125EXCAVATION FOR STRUCTURES AND PIPE

125-1 Description.

Excavate for box culverts, pipes, retaining walls, headwalls for pipes and drains, catch basins, drop inlets, manholes, and similar structures. Construct and remove cofferdams, sheeting, bracing, etc.; pump or otherwise dewater foundations; remove and dispose of any existing structures or portions of structures not covered by other items in the Contract, including foundations, abutments, piers, wings, and all other materials, obs tructions, etc., found necessary to clear the site for the proposed work; backfill, dispose of surplus material, and perform final cleaning, as may be necessary for the proper execution of the work. This Section does not include excavation for bases or pav ements, curbs, curb and gutter, valley gutter, ditch pavement, or rubble gutter.

125-1.1 Trench Excavation Safety System and Shoring, Special (Trench

Excavation): When performing trench excavation in excess of 5 feet in depth, comply with the Occupational Safety and Health Administration’s (OSHA) trench safety standards, 29 CFR 1926, Subpart P, and all subsequent revisions or updates adopted by the Department of Labor and Employment Security. Ensure that trench boxes are wide enough to accommodate compacti on and density testing. Submission of bid and subsequent execution of the Contract will serve as certification that all trench excavation in excess of 5 feet in depth will be in compliance with Section 553.62, Florida Statutes. Consider all available g eotechnical information when designing the trench excavation safety system. Consider these and any more stringent trench safety standards as minimum Contract requirements.

125-2 Classification.

Consider all materials excavated as unclassified and as exc avation regardless of the material encountered.

125-3 Cofferdams.

125-3.1 Construction:

125-3.1 1 Methods: Construct all foundations by open excavation, and shore,

brace, or protect the foundation openings with cofferdams. Provide cofferdams or cribs fo r foundation construction below the bottom of the footings. Provide sufficient clearance in the cofferdam interiors to permit construction of forms and inspection of their exteriors, and for pumping equipment.

125-3.1 2 Protection of Concrete: Construct cofferdams to protect green

concrete against damage from a sudden rising of the water and to prevent damage by erosion. Do not leave timber or bracing in cofferdams or cribs that extend into the substructure masonry except where permitted in writing by the Engineer.

125-3.1 3 Placing in the Dry: For placing footings in the dry, the Engineer may

require cofferdam sheeting to be driven to an elevation 6 feet below the elevation of the bottom of the footings and require sufficient pumping equipment to dewate r and maintain the cofferdam in a comparatively dry condition. FY 2023-24 Return to Table of Contents

125-3.1 4 Working Drawings: For substructure work, submit drawings showing

the proposed method of cofferdam construction and other details left to choice or not fully shown in the Plans. Obta in the Engineer’s approval of the type and clearance of cofferdams, insofar as such details affect the character of the finished work. For other details of design that do not affect the character of the finished work, assume responsibility for the successf ul construction of the work. Retain a Professional Engineer, registered in the State of Florida, to prepare the above construction drawing, and keep a signed and sealed copy on hand at the site at all times.

125-3.2 Removal: Unless otherwise provided, rem ove cofferdams or cribs, with all

sheeting and bracing, after completion of the substructure without disturbing or marring the finished masonry.

125-4 Excavation.

125-4.1 Requirements for all Excavation: Perform all excavation to foundation

materials, sat isfactory to the Engineer, regardless of the elevation shown in the Plans. Remove rock, boulders or other hard lumpy or unyielding material to a depth of 12 inches below the bottom of pipes and box culverts elevations. Remove muck or other soft material to the depth indicated in the Plans or as directed by the Engineer.

125-4.2 Earth Excavation:

125-4.2 1 Foundation Material other than the Rock: When masonry is to rest

on an excavated surface other than rock, take special care to avoid disturbing the bot tom of the excavation, and do not remove the final foundation material to grade until just before placing the masonry. In case the foundation material is soft or mucky, the Engineer may require excavation to a greater depth and to backfill to grade with ap proved material.

125-4.2 2 Foundation Piles: Where foundation piles are used, complete the

excavation of each pit before driving the piles. After the driving is completed, remove all loose and displaced material, leaving a smooth, solid, and level bed to receive the masonry.

125-4.2 3 Removal of Obstructions: Remove boulders, logs, or any unforeseen

obstacles encountered in excavating. Compensation will be in accordance with the requirements of 4-3.

125-4.3 Rock Excavation: Clean all rock and other har d foundation material, remove all

loose material, and cut all rock to a firm surface. Either level, step vertically and horizontally, or serrate the rock, as may be directed by the Engineer. Clean out all seams, and fill them with concrete or mortar.

