional registered in the State of South Carolina so as to prevent movement into the critical area.
(E) Minimum construction standards for berm. Berms within 15 feet of the critical line shall be designed by a certified design professional registered in the State of South Carolina and shall meet the following minimum standards:
(1) Berms shall be designed to prevent shedding of storm, flood and tide waters onto adjacent properties and a no adverse impact statement in congruence with other city ordinances including floodplain ordinances shall be included on designs provided during permitting.
(2) Berms shall be tied into existing grades along the entire length of their perimeter to ensure that berms are naturally appearing, and floodwaters are not impacting surrounding properties.
(3) Berms shall be compacted prior to planting, landscaping, or revegetation.
(4) Berms shall be landscaped with appropriate native vegetation such that at least 50% of the surface of the berm is covered by plant material when calculated using the a verage mature size of the proposed plantings. In the case of damage or erosion resulting in the loss of required vegetation, berms must be repaired and replanted to meet the requirements of this section.
(5) Naturally occurring, protected trees shall not be buried or incorporated within the berm so as to cause the trees to die unnaturally from piling up and stacking of soils above and around the natural ground level surrounding the tree trunks. Boxing of protected trees is acceptable.
(6) Any riprap used as the foundation of a berm must be completely covered by compacted earth so that no riprap is visible. In the case of damage or erosion resulting in the exposure or disturbance of riprap, berms must be repaired to meet the requirements of this section.
(7) Berms must be constructed so that the highest point of the berm is no more than three feet above the highest adjacent grade.
(F) Adherence to these minimum standards will not guarantee that erosion control devices will withstand wave or tidal forces or that it will protect against erosion. These standards are to prevent unsightly and inferior structures that would have little or no chance of success or could become a hazard or nuisance, and/or divert floodwaters to adjacent properties.
(Ord. 003-25, passed 5-13-25)