2008-213 (5) - Laserfiche WebLink

Home Browse Search

abandoned utilities, metal objects, concrete masses or any debris encountered shall be removed. All "materials of excavation" and "unforeseen obstacles" will be considered as incidental to construction and no additional compensation will be allowed. All roots, stumps, logs, limbs, boulders or any material which is not suitable for backfill material shall be removed from the site promptly as excavated and disposed of by the Contractor at his expense. 3) Length of Trench to be Opened - The length of trench to be opened or the area of surface to be disturbed and unrestored at any time will be limited by the Engineer with regard to expeditious construction and the convenience of the Owner. Excavation shall not advance more than 100 feet ahead of the pipe laying without the consent of the Engineer. 4) Sheeting and Bracing - The Contractor shall be responsible for properly supporting the sides of all trenches and excavations with timbers or other supports wherever necessary or required to properly safeguard the trenches, adjacent properties and structures and at restricted right-of-way. The cost of all necessary timber, sheeting and bracing whatsoever (left in place or removed), shall be included in the unit prices bid for mainlines. Portions of the timber sheeting driven below the elevation of the top of the pipe shall not be disturbed or removed. Timber sheeting and bracing shall be left in place if so ordered by the Engineer and/or where shown on the Plans to avoid undermining or otherwise endangering the work or adjacent structures. All sheering left in place shall be cut off or driven at least 18 -inches below finished grade, unless otherwise ordered. Great care shall be exercised in the selection of sheeting and bracing of adequate design, type, size and strength. The adequacy of the timber used for all supporting and bracing purposes shall be the responsibility of the Contractor, who shall use only men of seasoned experience for this type of work. The sizes and lengths of the timber used shall conform closely to the needs of the work and oversizing as well as undersizing should be avoided. In placing and driving the sheeting, proper workmanship and equipment shall be used to achieve a true alignment and close contact of the sheeting boards. Timber sheeting shall be straight and sound, free from shakes, cracks, large or loose knobs and other defects impairing its strength and durability. It shall be squared to the required dimension throughout its entire length. If required for the proper execution of the work where running sand, quicksand or other semifluid material difficult to handle is encountered, the timber sheering shall be tongue and groove. The Contractor may, in lieu of sheeting, bracing and shoring to maintain the allowable trench widths, use a "trench box" ("trench shield" or "mule") provided pipe sections are secured downstream by a cable(s) stretched through and secured to the end section of pipe by means of a timber and a cable clamp, all materials being of adequate size and strength. The cable shall be held taut during the process of advancing the "box". 02534 - 5 02534— Sanitary Sewer Force Mains