1 SOW - LITTLE RIO GRANDE BRIDGE REPAIRS AND MAINTENANCE.docx

US Department of Agriculture (USDA) Carson National Forest, Camino Real Ranger District Little Rio Grande Bridge NFSR 439 Repairs and Maintenance Statement of Work (SOW)

Contents

Project Little Rio Grande Bridge NFSR 439 Repairs and Maintenance

General Information

1.0 Scope of Work

The Camino Real Ranger District in the Carson National Forest is seeking repairs and maintenance of the Little Rio Grande Timber Bridge, which is located on National Forest System Road (NFSR 439, Mile Post 3.5) Figures 1 – 6 depict details of the bridge. The work will consist of replacing the wearing surface; removing existing bridge railing/curb and replacing with a crash tested TL-1 curb; substructure, superstructure, and deck treatment; vegetation clearing along wingwalls and approaches; constructing asphalt approaches; removing and replacing existing signs; and placing a riprap mat along the substructure and wingwalls.

Perform construction only during normal working daylight hours Monday thru Friday. Work on weekends or Federal Holidays must be approved in advance by the CO. Clean up work areas/sites and ensure road is passable at the end of each workday. Limit site disturbance, including earthwork and clearing of vegetation. Areas for staging material and equipment will be discussed with the CO at the pre-work meeting.

Bridge Dimensions:

Out-to-Out Width: 15.67-ft Travelway: 13.83-ft Bridge Full Length: 13.67-ft Skew: 30° Contractor is responsible for verifying all dimensions.

2.0 Background

Figure 1: Little Rio Grande Bridge - Downstream Elevation.

Figure 2: Little Rio Grande Bridge - Typical Approach.

Figure 3: Little Rio Grande Bridge Wearing Surface and Deck.

Figure 4: Little Rio Grande Bridge - Structure Underside.

Figure 5: Little Rio Grande Bridge - Upstream Elevation.

Figure 6: Little Rio Grande Bridge - Abutment Undermining.

Contractor Requirements

3.0 Technical Requirements / Tasks

Traffic Control: Provide traffic control adjacent to and within the project location. Submit traffic control plan to the CO and COR for approval. This item is indirectly associated to the project.

Clean Water Act: Work within this section may require a Clean Water Act (CWA) 404 permit in coordination with the U.S. Army Corps. of Engineers (USACE). Contractor is responsible for coordinating permit and/or any reporting requirements.

Deck Treatment: Upon existing wearing surface removal, and prior to installing the new wearing surface, clean all deck exposed members, including all cracks and crevices, to be free of any debris. Surface treat the existing deck surface with conventional liquid wood preservatives applied by brushing, squirting, or spray-flooding the wood surface. Creosote heated to 150 to 200°F, pentachlorophenol (Penta), copper naphthenate (Cu-Nap), or approved equivalents may be used as the primary preservative compounds. Alternate oil-based products may be considered. The Contractor shall submit the proposed preservatives for approval. The wood surface should be thoroughly saturated with preservative so that all cracks and crevices are treated; however, care must be exercised to prevent spilling or running off the surface and contaminating water or adjacent soil.

Superstructure Treatment: Prior to superstructure treatment clean all exposed members, including all cracks and crevices, to be free of any debris. Treat the exposed surface of all stringers using a preservative in semisolid grease or paste. Creosote, Penta, Sodium Fluoride, or approved equivalents may be used as the primary preservative compound. Alternate semi-solid grease or pastes may be considered. The Contractor should submit the proposed preservative for approval. The contractor must prevent any material and/or chemicals from reaching the stream course.

