Attachment_1_-_SOW_Grub_Dam_Repairs_0001.pdf

Bureau of Land Management Grub Dam Repairs Statement of Work

I. BACKGROUND:

Grub Dam – NID MT00734 – is located on Little Beaver Creek, a tributary of Willow Creek, approximately 25 miles southwest of Glasgow, Montana. The dam, which was reconstructed in 2022, received damage to the trash rack and low-level inlet piping due to flooding in the spring of 2023.

II. PROJECT LOCATION:

Grub Dam is located in Valley County, Section 35, T: 27N, R: 37E. Coordinates: 48.04260 Latitude,

106.90613 Longitude. Access to the dam is available using public roads.

III. DESCRIPTION OF WORK:

a. Task A: The trash rack on the dam’s principal spillway was damaged during the spring of 2023.

The trash rack was completely detached from the spillway and will need to be replaced as outlined in this statement of work.

b. Task B: Piping from the low-level inlet to the principal spillway was damaged and is in need of repair or replacement. Repair work includes unearthing the existing conduit from the low-level inlet to the 11.25° joint (6-10 feet from low-level inlet) located beneath existing rip rap armoring, removal of any damaged sections of pipe, site preparation, bedding, installation of any new low-level inlet piping, and encasing the piping section in concrete approximately one foot beyond the 11.25° joint.

IV. TASKS

a. Task A: Trash Rack Replacement

* Trash Rack: Basis of Design: 2W Livestock Equipment TR-500, or equal

i. General - Metal Fabrication:

1. Definition: Includes items made from iron and steel shapes, plates, bards, strips, tubes, pipes, and castings which are not a part of structural steel or other metal systems specified elsewhere

2. Submittals:

a. Shop Drawings: Submit shop drawings for replacement trash rack, including dimensions, anchorage connections, and any relevant installation information no later than seven days prior to placing fabrication order.

3. It is the CONTRACTOR's sole responsibility to ensure that the replacement trash rack will fit the existing primary spillway riser pipe.

ii. Materials:

1. Basis of Design: 2W Livestock Equipment TR-500, or equal

2. Finish: Gray powder coating.

3. Metals:

a. Metals, Surfaces, General: For fabrication of miscellaneous metal work which will be exposed to view, use only materials which are smooth and free of surface blemishes including pitting, seam marks, roller marks, rolled trade names and roughness.

b. Steel Plates, Shapes and Bars: ASTM A 36.

c. Structural Steel Sheet: Hot-rolled, ASTM A 1031; or cold-rolled ASTM A 1008, Class 1; of grade required for design loading.

d. Galvanized Structural Steel Sheet: ASTM A 924 of grade required for design loading.

e. Metallic Non-Shrink Grout: Pre-mixed, factory-packaged, ferrous aggregate grout complying with CE CRD-C588, Type M.

f. Non-Shrink, Non-Metallic Grout: Pre-mixed, factory-packaged, non-staining, non-corrosive, non-gaseous grout complying with CE CRD-C621.

Provide grout specifically recommended by manufacturer for interior and exterior applications of type specified in this section.

4. Fasteners: Use fasteners made of same basic metal as fastened metal except use galvanized fasteners complying with ASTM A 153 for exterior steel and aluminum units, unless otherwise indicated. Do not use metals which are corrosive or incompatible with metals joined. Provide fasteners of proper type and size required for application indicated.

5. Grout:

a. Metallic Non-Shrink Grout: Pre-mixed, factory-packaged, ferrous aggregate grout complying with CE CRD-C588, Type M.

b. Non-Shrink, Non-Metallic Grout: Pre-mixed, factory-packaged, non-staining, non-corrosive, non-gaseous grout complying with CE CRD-C621.

Provide grout specifically recommended by manufacturer for interior and exterior applications of type specified in this section.

6. Fabrication:

a. Workmanship: Use materials of size and thickness shown or, if not shown, of required size and thickness to produce strength and durability in finished product. Work to dimensions shown or accepted on shop drawings, using proven details of fabrication and support. Use type of materials shown or specified for various components of Work.

b. Form exposed work true to line and level with accurate angles and surfaces and straight, sharp edges. Ease exposed edges to a radius of approximately 1/32" unless otherwise shown. Form bent-metal corners to smallest radius possible without causing grain separation or otherwise impairing Work.

c. Weld corners and seams continuously, complying with AWS recommendations. At exposed connections, grind exposed welds smooth and flush to match and blend with adjoining surfaces.

d. Form exposed connections with hairline joints, flush and smooth, using concealed fasteners wherever possible. Use exposed fasteners of type shown or, if not shown, Phillips flat-head (countersunk) screws or bolts.

