Pocotaligo_Preserve_Phase_2_Scope_Document_(7-27-26).pdf

July 27, 2026

Scope of work for Phase 2 water management renovations at Pocotaligo Preserve, Beaufort County.

*As part of the total quote, prices should be broken down into per task price

*Request For Proposal (RFP) should have all parts completed to receive full consideration

Project Description: Beaufort County’s Land Preservation Department is seeking qualified contractors to renovate several water management features located within and associated with historic rice fields on Pocotaligo Preserve. The property is located in Yemassee, South Carolina, and has entrances off of US Hwy 17 and on Cotton Hall Rd (See attachment 1). This is phase 2 of a multi-staged renovation process of these former inland rice fields. The fields are broken and due to dated water control structures (WCS) and dikes, are now tidally influenced. The goal of phase 2 is to improve water management capabilities associated with the system to achieve the habitat objectives.

Task 1: Double pipes with flap gates and dike in inland field canal

Currently, there is a partially constructed dike in the inland field canal. This is the place of a former break in a cross dike. Two new 36” x 25’ or 30’ 14-gauge corrugated aluminum pipes will be installed, each with aluminum flap gates installed on the south side of the dike. The desired cross section of the complete dike will be approximately 40’ long x 16’ bottom width x 10’ top width with 2’ height of fill on top of the pipes. The fill can come from the canal adjacent to where the dike will be built. Approximately 115 cubic yards of material will be needed to build the complete dike. The built dike should match existing grades of surrounding dikes, or the southern dike can be raised to match the new grade following installation of pipes and fill placement. Approximately 11 cubic yards of rip rap will be placed on the upstream NW side to provide support during heavy storm runoff. (See attachment 3 and 4)

Specs:

- Two 36” x 25’ or 30’ 14-gauge corrugated aluminum pipes

- Two aluminum flap gates for the pipes

- Approximately 11 cubic yards of rip rap on the upstream NW side

- Approximately 115 cubic yards of material needed, this can come from the adjacent canals

Task 2: Install new rice trunk in center of cross dike

Existing structure: The existing structure shall be decommissioned in place by filling the culvert box with onsite material and entombing the entire structure within the existing dike.

Replacement Trunk: Install a standard 5’ x 32’x 18” with a 5-6’ riser Combahee style trunk with single side boards (4” width) and 3 paddle board pry bar lift at an adjacent site located in the embankment. The installation will include a 20’ bulkhead utilizing 3”x 10” lumber for cribbing boards and full length 3” x 10” Sloppy V puncheon boards. Bulkhead pilings are to be a minimum of 8” top and 25’ in length. Pilings shall be connected with either ¾” stainless cabling or all-thread rod. All wooden components used in both tasks shall be 2.5 CCA treated marine grade construction lumber and all metal fasteners shall be stainless steel. Any cut or untreated surfaces subject to long term inundation shall be treated with marine anti-fouling paint to reduce the risk of invasion by marine borers. Additionally, an aluminum riser cover with lock, and cable trunk door locks will be required to prevent public tampering and increase safety. (See attachment 5).

Specs:

- One standard sized 32’ x 5’ x 18” with a 5-6’ riser Combahee style rice trunk

- 20’ wooden bulkheads

- 2.5 CCA treated marine grade lumber

- Stainless steel hardware

- Aluminum riser cover with locks, cable trunk door lock

Task 3: Raise cross dike with fill from canal

Following installation of the rice trunk, the dike will be retopped. Trees and vegetation on the edge of the dike will have to be removed prior to retopping. This vegetative material can either be moved to an offsite location or mulched in place. The dike is approximately 810’ long, 18’ wide at the top, and 2’ of fill will be placed to raise the grade of the dike. This fill material will come from the eastern side of the dike with the purpose of also creating a circulation canal parallel with the dike. (See attachment 6)

Specs:

- Approximately 1,080 cubic yards of fill from the Tidal field 1 impoundment

Task 4: Repair break in dike

Task 4 is approximately 2,900’ east down an existing southern diversion dike in Tidal Field 1.

There is a break in the dike approximately 4’ long x 5’ deep x 15 wide. There is also a nonfunctional wooden structure that must be removed and disposed offsite. This break will be bulkheaded and plugged with fill to ensure sealing of the dike. This material can come from the adjacent canals or an offsite upland location. If fill is obtained from an offsite upland location it would need to be clean sand clay fill. The installation will include a 25’ bulkhead utilizing 3”x 10” lumber for cribbing boards and full length 3”x 10” Sloppy V puncheon boards. Bulkhead pilings are to be a minimum of 8” top and 25’ in length. Pilings shall be connected with either ¾” stainless cabling or all-thread rod. All wooden components used shall be 2.5 CCA treated marine grade construction lumber and all metal fasteners shall be stainless steel. Any cut or untreated surfaces subject to long term inundation shall be treated with marine anti-fouling paint to reduce the risk of invasion by marine borers. (See attachment 7)