Substructure Treatment: Prior to substructure treatment clean all exposed members, including all cracks and crevices, to be free of any debris. Treat the exposed surface of all substructure elements using a preservative in semisolid grease or paste. Creosote, Penta, Sodium Fluoride, or approved equivalents may be used as the primary preservative compound. Alternate semi-solid grease or pastes may be considered. The Contractor should submit the proposed preservative for approval. Use of semisolid preservatives are preferred at the groundline of piling where they are brushed on the surface several inches above the groundline. Upon preservative application, the treated portion must be wrapped with polyethylene, or other impervious material, to exclude moisture and prevent leaching of the treatment into the surrounding soil. The contractor must prevent any material and/or chemicals from reaching the stream course.

Wearing Surface Replacement:

· Remove the existing timber wearing surface. All removed existing components/material will become property of the contractor and must be hauled off Forest Service land and legally disposed in accordance with State and Local laws. New wearing surface must cover the full travelway width.

· Clean bridge deck: Remove all material/debris from the deck and wearing surface. Removed material/debris must not be allowed to enter the stream.

· Existing Wearing Surface Removal: Remove existing wearing surface minimizing any damage to the deck. Upon removal of wearing surface and fasteners, fastener holes must be treated with preservatives and tightly plugged with treated wood dowels. Drive dowel flush with deck surface (no depression) then treat and seal at surface.

· New Wearing Surface Material: Species such as Douglas Fir-Larch, Hemlock, and Spruce are acceptable. Edge-grain planks are preferred (growth rings form an angle of 45° to 90° with wide surface of the plank).

· New Wearing Surface Treatment: Waterborne preservatives should be used to treat the new timber planks to American Wood Preservers Association (AWPA) use category Ground Contact (UC4A). The following are acceptable waterborne preservatives: Alkaline Copper Quat (formulation A, B, C, or D), Copper Azole (formulation B or C), or Micronized Copper Azole (formulation C).

· New Wearing Configuration: The new timber wearing surface must consist of a series of rough-sawn timber planks placed edge to edge across the deck width. Planks must be 10- to 12-in wide, 2.5- to 3-in thick, a minimum of 8-ft long, and oriented in the direction of traffic. The most economical arrangement is an alternating repetition of longitudinal planks with odd lengths at the bridge ends. End joints in adjacent planks should be staggered by 3-ft minimum as depicted in Figure 7 When seasoned planks are used, a gap of ¼-in must be left between edge joints to allow for expansion. Tight edge joints are used for unseasoned (green) planks. At bridge approaches, bevel plank ends as depicted in Figure 8.

· Deck Attachment: The connection must keep the planks firmly attached. Fasteners should be recessed below the roadway surface. Seal the recessed holes with wood preservative epoxies or approved equivalents. To minimize decay and prevent splitting in the existing deck, all fasteners must be placed in lead holes that are pre-bored and field treated with liquid wood preservative. Connection to the deck must employ 3/8-in diameter, 5.5-in long, zinc plated or hot dipped galvanized lag screws, inserted vertically with a round steel cut washer under the head. Install lag screws using two pre-bored lead holes, see Figure 9, one diameter hole for the shank (1/16-in larger than the shank diameter) and bored to the depth of penetration of the shank. The lead hole diameter for the threaded portion, which is bored at least the length of the threads, should have diameter between 65 to 85% of the shank diameter. Plank attachment pattern is illustrated in Figure 10. When installing lag screws, the threaded portion must be inserted in the lead hole by turning with a wrench.

Figure 7. Plank layout for lumber wearing surface.

Figure 8. Beveled end-plank configuration.

Figure 9. Lag screw attachment details.

Figure 10. Wearing Surface Plank Attachment Pattern – Using Lag Screws.

Bridge Signage: Remove all existing bridge signage (object markers and weight restriction). Furnish and install, at each approach, new Type 3 Object Markers (obstructions adjacent to or within the roadway, OM3-L and OM3-R). Object Markers shall be configured and installed in accordance with the MUTCD, Section 2C.63 and 2C.64. Submit bridge sign layout to CO and COR for approval prior to installation. The minimum mounting height, measured from the bottom of the Object Marker to the near edge of the traveled way, should be 4-ft. Note: All removed material will become property of the contractor and must be disposed of properly.

