Specifications include, but are not limited to: Frames and covers must meet the following Town of Derry specifications. All castings for manhole covers and frames shall be class 30 conforming to the ASTM Standard Specification for Gray Iron Castings, designation A48. Allowances shall be made in the patterns so that specified thickness shall not be reduced. All lids which “Rock” and do not lie solid after construction is finished, shall be rejected and shall be replaced by adequate lids. No plugging, burning-in, or fillings will be allowed. Cover shall fit the frames in any position. All frames and manhole covers are to be manufactured in the United States. All frames and covers shall have an H-20 (8Ton) loading rating. The Total weight of each frame and cover shall be less than 500 pounds. The opening inside diameter shall be 30 inches and the minimum total height shall be six (6”) inches. The covers shall have the letter “S” or the word “SEWER” in (3) inch letters cast into the top.