125-4.4 Pipe Trench Excavation: Excavate trenches for pipes to the elevation of the

bottom of the pipe and to a width sufficient to provide adequate working room. Remove soil not meeting the classification specified as suitable backfill material in 125 -8.3.2.2, to a depth of 4 inches below the bottom of the pipe elevation. Where the soils permit, ensure that the trench sides are vertical up to at least the mid -point of the pipe. For pipe lines placed above the existing surface , place and compact the embankmen t, prior to excavation of the trench, to an elevation at least 2 feet above the top of the pipe and to a width equal to four pipe diameters, and then excavate the trench to the required grade. For pipe trenches utilizing trench boxes, ensure that the tre nch box used is of sufficient width to permit thorough tamping of bedding material under and around the pipes as specified in 125 -8.1.6. Do not disturb the installed pipe and its embedment when moving trench boxes. Move the trench box carefully to avoid excavated wall displacement or damage. As the trench FY 2023-24 Return to Table of Contents box is moved, fill any voids left by the trench box and continuously place and compact the backfill material adjacent to and all along the side of the trench box walls to fill any voids created by the tr ench box.

125-5 Preservation of Channel.

125-5.1 General: Unless shown in the Plans, do not excavate outside of caissons, cribs,

cofferdams, or sheet piling, and do not disturb the natural stream bed adjacent to the structure. If excavating or dredging at the site of the structure before sinking caissons, cribs, or cofferdams, complete the foundation and backfill all such excavations to the existing surface or other required elevation, with material satisfactory to the Engineer.

125-5.2 Removal of Excavated Materials: Do not allow materials that are deposited

adjacent to the stream area to infiltrate the water areas. Leave the stream in its original condition.

125-6 Disposal of Surplus.

Use suitable excavated materials for backfilling over or around the structure. Dispose of unsuitable materials. Meet the dispos al requirements pertaining to water pollution contained in Section 104 and in 7 -1.1.

125-7 Pumping.

Pump from the interior of any foundation enclosure in such manner as to preclude the possibility of any portion of the concrete materials being carried awa y. Do not pump while placing concrete, or for a period of at least 24 hours thereafter, unless using a suitable pump separated from the concrete work by a watertight wall.

125-8 Backfilling.

125-8.1 General Requirements for Structures and Pipe:

125-8.1 1 General: Backfill in the dry whenever normal dewatering equipment

and methods can accomplish the needed dewatering. A LOT is defined as one lift of backfill material placement, not to exceed 500 feet in length or a single run of pipe connecting two successive stru ctures, whichever is less. Backfill for structures and pipe compacted in one operation will be considered as one LOT within the cover zone. Backfill around structures compacted separately from the pipe will be considered as separate LOTs. Backfill on each side of the pipe for the first lift will be considered a separate LOT. Backfill on opposite sides of the pipe for the remaining lifts will be considered separate LOTs, unless the same compactive effort is applied. Same compactive effort is defined as the s ame type of equipment (make and model) making the same number of passes on both sides of the pipe. For multiple phase backfill, a LOT shall not extend beyond the limits of the phase. When placing backfill within trench box each lift of backfill is consi dered a LOT. Placement of backfill within trench box limits will be considered a complete operation before trench box is moved for next backfill operation. When the trench box is moved for next backfill operation this will start new LOTs for each lift. Fol low the density testing frequency in

125-9.3 1.

125-8.1 2 Equipment and Methods: Provide normal dewatering equipment

including, but not limited to, surface pumps, sump pumps, wellpoints and header pipe and trenching/digging machinery. Provide normal dewa tering methods including, but not limited to, constructing shallow surface drainage trenches/ditches, using sand blankets, perforated pipe drains, sumps and siphons. FY 2023-24 Return to Table of Contents

125-8.1 3 Backfill Materials: Backfill to the existing surface or subgrade surface

of openings made for structures, with a sufficient allowance for settlement. The Engineer may require that the material used for this backfill be obtained from a source entirely apart from the structure. Use only material accepted by the Engineer. Maintain a cl earance of at least 1 foot of clean select soil between recycled concrete aggregate (RCA) and aluminum or metalized drainage pipe. Do not allow heavy construction equipment to cross over culvert or storm sewer pipes until placing and compacting backfill material to the finished grade d surface or to an elevation at least 4 feet above the crown of the pipe.

125-8.1 4 Use of A -7 Material: In the backfilling of trenches, A -7 material may

be used from a point 12 inches above the top of the pipe up to the el evation shown in the Standard Plans as the elevation for undercutting of A -7 material.

