2019 – 2022 capital improvements program

Charleston Water System 2019 – 2022

Capital Improvements Program

October 2018

CHARLESTON WATER SYSTEM 2019-2022 CAPITAL IMPROVEMENT PROGRAM

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Introduction and Executive Summary The Charleston Water System’s Capital Improvements Program (hereinafter “CIP”) consists of recommended master plan improvements and expansions to water and wastewater infrastructure for the years 2019 through 2022. The CIP was developed by the Charleston Water System staff based upon the latest master planning undertaken by the staff and consulting engineers. The CIP was designed to accommodate projected growth within the service area, address needs for continued regulatory compliance, and from an asset management perspective includes substantial funds for rehabilitation and replacement of aging infrastructure; thus, helping to ensure exceptional fire protection, protection of public health, and water quality initiatives continue to be achieved. The CIP further includes project funding to help meet an increasing number of utility relocation needs resulting from SCDOT, County, and City drainage and road improvements projects, and for a new administrative and emergency operations facility. The construction schedule for the various improvements included in the CIP was determined on the basis of relative need and importance of each such improvement, the time required for planning and design work, and the extent to which modifications can be effected on existing facilities. If approved by the Commissioners, it is anticipated that the CIP totaling $199,900,000 will be financed out of proceeds of new revenue bonds, as well as from current and future revenues and funds of Charleston Water System. The CIP contains $109,800,000 for major improvements to the water utility that include upgrading a 1940s vintage raw water pumping station with associated mechanical and electrical improvements; disinfection process, chemical feed and electrical power distribution improvements at the water plant; transmission main extensions and water storage facilities to help meet growth and fire flow demands in retail and wholesale service areas; and various water infrastructure relocation needs associated with roadway and drainage improvements conflicts throughout the retail water service area. Charleston Water System must continue to make improvements to the Hanahan Water Treatment Plant and to the water distribution system to ensure available capacity to meet water demands associated with growth and fire protection, reliable operations, and to comply with a variety of increasing regulatory requirements. The CIP also contains $84,100,000 for major improvements to the wastewater utility that include replacement of the treatment plant solids handling facilities for greater capacity, reliability and flexibility for multiple solids disposal alternatives; new treatment process basins for regulatory compliance and capacity needs; disinfection storage and feed improvements; rehabilitation of collection system infrastructure; collection system extensions to help meet growth demands; and various sewer infrastructure relocation needs associated with roadway and drainage improvements conflicts throughout the retail sewer service area. Charleston Water System must continue to make improvements to the Plum Island Wastewater Treatment Plant and to the wastewater collection system to ensure available capacity to handle projected growth-related wastewater flows, reliable operations, and to comply with more stringent regulatory requirements. The CIP also contains $6,000,000 for a new administrative building on Charleston Water System property at the Armstrong Tract Parcel C. This building will provide resilient office spaces for daily administrative functions and for emergency operations. Charleston Water System is in


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need of additional office space at its current St. Phillip Street headquarters. There is also a need for a dedicated emergency operations center with facilities designed to accommodate staff for several days during a natural disaster. Make-shift space is currently being used in such events, which hinders effectiveness and creates disruptions to daily operations when critical functions have to be relocated from the St. Philip Street office to Hanahan Water Treatment Plant. On the following pages are brief descriptions of the proposed 2019 through 2022 CIP projects, as well as exhibits that provide the general project locations.


