§ 10-173. Same—Materials and installation.

(a)

Standard specifications.

(1)

All of the materials, methods of the construction, and workmanship for the work covered in reference to stormwater conveyance facility construction shall conform to the most recent edition of the state department of transportation standard specifications.

(2)

Allowable pipe material for all applications in drainage easements and public street rights-of-way, except as specified below, are aluminum-coated (Type 2) corrugated steel pipe (ASP), corrugated aluminum alloy pipe, smooth-lined corrugated polyethylene pipe (HDPE), or reinforced concrete pipe (RCP). Allowable pipe materials are indicated by an "X" in the Table of Allowable Pipe Use below.

(3)

For roads constructed with public funds, either wholly or in part, or roads classified as major thoroughfares, materials which meet the state department of transportation design standards shall be used unless an alternative is specifically approved by the community development director.

(4)

Reinforced concrete pipe (RCP) shall be used under non-local roads when the ADT is greater than 15,000 vehicles per day (vpd). Reinforced concrete pipe (RCP) or smooth-lined corrugated high density polyethylene (HDPE) pipe shall be used under non-local roads when the ADT is less than 15,000 vpd.

The community development director or designee may approve an alternative pipe material.

(b)

Minimum pipe and pipe coating requirements. The type of pipe material used shall be in accordance with the Table of Allowable Pipe Use, standard specifications.

(1)

Reinforced concrete pipe shall be in minimum eight-foot joint lengths. All joints shall be bell and spigot type, with a rubber gasket conforming to ASTM C-443. Pipe shall be manufactured in accordance with AASHTO M-170 and/or ASTM C-76. Class of pipe and wall thickness shall be in accordance with 1030-D, state department of transportation specification, Table No. 1.

(2)

Aluminum-coated (Type 2) steel pipe shall comply with AASHTO M-274 for the coating and AASHTO M-36 for the pipe fabrication. Aluminum alloy pipe shall comply with AASHTO M-196 for material and fabrication.

(3)

Each end of each corrugated metal pipe section, to be joined by a coupling band, shall have a minimum of two annular corrugations. Coupling bands shall be so constructed to lap on an equal portion of each of the pipe sections to be joined. The connecting bands shall have a minimum of two annular corrugations and fully engage, over the entire pipe periphery, one corrugation on each pipe. Bands shall be fabricated from the same material as the pipe. The minimum band gauges for aluminum pipe and aluminized pipe shall be as specified in AASHTO M-196, section 19, and AASHTO M-36, section 9, respectively.

(4)

Gaskets may be required as determined by the city in the field and shall be either sleeve type or O-ring type and shall meet the requirements for gaskets as specified in AASHTO M-36, section 9.3.

(c)

Smooth interior corrugated polyethylene pipe.

(1)

This specification applies to high density polyethylene corrugated pipe with an integrally formed smooth interior (HDPE). HDPE pipe manufacturers shall be approved by the community development director or designee.

(2)

This pipe shall conform to the requirements of AASHTO M-294, Type S.

(3)

Joints shall be as recommended by the manufacturer and approved by the city. Connections shall create a soil tight joint at a minimum and shall use a rubber gasket which conforms to ASTM F-477.

(4)

Installation shall be in accordance with ASTM Recommended Practice D2321, AASHTO section 30, or as specified by the city.

Certification from the manufacturer that the product was manufactured, tested, and supplied in accordance with this specification shall be furnished to the city upon request.