125-8.1 5 Time of Placing Backfill: Do not place backfill against any masonry or

concrete abutment, wingwall, or culvert until the Engineer has given permission to do so, and in no case until the masonry or concrete has been in place seven days or until the specified 28 day compressive strength occurs.

125-8.1 6 Placement and Compaction: Place the material in horizontal layers

not exceeding 6 inches compacted thicknes s, in depth above water level, behind abutments, wingwalls and end bents or end rest piers, under the haunches of the pipes and around box culverts and all structures including pipe culverts. When the backfill material is deposited in water, compact as spe cified in 125 -8.2.5 and 125 -8.3.4.

125-8.1 6.1 Thick Lift Requirements: The Contractor may elect to place

material in thicker lifts of no more than 12 inches compacted thickness above the Soil Envelope if the embankment material is classified as Group 1 in the table below. If the embankment material is classified as Group 2 in the table below and the Contractor chooses to place material in thicker lifts of no more than 12 inches compacted thickness above the soil envelope then the Contractor must demonst rate with a successful test section that density can be achieved. Thick lift around structures is only allowed above the soil envelope of the connecting pipe. Notify the Engineer in writing prior to beginning construction of a test section. Construct a tes t section of the length of one LOT. Perform five quality control (QC) tests at random locations within the test section. All five tests must meet the density required by 125 -9.2 and be verified by the Department. Identify the test section with the compacti on effort and soil classification in the Earthwork Records System (ERS) section of the Department’s database. In case of a change in compaction effort or soil classification, construct a new test section. When a QC test fails the requirements of 125 -9.2 or when the QC tests cannot be verified, construct a new test section. The Contractor may elect to place material in 6 inches compacted thickness at any time. FY 2023-24 Return to Table of Contents Table 125-1 Group AASHTO Soil Class Maximum Lift Thickness Thick Lift Control Test Section Requirements Within Cover Zone Above Soil Envelope Within Cover Zone Above Soil Envelope 1 A-3 6 inches 12 inches N/A Not Needed A-2-4 (No. 200 Sieve ≤ 15%) 2 A-1 6 inches without control test section N/A Maximum of 12 inches per

120-8.2 1.2 A-2-4 (No. 200 Sieve > 15%)

A-2-5, A-2-6, A-2-7, A-4, A-5, A-6 A-7 (Liquid Limit < 50)

125-8.2 Additional Requirements for Structures Other than Pipe:

125-8.2 1 Density: Where the backfill material is deposited in water, obtain a

12 inch layer of comparatively dry material, thoroughly compacted by tamping, before verifying the layer and density requirements. Meet the requirements of 125 -9.2.

125-8.2 2 Box Culverts: For box culverts over w hich pavement is to be

constructed, compact around the structure to an elevation not less than 12 inches above the top of the structure, using rapid -striking mechanical tampers.

125-8.2 3 Other Limited Areas: Compact in other limited areas using

mechanic al tampers or approved hand tampers, until the cover over the structure is at least 12 inches thick. When hand tampers are used, deposit the materials in layers not more than 4 inches thick using hand tampers suitable for this purpose with a face area of n ot more than 100 square inches. Take special precautions to prevent any wedging action against the masonry, and step or terrace the slope bounding the excavation for abutments and wingwalls if required by the Engineer.

125-8.2 4 Culverts and Piers: Backfill around culverts and piers on both sides

simultaneously to approximately the same elevation.

125-8.2 5 Compaction Under Wet Conditions: Where wet conditions do not

permit the use of mechanical tampers, compact using hand tampers. Use only A -3 material for the hand tamped portions of the backfill. When the backfill has reached an elevation and condition such as to make the use of the mechanical tampers practical, perform mechanical tamping in such manner and to such extent as to transfer the compaction force into the sections previously tamped by hand.

125-8.3 Additional Requirements for Pipe Greater than 12 Inches Inside Diameter:

125-8.3 1 General: Trenches for pipe may have up to four zones that must be

backfilled. Lowest Zone: The lowest zone i s backfilled for deep undercuts up to within 4 inches of the bottom of the pipe. Bedding Zone: The zone above the lowest zone is the bedding zone. Usually it will be the backfill which is the 4 inches of soil below the bottom of the pipe. When rock or other hard material has been removed to place the pipe, the bedding zone will be the 12 inches of soil below the bottom of the pipe. FY 2023-24 Return to Table of Contents Cover Zone: The next zone is backfill that is placed after the pipe has been laid and will be called the cover zone. This zone extends to 12 inches above the top of the pipe. The cover zone and the bedding zone are considered the Soil Envelope for the pipe. Top Zone: The top zone extends from 12 inches above the top of the pipe to the base or final grade.