Specs:

- Approximately 20 cubic yards of fill

- 25’ wooden bulkheads

- 2.5 CCA marine grade treated lumber

- Stainless steel hardware

Task 5: Install flashboard riser in middle of southern dike (before powerline)

Install a 36” x 30’ 14 gauge aluminum pipe with a 48” x 5’ aluminum riser with flap gate just before the powerline on the south diversion dike in Tidal Field 1. This structure should also have a locking aluminum cover on the riser and use aluminum flashboard riser boards. (See attachment 8)

Specs:

- One 36” x 30’ 14 gauge corrugated aluminum pipe with a 48” x 5’ aluminum riser

- One aluminum flapgate for pipe

- Aluminum riser boards

- Aluminum riser cover with lock

Task 6: Excavate circulation canal and use fill to widen existing dike

Following installation of the riser, an access dike is to be installed parallel to the existing south diversion dike leading back to cross dike separating Tidal Field 1 and 2. This berm will be built just outside the tree line of the trees located on the south diversion dike. It will have a 10’ top width x 15’ bottom width x a height that matches existing dike. This fill will come from Tidal Field 1 and also have the shared goal of creating a circulation canal. (See attachment 9)

Specs:

- 1,250’ berm creation: 10’ top W x 15’ bottom W x height that matches existing dike grade = 2,890 cubic yards of fill from impoundment

Task 7: Replace concrete pipe with new aluminum pipe and raise height of crossing

There is a pipe crossing that is low in elevation and experiencing some washout. The existing two concrete pipes will be removed and replaced with a 15” x 20’ aluminum pipe. The crossing will be raised 24” using approximately 60 cubic yards of upland fill. The grade should match the surrounding road (See attachment 10).

Specs:

- One 15” x 20’ 14 gauge corrugated aluminum pipe

- Approximately 60 cubic yards of upland fill

Project Considerations:

Contractor will provide all necessary equipment (excavators, trucks, etc.), materials, manpower and transportation required for timely completion of project.

Contractor will utilize designated ingress and egress route (s) and construction and staging area for project. All refueling and routine equipment maintenance shall be done at the staging area.

Staging area and construction site will be protected by appropriate safety fencing (standard orange mesh) along with appropriate signage. Equipment travel corridors shall be adequately marked for safety.

Trees and shrubs identified for removal (by flagging or painting) shall be removed and transported to a disposal area. Stumps, root balls, large roots and other woody debris (including chips and mulch) shall be removed from the project area during the process. Stump holes and other disturbed areas shall be filled and packed with offsite soil prior to final re-contouring.

Organic material such as roots and stumps shall not be placed on the dike.

All unnatural material removed during the construction process will be loaded and taken to an offsite disposal area. Example of these materials include asphalt, concrete, creosote lumber, metal debris, plastic debris, and old WCS.

At completion, all offsite fill on dikes and roadways to be sufficiently compacted to allow for immediate travel by vehicles and equipment. If fill material comes from the impoundment then time will be given to allow the material to set and settle.

All work shall be done during dry conditions to prevent rutting and ground disturbance. This includes movement of heavy equipment, storage of materials, and other activities that could cause ground disturbance. Rutting and ground disturbance shall not be tolerated.

Upon completion, disturbed soils will be seeded with an approved ground cover planting. Silt fencing will be placed along disturbed areas of the dike to reduce erosion of bare earth during ground cover establishment.

If any archaeological resources or remains found, work will be stopped immediately and assessed by a professional archaeologist.

Contractor will provide 3 references for recent projects of similar scope including the names, email addresses, and phone numbers of those references.

All work shall be guaranteed for one year after the completion of the project.

Produced by: Folk Land Management, Inc.

3515 White Hall Rd, Green Pond SC, 29446 Date: 7 / 15 / 2026

Attachment 3: Task 1 Cross Section – Install 2 Pipes with 2 Flap Gates and Build Cross Dike

Scale: 1” = 4’

Northwest Southeast

Proposed Bottom Width of Dike = 16’

36” 2’

Task 1 Pipe Installation: Install two new 36” x 25 or 30’ pipe with flap gates.

- 14 gauge corrugated aluminum pipe

- 2 aluminum flap gate for 48” pipe

Dike Installation:

- 16’ bottom W x 10’ top W x 2’ fill on top of pipes x 40’ L = 115 cubic yards of material

- Dike height should match existing dike grade or tie in with soft transition

- Material can come from adjacent canals

- Partial dike already built

Rip Rap Installation:

- Approximately 11 cu yards on upstream NW side

Proposed Top Width of Dike = 10’

New Dike

Rip Rap

Date: 7 / 15 / 2026

Attachment 4: Task 1 Cross Section – Install 2 Pipes with 2 Flap Gates and Build Cross Dike

Scale: 1” = 6’

Southwest Northeast Task 1 Pipe Installation: Install two new 36” x 25 or 30’ pipe with flap gates.