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Hanahan Water Treatment Plant

Bushy Park Reservoir Management: Recommended in the 2005 and 2014 HWTP Master Plans, a project to establish a reservoir management system is needed to provide an additional layer of treatment control to help combat taste and odor episodes. Reservoir management options could include enhanced aquatic vegetation control and nutrient management through periodic application of algaecides or an in-reservoir aeration system, which can take on a number of different forms. The project scope is being refined by the Charleston Water System Source Water Manager and Cadmus consultants utilizing data obtained through the recently completed USGS Bushy Park Reservoir Study. The engineer’s estimate is $2,400,000. (See Exhibit A) Gibson Raw Water Pump Station Improvements: Recommended in the 2005 and 2014 HWTP Master Plans, upgrades to the Gibson Raw Water Pump Station are needed to provide reliable stand-by raw water pumping capacity. The project will include replacement of the existing pumps with four new 10 MGD pumps equipped with variable frequency drives, piping and valve improvements, miscellaneous building improvements, and electrical improvements. The project will also include new 4160-volt electrical service to the building replacing the 2400-volt system as part of the plant-wide transition to a 4160-volt electrical distribution network for safety reasons. The engineer’s estimate is $5,700,000. (See Exhibit A) Ammonia Gas Alternative: Recommended in the 2014 HWTP Master Plan, this project will replace the existing aging storage and feed system with a new facility closer to the ammonia feed location in the treatment process. The new facility is proposed as a liquid ammonium sulfate feed facility to improve safety and eliminate the need for the Process Safety Management Program due to anhydrous ammonia gas storage. The engineer’s estimate is $2,100,000. (See Exhibit A) Electrical System Improvements: This project is intended to add the next phase of new electrical distribution infrastructure from the Plant’s new Electrical Distribution and Stand-by Generator Facility. This phase will provide stand-by power for 100% raw water pumping capacity and continue the plant-wide replacement of the existing 2400-volt electrical distribution network for safety reasons. The engineer’s estimate is $4,500,000. (See Exhibit A) Disinfectant Contact Basin: Recommended in the 2014 HWTP Master Plan, construction of a 2 MG disinfection contact basin downstream of the Stoney Filter Plants and prior to Clearwells 3 and 4 will enhance disinfection efficiency and optimize existing clearwell storage capacity for distribution pumping needs. The engineer’s estimate is $7,400,000. (See Exhibit A)


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Water Distribution & Transmission

Peninsula Trunk Main 3A – Phases 1 and 2 Recommended in the 2006 Water Distribution Master Plan, this project is for a planned transmission main that will provide a third major feed to the Charleston Peninsula. This new supply for the downtown area is needed to reinforce aging infrastructure and to support higher density growth and fire protection needs. The transmission main, identified as Peninsula Trunk Main Phase 3A (PEN 3A), will extend from the existing 48-inch transmission main at the intersection of Ubank Street and Spruill Avenue to the Nassau Street Ground Storage Tank with planned connections to the existing 24-inch transmission mains in Meeting and King Streets, as well as the 20-inch main at Greenleaf Street. The approximate total project length of Phase 1 is 17,100 feet, of which approximately 5,400 feet is planned as trenchless installation. The approximate total length of Phase 2 is 9,900 feet, of which 5,100 feet is planned as trenchless installation. The engineer’s estimates of Phase 1 and Phase 2 are $21,000,000 and 14,000,000, respectively. (See Exhibit B) West Ashley Transmission Main: This project is a variation of the 2006 Water Distribution Master Plan recommendation for a planned water transmission main from the Bees Ferry Storage Complex southward to the Croghan Right-of-Way connecting with the existing Main Road feed to Johns Island. Hydraulic modeling performed as part of the Water Distribution Master plan identified existing infrastructure as inadequate to meet the projected demands of areas of West Ashley, the Towns of Hollywood and Ravenel, and wholesale customer St. Johns Water Company. Preliminary engineering was completed previously to evaluate routing options and easements needed to construct the main. The approximate project length is 23,000 feet. The engineer’s estimate is $22,000,000. (See Exhibit C)

