a__SOW_1305M226Q0042.pdf

Project - Re-Route 8” Seawater Line at Horn Point Laboratory Scope of work Page 1 of 10

Project: Seawater Distribution Line Repair and Reroute

Project location - University of Maryland - Horn Point Laboratory 2020 Horns Point Rd, Cambridge, MD 21613

Background -

NGS installed a new Foundation Continuously Operating Reference Station (FCORS) back in February 2025 and unfortunately during the installation, an existing 8” seawater line was broken (land owner: University of Maryland). This damage wasn’t known until March 25, 2025, when the University started up their seawater pumps for the season and seawater gushed out of the base of the monument of the newly installed Foundation CORS station.

The University was able to isolate the damaged section so they could resume seawater pumping operations for their oyster hatcheries; however, the upstream valve to the damaged section is not holding, and therefore included in this scope is to install a new 8” isolation valve.

Also, in August 2025, the existing 8” PVC line was capped, upstream of the break, as indicated in the figures below

Scope of Work -

(1) The Contractor shall provide all labor, materials, and equipment to perform the following:

● Reroute Distribution Line:

○ Reroute approx. 100 linear feet of the existing 8-inch pressurized seawater distribution line as shown in the figures within this document.

● Field Verification:

○ Contractor to field verify tie-in locations to determine the exact pipe lengths and other buried utilities prior to proposal submission.

● Material Specifications:

○ New piping shall be PVC Schedule 40 pressure-rated pipe.

○ Fittings and valves must be compatible with corrosive seawater environments (e.g., bronze, 316 stainless steel, or specialized PVC).

○ Gravel bed - No. 57 washed, crushed stone.

● Isolation Valve Installation:

○ Install one (1) 8-inch isolation gate valve at the connection point upstream of the current August 2025 cap.

● Thrust Restraints and Pipe Bedding:

○ The contractor is responsible for the design and installation of concrete thrust blocks at all changes in direction, dead ends, and valve locations to prevent joint separation under pressure.

○ Min 6” gravel bed depth

○ Bedding shall be leveled to provide continuous load-bearing support.

Upon pipe placement, stone shall be hand-placed and tamped

● Burial Depth:

○ The existing seawater line is approximately 36 inches below grade. This https://g.co/kgs/hjT4nd1

Scope of work Page 2 of 10 depth should be kept for the new section of pipe.

● Tracer Tape:

○ Install detectable warning tape with the following requirements:

■ Install 6-inch-wide Purple detectable warning tape (min. 5.0 mil thickness with 0.35 mil solid aluminum foil core) at a depth of 12- 18 inches below finished grade.

■ Tape shall bear the legend 'CAUTION BURIED RECLAIMED WATER LINE BELOW' and comply with APWA Uniform Color Codes.

● Site Restoration:

○ Upon completion of backfilling and compaction, the Contractor shall regrade all disturbed areas to match the pre-existing contours

○ Apply a minimum of 4 inches of clean topsoil over all disturbed areas. The soil shall be loosened to a depth of 3 inches and raked to remove stones larger than 1 inch in diameter.

○ Seed area using a "Maryland Certified" Turf-Type Tall Fescue (TTTF) Blend (90–95%) mixed with Kentucky Bluegrass (5–10%)

○ All seeded areas shall be covered with clean, weed-free straw

(2) Site Preparation and Hand-Digging Requirements

● Geodetic Integrity:

○ Work is adjacent to a geodetic control station (Foundation CORS) which is vital to the National Spatial Reference System (NSRS). The station is highly sensitive to motion; any disturbance may result in data invalidation or damage to the station. No mechanical excavation is permitted within 5 feet of the station hardware and braced monument.

● Utility Verification:

○ The Contractor must hand-dig to field-verify the exact locations of the newly installed electrical conduits and the station’s grounding ring prior to laying the new 8-inch pipe.

● Oversight:

○ An NGS representative will be on-site to monitor work in the "sensitive zone."

(3) Work Plan, Compliance, Quality Control

● Installation must comply with the 2021 International Building Code (IBC) and

2021 International Residential Code (IRC) as adopted by Dorchester County.

○ The Contractor shall submit a formal Work Plan to the government for approval prior to mobilization, including the following:

■ Material Summary:

● Detailed list of pipe, valve and other materials used on this project.

■ Testing Protocol:

● A hydrostatic pressure test at 1.5 times the rated working pressure (or as required by local code) held for a minimum of 15

Scope of work Page 3 of 10 to 30 minutes to prove system integrity.

■ Sediment erosion control

● Indicate the mitigation efforts, as required by Maryland Department of the Environment (MDE)

■ Performance Schedule:

● Proposed timeline including the mandatory 5-day notice period.

■ Site restoration measures

(4) Coordination:

(a) The Contractor shall provide five (5) business days' notice to both the NGS and the University of Maryland Horn Point Facilities Office before commencing on-site work.

Support material provided in the following pages

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Figure 1 - Site plan showing existing 8” seawater line, path of new line, location of Foundation CORS and support equipment

Cross section between Foundation CORS and

Downstream tie-in location for new 8” pipe - exact location

Abandon in l i i

F d ti

S t F d ti CORS

New 8” P i d

See cross section below, note -

Newly installed 8” cap (installed 08/2025)

Remove cap

HNP2

Existing 10” storm sewer

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Figure 2 - 1990 Utility site plan - noting location of Foundation CORS station

Location of FCORS

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Figure 3 - Profile view of new Foundation CORS ID: HNP2

Buried conduits and grounding ring with ground d d

Note - geodetic control station’s legs extend approx.

30’ b l

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Figure 4 - Isometric view of the FCORS ID: HNP2 station (not show is the grounding ring and ground rods)

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Figure 5 - NOAA National Geodetic Survey Foundation CORS (FCORS) station ID: HNP2 and location of 8” seawater line break

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Figure 6 - Close up view of the FCORS station leg penetrating the existing 8” PVC seawater line 8”

Fou

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Figure 7 - site conditions, showing new station HNP2 with support electronics in background. Note, buried conduits and grounding ring (with rods) surround the site as noted above

N F d ti

HNP2