- 14 gauge corrugated aluminum pipe

- 2 aluminum flap gate for 48” pipe

Dike Installation:

- 16’ bottom W x 10’ top W x 2’ fill on top of pipes x 40’ L = 115 cubic yards of material

- Dike height should match existing dike grade or tie in with soft transition

- Material can come from adjacent canals

- Partial dike already built

Rip Rap Installation:

- Approximately 11 cu yards on upstream NW side

Flap Gates Installed on both sides

18”

Length of Proposed Dikes = 40’

2’

Existing Dike Existing Dike 36”

Attachment 5:Task 2 - Cross Section of a Combahee Trunk

Typical Dimensions of a full-size ‘Combahee’ Field Trunk Length of Trunk = 32ft, Width = 5ft Outside Height of Trunk-box = 2ft Inside height of Trunk-box = 18in Height of Uprights = ~11-12ft Height of Flashboard Riser = ~6ft

‘muzzle ’

‘trunk gate’ or ‘door’

- ‘trunk-box’ -

- f i e l d–d i k e s u r f a c e

20’ bulkhead installed on both sides of trunk

‘flashboard riser-box’

‘upright’

- ‘trunk-box’ -

‘gate ’ is typically set at 15° off vertical is typically set at 15° to trunk-box & door

‘spindle post’

‘lift boards ’ (2 or 3 per gate)

‘spanner board ’

Produced by: Folk Land Management, Inc.

3515 White Hall Rd, Green Pond SC, 29446 Date: 7 / 15 / 2026

Task 2: Rice Trunk Installation

- Remove existing wooden structure

- Install new standard 32’ x 5’ x 18” Combahee style rice trunk

- Install 20’ bulkheads on both sides of the dike to provide support to dike and structure

Date: 7 / 15 / 2026

Attachment 6: Task 3 - Cross Section Dike Retopping

Scale: 1” = 5’

West East

Retopping Width = 18’

Retopping Height = 2’

Task 3 Dike Retopping: Increase height by 2’ with fill from eastern side of dike and create a circulation canal in Tidal Field 1

- 810’ L x 18’ W x 2’ H = 1,080 approximate cubic yards of fill

- New canal dimensions = 7’ x 3-5’

Field Bed

New Canal Width = 7’

New Canal Depth = Average 3 - 5’

Berm = 7.5’

Existing Dike

New Canal

Date: 7 / 15 / 2026

Attachment 7: Task 4 – Repair Break in Dike

Scale: 1” = 4’

Northwest Southeast

5’

Task 4 – Repair Break in Dike

- Remove nonfunctional wooden water control structure

- 5’ L x 15’ W x 5’ H = Approximately 20 cubic yards of fill

- Fill can come from adjacent canals

- 25’ bulkhead

15’ Existing Dike Existing Dike

Bulkhead = 25’

(Birds eye view)

Date: 7 / 15 / 2026

Attachment 8: Task 5 – Install New Pipe and Flashboard Riser

Scale: 1” = 5’

South North

Pipe Length = 30’

Task 5 – Install new pipe and flashboard riser in existing dike

- 36” x 30’ 14 gauge aluminum pipe with a 48” x 5’ flashboard riser and flapgate

- Aluminum riser boards

- Aluminum riser cover with lock

Existing Dike

Pipe Height = 36” Riser Height = 5’

Tidal Field 1Southern Canal

Date: 7 / 15 / 2026

Attachment 9: Task 6 – Excavate Circulation Canal and Use Fill to Widen Existing Dike

Scale: 1” = 10’

South North

Height = match existing dike gradeExisting Dike

Width = 15’

New Circulation Canal

Task 6 – Excavate circulation canal and use fill to widen existing dike

- 1,250’ L x 15’ W x existing dike height = approximately 2,890 cubic yards

- Material to be excavated from Tidal field 1t to create circulation canal

New Circulation Canal

New Fill

Attachment 10: Task 7 – Pipe Replacement and Increased Road Height

3515 White Hall Rd, Green Pond SC, 29446 Date: 7 / 15 / 2026

Scale: 1” = 3’

Task 7 - Pipe Replacement:

- Remove existing 2 concrete pipes

- Install new 14 gauge corrugated aluminum 15” x 20’ pipe

Fill Placement: Set approximately 60 cu yards of fill on the pipe crossing and extending on either side of the road to bring grade up to surrounding road.

- Increase height by approximately 2’

Southwest Northeast

Existing Ditch Existing Ditch

New Fill

New Aluminum Pipe = 15” x 20’