e. Provide for anchorage of type shown, coordinated with supporting structure. Fabricate and space anchoring devices to provide adequate support for intended use.

f. Cut, reinforce, drill and tap miscellaneous metal work as indicated to receive finish hardware and similar items.

g. Galvanizing: Provide a zinc coating for those items shown or specified to be galvanized, as follows:

i. ASTM A 153 for galvanizing iron and steel hardware.

ii. ASTM A 123 for galvanizing iron and steel products Fabricate joints which will be exposed to weather in a manner to exclude water or provide weep holes where water may accumulate.

h. Shop Painting: Shop paint miscellaneous metal work, except members or portions of members to be embedded in concrete or masonry, surfaces and edges to be field welded, and galvanized surfaces, unless otherwise specified.

i. Remove scale, rust and other deleterious materials before applying shop coat. Clean off heavy rust and loose mill scale in accordance with SSPC SP-2 "Hand Tool Cleaning", or SSPC SP-3 "Power Tool Cleaning", or SSPC SP-7 "Brush-Off Blast Cleaning".

ii. Immediately after surface preparation, brush or spray on primer in accordance with manufacturer's instructions, and at a rate to provide uniform dry film thickness of 2.0 mils for each coat. Use painting methods which will result in full coverage of joints, corners, edges and exposed surfaces.

7. Miscellaneous Framing and Supports: Provide miscellaneous steel framing and supports which are not a part of structural steel framework, as required to complete Work.

a. Fabricate miscellaneous units to sizes, shapes and profiles shown or, if not shown, of required dimensions to receive adjacent other Work to be retained by framing. Except as otherwise shown, fabricate from structural steel shapes and plates and steel bars, of welded construction using mitered joints for field connection. Cut, drill and tap units to receive hardware and similar items.

b. Equip units with integrally welded anchors for casting into concrete or building into masonry. Furnish inserts if units must be installed after concrete is placed.

c. Galvanize miscellaneous frames and supports where indicated.

iii. Execution:

1. Preparation: Coordinate and furnish anchorages, setting drawings, diagrams, templates, instructions, and directions for installation of trash rack anchorages, such as concrete inserts, sleeves, anchor bolts and miscellaneous items having integral anchors, which are to be embedded in concrete or masonry construction.

Coordinate delivery of such items to project site.

2. Installation

a. General:

i. Fastening to In-Place Construction: Provide anchorage devices and fasteners where necessary for securing miscellaneous metal fabrications to in-place construction; including, threaded fasteners for concrete and masonry inserts, toggle bolts, through-bolts, lag bolts, wood screws and other connectors as required.

ii. Concrete Repair: repair any concrete damage to the drop inlet structure that was damaged – including from the previous trash rack. Fill in any damage caused by the removal of any previous anchorage points and remove any existing anchors. Restore mounting surface to a flush finish suitable for mounting the new trash rack.

iii. Cutting, Fitting and Placement: Perform cutting, drilling, and fitting required for installation of miscellaneous metal fabrications. Set Work accurately in location, alignment, and elevation, plumb, level, true and free of rack, measured from established lines and levels. Provide temporary bracing or anchors in formwork for items which are to be built into concrete, masonry, or similar construction.

1. Fit exposed connections accurately together to form tight hairline joints. Weld connections which are not to be left as exposed joints, but cannot be shop welded because of shipping size limitations. Grind exposed joints smooth and touch-up shop paint coat. Do not weld, cut or abrade the surfaces of exterior units which have been hot-dip galvanized after fabrication, and are intended for bolted or screwed field connections.

iv. Field Welding: Comply with AWS Code for procedures of manual shielded metal-arc welding, appearance and quality of welds made, and methods used in correcting welding Work.

b. Setting Loose Plates: Clean concrete and masonry bearing surfaces of any bond-reducing materials, and roughen to improve bond to surfaces. Clean bottom surface of bearing plates.

i. Set loose leveling and bearing plates on wedges, or other adjustable devices. After the bearing members have been positioned and plumbed, tighten the anchor bolts. Do not remove wedges or shims, but if protruding, cut-off flush with the edge of the bearing plate before packing with grout. Use metallic non-shrink grout in concealed locations where not exposed to moisture; use non-metallic non-shrink grout in exposed locations, unless otherwise indicated.

ii. Pack grout solidly between bearing surfaces and plates to ensure no voids remain.

iii. Weld non-removable units to supporting members or framework.

c. Adjust and Clean:

i. Touch-Up Painting: Immediately after erection, clean field welds, bolted connections, and abraded areas of shop paint, and paint exposed areas with same material as used for shop painting.

