212Structure, Rock, and Wet Excavation

212.1-DESCRIPTION: This work shall consist of the excavation and backfill or disposal of all materials required to be removed for the construction of retaining walls, box culverts, catch basins, drop inlets, manholes, bridge foundations, and other structures for which excavation is not otherwise provided; the removal of all old structures, including abutments, piers and w ingwalls, unless otherwise specified or directed; in accordance with these Specifications and in reasonably close conformity with the lines, grades and typical cross sections shown on the Plans or established by the Engineer. It shall include pumping, draining, sheeting, and constructing cribs and cofferdams if necessary. 212.2-MATERIALS: Select material for backfilling shall be crushed stone, gravel, slag, or any combination thereof meeting the requirements of Section 703. The grading shall be such that 100 percent (100%) of the material passes the 2 inch (50 mm) sieve and 0 to 5 percent (0-5%) passes the No. 16 (1.18 mm) sieve. Any of the standard coarse aggregate sizes from AASHTO No . 4 thro ugh AASHTO No. 8, as shown in Table 703.4, would comply with the above gradation requirement. Controlled low strength material shall meet the requirements of Section 219. Quality Control of select material for backfilling is the responsibility of the Con tractor as specified in 106.1. Engineering fabric shall be fabric for subsurface drainage or separation meeting Subsection

715.11

212.2.1-Quality Control Testing: Quality control of the select material for backfill is the responsibility of the Contractor as specified in Subsection 106.1. The Contractor shall maintain necessary equipment and qualified personnel to perform all sampling and testing necessary to determine the magnitude of the various properties of the material governed by the Specifications and shall maintain these properties within the limits of the Specifications. The Contractor shall submit a quality control plan detailing the methods by which the quality control program will be conducted. This plan, prepared in accordance with the guidelines set forth in the appropriate portions of MP 307.00.50 and MP 717.04.21, shall be submitted to the Engineer at the preconstruction conference. The work shall not begin until the plan is reviewed for conformance with the contract documents. 212.2.2-Acceptance Testing: Quality control sampling and testing performed by the Contractor shall be used by the Division for acceptance. 212.2.3-Sampling and Testing: Frequency of sampling and testing shall be in accordance with the Contractor’s quality control plan. The minimum sampling and testing frequencies for gradation shall be as indicated in Attachment 1 of MP 307.00.50. The material shall be sampled in accordance with MP 700.00.06. The minimum sampling and testing frequency for compaction will be in accordance with MP 700.00.24. 132 212.2.4-Acceptance Procedure: Material conforming to the specification requirements will be accepted at full contract price. Material failing to comply with the quality requirements of Table 704.6.2B shall not be incorporated into the work. Acceptance of the material for compactio n and for gradation shall be in accordance with 212.2.1. 212.2.5-Acceptance Plan: 212.2.5.1-Compaction: Compaction of random material and select backfill material shall meet 212.10. 212.2.5.2-Gradation: The material shall be sampled and tested in a ccordance with

212.2.3Acceptance for gradation shall be based on test results of consecutive random

