SPECIAL NOTICE
R -- Environmental Remediation Dredging of tidal flats and an outfall drainage channel Stratford Army Engine Plant
- Notice Date
- 6/12/2020 10:54:05 AM
- Notice Type
- Special Notice
- NAICS
- 562910
— Remediation Services
- Contracting Office
- W2SD ENDIST NEW ENGLAND CONCORD MA 01742-2751 USA
- ZIP Code
- 01742-2751
- Response Due
- 7/13/2020 12:00:00 PM
- Archive Date
- 07/28/2020
- Description
- The U.S. Army Corps of Engineers, New England District (CENAE) is issuing this Special Notice for Environmental Remediation Dredging of tidal flats and an outfall drainage channel in the Housatonic River adjacent to the Stratford Army Engine Plant, Stratford, Connecticut. The purpose of this announcement is to solicit input from industry as to the construction means and methods as well as anticipated construction durations for the proposed work. The NAICS code for the work described below is 562910 (750 employees).� CENAE plans to award this project using a Design-Bid-Build model.� The Request for Proposal, which will include (100%) design, to be issued on or about November 2020.� The construction is expected to take 18 months, with in-water work beginning on or around July 1, 2021.� The solicitation is not available at this time. This special notice does not constitute a commitment by the Government. �Work consists of environmental remediation via mechanical dredging of the tidal flats and an outfall drainage channel adjacent to the Stratford Army Engine Plant to remediate metals and PCBs-affected sediments.� Approximately 140,000 cubic yards (cy) of material need to be removed from the tidal flats and an additional 8,000 cy from the drainage channel. Dredged material must be dewatered, solidified with cementitious materials for purposes of handling and stockpiling, and placed on-site for future beneficial re-use. A small portion of this material requires off-site disposal at RCRA D (solid waste) and RCRA C/TSCA approved landfills. Dredged material will require segregation during dredging. The tidal flats will require backfilling with sand material and restoration of roughly 2 acres of salt marsh. Included with this special notice are excerpt figures from the draft construction documents to further depict the required work. Items shown on these figures are subject to change as the design process is still ongoing. Project Requirements: The selected contractor will need to meet precise dredge target elevations (overdredge allowance will be approximately 2 inches). Dredging, placement of material into scows, dewatering, water treatment/discharge, transfer of material into trucks, and depositing of material onsite must be performed with minimal spillage or turbidity. Measures will be required to minimize the spread of contaminated sediments and contain turbidity. Deployment of a bottom seal silt curtain will be required. Dredging is generally limited to depths below mudline of 1 to 4 ft, ranging in tidal water depths of 2 ft [high tide] to approximately 10 ft. Dredged material must be segregated into three categories for purposes of disposal/reuse characterization based upon PCB concentration (=1 to = 50 mg/kg). Materials containing less than 1 mg/kg PCBs are suitable for on-site re-use. Materials containing greater than 1 mg/kg PCBs must be disposed of off-site at facilities licensed to accept these materials. All in-water work must be completed within an 18-month continuous allowable work window. Dredging accuracy will be key to minimizing the amount of over-dredging while still attaining the target cleanup goals of the project. The tidal flats dredging shall be performed using precision mechanical dredging methods.� Sediments shall be dredged using a sealed environmental level cut bucket to limit the generation of resuspended sediments and overdredge required to meet project objectives. State-of-the-art monitoring and positioning systems are required to ensure the allowable overdredge can be achieved. Turbidity measurements and comparison to project-specific standards (to be determined) will be required up- and downstream of the active work area.� The dredging shall be performed in a careful, well-designed manner so that downstream project-generated turbidity is kept to a minimum, and when appropriate, actions may be required to reduce turbidity generation to maintain compliance. The dredged sediment shall be dewatered and Portland cement added for purposes of onsite stockpiling and future reuse on the site. � Excavation of the Outfall 008 drainage channel can be performed �in the dry� or �in the wet�.� The means and methods of the excavation shall be selected by the contractor and approved by the Government.� The drainage channel will require backfilling and restoration. The tidal flats shall be backfilled to within one foot of original grade using a sandy material. �The contactor shall procure the sand material from an offsite upland source or by utilizing a designated borrow area at the mouth of the Housatonic River. USACE is in the process of testing this material for suitability and coordinating with the various state and federal agencies for mining and placing the in-river sand material. The Contract shall have as an option, dredging and placement of this designated sand material as an alternative backfill source for the tidal flats, the benefits of which include potential cost savings, reduced truck traffic, improved navigation, and higher value use of natural resources. Saltmarsh restoration and establishment period monitoring will be required for resource areas impacted by dredging operations under this contract.