BC1415 Construction Sequencing Criteria_v12.pdf

BC1415 Construction Sequencing Criteria_v10.pdf Page 1 of 6 September 24, 2024

BC 14 & 15 Construction Contract Sequencing

Contractors shall develop a construction schedule consistent with the contract documents and the following sequencing criteria that satisfies the projects’ water supply and dam safety requirements. A detailed Gantt construction schedule with logic, tasks, task dependencies, critical path, float, resources, and costs identified shall be submitted along with the contractors bid.

Anticipated Schedule Overview

Task Start Finish

Bid & Award October 2024 January 2025

Preconstruction Activities January 2025 February 2025

Notice to Proceed March 15, 2025 March 15, 2025

Construction Season 1 March 15, 2025 December 15, 2025

Winter Shut-down December 15, 2025 March 15, 2026

Construction Season 2 March 15, 2026 December 15, 2026

Winter Shut-down December 15, 2026 March 15, 2027

Construction Season 3 March 15, 2027 December 15, 2027

Winter Shut-down December 15, 2027 March 15, 2028

Construction Season 4 March 15, 2028 December 15, 2028

General Notes

• Sites 14 & 15 serve as the primary water supply reservoirs for the Green Valley Glenwood Public Service District (PSD).

• Typical operation of the reservoirs by the PSD includes withdrawing raw water from Site 14 from the beginning of December to the end of May and withdrawing raw water from Site 15 from the beginning of June to the end of November.

• The PSD withdraws about 1.5 million gallons daily from either Site 14 or Site 15 with the treatment plant operating about 18 hours per day (1400gpm). Work must be performed and sequenced so that one pool is available for water withdraw at all times.

• The time limits and sequencing criteria identified below are intended to maintain this supply with typical weather and inflow conditions.

o Liquidated damages noted below are based on the completion of contracted work activities and are not based on reservoir pool levels or refilling durations. (i.e. the contractor is responsible to complete the work items necessary to allow refilling of the reservoirs to begin, but is not responsible if the duration of refilling is delayed due to drought)

• The construction sequencing shown in the erosion and sediment control plans is provided as the basis of design and was used to obtain the projects NPDES permit. The contractor shall provide a construction sequence for the installation of erosion and sediment controls consistent with their proposed construction schedule and consistent with the intent of the erosion and sediment control measures. Once the project is awarded, the contractor shall

BC1415 Construction Sequencing Criteria_v10.pdf Page 2 of 6 provide the amended E&S sequence and assist the owner with obtaining an amendment to the NPDES permit as necessary.

Time Limits

• All project work shall be completed within four or less consecutive construction seasons. A construction season is defined as March 15th to December 15th in a calendar year.

o A three-month winter shutdown from December 15th to March 15th shall be included between construction seasons.

o Incidental work, such as erecting construction trailers, developing staging areas, material stockpiles, dewatering, supplemental pumping, E&S controls, stream diversion measures, RCC Plant setup, and similar activities, to prepare for construction and maintain the sites will be required during the winter shutdowns.

• Site 14 o All work shall be completed within two or less consecutive construction seasons, separated by a winter shutdown.

Liquidated Damages (LD14A) – If all Site 14 work is not completed within two or less consecutive construction seasons, ending December 15th of the second season, liquidated damages may be enforced.

o All upstream and downstream embankment work shall be completed within the same construction season.

Liquidated Damages (LD14B) – If all the upstream & downstream embankment work is not completed by the end of the construction season ending December 15th, thus allowing reservoir refilling to begin, liquidated damages may be enforced.

• Site 15 o All work shall be completed within four or less consecutive construction seasons.

Liquidated Damages (LD15A) – If all Site 15 work is not completed within four or less consecutive seasons, ending December 15th of the fourth season, liquidated damages may be enforced.

o Upstream riprap berm installation and riser work the contractor shall drain the reservoir starting at the beginning of August of the construction season indicated by the construction contractor, per the approved schedule.

the reservoir drain gate may remain open from August to the first week in December of the same year.

the reservoir drain gate shall be closed the first week of December to begin refilling. In December, water supply gate II at elevation 2454.47 may remain open. At the end of the construction season (December 15th) all gates must be closed to facilitate complete refilling the reservoir to normal pool elevation.