Airport Perimeter Road Water Main: This project is proposed to relocate the water transmission main along International Boulevard as part of the Airport Connector Road realignment planned by the Charleston County Aviation Authority, Charleston County, and Boeing. The project includes approximately 4,000 feet of 16-inch diameter water main along the proposed new airport access road route, approximately 7,000 feet of 20-inch diameter transmission main along the proposed new route of Michaux Parkway, and approximately 2,000 feet of 36-inch transmission main along West Montague Avenue. It is expected that the cost for relocation of the 16-inch and 20-inch mains from International Boulevard will be borne by Boeing to facilitate their campus expansion. The engineer’s estimate is $2,500,000. (See Exhibit D) Ben Sawyer – Intracoastal Water Main Crossing: This project is proposed to enable the provisions of the Wholesale Water Supply, Treatment and Transmission Services Contract between MPW and CWS for MPW to acquire a third wholesale point of delivery from CWS by way of a connection to the CWS 20-inch transmission main on Sullivan’s Island. Such a connection will not only benefit MPW, but it could also benefit CWS by enabling an emergency water supply from MPW for CWS wholesale customers Isle of Palms and Sullivan’s Island in the event the 20-inch transmission main from James Island is out of


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service. The approximate project length is 5,700 feet of 16-inch water main, of which approximately 5,100 feet will be directionally drilled beneath the Intracoastal Waterway. The engineer’s estimate for the total project cost is $10,000,000. MPW and CWS are sharing the cost of this project due to the mutual benefits for each utility, thus CWS’s estimated cost-share is approximately $5,000,000. (See Exhibit E) Ravenel Aquifer Storage and Recovery – Phase 1: This project is proposed to take the next step towards development of an Aquifer Storage and Recovery (ASR) facility near Ravenel according to the feasibility study completed by BP Barber in 2009. CWS acquired approximately 80 acres from Mead Westvaco Development in 2017, namely the Jericho Tract, for this proposed ASR facility. Additionally, CWS will soon complete a 16-inch water transmission main loop between Hollywood and Ravenel to help provide water to the ASR facility. The phase one project scope is for installation of a test well to verify the feasibility study and water recovery rate. Successful implementation of ASR at this location will serve to aid maintenance of water quality, enhance fire protection, meet peak demands, serve new growth areas, and meet emergency storage needs in the Hollywood / Ravenel service area. The engineer’s estimate is $4,000,000. (See Exhibit F) Market Street Drainage Project Water Utility Relocations: This project is intended to relocate existing water infrastructure in the North and South Market Street corridor to mitigate conflicts with proposed drainage improvements as part of the City’s Market Street Drainage Project. The engineer’s estimate is $3,200,000. Water Main Replacements/Rehabilitation Program: This project will provide funding for the replacement and rehabilitation of aging infrastructure with a focus on older tuberculated water mains. Priority is given to water main rehabilitation or replacement needs identified in the 2006 Water Distribution System Master Plan and supplemented with additional needs identified by the Water Distribution Department. This project will improve system reliability, enhance fire protection, and reduce operation and maintenance costs. The engineer’s estimate is $8,000,000. SCDOT / RoadWise Required Water Main Relocations: The South Carolina Department of Transportation requires utilities to relocate infrastructure that exists inside SCDOT rights-of-way when it is in conflict with road improvement projects. This project allocates funding for planned and unplanned SCDOT relocation projects. The engineer’s estimate is $4,000,000. We have traditionally budgeted similar amounts for such needs in the past. Cainhoy Area Water Mains: Charleston Water has a contractual obligation to provide arterial water mains for portions of the Cainhoy area. This project would allocate funding to meet these obligations. The engineer’s estimate is $4,000,000. (See Exhibit G-1 Overall Map; Exhibit G-2 North Area; Exhibit G-3 South Area)


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Plum Island WWTP

Plum Island WWTP Phase 4 Improvements: A number of Phase 4 improvement projects at Plum Island are recommended as part of the 2005 Master Plan and the 2013 Master Plan Update Addendum to properly address the new NPDES permit limits, increasing flows, and replacement of aging infrastructure. The Phase 4 Improvements are identified as a candidate for alternative delivery by bundling the recommended projects to expedite construction and facilitate integration of new facilities with minimal disruption of plant operations, as well as to maximize the improvements scope within the project budget. The engineer’s aggregate estimate for the following Phase 4 improvements projects is $45,900,000. (See Exhibit H)

1. Final Settling Tanks: The 2013 Plum Island Master Plan Update Addendum recommended addition of final settling tanks for the B-side treatment train to meet tighter effluent permit limits, hydraulic capacity and improved redundancy. The new anoxic selector is expected to improve solids settleability, thus enabling a higher loading rate for the final settling tanks that matches the existing aeration tanks’ loading rate of approximately 3.5 MGD each.

