20220513_ND00146_Pipestem_Pre-Bid_Site_Visit_Notes.pdf

Pipestem Dam Spillway Modification Project Pre-Bid Contractor Site Visit – 10 May 2022 Government Notes

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NOTE: This document is informational only and is not binding. If there is a discrepancy between the solicitation, specifications or drawings and this document, contractors should abide by the solicitation and associated documents.

1. The expected solicitation date for the Step 2 IFB is mid-June 2022.

2. A contractor representative asked if the government would consider releasing the preliminary contract bid schedule showing expected quantities so that contractors may use it in developing their Step 1 IFB responses. He noted that if all prospective bidders were working with the same set of quantities, they would be able to develop more easily comparable responses, particularly regarding construction approach.

Note that the government posted the preliminary contract bid schedule to SAM.gov on 13 May 2022.

3. There will be excess fill material on this project, and spoil areas for excess fill material are shown on the contract plans.

4. The contract plans and specifications include some construction sequencing requirements. There are initial grading requirements and final grading requirements. The intent of the initial grading is to have sufficient features in place (all structures and initial dikes) to safely pass spillway flows prior to lowering the entire spillway channel. Also, the contractor is required to construct the dikes, excavate and place the soil cement keys, and backfill to original grade in only 400 lineal foot segments at once. This dike, soil cement key, and backfill placement is required to start upstream and work downstream to ensure that upstream protection is in place before the next downstream 400-foot section is constructed.

5. The government intends for excavated sand to be used in production of the soil cement for the project.

6. The contractor QC lab and the government QA lab are to be co-located, and the location of the labs is shown on the contract plans.

7. The contract instrumentation specification requires placement of a number of different instruments, including uplift cells, which are vibrating wire piezometers intended to measure uplift pressure on the bottom of the stilling basin slab.

8. The contract will require Web-based data management, and the contract specifications detail the data management requirements. In general, the data management approach includes contractor development and maintenance of databases (SQL EDB and Geodatabases) that store the construction data (testing and spatial). The contractor will provide web-based data storage (e.g., SFTP site and ESRI GIS REST Services) of the data and data-linkages for the Contracting Officer’s Representative to access. The contractor will not be required to develop a Web viewer.

9. The contractor will be required to perform shale mapping during excavation. As detailed in the contract specifications, if the shale is to be exposed for longer than 8 hours, the contractor will be

2/3 required to propose a protective coating for approval to prevent the surface from slaking, degradation, erosion, or other damage. The protective coating material will need to be removed to the satisfaction of the Contracting Officer prior to placement of fill material or aggregate.

10. The government expects dewatering of this site to be challenging, which is why the dewatering is emphasized in the Step 1 technical evaluation criteria. The contract specifications detail the dewatering requirements. The contract will generally require that the water level be lowered to 2 feet from any face of the excavation during all excavation phases, including backfilling procedures.

The contractor will be required to develop a dewatering plan that meets the contract specifications.

The solicitation includes the Geotechnical Data Report and Geotechnical Interpretation Report developed by the government. These reports contain information that may be useful in considering the dewatering requirements. However, it is emphasized that the contractor should make their own interpretation of the site conditions and groundwater conditions at the site.

11. The contract will require the contractor to remove surface sands in the spillway channel and replace them with clay material. The government plans to complete an investigation of the surface sands during summer 2022 to better quantify them. The quantity of surface sands will be incorporated into the Step 2 solicitation documents.

12. The water from dewatering operations will be discharged to Pipestem Creek. The contract specifications include requirements for settling basins for sediment control prior to discharge into the creek. The specifications also include requirements for discharge water quality and procedures, in accordance with State of North Dakota rules and regulations, including application for a discharge permit, and any continued requirements by the North Dakota regulatory agency to maintain the permit.

13. There is a culvert under 32nd Street SE at Pipestem Creek, and there is a load restriction posted for this road. Per the contract specifications, the contractor will be required to verify with Stutsman County whether this limit is still applicable and whether it applies to the road, the culvert, or both.

14. Per the contract specifications, the contractor will be responsible for maintenance of haul routes.

The specifications detail the maintenance requirements for haul routes.

15. The government expects that nighttime work will be required, especially during placement of RCC.

The contract specifications state that normal working hours are Monday through Friday from 8:00 AM to 5:00 PM, but that the government may allow work outside of normal working hours with prior approval. The procedure for obtaining prior approval is detailed in the contract specifications.

The government will have a public outreach specialist who will work closely with government construction oversight staff to help coordinate work with affected members of the public.

16. The contract specifications require use of batch plant for RCC. The specifications require that the soil cement mixing plant be either a weigh-batch type or continuous type.

17. The Pipestem Dam spillway has not flowed since the dam was constructed; however, the reservoir level has come within approximately 4 feet of the spillway crest in the past. The contract plans and specifications include available historical data that may be useful in assessing and managing risk

3/3 from potential spillway flow or outlet works releases during construction. The specifications require the contractor to develop a Construction Flood Contingency Plan for ensuring that all personnel, materials, and equipment are appropriately protected from potential flooding impacts.

18. The contract plans and specifications require the construction of a cofferdam along Pipestem Creek.

The plans and specifications detail the cofferdam requirements.

19. The contract plans and specifications require either “Standard Compaction” or “Method

Compaction” for fill areas. The specifications detail the compaction requirements.