DEP comments on drainage plans, Oct 1983

NYC 9/11 Public Portal Document

-2- 10) Show the invert elevations for the existing sewer to be replaced at the existing manhole and proposed manhole No. 1.

11) Show rim elevations for the proposed manhole and the existing manhole.

12) Submit hydraulic computations for the capacity of the proposed 30" R.C.P sewer and the existing 4’-0" X 2’-8" egg shaped sewer to be replaced. In the event the capacity of the proposed sewer is less than the eexisting sewer being replaced, computations must be submitted to show that the pro­ posed sewer can handle the runoff from the area according to the drainage criteria of NYCDEP.

The following general notes regarding proposed drainage work should appear on the contract plans:

1) All proposed drainage work should be done in conformance with the latest standards of the Department of Environmental Protection.

2) All existing sewer house connections should be continuously maintained during construction. If any house connection must be disconnected for construction purposes, flow must be maintained by flu ing or other suitable means as directed by the engineer and in such a manner that no back-ups occur. Any and all existing sewers, house connections,or other sewer appurtenances which are to remain, and which must be dis­ turbed for construction purposes, shall be restored to their present condition after completion of the work, and any damage done as a re­ sult of the work shall be repaired at no cost to this department.

3) All existing sewer manholes to be retained within the contract limits should be'adjusted as necessary, so that they will be flush with the finished grades after completion of the work. Any of these manholes which have damaged, worn or non-standard frames and covers should be provided with new 27" castings in accordance with the latest standards of New York City's Department of Environmental Protectioni,''Including aaay necessary modifications of the manhole masonry. Any damage to the manhole caused by this work shall be repaired or replaced by the con­ tractor as directed by the engineer, and at no cost to the City.

4) The requirements of this department regarding clearances to be main­ tained with respect to the water main installation are as follows:

a) For Water Mains Installed Parallel to Sewers: Where the height to the bottom of the sewer is less than 10 feet, the horizontal clearance between the outside of the water main and the centerline of the sewer should be not less than 6.0 feet plus one half the sewer diameter.

Where the depth to the bottom of sewer cradle is ten (10) feet or more, the horizontal clearance between the outside of the water main and the centerline of the existing sewer shall be increased one (1) foot for each additional five (5) ft. of depth over ten (10) feet, or portion thereof. Water Mains Crossing Sewers: Wherever the vertical clearance between the top of the sewer and the bottom of the proposed water main, at their crossing is less than one (1) foot, the water main is to be supported by a truss arrangement and the clearance space is to be filled with layers of compressible material to avoid excessive bearing pressure on the sewer pipe. In no case, how­ ever, should this clearance be less than 6".

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