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 se ctions 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 per iod 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 noti fy 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.
135 212.8 -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 r est 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, place d 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%. Spec ial 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,