1、Placing and protecting fill Fill shall be placed so that mo part of the final foundation surface remains exposed for more than 72 hours. Fill shall be placed in such methods as will prevent segregation of the material. Where the Contract requires the placing of different types of fill in separate zo
2、nes,the Contractor shall carry out the work so as to prebent mixing of different types of fill.Shoud there be ,in the opinion of the Engineer, any excessive mixing of different types of fill , such mixed materials shall be removed to a spoil tip and replaced with fresh fill. Any undesirable material
3、 accumulated on the fill surface shall be removed before placeing the next layer of fill.No fill material shall be placed on a previous layer of that has dried out,become saturated or in any way deteriorated by exposure or by spilling of other material or disterbance by mechanical transport or by de
4、position of wind blown particles or by any other means. Before fresh fill material is placed aoo such deteriorated fill or foreign material shall be removed to a depth at which material of an acceptable standard is exposed. The surface of each layer is to be approved by the Engineer before the next
5、layer is placed. Any fill shall be placed in uniform layers not greater than the approved thickness as specified hereafter and in an orderly sequence approximately horizontal along the centreline of the embankments.Except where specified of directed otherwise, no portion of any embankment shall be s
6、tepped more than 3 feet higher than any immediately adjacent portion except where permitted by the Engineer and the slope formed by such steps shall not exceed 1V:3H and not less than 1V:4H from one level to another.Except as shown on the Drawings or as otherwise directed, all fill placement surface
7、s shall be sloped at right angles to the centerline of the embankment in both the upstream and downstream direction from the downstream edge of the core so as to allow run-off and prevent the accumulation of water. The drainage slope on the temporary surface of anny zone shall not exceed 1 on 30 and
8、 the highest point shall be de downstream edge of the core. Where,due to the specified geometry of the excavation into the top of the existing embankments, the surface slope is towards the downstream edge of the core, the Contractor shall take such measures an necessary to prevent erosion of fine ma
9、terial being washed into the filter zones downstream of the core. Any surface layer of filter material contaminated by such drainage or other cause shall be removed and replaced with fresh filter material before placing the next layer above. Construction of any one embankment shall be carried out ov
10、er the maximum possible length,mo less than 1500 feet,of that embankment in such a manner that mo temporary construction slope crosses the axis of the embankment except as approved by the Engineer. Where a temporary constrction slope crossing the axis of the embankment is permitted by the Engineer i
11、t shall be formed at a gradient of 1V： 5H. When subsequently placeing material against this slope it shall be cut back in steps equal to the layer thickness to avoid feather edges. The Contractor shall complete each layer of fill fully up to the abutment contacts and structures and against sloping f
12、oundations and ensure that the fill is compacted an specified throughout. The Contractor shall not allow the fill in those areas to lag behind or to get ahead of the normal fill placing operations and form feather edges, except where fill has been placed in advance to cover grouted surface. Where th
13、e Contractor is allowed to use either grvel fill and /or sandstone no intermixing of the two materials in a layer shall be allowed. The Constractor may place either of the materials in adjacent layers or sections of the embankment. The Constractor shall be responsible for protecting temporary fill s
14、urfaces against damage of erosion. At the end of each working day,or if it start to rain ,the surface of the fill shall be made smooth and compacted with a smooth drum roller with a drainage slope to induce runoff from the filled areas and leave no areas that can retain water. Where necessary, grips
15、,drainage ditches and the like shall be formed to assist drainage and to prevent runoff from damaging placed material.Runoff from heavy rain shall be controlled to prevent gully erosion of the placed fill. Any gully erosion shall be repaired with material compacted in accordance with the Specificati
16、on, and eroded surfaces shall be restored and graded to ensure a proper bond with new fill placed on them.Any eroded material other than gravel and any contaminated material shall be removed from the embankment and placed in designated spoil tips. In particular the Contractor shall ensure that no ma
17、terial is washed into filter or drain material. Where placing of the filter material of drain material is not continuous ,the Constractor shall protect such filter or drain materials by a 2 foot thick layer of course filter material or in such other manner approved by the Engineer,and the Contractor
18、 shall maintain the protective layer. The Contractor shall keep the work free from standing water to prevent damage to the fill material. When working below the surrounding level, the Contractor shall ensure that material from adjacent areas does not contaminate the fill material,and that runoff doe
19、s not flow onto the fill. The Contractor shall arrange the timing and rate of placing fill material in sucn way that no part of the workes is over stressed,weakened or endangered. Any part of the fill that be comes saturated or attains excessive moisture content or that is rendered unsuitable due to
20、 poor surface drainage, uncontrolled traffic,or for any other reason, shall be excavated and removed to a spoil tip and replaced by fresh fill .If permitted by the Engineer, such fill may be scarified and re-compacted. Unless otherwise approved by the Engineer unrestrained edges of fill, whether for
21、 temporary or permanent slops, shall be overbuilt as necessary to allow full compaction to be achieved within defined limits of the fill. The excess material shall be trimmed and removed to leave a regular compacted surface. Slope exposed to view,including riprap and downstream protection slopes, shall be dressed to neatly appearing final surfaces matching the existing slopes.