125-8.3 2 Mate rial:

125-8.3 2.1 Lowest Zone: Backfill areas undercut below the bedding zone

of a pipe with coarse sand, or other suitable granular material, obtained from the grading operations on the project, or a commercial material if no suitable material is avail able.

125-8.3 2.2 Soil Envelope: In both the bedding zone and the cover zone

of the pipe, backfill with materials classified as A -1, A-2, or A-3. Material classified as A -4 may be used if the pipe is concrete pipe.

125-8.3 2.3 Top Zone: Backfill the area of the trench above the soil

envelope of the pipe with materials allowed on Standard Plans, Index 120-001.

125-8.3 3 Compaction:

125-8.3 3.1 Lowest Zone: Compact the soil in the lowest zone to

approximately match the density of the soil in which the trench was cut.

125-8.3 3.2 Bedding Zone: If the trench was not undercut below the

bottom of the pipe, loosen the soil in the bottom of the trench immediately below the approximate middle third of the outside diameter of the pipe. If the trench was undercut, place the bedding material and leave it in a loose condition below the middle third of the outside diameter of the pipe. Compact the outer portions to meet the density requirements of the acceptance criteria. Place the material in lifts no greater than 6 inches (compacted thickness).

125-8.3 3.3 Cover Zone: Before placing the cover zone material, lay pipe

according to Section 430. Excavate for pipe bells before laying pipe. Place the material in 6 inch layers (compacted thickn ess), evenly deposited on both sides of the pipe, and compact with mechanical tampers suitable for this purpose. Hand tamp material below the pipe haunch that cannot be reached by mechanical tampers. Meet the requirements of in 125 -9.2.

125-8.3 3.4 Top Zone: Place the material in layers not to exceed

12 inches in compacted thickness. Meet the requirements of the density acceptance criteria.

125-8.3 4 Backfill Under Wet Conditions: Where wet conditions are such that

dewatering by normal pumping methods would not be effective, the procedure outlined below may be used when specifically authorized by the Engineer in writing. The Department will pay for any select material which is not available from the grading as Unforeseeable Work. The Department will not pay for select material that might be used by the Contractor for his own convenience instead of dewatering. The Department will permit the use of granular material below the elevation at which mechanical tampers would be effective, but only material cl assified as A -3. Place and compact the material using timbers or hand tampers until the backfill reaches an elevation such that its moisture content will permit the use of mechanical tampers. When the backfill has reached such elevation, use normally accep table backfill material. Compact the material using mechanical tampers in such manner and to such extent as to transfer the compacting force into the material previously tamped by hand. The Department will permit the use of coarse aggregate below the elevation at which mechanical tampers would be effective. Use coarse aggregate as specified in FY 2023-24 Return to Table of Contents Section 901 for Aggregate Size Number 89, 8, 78, 7, 68, 6, or 57. Place the coarse aggregate such that it will be stable and firm. Fully wrap the aggregate with a layer of Type D-4 filter fabric, as specified in Section 985. Do not place coarse aggregate within 4 feet of the ends of the trench or ditch. Use normally accepted backfill material at the ends.

125-9 Acceptance Program.

125-9.1 General Requirements: Meet the requirements of 120 -10, except replace the

requirements of 120 -10.1.6 with 125 -9.1.1, 120 -10.2 with 125 -9.2, and 120 -10.3 with 125 -9.3.

125-9.1 1 Reduced Testing Frequency: Obtain the Engineer’s approval in

writing for the option to reduce density testing frequency to one test every two LOTs or one every four LOTs for trench box operations if the following requirements are met:

125-9.2 Acceptance Criteria:

125-9.2 1 Density: Obtain a minimum QC density in any LOT of 100% of the

Standard Proctor maximum density as determined by FM 1-T099 or the requirements of

125-8.3 3.1 when applicable. When th e cover height below the bottom of base under asphalt

pavement, below concrete pavement, or below unpaved ground, exceeds 15 inches, compact the pipe backfill in the cover zone to a density of at least 95% of the Standard Proctor maximum density as determi ned by FM 1-T099. For density requirements around drainage structures, obtain a minimum QC density in any LOT of 100% of the Standard Proctor maximum density as determined by FM 1-T099 for a distance of one pipe diameter but not less than 3 feet from th e outside face of the structure.

