§ 90-266. Construction and placement.

(a)

The requirements of sections 90-236 through 90-263 shall apply as they relate to the placement of manholes.

(b)

Excavation for manholes shall be made with vertical sides and minimum dimensions permitting construction of the manhole. Manholes shall be built to an elevation not less than that of the existing ground surface or as shown on the approved drawings.

(c)

Base sections for precast manholes and for cast-in-place manholes, if approved, shall be placed on bedding rock.

(d)

The bedding rock shall be firmly tamped and made smooth and level to ensure uniform contact and support of the precast structure.

(e)

The precast base shall be carefully placed on the bedding so as to be fully and uniformly supported in true alignment, ensuring that all entering pipes can be inserted at proper grade.

(f)

The first precast section shall be placed and carefully adjusted to true grade and alignment. The sections shall be uniformly supported by the base structure and shall not bear directly on any of the pipes.

(g)

Precast sections shall be placed and aligned to provide vertical alignment with a one-fourth-inch maximum tolerance per five feet of depth. The completed manhole shall be rigid, true to dimensions, and watertight.

(h)

All inlet pipes shall be properly installed so as to form an integral watertight unit. Special care shall be taken to ensure that openings for pipes are provided with watertight connections. For polyvinyl chloride pipe and ductile iron pipe, connections shall conform with ASTM C-923. For concrete pipe, connections shall be made with nonshrink, nonmetallic grout.

(i)

Castings for manhole frames shall be fully bedded in mortar with adjustment brick courses placed between the frame and manhole. Bricks shall be a minimum of two and a maximum of four courses. Mortar shall conform to ASTM C-270, type M. Bricks shall be clay, in conformance with ASTM C-216, grade SW, and shall be 3½ inches in width, eight inches in length, and 2¼ inches in height.

(j)

Castings located in pavement, shouldered areas and sidewalks shall be set flush with grade. Castings located outside of these areas shall be placed a minimum of six inches above grade or at a height specified by the city.

(k)

Manhole flow channels shall be constructed with smooth and carefully shaped bottoms, built-up sides, and benching using cement and brick with no voids. Channels shall conform to the dimension of the adjacent pipe and shall provide changes in size, grade and alignment evenly. Cement shall be Portland type II only.

(l)

All newly constructed manholes shall be cleaned of any accumulation, silt, debris or foreign matter of any kind and shall be free from such accumulations at the time of final inspection.

(Ord. No. 96-2, § 2(58-59), 10-24-1995)