samples from a lot. A sublot is the quantity of material represented by a single gradation test as defined in MP 700.00.06. A lot shall be considered t he quantity of material represented by an average test value, not to exceed five sublots. In the case where only one sample is needed for the total plan quantity, this sublot shall be considered the lot. The average shall start on the second sample resul t. The average is continued for the third through fifth sample result, averaging all previous sample results. Thereafter, only the last consecutive five sample results will be averaged (i.e., second test value through sixth test value, third test value t hrough seventh test value, and so forth) as defined in MP 300.00.51. When the average test values of a lot and the test value of the last sublot, or when the last three consecutive individual test values of a lot fall outside the limits specified in 212.2, the lot of material represented will be considered nonconforming to the extent that the last of its sublots is nonconforming. When this occurs, the last sublot shall have its price adjusted in accordance with 212.2.5.3. 212.2.5.3-Degree of Nonconformance: When a sublot of material is to have its price adjusted, the percentage point difference between the nonconforming test value and the specification limit shall be determined for each sieve size determined to be nonconforming, and this value shall be multiplied by its appropriate multiplication factor as set forth in Table 212.2.5.3 to determine the degree of nonconformance of that sieve. TABLE 212.2.5.3 Nonconforming Sieve Size Multiplication Factor 2 in. (50 mm) 1.0 No. 16 1.0 The total measure of nonconformance of an individual sublot is the sum of all nonconformance of an individual sieve sizes of that sublot. When the total degree of nonconformance has been established and it is 12.0 or less, the material will be paid for at an adjusted contract price as specified in Table 212.12.1. When the degree of nonconformance is greater than 12.0, the nonconforming sublot shall be resolved on an individual basis, requiring a special investigation by the Engineer to determine the appropriate cou rse of action to be followed. Pending resolution of the matter, additional lifts of select material for backfill shall not be placed over the nonconforming material. 133 CONSTRUCTION METHODS 212.3-GENERAL: The foundation pits shall be excavated according to the outlines of footings as shown on the Plans and shall be of sufficient size to permit the placing of the full width and length of the footing. The Engineer may order, in writing, such changes in dimensions or footing elevations as may be necessary to secure a satisfactory foundation. Structural excavation for pipe culverts and underdrains shall be accomplished in accordance with the sections covering pipe culverts and underdrains. All foundation excavation adjacent to the tracks of any railroad shall be shored, braced and supported as required by the railroad company or the Engineer, and the Contractor will be held responsible for secu ring such information and complying. Plans for this shoring, bracing, and supporting shall be submitted to and shall meet with the approval of the Chief Engineer of the railway company before starting excavation. Bracing, shoring, and supporting excavati on at structures other than railroad tracks shall meet with the approval of the Engineer. 212.4-DISPOSAL OF MATERIAL: The excavated material, unless otherwise directed by the Engineer , shall be utilized for backfill or embankments. Surplus material shall be disposed of in such a manner that the efficiency or appearance of the structure shall not be impaired, and the stream not muddied or obstructed. 212.5-COFFERDAMS: The term cofferdam designates any barrier system that provides a dry, watertight as practicable, area for excavation, inspection or placing concrete. Subject to other requirements in these Specifications, a co fferdam may be constructed of materials including sheet piling, wood, sand bags, earth embankment, etc. or a combination of any of these. Cofferdams shall, in general, be carried well below the bottom of the footings and shall be well braced and as watert ight as practicable. The interior dimensions of cofferdams shall be sufficient to give adequate clearance for the construction of forms and to permit pumping from outside of the forms. When sandy or porous material is encountered in the foundation which renders it impracticable to dewater the excavation before placing masonry, the bottom may be sealed with concrete placed by the tremie method, after which the remainder of the work shall be carried on in the dry. No bracing of any kind shall be left in co fferdams in such a way as to extend in to the substructure masonry without the written permission of the Engineer. Cofferdams shall be removed by the Contractor upon completion of the substructure. 212.6-PUMPING: Pumping from the interior of any foundation enclosure shall be done in such a manner as to preclude the possibility of the passage of water through fresh concrete. No pumping will be permitted during the placing of concrete, or for a period of at least 24 hours, unless it is done with a suitable pump separated from the concrete by a water-tight wall. 212.7-INSPECTION: After an excavation is completed, the Contractor shall notify the Engineer, and no footing, pipe, or other structure shall be placed until the Engineer has approved the depth of excavation, the character of foundation material encountered, and has obtained the necessary foundation measurements. 134 212.8-PREPARATION OF FOUNDATIONS: Rock or other hard foundation material shall be free from all loose material, cleaned and cut to a firm surface, stepped or serrated as directed by t he Engineer. All seams shall be cleaned and filled with concrete, mortar, or grout. Excavation in rock shall be made to the neat lines of the footing as nearly as practicable and the concrete placed against the rock without forming. When masonry is to rest on an excavated surface other that rock, special care shall be taken not to disturb the bearing surface, and the final removal of foundation material shall not be made until just before masonry is to be placed. 212.9-DRAINAGE: Adequate drainage for the backs of retaining walls, abutments and wing walls shall be provided by outlet tile or pipe drains extending through the walls at the ground line or as indicated on the Plans. In case the outlet end of these drains is below the g round line or would be covered by fill material, the drains shall connect to pipe outlets or be extended to the toe of the slope of the fill. When drain pipes are not called for or indicated on the Plans for these drains, the drains shall be constructed t o a minimum sectional area of twenty-four (24) by twenty-four (24) inches and shall consist of sand, crushed stone, or gravel. Excavation and backfilling shall conform to the requirements of this Specification. When underdrains with pipe are shown or in dicated on the Plans and there are bid items for the same, they shall conform to the applicable requirements of Section 606. The back of retaining walls, abutments and wing walls shall have porous drains, one (1) foot thick or as shown on the Plans, placed on the back side of the walls and abutments for the entire length and height of the same, beginning at the elevation of the outlet drains.