Apply by brush or spray to provide a minimum dry film thickness of 2.0 mils.

ii. For galvanized surfaces: Clean field welds, bolted connections and abraded areas and apply two coats of galvanizing repair paint.

b. Task B: Low-Level Inlet Piping Repair

i. General: Work includes removing existing rip rap armoring the low-level inlet pipe and stockpiling the rip rap material; repair, removal and/or replacement of existing piping (and all related appurtenances) from the low-level inlet to the 11.25° joint, encasing a portion of the repaired or new piping in concrete; and armoring new or repaired piping with salvaged rip rap.

1. Submittals:

a. The following submittals shall be provided to the Government for review no later than seven days prior to the proposed work.

i. Piping material rating and technical data sheets.

ii. Waterproofing products: Provide technical data and material data safety information for waterproof coatings and waterstops.

iii. Proposed concrete mix and admixtures.

iv. Metal reinforcement bar material rating and technical data sheets.

ii. Materials:

1. 24-inch PVC Low-Level Inlet Piping

a. PVC Pressure Pipe: SDR 26, conforming to ASTM D2241 with integral bell joint meeting requirements of ASTM D3139.

b. Rubber Gaskets: Manufactured and tested in accordance with ASTM F477.

c. Watertight Rubber Pipe to Manhole Connector: manufactured of synthetic rubber meeting requirements of ASTM C923. Connector shall be PSX: Direct Drive manufactured by Press-Seal Gasket Corporation, Fort Wayne, IN or approved equal.

2. Concrete:

a. Cementitious Materials:

i. Portland Cement:

1. ASTM C 150, Type V, gray color. Meet equivalent alkalies requirements of ASTM C 150 - Table 2.

ii. Low-alkali Blended Hydraulic Cement in accordance with ASTM C595, Type IS, IP, IL, or IT, designated with special property HS for high-sulfate resistance.

iii. Pozzolan:

1. ASTM C 618, Class C or F. Test for effectiveness in controlling alkali-silica reaction (ASR) under supplementary optional physical requirements in Table 3 of ASTM C 618. Use low-alkali cement for test.

b. Water:

i. Potable water is acceptable without testing. Where non-potable water will be used (wholly or blended with potable water), the water shall comply with ASTM C 1602, including the optional requirements of Table 2.

c. Aggregates:

i. Fine Aggregate: ASTM C 33, except allowable fines content

(material passing No. 200 sieve) less than 3 percent.

ii. Coarse Aggregate: ASTM C 33; nominal maximum size aggregate

(NMSA) as identified in Table 03300A – Mix Design Table.

d. Admixtures:

i. Admixtures are limited to those approved.

ii. Do not use chemical admixtures, which contain more than 0.1 percent chloride, by weight.

iii. Admixtures shall be compatible with each other as certified by the manufacturers or demonstrated through trial batches.

iv. Air-Entraining Admixture shall comply with ASTM C 260.

v. Chemical admixtures shall comply with ASTM C 494, and plasticizing admixtures shall be tested in accordance with ASTM C 1017.

e. Waterstop

i. Hydrophilic waterstop shall be a preformed joint sealant that swells in the presence of water, such as Hydro-Flex Waterstop HF302, or approved equal.

ii. Hydrophobic waterstop shall be a preformed joint sealant that does not swell in the presence of water, such as Synko-Flex Waterstop SF302, or approved equal.

f. Curing Materials:

i. Water: ASTM C 1602, including optional requirements of Table 2 within ASTM C 1602. Curing Compound:

ii. Curing Compound: ASTM C 1315, type II (white pigmented).

iii. ASTM C 309, Type 1-D.

iv. Sheet Materials: ASTM C 171.

g. Bonding Agent:

i. Non-rewettable type for use in water retaining structures.

ii. Available Product: Subject to compliance with requirements, products which may be incorporated into the work include, but are not limited to, the following:

1. "Weld-Crete"; Larson Products

2. "Everbond"; L&M Construction Chemicals

3. "AKKRO 7T"; Euclid Chemical Co.