� The work requires compliance under OSHA 29 CFR 1910.120 including a Health and Safety Program, Site Specific Health and Safety Plan, and Training (40 Hour HAZWOPER and 8 Hour Refresher Training) for all onsite workers. Questions for Industry: Does the construction industry foresee any issues with completing the removal of approximately 140,000 CY of material from the tidal flats and subsequent capping with sand material within the 18-month construction window? Note that 24-7 dredging is allowed to maximize work under the tidal cycle constraints of the shallow tidal flat. Consider the following constraints (at a minimum) when providing a response: � The volume of material; The proposed overdredge allowance; Dewatering of the material (grain size varies but generally 60 to 80% silt, 10 to 30% sand, and 10 to 20% clay, and organic content of 4 to 6%). Batch sediment contaminant testing (Laboratory testing) for on-site reuse and off-site disposal designation purposes; Addition of cementitious solidification agents for purposes of on-site stockpiling and off-site disposal; Segregation during dredging, stockpiling, and characterization based on three PCB concentration thresholds; Off-site disposal of approximately 15,000 tons of material meeting two different regulatory categories; and Non-workable periods of the tidal cycle due to exposed tidal flats or shallow water. Regarding the dredging of sand material from the Housatonic River to be used as backfill material in lieu of an offsite source: Can the approximately 100,000 CY of material be dredged from the Housatonic and placed within the tidal flats within the three month dredge restriction window (between December 2022 through February 2023), within the overall 18-month window for the whole project? Consider the timing and coordination of completion of the tidal flats dredging and phasing in of backfilling. What should be considered with respect to storage and use of the sand material given the logistics and timing of completing all the work? Would stockpiling of the sand material be necessary to accommodate productivities, work windows, and ongoing contaminated sediment dredging? What methods are most appropriate to dredge, transport, and place the material, considering the distance from the site, the nature of the material (medium to fine sand), placement requirements, three-month window, and logistics of the overall project? What factors, including environmental and water quality impacts, need to be considered when selecting these methods? For mechanical dredging and transport methods, what factors need to be considered when managing scow traffic and handling of dredged material given potentially large discrepancies in productivities of the dredging vs. backfill operations? How would the potential offeror maintain the turbidity barrier at the site during these operations? For hydraulic dredging/transport, what challenges does the distance and routing of the pipeline present and what approaches would work best? If sand material is hydraulic transported, how would the material be placed in the tidal flats, and how would the resulting large flow of water be managed to prevent scour and turbidity concerns? 3) Given the shallow nature of the tidal flats which limits certain bathymetric surveying technologies, does the potential offeror have a method/approach to accurately survey the post-dredge surface to ensure the target removal levels have been achieved? 4) How will the potential offeror control dust and odors produced by the dredging and upland work to minimize impacts to the surrounding private and municipal properties? 5) Do potential offerors have the means for controlling turbidity during tidal flat dredging activities in such a way that suspended sediments don�t re-contaminate previously �cleared� areas of the flats during construction? Sediment surface samples will be taken of the post dredge area to confirm clean levels have been achieved.� What methods can the contract use to avoid time consuming and costly shutdowns or project modifications due to exceedance of the maximum allowable turbidity level, particularly given the window to complete the work? 6) Given the precision required of the dredge equipment and operators, are potential offerors able to achieve dredge cuts to within the 2-inch tolerance limit?� If not, what is a reasonable target? 7) Based on the information available, does industry have a preference on whether the Outfall 008 drainage ditch should be excavated in the wet or dry? Consider the following: The volume of dewatering needed to maintain productivity, and potential for interim control measures that might be needed (i.e. temporary sheeting of areas to control water), particularly at the compromised tide gate and berm between the SAEP and municipal airport drainage ditches; The requirement of accurate surveying of the post excavation surface to ensure required removal goals have been met; Potential for additional material being handled and processed based on side slope stability of wet vs. dry conditions; Backfilling and slope stabilization of the drainage ditch; Proximity to the municipal airport runway and equipment/operating limitations due to the work location. Due Date: Responses are due by 13 July 2020. Responses should be addressed to the U.S. Army Corps of Engineers, New England District, 696 Virginia Road, Concord, MA 01742-2751, ATTN: Heather Skorik, or via email to heather.skorik@usace.army.mil. Interested firms shall provide the above documentation in one original form and one copy, if mailed. �
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