Specs.pdf

CHIMNEY ROCK FIRE LOOKOUT TOWER REMOVAL

PROJECT PROPOSAL

Purpose:

The purpose of this project is to dismantle, remove, and dispose of the existing Fire Lookout Tower located at the Chimney Rock Archeological Area on the San Juan National Forest. Work also includes construction of a viewing plaza near the visitor information area adjacent to the lower parking lot.

Location:

The Chimney Rock Archeological Area (CRAA) is located approximately 15 miles southwest of Pagosa Springs, CO; specifically 3 miles south of US Hwy 160 on State Hwy 151. The project area is located in portions of sections 17 and 20, T34N, R4W, N.M.P.M.

Existing Conditions:

The base of the tower is constructed of native stone. It is part of the original structure built in 1940. Inside the base, consisting of four walls, is a circular masonry column that serves as a support for the center of the floor framing. This circular column is also constructed of native stone and was constructed inside the tower base in 1975. it is 5'-5" in diameter and 9'-10" tall. The upper timber framed cab structure was built in the late 1980s. It is a wooden structure, approximately 729 square feet in size. The approximate elevation of the Tower is 7,600 feet. See attached photos.

The project area is located in the greater Chimney Rock Archaeological Area, an area where over 200 sites dating to the Pueblo II period have been identified. This Pueblo II community was at its florescence between 900 and 1150 AD. The Pueblo II community at Chimney Rock constitutes one of the largest Pueblo II communities in southwestern Colorado and one of the finest representatives of a Chacoan culture "Outlier." The tower itself is co-located on top of the mesa with the Chimney Rock Great House, a Chacoan Style Great House. Strict adherence to cultural requirements regarding this project will be necessary to ensure that prehistoric cultural resources are not damaged.

Scope of Work:

Based on a study assessing the feasibility of removing the existing Fire Lookout Tower the scope of work at this site includes:

• Disassemble the roof framing from the wall framing of the tower and move in small packages by helicopter to a temporary staging area near the entrance to the site. Staging area to be designated by Contracting Officer. See attached project map.

• Disassemble the four wooden cab walls into small sections and move by helicopter to the temporary staging area.

• Disassemble and remove the floor framing and move by helicopter to the temporary staging area.

Miscellaneous Tower Information:

• Helicopter flights, noise, etc., should be minimized to reduce impacts to falcons in area.

• Crews will access the project area by foot from the upper parking area (a hike of approximately 1A mile).

• As depicted in the attached photos, the tower is located on a narrow ridge.

Landing a helicopter here during removal is not possible.

• Power is not available at the site. Dismantling of the tower will require using hand tools or generator powered tools.

• All work will be conducted in an archaeologically sensitive area. Coordination with Forest Service (FS) archaeological monitors will be required.

• A Forest Service archaeological monitor will be on site during any potentially ground disturbing work to insure that the prehistoric site is not adversely affected.

• All work crews at the site will be educated on archaeological protection measures by the archeological monitor prior to commencing work. The archaeological monitor will assess rocks removed from the structure for possible rock art and retain for Government use.

• A FS archeological monitor will identify any stones to be retained by the FS that need to be transported to the staging area.

• Approximate elevation of staging area: 6,600 feet.

• Approximate distance between tower location and staging area: 1.25 air miles.

• Approximate weight of wooden framed cab structure (roof, walls, floors): 25,000 Ibs.

• Approximate weight of masonry tower base: 160,000 - 180,000 Ibs.

Applicable Notes:

All concrete work shall meet the following requirements:

• 4000 psi 28-day compressive strength concrete.

• Steel reinforcement, AS SHOWN ON THE DRAWINGS.

• Medium broom finish.

• Expansion joints shall be 1/2" bituminous felt and constructed at structure/concrete interfaces.

• 6" thick concrete slab with 4" of CDOT Class 6 bed course.

• Subgrade and base course shall be compacted to 95% of the maximum dry density as determined by AASHTO T-180.

• Comply with Section 03301, Concrete, Formwork and Reinforcement.

Government Furnished Materials:

The Government will provide the following:

• Access to the site and the tower; a Forest Service "Yale" key will be provided for use during duration of contract.

• Copy of feasibility study for removal of tower, upon request.

• Copy of tower drawings, upon request.