Table of Allowable Pipe Use

Pipe Type		Reinforced Concrete Pipe	Metal Pipe		Plastic Pipe
			Aluminized Type 2 Steel	Aluminum Alloy	Corrugated Polyethylene	Smoothed Lined High Density Polyethylene Type "S"
Specifications (See note 1)		ASTM C76, AASHTO M170	ASTM A760, A929; AASHTO M36, M274	ASTM B744, B745; AASHTO M196, M197, GDT17	AASHTO M252	ASTM F-2306; AASHTO M294(see note 2)
Minimum thickness/class		Per state department of transportation Std. 1030D	Per state department of transportation Std. 1030D	Per state department of transportation Std. 1030D	AASHTO M252	AASHTO M294
Type Installation
Longitudinal		X	X	X		X
Cross drains on road w/over 15,000 ADT	Cross drain < 10 percent slope	X
	Cross drain >10 percent slope	Check w/community development director concerning pipe type to be used when cross-drain < 10 percent and ADT > 15,000
Cross drains on nonlocal road w/less than 15,000 ADT	Cross drain <10 percent slope	X				X
	Cross drain >10 percent slope					X
Cross drains on local road (s/d road) w/less than 15,000 ADT	Cross drain <10 percent slope	X		X		X
	Cross drain >10 percent slope			X		X
Lateral systems		X	X	X		X
Slope drain			X	X		X
Perforated underdrain			X	X	X	X
Dams H &gt 9 feet and V > 20 Ac-Ft		X
Perennial streams		X				X
Minimum allowable design velocity		2.5 fps	2.5 fps	2.5 fps	—	2.5 fps
Maximum allowable design velocity		15 fps	5 fps	15 fps	—	15 fps
Minimum soil pH/resistivity		—	6/1500 ohm/cm	—	—	—
Notes:  1) All pipe materials shall meet the minimum requirements of the state department of transportation's    Standard Specifications Construction of Transportation Systems, most current edition.  2) Allow smoothed-lined HDPE, Type S (AASHTO M294) pipe for storm (longitudinal and cross) and side drain applications   through 48-inch diameter so long as roadway's ADT is less than 15,000 vehicles per day.

 

 

(d)

Backfilling. Backfill for CSP, CAP, and HDPE pipe installations shall be constructed using graded aggregate base or crusher run six inches below the bottom of pipe to 12 inches above the pipe crown. Backfill for RCP pipe installations shall be constructed using graded aggregate base or crusher run six inches below the pipe invert to one-quarter of the pipe diameter. Foundation backfill material shall be used for RCP above one-quarter of the pipe diameter (if graded aggregate base is not used above one-quarter of the pipe diameter) as per Type I or Type II, as specified in sections 812.01 and 812.02 respectively, in state department of transportation Standard Specifications. These materials shall be placed in layers of not more than six inches loose. Compaction of these materials shall be accomplished by hand tamping or machine tamping. Required compaction levels are as follows:

(1)

Within street right-of-way. Backfill within all street rights-of-way shall be compacted to 95 percent maximum density, tested using the AASHTO Method T-99.

(2)

In other areas. Backfill in all other areas shall be compacted to 90 percent maximum density, tested using the AASHTO Method T-99.

(3)

Construction loads and minimum covers. If drainage pipe is installed prior to the completion of grading, a minimum of four feet of fill should be provided where needed to adequately protect the drainage structure during the land development phase, unless the structure itself is designed to withstand the anticipated live load during construction.

(e)

End finish.

(1)

Headwalls or other end treatments are required on all culverts and at the outlet of all piped collection systems. Where ends of pipe are located within, or near, the right-of-way and are parallel, or nearly parallel, with the roadway, safety end sections shall be required when the posted speed limit is 35 mph and over.

(2)

Headwalls are to be precast concrete, stone masonry with reinforced concrete footings, or poured in place, reinforced concrete with reinforced concrete footings. Precast concrete headwalls for corrugated aluminum coated steel pipe or aluminum alloy pipe shall be made with aluminum coated steel or aluminum alloy pipe stubs.

(3)

End treatments that conform to the slope may be pre-cast concrete end sections, aluminum coated steel or aluminum alloy end sections, masonry, PE end sections, reinforced poured-in-place slope collars, or grouted rip-rap. Concrete and metal flared end sections shall conform to applicable state department of transportation Standard Drawing 1120, 1122, or detail D-39.

(f)

Junction boxes and catchbasins. Junction boxes and catchbasins shall have metal manhole frames and lids for access.

(g)

Other structures. Natural bottom arches and box culverts may be used in accordance with the latest standard specifications of the state department of transportation. Bottomless culverts shall require that a scour analysis be done by a registered professional engineer in that field to state department of transportation specifications and standards to ensure the soundness of the proposed structure.

(Ord. of 8-11-2016, § 3.19)