4. Euco #452 Epoxy System; Euclid Chemical Co.

5. "Daraweld C"; W.R. Grace

6. "Acryl 10"; BASF

h. Reinforcement

i. Reinforcing steel shall be No. 5 bar and shall meet the requirements of ASTM A 615, Grade 60. Store reinforcing steel clear of the ground and protect against rusting and damage. Rust, scale, millscale, or other coating that will destroy or reduce bond is not acceptable. Steel reinforcing shall be furnished in full lengths where practicable. Design, materials, fabrication, and installation shall comply with the requirements of ACI 318, Chapter 7 and Part 4.

ii. Reinforcement Accessories: Tie wire shall be annealed, minimum 16 gauge. Chairs, Bolsters, Bar Supports, and Spacers: Shall each be sized and shaped for adequate support of reinforcement during concrete placement.

iii. Execution:

1. Demolition:

a. Remove overburden/rip rap until the existing low level inlet pipe is exposed between the low-level inlet to past the 11.25° joint, allowing for room to repair any damage to the pipe.

b. Stockpile rip rap armoring the existing low-level inlet piping.

c. In the event any pipe sections need to be removed, discard existing pipe in a manner that does not damage any adjacent structures.

2. Excavation:

a. Water Control/Dewatering: Consists of dewatering around the work area and other water control measures necessary to complete the Work in accordance with this Statement of Work.

i. Any water control efforts shall be approved by GOVERNMENT prior to implementation. Dewatering is an option item for this contract, which may not be required in order to complete work.

ii. Includes all design, equipment, facilities (including, but not limited to pumps, hoses, trenches, dikes, wells, sediment control), and operation required to maintain excavations and work areas free from water. Work includes removal of dewatering facilities upon completion of construction. The CONTRACTOR is responsible to design and maintain all construction water control features to prevent damage to the existing embankment.

iii. No water control features shall be allowed that will in any way impact the integrity of the dam structure. All dewatering methods shall be approved by GOVERNMENT a minimum of seven (7) days prior to implementing.

b. Classification: No classification as to class, nature, or condition will be made of any soil or rock from required excavations or borrow areas.

However, the GOVERNMENT will determine the difference between Common and Muck Excavation. If the CONTRACTOR believes the excavation class has changed, CONTRACTOR shall notify GOVERNMENT.

c. Any muck excavation efforts shall be approved by GOVERNMENT prior to implementation. Muck excavation is an option item for this contract, which may not be required in order to complete work.

d. Backfill unauthorized excavations, excessive soil excavations, muck excavations, unsuitable soil excavations, and excavations for CONTRACTOR convenience with approved materials as determined by the GOVERNMENT, at no additional cost to the GOVERNMENT. This may include importing materials if suitable materials are not available on site.

3. Piping:

a. In the event of damaged piping, install new 24-inch pipe, matching the existing connections, joints, and related appurtenances of existing pipe.

i. Provide watertight rubber pipe to manhole connection meeting

ASTM C923. Press-seal gasket corp. PSX: Direct Drive or approved equal.

b. Pipe shall be installed in a manner that maintains a uniform slope between the controlling invert elevations of adjacent structures.

c. Bedding:

i. Bedding foundation shall be prepared to inhibit differential settlement. Minimum of one foot of ¾-inch minus crushed aggregate base material compacted in two equivalent lifts. Place any additional unused bedding material as directed by the GOVERNMENT in the field using same compaction methods described in this section.

ii. In-place density tests shall be done using AASHTO T310 and shall achieve at least 98 percent of the maximum dry density as determined by AASHTO T180.

iii. Material shall meet the following gradation:

Sieve Size Percent Passing

3/4 inch 100 percent

No. 4 40-80 percent

No. 10 25-60 percent

No. 200 5-20 percent

iv. Any excess bedding material to be placed in a designated location specified by the GOVERNMENT and shaped and compacted by

CONTRACTOR.

d. Formwork:

i. Design, construct, and remove formwork in accordance with ACI

347. Tolerances:

ii. Tolerances are based on the finished concrete surfaces as described in ACI 117.

iii. Prepare for encasing new low-level inlet pipe by setting concrete frames at a minimum distance of 12 inches from the outside edge of the new piping.

e. Concrete

i. Design Mix:

1. In place of a prescribed strength rating (i.e.: 4,000 psi), a 6-sack concrete mix is required for the pipe encasement mix.

a. Water cement ratio shall not exceed 5 gallons per 94-pound sack of cement, inclusive of water in the aggregate.

ii. Hot Weather: In accordance with ACI 305R.

iii. Cold Weather: In accordance with ACI 306.1.

iv. Reinforcing Steel:

1. Concrete piping encasement shall include #5 reinforcement bar at 12 inches O.C. both ways.

2. Reinforcement bar shall be doweled into low-level inlet structure to a depth of one half the thickness of the adjoining structures.

3. A minimum of 3-inch clearance between reinforcing steel and all formwork.

4. Anchoring shall be made using epoxy resin anchoring rated for no load reduction and submersible structures.

a. Basis of Design: Hilti-RE 500 V3 or approved equal.

5. Reinforcement shall be held securely by steel wire, mortar blocks or metal chairs during placement of concrete.

6. Reinforcement shall be securely wired in proper positions and shall be adequately supported before concrete is placed.