• Three 36"w x 24"h interpretive exhibit sign panels.

Disclaimer:

Although individual work items are identified above, it is the Contractor's responsibility to inform himself fully of the conditions relating to the scope of work and to carry out the obligations of the contract and to complete the work described. The exact method, procedure, or means of removal shall be determined by the Contractor.

Payment:

All items are included on the attached bid schedule as lump sum items. Any work or materials required for completion of the identified items shall be considered incidental and no separate payment will be made.

For additional information contact Laurie Yeager at (970) 385-1309 or Wendy Sutton at (970)264-1519.

SECTION 03301

CONCRETE, FORMWORK, AND REINFORCEMENT

PART 1 GENERAL

1.01 SCOPE

A. Applies to cast-in-place concrete, formwork, and steel reinforcement.

PART 2 PRODUCTS

2.01 FORMS

A. Plywood, hardboard, wood, metal, or other approved material to yield the required finish. Free of bulge, warp, or other defects, which would cause blemishes. Forms shall be thoroughly clean.

2.02 STEEL BAR REINFORCEMENT

A. Deformed bars of intermediate grade with minimum yield stress of 40,000 pounds per square inch (psi), conforming to AASHTO M-31, M-42; or M-53; or ASTM A-615, A-616; or A-617, respectively.

2.03 WELDED WIRE FABRIC

A. AASHTO M-32 and M-55 or ASTM A-82 and A-185.

2.04 PORTLAND CEMENT

A. AASHTO M-85 or ASTM C-150, type I.

2.05 AGGREGATES

A. Maximum size 1" for reinforced work and 1-1/2" for non-reinforced. AASHTO M-6 and M-80, or ASTM C-33.

2.06 WATER

A. Clean, fresh, and free from injurious amounts of mineral and organic substances.

2.07 ADMIXTURES

A. Air-entraining admixtures shall conform to ASTM C-260 (AASHTO M-154).

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B. When approved for use, water-reducing admixtures, retarding admixtures, and accelerating admixtures shall conform to ASTM C-494 (AASHTO M-194).

2.08 CONCRETE MIX DESIGN

A. Proportion and mix to obtain concrete of 4,000 psi minimum compressive strength at 28 days. Water/cement ratio shall not exceed 0.46 by weight, including free surface moisture on the aggregates and liquid admixtures. Slump shall not exceed 4" or be less than 1".

B. Add air-entraining admixtures to the concrete mix in an amount to produce for 1" aggregate 6 percent + 1 percent, for 1-1/2" aggregate 5 percent + 1 percent air by volume.

C. Use of other admixtures not permitted unless written approval is obtained from the CO.

2.09 CURING COMPOUNDS

A. Liquid membrane-forming compounds suitable for application on horizontal and vertical concrete surfaces complying with ASTM C-309-74, type I.

2.10 BONDING AGENTS

A. High strength, moisture insensitive, dry or damp cure, epoxy adhesive, Sikadur Hi-Mod as manufactured by Sika Chemical Corp., P.O. Box 297, Lyndhurst, NJ 07071, (201) 933-8801, or approved equal.

2.11 ANCHOR BOLTS

A. Size and type as shown on the drawings and complying with ASTM A-307.

2.12 GROUT

A. Nonshrink Grout: In the liquid state, grout shall show no shrinkage in accordance with ASTM 827-78, and in the hardened state under ASTM C-157-

77. The effective bearing area (EBA) shall be not less than 95 percent. The grout shall have a time of initial set of not less than 60 minutes under ASTM C- 191-74. Perform all grouting in accordance with the manufacturer's published specifications for mixing and placing. All nonshrink grout shall be Five Star Grout as manufactured by U.S. Grout Corp., Old Greenwich, CT 06870, (203) 637-4303, or approved equal.

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2.13 FORM TIES

A. Steel with metal or plastic cone form spreaders, 3/4" minimum back break.

2.14 WATERSTOPS

A. Polyvinyl chloride material; ribbed-centerbulb (expansion joints), flat-ribbed (construction joints), or split-ribbed (expansion/ construction joints), as manufactured by the Vinylex Corp., 2636 Byington-Solway Road, Knoxville, TN 37921, (615) 690-2211, or approved equal.