Brush Approaches and Wingwalls: Remove vegetation and brush, from both approaches that obstruct view of both the bridge and signage. Cut vegetation at six inches from groundline at approaches. Remove all vegetation from wingwall banks as required for riprap placement. Limit site disturbance, remove from Forest Service land and legally dispose in accordance with State and Local laws. The item is indirectly associated to the project.

3.1 Design and Work Items

The following items require design efforts. The designs, calculations and plans must be prepared under the supervision of a Professional Engineer (PE) registered in the State of New Mexico and all design documents must bear the PE seal. Provide design documentation (e.g., calculations and drawings) for approval before beginning any work.

Erosion Control: Provide soil erosion and sediment control by furnishing, constructing, and maintaining devices to eliminate or minimize pollutants and debris from reaching the stream course. Submit soil erosion and sediment control plan for approval before earth disturbing operations begin.

Roadway Bridge Approaches; Asphalt Concrete Pavement: Re-establish both approaches to provide a smooth transition from the road to the bridge wearing surface. Perform roadway excavation and surface preparation to resurface 130-feet both approaches with a compacted layer of aggregate base course (4-in thick) and asphalt concrete pavement (3-in thick). Final pavement shall consist of a single lane road, 14-ft wide with 1-ft shoulders, and 130-ft long at each bridge approach. Pavement transition to bridge wearing surface and existing road must match existing grade. Submit pavement layout and a mix design to the CO and COR for approval prior to construction. Aggregates for base courses and asphalt concrete must meet FP-14 Sections 703.05 and 703.07, respectively. Asphalt concrete mix design must meet FP-14 Section 401. NMDOT approved asphalt concrete mix designs shall be considered and submitted to the CO and COR for approval.

Bridge Traffic Safety Features:

· Remove Existing Bridge Rail and Curb: Upon removal of bridge rail and curb, fastener holes must be treated with preservatives and tightly plugged with treated wood dowels. Drive dowel flush with deck surface (no depression) then treat and seal at surface. Prior to installing the new bridge curb, surface treat the existing deck surface as indicated in the Deck Treatment paragraph above. Note: All removed material will become property of the contractor and must be disposed of properly.

· Furnish and install a timber curb-type bridge railing: Provide a new bridge Crash Tested (MASH TL-1), timber curb-type bridge railing for use on transverse, nail-laminated decks. The West Virginia TL-1 Timber Curb-Type Bridge Barrier might slightly be modified to fit the Little Rio Grande Bridge. Constructability details of the West Virginia TL-1 curb may be found at the following site below. The Contractor shall field verify bridge dimensions and submit for approval for necessary modifications to fit the TL-1 curb in the bridge.

· The minimum height for a TL-1 curb is 18-in, measured from the deck wearing surface. Refer to AASHTO’s LRFD Bridge Design Specifications for additional geometric requirements.

· https://highways.dot.gov/safety/rwd/reduce-crash-severity/hardware-eligibility-letters/safety-eligibility-letter-b-198.

Riprap at Bridge Abutments and Wingwalls: Design a riprap mat to protect the abutments by armoring the approach embankment of the channel in proximity and up to the existing vertical wingwalls. Based on the design, designate the riprap class in accordance with the gradation requirements of FP-14, Table 705-1. To avoid additional channel encroachment, the design should consist of two sections. The riprap section through the abutments should be a keyed riprap, flush with the main channel grade. The second section, extending through the wingwalls, should be placed against the wingwalls to a height 2-ft higher than the design high water (Q100). The minimum riprap thickness at both sections should be twice D50 (median stone diameter). Provide a smooth transition between both sections. A geotextile fabric, Class 1, Type C, meeting the requirements of FP14, Table 714-1, should be used for the riprap protection. Calculations for riprap design should be in accordance with Hydraulic Engineering Circular No. 23, Design Guideline 14 – Rock riprap at bridge abutments. For this bridge, the set-back ratio (SBR) may be assumed to be less than 5 for both abutments. Place riprap in accordance with FP-14, Section 251.