125-9.2 2 Exceptions to Structures and Pipe Density Requirements: Compact

the backfill to a firmness approximately equal to that of the soil next to the pipe trench in locations outside the plane described by a one (verti cal) to two (horizontal) slope downward from the roadway shoulder point or the gutter line in accordance with Standard Plans, Index 120- 001 or 120 -002. Apply 125 -9.2.1 when compacting side -drain pipe backfill under driveways serving a property that is not a single residential lot.

125-9.3 Additional Requirements:

125-9.3 1 Frequency: Conduct Standard Proctor maximum density sampling and

testing at a minimum frequency of one test per soil type. The summary of tests and frequency is shown in Table 125-2 below. FY 2023-24 Return to Table of Contents Table 125-2 Test Name Quality Control Verification Standard Proctor Maximum Density One per soil type One per soil type Density One per LOT One per four consecutive LOTs and for wet conditions, the first lift not affected by water Soil Classification and Organic Content One per Standard Proctor Maximum density One per Standard Proctor Maximum density

125-10 Verification Comparison Criteria and Resolution Procedures.

Meet the requirements of 120 -10.4.

125-11 Site Restoration.

Wherever the existing site is disturbed solely for the purpose of constructing or removing box culverts, pipes, inlets, manholes, etc., completely replace and restore the site to the Engineer’s satisfaction, without additional compensation.

125-12 Cleaning Up.

Upon completion of the work, leave the structure and all adjacent areas in a neat and presentable condition, clear up all temporary structures, rubbish and surplus materials and leave the space under the structure unobstructed and in such shape that drift will not collect nor scour or be induced. Pile all material from existing structures that have been removed neatly on the bank, unless otherwise directed by the Engineer. Pull false work piling unless the Engineer permits it to be cut or broken off i n which case it will be cut or broken off at least 2 feet below the finished grade or stream bed.

125-13 Method of Measurement.

No separate measurement or payment will be made for work under this Section.

125-14 Basis of Payment.

Payment for excavation o f bridge structures will be made under Section 120. Payment for excavation of drainage system items will be incidental to those items. FY 2023-24 Return to Table of Contents SECTION 145 GEOSYNTHETIC REINFORCEMENT

145-1 Description.

This Section specifies the construction requirements for geosynthetics used in: geosynthetic reinforced soil slopes, and geosynthetic reinforced foundations constructed on soft in-situ soils. Furnish and place geosynthetics and any associated facing material or drainage blankets.

145-2 Responsibility.

Construct the geosynthetic reinforced feature, including materials, method, and installation based on information provided in the Contract Documents and the geosynthetic supplier’s recommendations. Submit shop drawings in accordance with Section 5 showing the details and distribution of the selected geosynthetics that meet the design shown in the Plans. Alternate designs optimizing the selected geosynthetic materials may be submitted. For alternate designs, submit complete design calculations and details which include plan view, elevation view, and details in accordance with the Contract Documents. These shall show the extent, numbe r of layers of geosynthetic reinforcement, minimum properties of each geosynthetic reinforcement layer, vertical spacing of geosynthetic reinforcement, orientation of geosynthetic facing details, details at special structures or obstructions, typical const ruction sequence, and top and bottom elevations of the geosynthetic reinforcement. Calculations shall be submitted to substantiate the design meets the requirements of Chapter 263 of the FDOT Design Manual and in accordance with the Plans. As a minimum , these shall clearly show the derivation of reinforcement requirements (i.e., type, spacing, length, etc.) and determination of all design parameters and factors. All plans and calculations are to be signed and sealed by a Professional Engineer registered in the State of Florida.

145-3 Materials.

145-3.1 Geosynthetic Materials: Use materials meeting the requirements of Section 985

and are listed on the Approved Product List (APL) . Deliver geosynthetic materials (including facing and drainage elements) to th e job site in unopened shipping packages labeled with the supplier’s name and product name. During shipping and storage, protect the geosynthetic from physical damage, debris and from temperatures greater than 140°F. Follow the supplier’s recommendations r egarding protection from direct sunlight. At the time of installation, the Engineer will reject the material if it has defects, tears, punctures, flaws, deterioration, or other damage. However, if approved by the Engineer, the Contractor may repair torn or punctured sections by placing a patch over the damaged area. Replace or repair any rejected geosynthetic at no additional expense to the Department.

145-3.2 Backfill Materials: Use only free draining backfill material in the reinforced fill

volume as sho wn in the Plans meeting the following gradation limits as determined in accordance with AASHTO T 27 and FM 1-T011: Table 145-1 Sieve Size Percent Passing 3-1/2 inches 100 FY 2023-24 Return to Table of Contents