Reservoir draining and all upstream riprap berm installation and riser work shall be completed between August and the winter shut-down on December 15th.

The contractor is permitted to work multiple shifts to complete the upstream berm work within the specified time period.

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Liquidated Damages (LD15B) – If the Site 15 reservoir draining, upstream riprap berm installation, and riser work is not completed by December 15th, liquidated damages may be enforced.

o Downstream Embankment work To support the Impact Basin and PSW conduit extension work, the reservoir may be lowered up to 10' from normal pool elevation per CS11. The contractor is encouraged to lower the reservoir only the amount and duration necessary to perform the work.

Lowering the reservoir for this purpose shall be limited to a duration of

3-months.

This applies if the Impact basin and PSW conduit extension work is not completed during the period when the Site 15 reservoir is drained for the upstream riprap berm installation and riser work from August to December.

Liquidated Damages (LD15C) – If lowering of the reservoir for the purpose of extending the PSW conduit and construction of the Impact basin extends beyond a 3-month duration, liquidated damages may be enforced.

o At least $2,800,000 of work at Site 15 shall be completed and approved by

September 2028.

Contractor shall include the purchase, delivery, and stockpile of upstream riprap berm and RCC materials to ensure this requirement is achieved.

Liquidated Damages (LD15D) – If completion of $2.8 million of Site 15 work is not complete and approved by September 2028, liquidated damages may be enforced.

Water Supply - construction must be sequenced so that either the Site 14 or Site 15 pool is available for water withdraw at all times.

• The Site 14 upstream and downstream embankment work shall be sequenced to occur before the Site 15 upstream embankment and riser work.

• The Site 14 pool may not be drained for construction while the Site 15 pool is lowered, drained, or the Site 15 upstream or downstream embankment work is being performed.

• The Site 15 pool level may not be lowered or dewatered for construction while the Site 14 pool is dewatered. Site 14 must be refilled to normal pool level prior to lowering or draining Site 15.

• The Site 15 pool can be lowered and drained for specific construction purposes in accordance with Construction Specification 11 and the time limits noted above.

• The Site 15 pool may be lowered (10’ max drawdown from normal pool elevation) for installation of the PSW conduit extension and impact basin installation. Contractor shall maintain normal pool level when possible and only lower the amount necessary for construction to maintain the maximum available water supply. This applies if the impact basin and PSW conduit extension work is not performed during the period when the Site 15 reservoir is drained for the upstream riprap berm installation and riser work from August to December.

• The Site 15 pool can be drained only to perform the upstream riprap berm installation and riser work.

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• The contractors schedule should include time in the construction schedule for draining and refilling the reservoirs.

• Time for draining the reservoirs should be consistent with the contractor’s stream diversion and dewatering plan. The maximum drawdown rate shall be 1’ in pool elevation per day.

• Refilling Time

• Site 15 - it is anticipated that the Site 15 complete reservoir refilling may take +/- 4-6 months during the wet season (Dec-May), depending on weather conditions and supplemental pumping which is to be performed by the PSD.

• Site 14 - it is anticipated that the Site 14 reservoir will refill within +/- 2- 3 months, depending on the time of year refilling occurs.

• Reservoir refilling time estimates are shown at the end of this section.

• The contractors schedule should include these durations for reservoir refilling. If drought conditions delay reservoir refilling beyond the anticipated durations above, the Contracting Officer may allow more performance time based on the contractor’s request. If shorter durations for reservoir refilling are selected by contractor, subsequent work activity delays resulting from reservoirs not refilling are the responsibility of the contractor.