4.0 Government Furnished

All materials and execution of tasks will be the responsibility of the contractor. The Forest Service will provide a review of the deliverables mentioned below.

5.0 Deliverables / Schedule

Tasks and Associated Deliverables: Timely submission of deliverables is essential to successful completing these requirements. Schedules for deliverables are specified in Table 1. Key Deliverables. All deliverables shall be prepared and submitted according to format, content, and schedule described in the SOW. All work shall be accomplished within 180 days of the Notice-to-Proceed.

Table 1. Key Deliverables

6.0 Travel / Project Location

Head southwest on NM-68 S/Paseo del Pueblo Sur from Taos, NM. Turn south on NM-518S/High Road to Taos, continue road for 8.0 miles and turn southeast onto NFSR 439. Continue NFSR 439 for 3.5 miles until you arrive at bridge.

Coordinates of beginning NFSR 439: Latitude: 36.254650; Longitude: -105.581486 Coordinates of Bridge: Latitude: 36.231343; Longitude: -105.590698

7.0 Contractor’s Key Personnel

Contractor shall designate a representative during the duration of the project to coordinate with the Forest Service Contracting Officer (CO).

8.0 Specifications

The specifications used is this contract are found in “Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects” (FP-14), to be consistent with Forest Service and Federal Agency Policies, and the Forest Service Supplemental Specifications (FSSS) included within the contract. FSSS may add to, delete from, or modify the FP-14 Specifications. FSSS are applicable to this project and are included in full text as an attachment. The requirements contained in these specifications are hereby made a part of this solicitation and any resultant contract. FP-14 is available from: http://flh.fhwa.dot.gov/resources/specs/fp-14.htm. FP-14 is found on this site under Home > Resources > Specifications.

Applicable sections include sections listed below and sections or subsections referenced therein.

DIVISION 100 - GENERAL REQUIREMENTS (ALL)

DIVISION 150 - PROJECT REQUIREMENTS (ALL)

DIVISION 200 - EARTHWORK (AS APPLICABLE)

DIVISION 250 - SLOPE REINFORCEMENT AND RETAINING WALLS (AS APPLICABLE)

DIVISION 300 - AGGREGATE AND BASE COURSES (AS APPLICABLE)

DIVISION 400 - ASPHALT PAVEMENTS AND SURFACE TREATMENTS (AS APPLICABLE)

DIVISION 550 - BRIDGE CONSTRUCTION (AS APPLICABLE)

DIVISION 600 - INCINDENTAL CONSTRUCTION (AS APPLICABLE)

DIVISION 700 - MATERIAL (AS APPLICABLE)

Other Applicable References

· Forest Service -Timber Bridges – Design, Construction, Inspection, and Maintenance.pdf (Chapters 11 and 14)

· Manual on Uniform Traffic Control Devices for Streets and Highways https://mutcd.fhwa.dot.gov/

· Forest Service Handbook FSH 7709.56b Transportation Structures Handbook Chapter 70 – Road Bridge Design https://www.fs.usda.gov/cgi-bin/Directives/get_dirs/fsh?7709.56b

· Standard Specifications for Highway and Bridge Construction – Division 400 - SURFACE TREATMENTS AND PAVEMENTS

· https://www.dot.nm.gov/infrastructure/plans-specifications-estimates-pse-bureau/standards/

· AASHTO Roadside Design Guide

· AASHTO Guidelines for Geometric Design of Low-Volume Roads

· AASHTO LRFD Bridge Design Specifications, 9th Ed. 2020 image1.png image2.emf image3.emf image4.emf image5.emf image6.emf image7.png image8.png image9.png image10.png image11.png image12.png