Phase 3 Drainage Project - Outfalls & Basin
Milestone timeline:
The City has initiated the third phase of a project to improve storm water and tidal drainage across the island. This project is intended to make significant drainage improvements to the 30th, 36th and 41st Avenue outfalls which will improve conditions on the amount of standing water events experienced by residents and property owners.
The project began in 2017 when City Council tasked the Planning Commission with developing a strategy to address drainage problems. As part of the project, smaller but impactful drainage improvement projects along the basin will also be addressed. These are located at Sparrow Drive, Forest Trail, Cross Lane, 32nd Avenue and 41st Avenue.
The construction of the 30th and 36th Avenue outfalls began in early 2022 and expected completion in 2023. The construction of the drainage improvements to the 41st Avenue outfall is scheduled to begin in the fall/winter of 2023.
Project Updates
30th & 36th Avenue:
- Golf course portion of the work completed
- Road work/closure at 30th Ave delayed due to box culvert approval process and 8–10-week manufacturing lead time
- Work on 30th Ave expected in the next two weeks – contractor & engineer installing yard inlet to manage storm water from yard of adjacent resident and complete installation of pipes between homes and up to the road.
41st Avenue:
- Wetland permit (OCRM and USACE) still pending. City has conditional approval from OCRM. All other permits are contingent on the wetland permit.
- Project was put on public notice on April 14 until May 14.
- City received $1.4M grant from the SC Office of Resilience from CDBG-MIT funds for construction.
- City held kick-off meeting with Office of Resilience staff and Thomas & Hutton to determine next steps to get the project ready to go to bid once permits are in hand.
- Grant writer and staff working on a grant amendment request for the extension of pipe along 41st Avenue.
30th & 36th Avenue:
- Construction started at 30th Avenue
- Golf course portion of the work completed by mid June
- Waterway & 30th road closure to start in Mid August
- Waterway & 36th road closure late September - mid October
41st Avenue:
- Wetland permit (OCRM and USACE) still pending. City has conditional approval from OCRM. All other permits are contingent on the wetland permit.
- Project was put on public notice on April 14 until May 14.
- City received $1.4M grant from the SC Office of Resilience from CDBG-MIT funds for construction.
- City held kick-off meeting with Office of Resilience staff and Thomas & Hutton to determine next steps to get the project ready to go to bid once permits are in hand.
- Grant writer and staff working on a grant amendment request for the extension of pipe along 41st Avenue
Construction has started on portions of the City's Phase 3 Drainage Project in the areas of 30th Avenue, Forest Trail and Waterway Boulevard.
The project will provide a much-needed improvement to the flow of storm water out of the area, while also slowing tidal water from entering the system.
The improvements will include new piping under the pavement at the intersection of 30th Avenue, Waterway Boulevard and through the golf course, cleaning the channel through the marsh, as well as a new backflow valve system.
There will be a certain level of inconvenience associated with the work including construction sounds, large moving equipment, the storage of materials, and ultimately the closure of Waterway Boulevard with a detour. The detour is expected to begin in mid August and last several weeks. The portion of the project around 30th Avenue should be complete in early September and the contractor will then move to the Forest Trail area.
During the temporary road closure, all traffic on Waterway Boulevard will be rerouted at 29th Avenue and 31st Avenue to Palm Boulevard.
30th & 36th Avenue:
- Construction started at 30th Avenue
- Golf course portion of the work completed by June
- Waterway & 30th road closure mid/late July to end of August
- Waterway & 36th road closure late September - mid October
City staff met with Dominion Energy, Thomas & Hutton and Quality Enterprises on site at 30th Avenue on May 17, 2022 to coordinate efforts to temporarily relocate the power pole located at the corner of the ditch where the new drainage infrastructure is being installed. The power pole and the guide wire need to be moved approximately 4 feet away from the ditch, but within the existing drainage easement.
Additionally, the contractor has indicated that the overhead power lines may need to be temporarily moved as well while the crane installs the box culvert to allow the proper clearance (15 feet) between the active power lines and the crane lifting the box culvert from truck and placing it on the ground. All stakeholders are coordinating efforts to evaluate alternatives to facilitate installation while minimizing disruption and avoiding delays in the schedule.
41st Avenue:
- Wetland permit (OCRM and USACE) still pending. City has conditional approval from OCRM. All other permits are contingent on the wetland permit.
- Project was put on public notice on April 14 until May 14.
- City received $1.4M grant from the SC Office of Resilience from CDBG-MIT funds for construction.
- City held kick-off meeting with Office of Resilience staff and Thomas & Hutton to determine next steps to get the project ready to go to bid once permits are in hand.
30th & 36th Avenue:
- Pre-construction meeting held today, 4/19 with Thomas & Hutton, Quality Enterprises & IOPWSC
- May 2 – site prep begins, and May 5 construction begins
- Golf course portion of the work completed by June
- Waterway & 30th road closure July 28 – August 8 (10 days)
- Waterway & 36th road closure October 3 – October 8 (5 days)
41st Avenue:
- Wetland permit (OCRM and USACE) still pending. City has conditional approval from OCRM. All other permits are contingent on the wetland permit.
- Project was put on public notice on April 14 until May 14.
- City received $1.4M grant from the SC Office of Resilience from CDBG-MIT funds for construction.
- City held kick-off meeting with Office of Resilience staff and Thomas & Hutton to determine next steps to get the project ready to go to bid once permits are in hand.
30th & 36th Avenue:
- Start date for 30th Avenue outfall construction in early April
- Golf course work completed by June
- Waterway and 30th road work July – August
- Waterway and 36th road work September – October
41st Avenue:
- Wetland permit (OCRM and USACE) still pending. City has conditional approval from OCRM. All other permits are contingent on the wetland permit.
- City received $1.4M grant from the SC Office of Resilience from CDBG-MIT funds for construction.
- Mitigation – Most cost-effective option for the City is to purchase mitigation credits. Mitigation project evaluated would be more costly: construction, monitoring and ongoing maintenance.