Dam Safety - construction must maintain an adequate level of dam safety at all times. The criteria below are divided into upstream, downstream, and ASW work areas. These areas are depicted on the work area illustration at the end of this section. The upstream embankment work is considered work upstream of the dam centerline, which would include upstream embankment grading, riser work, and wave protection work. The downstream embankment work would include downstream embankment grading, PSW pipe extension, impact basin construction, and toe drain installation. The ASW work includes excavation, RCC placement, and backfill within the auxiliary spillway areas. The ASW at Site 14 also includes the relocation of the access road to the left training dike.

• Site 14 During Site 14 Upstream & Downstream Embankment Work:

• The pool must be completely dewatered per CS11,

• The Site 14 ASW shall not be excavated,

• Open excavations in the embankments are not permitted during a winter shutdown period. All embankment work needs to be completed, backfilled, and stabilized prior to the winter shutdown.

• The Site 15 upstream or downstream embankments shall not be excavated.

During Site 14 ASW Work:

• The pool can’t be lowered or dewatered to support this work,

• The Site 14 embankment shall not be excavated (original or proposed condition),

• RCC placement shall not be performed simultaneously B at Site 14 & 15.

• The ASW shall not be excavated during a winter shut-down.

• Site 15 During Site 15 Upstream Embankment work:

• The pool must be drained per CS11 to perform the upstream riprap berm installation and riser work.

• See the Time Limits section above for Site 15 draining requirements.

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• The Site 15 ASW shall not be excavated (except for the grading work described in the considerations section below A).

• The Site 14 upstream or downstream embankments shall not be excavated.

During Site 15 Downstream Embankment work:

• The reservoir pool shall be operated at normal pool level (all gates closed), but may be lowered up to 10-feet from normal pool elevation to support the Impact Basin and PSW conduit extension work, per CS11 and the time limits noted above.

• The Site 15 ASW shall not be excavated.

• The Site 14 upstream or downstream embankments shall not be excavated.

• All downstream embankment work shall be completed within the same construction season. Open excavations in the downstream embankments are not permitted during a winter shutdown period. All embankment work needs to be completed, backfilled, and stabilized prior to the winter shutdown.

• The contractor should consider performing the downstream embankment work in the same construction season as the upstream embankment work to take advantage of the pool being drained during a portion of this season.

During Site 15 ASW work:

• The reservoir may not be lowered or dewatered to support this work.

• The Site 15 embankment shall not be excavated (embankments may be in their original or proposed condition).

• RCC placement will not be performed simultaneously B at Site 14 & 15.

• The ASW shall not be excavated during a winter shut-down.

Common Elements

• Contractors may elect to combine these Site 14 & 15 facilities to serve the project.

Contractor shall note this choice within their proposed construction schedule.

o Contractors Offices o COR Office o Laboratory o RCC Plant and material stockpiles – (contractor must verify all project requirements for RCC production, delivery, and placement can be achieved at each site if using one plant)

Considerations

• Site 14 is designed with imported fill from Site 15. Rough grading A of the Site 15 ASW RCC area can be performed to generate fill for Site 14 construction ahead of Site 15 construction.

This grading, if performed outside the scheduled Site 15 ASW work, shall be temporarily stabilized in accordance with Construction Specification 6 – Seeding, Sprigging, and Mulching. Note – this grading does not prohibit the Site 15 embankment work from occurring simultaneously.

• Supplemental Pumping may be performed by the Green Valley Glenwood Public Service District (PSD) to facilitate water supply and/or reservoir refilling. The anticipated pumping location and pipeline route is shown on the attached work area illustration. The contractor shall accommodate and protect the pipeline route through the Site 15 work area. The PSD is responsible for all supplemental pumping work.

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• No tree cutting shall be performed between June 1st and July 31st at Site 14 or Site 15.

• WVDNR Right of Entry Permit does not allow in-stream work to be performed during the cold-water fish spawning season (September 15-March 31) and warm-water fish spawning season (April 1 – June 30). Spawning waivers may be obtained from the WVDNR Environmental Coordination Unit. Site 14 has received a waiver. The owner will obtain a waiver for Site 15 once the contractors schedule is approved.

