Municipal Design Standards Part 4 – Alleys

4.01 APPROVALS, PERMITS, AS-BUILTS AND MAINTENANCE BONDS:

A. Plans and specifications for public alley improvements must be certified by a professional engineer registered in the State of Iowa and utilize the NGVD of 1929.

B. Plans and specifications for public alley improvements must be reviewed and approved by the City Engineer prior to construction.

C. Other local, state and federal permits may be required, depending on the circumstances. It shall be the responsibility of the Engineer of Record to acquire all applicable permits. A copy of all permits shall be provided to the City Engineer before construction.

D. The Engineer of Record is responsible to submit “Record of Construction” drawings to the City Engineer on reproducible vellum or mylar.

E. A five-year maintenance bond covering defective materials and workmanship is required for all alley improvements.

4.02 ALLEY CLASSIFICATION:

A. A Residential Alley is a route located between local streets used primarily for access to the rear of residential property.

B. A Commercial Alley is a route located in commercial areas used primarily for access to the rear of commercial property.

4.03 RIGHT-OF-WAY WIDTH:

A. The right-of-way width shall be 20 feet for all alleys.

4.04 PAVEMENT WIDTH:

A. Residential alleys shall have a pavement width of 18 feet.

B. Commercial alleys shall have a pavement width of 20 feet.

4.05 ALLEY GRADES:

A. The maximum grade for alleys shall be 12% for residential and 10% for commercial alleys. The minimum grade shall be 0.5% for all types of alleys.

4.06 ALLEY PAVEMENT CROSS SECTION:

A. The pavement shall have a 4% inverted crown cross-section.

4.07 PAVEMENT MATERIAL AND THICKNESS:

A. The pavement slab may be constructed of the following materials:

1. Non-reinforced Portland cement concrete conforming the IDOT specifications C-3 mix or M-3 mix as applicable.

2. Full depth asphaltic concrete hot mix conforming to the IDOT specifications for Type “B” base and Type “A” surface course.

B. Minimum alley pavement thickness:

Portland Cement Concrete 7″(Resident) 8″ (Commercial)
Asphalt Cement Concrete 9″ (Resident) 10″ (Commercial)

4.08 SUBGRADE REQUIREMENTS:

A. The subgrade shall be scarified to a depth of 6 inches below the pavement, and compacted to 90% of Modified Proctor Density.

B. All fill sections shall be compacted to 90% of Modified Proctor Density.