212.10BACKFILLING:

Backfill material shall be sui table random material, controlled low strength material or select backfill material. Random material shall be free from particles larger than three (3) inches, frozen lumps, wood, or other extraneous material. Unless otherwise specified in the plans, any of the types of controlled low strength material may be used and shall be an alternative to random material at the contractor’s option. Select backfill material shall be in accordance with All spaces excavated and not occupied by abutments, piers, or other structures shall be backfilled to the surface of the surrounding ground. All backfill, except controlled low strength material, shall be thoroughly compacted by ro lling or tamping as prescribed below and the top surface neatly graded. Random material and select backfill material behind and around abutments, wingwalls, piers, bents, pedestals and all other structures, including those inaccessible to a roller, shall be compacted in layers not to exceed four ( 4) inches after compaction. Controlled low strength material shall be placed according to Section 219. The quality control and acceptance of controlled low strength material shall be in accordance with Section 219. The quality control and acceptance for compaction of random material shall be in accordance with applicable sections of 207 and 716. Five density tests shall be performed for quality control. The target percentage of dry density shall be 95%. Special precautions shall be taken to prevent any wedging action against the masonry and the slope bounding the excavation for abutments and walls. Such condition shall be prevented by stepping or serrating to destroy wedge action. Jetting of fill behind ret aining walls, abutments, 135 and wing walls will not be permitted. Backfill over and around abutments, culverts, arches, and columns shall be brought up uniformly to avoid bending or distortional stresses in the structures, shall be made as soon as practicabl e after forms are removed, and shall be sloped to drain. The four (4) inch layer requirement and compaction for backfill in water will be waived. The testing of backfill compaction, at piers or other structures, which will not become part of an embankment or highway pavement or shoulder area will be waived. Select backfill material shall be placed behind abutments, wingwalls, retaining walls, and box culverts to the dimensions shown on the Plans. The material shall be placed in horizontal layers not to exceed four (4) inches compacted. The quality control testing and acceptance for the select backfill material shall be in accordance with applicable sections of 207 and 716. A lot shall normally consist of the quantity of backfill material required to fil l behind and around abutments, wingwalls, piers, bents, pedestals and all other structures as approved by the Engineer. The select backfill materials shall be tested according to MP 700.00.24. Five density tests shall be performed for quality control. The target percentage of dry density shall be 95%. In all areas where select backfill will contact random material, engineering fabric shall be placed in accordance with the last paragraph of Subsection 207.9.