• The Mercer County Commission will be performing dredging work in the Site 14 upstream pool area while the reservoir is drained. This work will be managed and sequenced to avoid conflicts with the dam rehab contractor’s work and costs.

• The WVCA Contracting Officer can authorize adjustments to the requirements in this document to facilitate dam safety or water supply needs of the project.

• WVCA Contracting Officer approval is required for all contractor-imposed reservoir changes in pool level or gate operation.

• Rough Grading A of the Site 15 ASW RCC area – this work may be performed to generate fill for Site 14 construction. The grading area shall be between ASW station 25+00 and 27+00.

• Simultaneously B - Concurrent RCC placement at each site is not permitted. If RCC placement is proposed to alternate between sites, the work shall be sequenced to provide time for one quality assurance crew to perform preplacement inspections, during RCC placement inspections, and post placement inspections of a completed lift before moving to the next site.

Estimated Inflow to Site 14 & 15

• Reservoir stage / storage information is included in the attachments.

Attachments

1. Site 14 & 15 Work Area Illustration

2. Site 14 & 15 Sequencing Criteria Chart

3. Reservoir stage storage data

Site 15 2.4 3.6 4.1 3.0 2.0 0.9 0.5 0.4 0.3 0.4 0.6 1.5 Site 14 7.3 11.2 12.7 9.3 6.3 2.8 1.7 1.1 0.9 1.1 1.8 4.7

(MGD) - Million gallons per day

Oct Nov DecMay Jun Jul Aug Sep Estimated Inflow

(MGD) Jan Feb Mar Apr

Sequencing Attachment 11

Downstream Embankment (pool is lowered)2

Upstream Embankment (pool is drained)1 ASW Pool Level Time Limits Water Supply Funding

Downstream Embankment (pool is drained) concurrent work is NOT acceptable concurrent work is NOT acceptable concurrent work is acceptable Site 15 at normal pool Site 14 pool drained

Site 15 is primary water supply na

Upstream Embankment (pool is drained) concurrent work is NOT acceptable concurrent work is NOT acceptable concurrent work is acceptable Site 15 at normal pool Site 14 pool drained

Site 15 is primary water supply na

ASW concurrent work is acceptable concurrent work is acceptable concurrent work is acceptable

(except for simultaneous RCC placement) one pool must be available for water supply at all times

Site 14 or 15 depending on time of year per PSD operations na

Pool Level

Site 14 at normal pool

Site 15 lowered for portions of work2 and limited to a 3-month duration (LD15C)

Site 14 at normal pool

Site 15 drained per time restriction 1 one pool must be at available for water supply at all times one pool must be at available for water supply at all times na Site 14 at normal pool na

Time Limits

Site 15 downstream embankment work to be performed within the same construction season

Site 15- the reservoir draining, upstream riprap berm installation, and riser work must be completed by December

15th(LD15B) na

Site 15 pool may be lowered and drained for portions of the downstream work, refer to CS11.

1,2

All Site 15 work to be completed in 4 or less consecutive construction seasons (LD15A) na

At least $2,800,000 of work at Site 15 shall be completed and approved by September 2028

(LD15D)

Water Supply Site 14 or 15 depending on time of year per PSD operations

Site 14 is primary water supply Site 14 or 15 depending on time of year per PSD operations

Site 15 min pool level to provide water withdraw is elevation

2479.5 which is 10' below normal pool na na na

(LD) Liquidated damages may apply

Si te

All Site 14 work to be performed within 2 or less consecutive construction seasons (LD14A)

The Site 14 upstream and downstream embankment work shall be completed within the same construction season ending

Dec 15th (LD14B)

Site 15 Site 14 & 15

Sequencing Criteria Chart work items criteria w or k ite m s cr ite ria

1 Contractor shall drain pool to perform upstream work at specified time and duration only, refer to CS11.

2 Contractor shall lower pool to perform select downstream work for a limited duration only. Refer to CS11.

Sequencing Attachment 2

Brush Creek Site 14 Stage Storage Curve

Brush Creek Site 15 Stage Storage Curve

Sequencing Attachment 33