Sections:
13-19-001-0001 General Design Criteria
13-19-001-0002 General System Criteria
13-19-001-0001 General Design Criteria
A. Sprinkler irrigation system installation shall be in accordance with MAG Specification 440 unless modified by City of Flagstaff Engineering Standards. Wherever available, preference is given for the use of reclaim water irrigation systems.
1. Irrigation system static pressure range shall not vary by more than ten percent (10%) and shall be designed to provide for a maximum pressure of eighty-five (85) psi.
2. Design irrigation system lateral piping to limit pressure drops to less than twenty percent (20%) of the average sprinkler operation pressure.
3. Install sprinkler heads and nozzle types of the same manufacturer and pressure rating within the same irrigation zone.
4. Zone the irrigation system according to plant water requirements, targeting plants with similar water requirements. Zone trees, shrubs, planting beds, turf and hydroseed areas separately.
5. Integrate existing and new irrigation systems to insure a homogeneous system with balanced coverage. When there is an alteration to an existing irrigation system, test existing mainline, control valves, lateral lines, sprinklers, drip lines and wiring prior to alteration. Perform mainline static and working pressure tests, lateral line working pressure, GPM and coverage tests and circuit continuity testing for control wiring.
6. Design all sprinkler layouts for head to head coverage.
7. Provide matched precipitation rates for sprinklers within the same irrigation zone.
8. Contingent upon soil texture and slope, precipitation rates shall not exceed infiltration rates.
9. Design mainline flow based upon the largest zone GPM plus a single quick coupler at twenty (20) GPM.
10. Design piping with a horizontal layout on slopes. Do not design with elevation changes that exceed the capacity of sprinkler check valves. Compensating emitters shall be required on slopes.
11. Irrigation system as-built plans shall be provided to the Parks and Recreation Division. Preference is for as-built plans to be submitted on compact disc (CD). Provision of as-built plans is a condition of project acceptance.
12. The backflow prevention device shall be tested by a certified tester prior to project acceptance.
13. The contractor shall be responsible for providing and installing all necessary signage for reclaimed water systems. Reclaim work shall comply with Title 18, Chapter 9, Articles 6 and 7 of the Arizona Administrative Code. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-19-001-0002 General System Criteria
A. A manual shutoff ball valve is required to isolate the irrigation system from the water supply main.
B. Provide a quick coupler valve at a maximum distance of two hundred (200) feet throughout the project. Locate quick coupler valves to minimize the necessity of water hoses crossing walkways, driveways and roads.
C. Sprinkler swing assemblies shall be one (1) piece and shall not exceed twenty four (24) inches.
D. Provide two (2) spare control wires to all remote mainline legs. A spare common wire shall be installed through the entire project. A spare hot wire is required to be run to every valve.
E. The ProMax remote controller shall be hard wired into each irrigation controller in accordance with the manufacturer’s written instructions.
F. Provide a three (3) foot loop of irrigation wiring at each valve box.
G. All irrigation wiring shall be contained in adequately sized conduit.
H. Locate valve boxes, valves and quick coupler valves at a minimum of thirty-six (36) inches from hardscape edges.
I. All backflow prevention devices shall be contained in an insulated hot box.
J. Isolation ball valves are required before all electric control valves.
K. A quick coupler is required immediately following the backflow prevention device.
L. A filter is required immediately prior to the backflow prevention device.
M. Strainers are required a minimum of every two hundreds (200) linear feet in the main irrigation line.
N. A surge protection device and quick disconnect box shall be placed before the irrigation controller.
O. A twenty (20) amp breaker is required in the backflow prevention device hot box (for heat tape use).
P. Provide a tee, with a plug facing up, after the water meter and before the backflow prevention device.
Q. Provide a ball valve on the main water line after the curb stop and before the tee with plug. Ball valve and plug shall be contained within the same irrigation box.
R. Emitters shall come off of PVC line and not drip tubing.
S. A manual drain valve shall be placed at the end of the irrigation water main line and at the end of each system line.
T. Telescoping unions (slip fix) shall be placed after the electric control valves.
U. Sleeves are required below sidewalks, driveways, trails, retaining walls, and/or other similar features, and shall extend ten (10) inches past the structures. Sleeves shall be set a minimum of twenty four (24) inches deep.
V. All drip tubing shall be installed at a minimum of three (3) inches deep.
W. The main irrigation line and the irrigation wires shall share the same trench. The trench shall be a minimum of twenty four (24) inches deep.
X. The trench for lateral irrigation lines shall be a minimum of eighteen (18) inches deep.
Y. Trenches shall not be backfilled until all required inspections and tests are performed.
Z. All PVC irrigation lines shall be bedded, shaded and backfilled to four (4) inches above the top of pipe with clean native or fine granular import material, free of clods, stone or other deleterious material, one-half (1/2) inch in diameter or larger. Backfill above the initial backfilling, as described above, shall be clean native or fine granular import material, free of clods, stone or other deleterious material, one and one-half (1-1/2) inch in diameter or larger. In turf areas, the one-half (1/2) inch maximum size of clods, stone or other deleterious material shall apply for all backfill.
AA. Pipe backfilling shall be in six (6) inch maximum lifts, mechanically compacted, to a dry density equal to adjacent undisturbed soils in landscaped areas. Compaction beneath pavements and other hardscape shall be as specified on the plans and/or in the applicable specifications.
BB. Backfill shall conform to the line and elevation of adjacent grades with no surface irregularities.
CC. If settlement occurs, the Contractor shall make all necessary adjustments and repairs to pipes, valves, heads, lawns, plantings and other construction at no cost to the owner.
DD. Irrigation marking tape is required to be installed over the irrigation water main at a nominal depth of twelve (12) inches. (Ord. 2017-22, Rep&ReEn, 07/05/2017)