2. Sludge Storage:

Recommended in the 2013 Master Plan Update Addendum, additional primary and waste activated sludge storage will allow greater operational flexibility and capacity for future expansion needs. It’s anticipated that up to 2 million gallons of storage capacity will be added to replace the current 260,000-gallon tank in the Phase 4 Project.

3. Consolidated Solids Thickening and Dewatering Facilities: To reach the solids handling capacity needed for plant build-out flows, the 2005 Master Plan included a recommendation for a larger solids handling building for the additional equipment that would be needed. In order to conserve space, the proposed new building is planned to house consolidated thickening and dewatering processes. Due to significant structural issues and space constraints in the existing solids handling building, staff recommends advancing this project in lieu of trying to make structural repairs that are not considered a long-term solution. The sizing, configuration, and functionality of this new consolidated thickening and dewatering facility are being refined as part of the on-going Biosolids Master Plan. It is intended that the new facilities will allow for flexibility of solids processing methods that can be modified as needed for suitability with various long-term disposal alternatives.

4. Primary Clarifier: The Phase 3 Improvements Project originally included three new circular primary clarifiers pursuant to recommendations from the 2005 Plum Island Master Plan. Due to project funding constraints, only two new primaries were constructed as part of the Phase 3 Project. The third primary is needed to have adequate capacity to handle average daily flows greater than 24 MGD and to provide a level of redundancy.


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5. Disinfection Feed and Storage Facility: The 2005 Plum Island Master Plan recommended replacement of the existing disinfection facilities due to storage capacity limitations to meet regulatory requirements and to make room for future final settling tank expansions. This project will include a new building to house feed equipment and provide adequate bulk chemical storage to meet regulatory requirements.

6. Electrical and SCADA Improvements: These improvements are necessary to provide monitoring and control, as well as normal and standby power for the equipment and facilities included in the projects listed above.

7. Potable and Non-Potable Water System Improvements:

These improvements are necessary to provide process water and fire protection for the equipment and facilities included in the projects listed above.

Daniel Island Tunnel Headworks: This project is recommended to help minimize the volume of solids and grit material entering the Daniel Island Tunnel, thus and saving on O&M costs for cleaning the tunnel and to prevent sediment deposits in the tunnel pipe beneath the Cooper River. The proposed headworks infrastructure would be located at the Daniel Island WWTP site. The engineer’s estimate is $5,500,000.

Wastewater Collection

John’s Island Wastewater Interceptor System Expansion - Phase 3: The existing collection system on John’s Island consists of limited gravity lines and a series of pump stations and force mains located mostly north of Maybank Highway. The first two phases of this project established a regional pump station and extended gravity interceptor sewers to portions of the CWS service area south of Maybank Highway. Phase 3 consists of extension of a force main from the Phase 2 gravity sewer southward along River Road to a regional pump station in the Johns Island Airport area. Collectively with Phases 1 and 2, these projects will provide infrastructure to accommodate future wastewater flow from development in the portions of Johns Island within the CWS Service Boundary south of Maybank Highway. The engineer’s estimate for Phase 3 is $5,500,000. (See Exhibit I) Red Top Interceptor System - Phase 3: Much of the existing collection system in the Red Top area consists of limited gravity lines and a series of older pump stations and force mains formerly owned by the St. Andrews PSD. The first two phases of this project established a new regional pump station and extended larger gravity interceptor sewers to serve new growth and decommission older assets that had reached the end of their service life. This project is intended to continue expansion of the gravity interceptor system in the Red Top area to new growth areas and for removal of older pump stations from service saving O&M costs. The engineer’s estimate is $3,000,000. (See Exhibit J)