PART 3 EXECUTION

3.01 FORMWORK

A. Form to shapes, lines, and dimensions shown on the drawings. Brace or tie forms tightly together to maintain position and shape, and to prevent leakage of mortar.

B. Do not remove forms until the concrete has hardened sufficiently to resist damage from removal operations. Construction loads shall not be placed upon, or any forms removed from, the concrete until it has attained sufficient strength to safely support its weight and construction loads.

C. Prior to placing the reinforcing steel, place moisture barrier, if required; clean and seal forms with form oil, form sealer, or an approved non-absorptive liner.

3.02 REINFORCEMENT

A. Bending: Reinforcement shall be bent cold. Do no bend reinforcement partially embedded in concrete. Bend bars and fabric in accord with ACI 318, Chapter 7.

B. Surface Conditions: Reinforcement shall be free from dirt, oil, paint, grease, loose mill scale, and loose or thick rust when placed.

C. Tie all bar-to-bar crossings with wire.

D. Splice welded wire fabric by lapping one grid plus 2" each side.

E. Splice steel bar reinforcement with an overlap of not less than 18".

F. Extend reinforcement through contraction and construction joints.

Reinforcement shall not be extended through keyed joints. Expansion joints shall be reinforced as shown on the drawings, when applicable.

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3.03 PREPARATION FOR PLACING

A. Before placing concrete, complete the formwork; place moisture barrier and expansion joint filler, if required; secure reinforcement; install anchors and other embedded items; and, obtain approval of the entire preparation from the CO.

B. Anchors for fastening equipment arid materials to concrete shall be as shown on the drawings.

C. Anchors and accessories that are required to be cast with the concrete shall be set and maintained in their required positions.

D. Anchors and accessories that are set in concrete after the concrete has set shall be located as shown on the drawings or at such location as to prevent spalling or other damage to the concrete.

E. Finish elevation of anchors shall ensure at least 1-1/2 full threads above the nut when the appropriate accessory is bolted to the anchor.

3.04 PLACING

A. Notify the CO 24 hours in advance of any concrete placing. Do not place concrete except in the presence of the CO. Temperature of fresh concrete at placement shall be between 55° and 80° F.

B. Place only upon clean, damp surfaces free from debris, frost, ice, and water, and never upon mud or dried, porous earth.

C. Consolidate by thoroughly working around reinforcement and embedded items, and into corners of forms, eliminating all air or stone pockets. Method of consolidation shall be approved by the CO.

1. Stop consolidation before any segregation of concrete occurs.

2. Where a surface mortar is to be the basis of the finish, work the coarse aggregate back from the forms to bring a full surface of mortar against the forms without the formation of voids.

3.05 CONCRETE WORK IN COLD WEATHER

A. During cold weather, maintain temperatures of concrete at 70° F for 3 days, or 50° F for 5 days. Do not allow concrete to freeze during the next 4 days.

B. Frozen concrete shall be removed at the Contractor's expense.

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3.06 CONCRETE FINISHING

A. After the concrete has been placed and consolidated, surplus concrete on unformed surfaces shall be struck smooth.

B. Vertical formed surfaces shall be ordinary finish, which is defined as the finish left on the surface after removal of forms, filling all holes left by form ties, and repairing all defects. The surface of ordinary finish shall be true and even, free from stone pockets and depressions or projections.

C. Interior slabs shall be steel trowel finished. Pitch to door or floor drains as indicated on the drawings. Exterior slabs shall be rough broom finished with tooled edges and weak plane joints.

3.07 BAR SUPPORTS

A. Support reinforcing bars and welded wire fabric to prevent displacement by construction loads or placing of concrete.

B. On-the-ground, and when necessary, approved bar supports with sandplates shall be used.

C. Over formwork, approved bar chairs and spacers shall be used.

3.08 CURING AND PROTECTION

A. Regardless of temperature, weather, or season, protect all concrete from premature drying and damage for a period of not less than 7 consecutive days.

Curing may be accomplished by saturating with clean water, or with an approved curing compound, of the surface membrane type, as approved by the

CO.

3.09 GROUTING

A. All voids and honeycombs shall be grouted with cement mortar. All surfaces to receive grout shall be clean and sound. The surface may be dry, damp, or wet, but free of standing water.

B. Prior to placing grout, apply bonding agent to the surface receiving the grout according to the manufacturer's recommendations.

END OF SECTION

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