212.11METHOD OF MEASUREMENT:

The quantity of work done for Item 212001 -*, "Structure Excavation", Item 212002 -*, "Wet Excavation", Item 212003 -*, "Rock Excavation" and Item 212005 -*, "Select Material for Backfilling", will be the number of cubic yards measured. Any additional work beyond the scope of the Plans, authorized by the Engineer, will be measured in cubic yards for the excavated material removed or Select Backfill in place and paid for in accordance with the Subsection and 109.2. Measurement for "Structure Excavation" and "We t Excavation" will be limited to the volume bounded by vertical planes eighteen ( 18) inches outside the neat line of footings and parallel thereto; "Rock Excavation" will be limited to the volume bounded by the neat lines of the footings. When an increase in depth of foundation has been ordered by the Engineer, the excavation for the first five (5) feet or fraction thereof below the elevation shown on the Plans will be paid at the unit bid price. The Engineer may require the Contractor to make excavation to a depth greater than five (5) feet below Plan elevation in accordance with Subsection 104.3. All excavation performed under this section will be classified as "Structure Excavation", except as stated. When the Plans specify "Rock Excavation", all material encountered in the excavation requiring blasting for its removal and all boulders greater the 1/2 cu. yd. in volume will be considered as "Rock Excavation" and be paid for as such. When a quantity of "Wet Excavation" is shown on the Plans, and a normal pool elevation is indicated, excavation below the normal pool elevation, except that classified as "Rock Excavation", will be considered "Wet Excavation" and will be measured below normal pool elevation from the stream bed to the bottom of the footings. The cost of bracing, shoring and supporting excavation adjacent to railroad tracks and other structures shall be included in the unit price bid for "Structure Excavation", "Wet Excavation", or "Rock Excavation". Structural excavation for old structures requiring removal will be limited to the outside dimensions of the structure. Excavation for the d rains specified in Subsection 212.9 will be paid as Item 212001 -*, "Structure Excavation", and the cost of backfilling drains with sand, crushed stone or gravel shall be included in the price bid for "Structure Excavation". 136 Clearing of right-of-way within the construction limits of piers, abutments, retaining walls, etc., and backfilling to the level of the original ground will be included in unit prices bid for "Structure Excavation", except that select material for backfilling will be paid for under Ite m 212005-*. If backfill above original ground is required, material for the backfill will be measured and paid for as prescribed under Sections 207 or 211. The measurement and payment for engineering fabric will be included in the unit price bid for "Select Material for Backfilling". Item 212004-* "Cofferdams", will be measured and paid for each unit complete in place, including their removal, and shall include all labor, materials, and equipment incidental to the construction, pumping and removal. Prog ress payments, determined by the Engineer, may be made.

212.12BASIS OF PAYMENT:

The quantities, measured as provided above, will be paid for at the contract unit price bid for these items, which prices and payments shall be full compensation for furnishing all materials and doing all the work prescribed in a workmanlike and acceptable manner, including all labor, tools, equipment, supplies, and incidentals necessary to complete the work, and also including cost of cofferdams and their removal, except when a separate bid item is provided for Item 212004 -*, "Cofferdams".

.1-Price Adjustment: Select material for backfill not conforming with the

gradation requirements as described in subsection 212.2.5.3 will be paid for at the adjusted contract price base on the degree of nonconformance as specified in Table 212.12.1. TABLE 212.12.1 Adjustment of Contract Price for Gradation not Within Specifications Degree of Nonconformance Percent of Contract Price to be Reduced 1.0 to 3.0 2 3.1 to 5.0 4 5.1 to 8.0 7 8.1 to 12.0 11 Greater than 12 * * The Division will make a special evaluation of the material and determine the appropriate action.

212.13PAY ITEMS:

ITEM DESCRIPTION UNIT 212001-* Structure Excavation Cubic Yard 212002-* Wet Excavation Cubic Yard 212003-* Rock Excavation Cubic Yard 212004-* Cofferdam Each 212005-* Select Material For Backfilling Cubic Yard * Sequence number SECTION 213 THROUGH SECTION 216-BLANK 137