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Thomas Island Regional Pump Station and Sewer System - Phase 1: This project is intended to convert an existing pump station into a larger regional pump station and extend gravity sewers on Thomas Island to establish a base trunk system to facilitate growth demands in the I-526 / Clements Ferry Road Interchange area. The engineer’s estimate is $7,000,000. (See Exhibit K) Market Street Drainage Project Wastewater Relocation/Rehabilitation: This project is intended to rehabilitate or relocate existing gravity interceptors in the North and South Market Street corridor to mitigate conflicts with proposed drainage improvements as part of the City’s Market Street Drainage Project. The engineer’s estimate is $1,200,000. Pump Station and Collection System Rehabilitation: Based on design information, flow monitoring results, repair history, and field observations by CWS staff, a list of pump stations and sewer mains needing specific improvements is maintained for rehabilitation or replacement. Many of the assets on the list are older and nearing the end of their anticipated useful life, while some need additional capacity to handle peak flows. Rehabilitation of these assets will provide increased reliable capacity for the affected areas. The engineer’s estimate is $5,000,000.

SCDOT / RoadWise Required Wastewater Main Relocations: The South Carolina Department of Transportation requires utilities to relocate infrastructure that exists inside SCDOT rights-of-way when in conflict with road improvement projects. This project allocates funding for planned and unplanned SCDOT relocation projects. The engineer’s estimate is $3,000,000. We have traditionally budgeted similar amounts for such needs in the past. Cainhoy Area Wastewater Mains: Charleston Water has a contractual obligation to provide trunk sewer systems for portions of the Cainhoy area. This project would allocate funding to meet these obligations. The engineer’s estimate is $8,000,000. (See Exhibit L-1 North Area; Exhibit L-2 South Area)

Administration Customer Service / IT / Emergency Operations Facility: This project is intended for a new administrative building on Charleston Water System property at the Armstrong Tract Parcel C, which is located on high ground near the Hanahan Water Treatment Plant. This building will provide resilient office spaces for daily and emergency operations. The new building is intended to replace the leased North Area Customer Service Center, as well as provide space for relocation of the utility’s Customer Contact and Dispatch Centers, and Data Center. In addition, the building will house an Emergency Operations Center with support facilities, which together with the aforementioned functions, will help ensure resilient, sustainable administrative operations during and after natural or man-made disasters. The engineer’s estimate for the total project cost is $12,000,000. Of that amount $6,000,000 is proposed for inclusion in the bond issue with 60% funding from the water funds and 40% from the wastewater funds. The balance is anticipated from the sales of Armstrong Tract Parcels A1 and A2. (See Exhibit M)


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EXHIBIT A

Hanahan Water Treatment Plant


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EXHIBIT B

Peninsula Trunk Main 3A – Phases 1 and 2


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EXHIBIT C

West Ashley Transmission Main


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EXHIBIT D

Airport Perimeter Road Water Main


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EXHIBIT E

Ben Sawyer – Intracoastal Water Main Crossing


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EXHIBIT F

Ravenel Aquifer Storage and Recovery – Phase 1


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EXHIBIT G-1

Cainhoy Area Water Mains (Overall Map)


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EXHIBIT G-2

Cainhoy Area Water Mains (North Area)


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EXHIBIT G-3

Cainhoy Area Water Mains (South Area)


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EXHIBIT H

Plum Island WWTP Phase 4 Improvements


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EXHIBIT I

John’s Island Wastewater Interceptor System Expansion – Phase 3


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EXHIBIT J

Red Top Interceptor System – Phase 3


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EXHIBIT K

Thomas Island Regional Pump Station and Sewer System – Phase 1


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EXHIBIT L-1

Cainhoy Area Wastewater Mains (North Area)


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EXHIBIT L-2

Cainhoy Area Wastewater Mains (South Area)


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EXHIBIT M

Customer Service / IT / Emergency Operations Facility


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2019 – 2022 capital improvements program

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