7. Steel bars shall have a minimum overlap of 24 inches and splices staggered.

v. Batching, mixing, and transporting

1. Batch, mix, and transport concrete to site in accordance with ASTM C 94. The CONTRACTOR must allow GOVERNMENT access to the batch plant to observe batching operations, sequence of batching, and to confirm batch component tolerances.

2. Chemical admixtures shall be incorporated into the mix in accordance with ACI 212.3R and the manufacture’s recommendations.

3. For hauls longer than 1-1/2 hours, extended set control admixtures may be used as approved during the mix design approval process.

vi. Placement

1. In accordance with ACI 304R.

2. Formwork and concrete placement shall be performed in a manner that maintains the minimum thickness and density of the underlying bedding material.

3. Clean and roughen surfaces of existing concrete to be covered with fresh concrete.

a. Remove laitance, loose, or defective concrete, coatings, sand, curing compound, and other foreign material.

b. Wash surface thoroughly

4. Provide three days advance notification to Government for concrete placement.

5. Before placing concrete, verify that installation of formwork, reinforcement, and embedded items is complete. Government inspection and approval of all formwork and reinforcement is required prior to concrete placement.

vii. Finishing:

1. Formed Surfaces: Below Grade Surfaces: Smooth-form finish as defined in ACI 301

2. Unformed Surfaces and Flatwork: Float finish as defined in

ACI 301 or as otherwise directed by the Government in the field.

viii. Curing:

1. Cure concrete in accordance with ACI 308R

ix. Protection:

1. Protect concrete from damage until final acceptance by the Government and in accordance with any special considerations already outlined in this statement of work.

2. Do not load, remove forms or shoring, or backfill against concrete until concrete has gained sufficient strength to safely support its weight and imposed loads. Minimum cure time shall be three (3) days prior to backfilling. Rip rap backfill shall be placed in a manner that avoids damage to adjacent structures.

3. Protect fresh concrete against erosion from rain, hail, sleet, or snow; contamination from foreign materials; and damage from foot traffic until the concrete has hardened.

4. Protect concrete from heavy foot traffic and other construction activities by covering with plywood or other suitable material. Protect Concrete when Freezing Temperatures are Imminent.

5. Maintain concrete at a temperature of 50 degrees Fahrenheit or greater for 72 hours, minimum, after placement. Vent heater and prevent concrete from drying where artificial heat is employed.

6. When water curing, protect concrete from freezing during. After discontinuance of water curing, maintain at a temperature of 50 degrees Fahrenheit or greater for next 72 hours.

7. Discontinue protection against cold weather such that the drop in temperature of the concrete will be gradual and will not exceed 5 degrees Fahrenheit per hour and 40 degrees Fahrenheit in 24 hours for thin sections, and 5 degrees Fahrenheit per hour and 20 degrees Fahrenheit in 24 hours for massive sections (smallest dimension greater than 36 inches).

V. PAYMENT:

a. Method of Measurement: The cost of any work not listed under a specified bid item shall be accounted for under the cost of the bid items listed in the Bid Schedule and accounted for accordingly to ensure a fully functional product.

i. Trash Rack: Work described for the fabrication and installation of the trash rack shall be made at the Contract price per lump sum bid item.

ii. Bedding Material: Work described under this pay item shall be made at the Contract price per loose cubic yard.

iii. Piping: Work described for piping work shall be made at the Contract price per lump sum bid item.

iv. Concrete: Work described under this pay item shall be made at the Contract price per cubic yard.

v. Common Excavation and Earthwork: Work described for excavation, backfilling and all earthwork requirements deemed acceptable by GOVERNMENT shall not be made under a specific pay item and shall be considered under the cost of other bid items.

vi. Muck Excavation: Work consists of excavation and wasting, as necessary, to remove muck (saturated soil) from the area of the low-level inlet. This work will be an option item based on site conditions and shall be incorporated at the discretion of the Government. If this work is needed, payment will be made at at the Contract price per cubic yard.

vii. Water Control/Dewatering: Work consist of dewatering around the work area and other water control measures necessary to complete the work. This work will be an option item based on site conditions and shall be incorporated at the discretion of the Government. If this work is needed, payment will be made at the Contract price per lump sum.

b. Basis of Payment

i. The accepted quantities will be paid for at the contract price per unit of measurement for the pay item shown in the Bid Schedule. Price and payment shall be full compensation for any demolition, removal, and placement or furnishing of all materials – including all labor, equipment, tools, incidentals, and related appurtenances – necessary to complete the requirements described in this Statement of Work.