(A) All manholes shall be precast concrete. All precast concrete manholes shall conform to ASTM Specification C-478 with joints conforming to ASTM Specification C-443. All manholes shall be a minimum of four feet in diameter.
(B) Sanitary manhole bottom sections shall have the bottom section precast integral with the manhole base. Sanitary manhole fillets shall be poured integral to the manhole base. The fillet shall be sloped to allow drainage from the edge of the manhole invert. Sanitary manhole pipe openings in new manholes shall be A-LOK or approved equivalent. New connections in existing sanitary manholes shall be core drilled and a gasketed flexible watertight connection shall be made using press-seal press-boot, link-seal system or approved equivalent.
(C) Storm sewer manhole bases shall be either precast or cast-in-place reinforced concrete. If using a precast base, it shall conform to ASTM Specification C-478. If using a cast-in-place base, use a minimum 3,000 psi compressive strength. The thickness of the cast-in-place base will be one inch for every two feet of height of the manhole with a minimum thickness of eight inches, with a minimum horizontal dimension of 12 inches greater than the outside diameter of the manhole. Base and manhole weight shall be greater than the uplift force caused by ground water displaced by the manhole. The cast-in-place base reinforcing shall be one-half inch deformed bars so placed to form a grill work of 12 inches squares and placed at the center height of the base. Highchairs or cradles shall be used to hold reinforcing in proper location. Storm manhole fillets may be poured integral to the manhole base or cast-in-place. The fillet shall be sloped to allow drainage from the edge of the manhole invert. Storm manhole pipe openings shall be closed with non-shrink grout collar.
(D) The contractor shall provide pre-cast concrete or manufactured rubber or HDPE adjusting on manholes to place lid at the required elevations. There shall be a minimum of one three-inch adjusting ring per manhole with a maximum height of manhole adjustment rings of 12 inches. External chimney seals shall be installed on all sanitary and storm manholes.
(E) If the vertical separation between the crowns of two connecting pipes in a sanitary manhole is greater than two feet, an interior drop manhole shall be constructed in accordance with the standard drawings. When the difference in elevation between the incoming sewer and the manhole invert is less than 24 inches, the invert should be filleted to prevent solids depositions.
(F) Manhole ring and cover shall be East Jordan Iron Works 1045Z frame with 1040 AGS gasketed lid with E-Pic double concealed pickhole. Manhole casting shall not extend beyond outer edge of manhole. Watertight cover assembles shall be required. Bolt down cover assembles shall be required on manholes subject to surcharging. Bolt down cover assemblies shall be East Jordan Iron Works 1045ZPT frame with 1040 APT gasketed bolt down lid with E-Pic double concealed pickhole.
(G) Contractor shall place a permanent saw cut in concrete curbs adjacent to all manholes located beyond the back of curb. A four-inch by four-inch square shall be sawcut into the curb to mark the manhole location, and the sawcut area shall be spray painted green.