36C78619R0076-003.pdf

MEMORANDUM

July 27, 2018

TO: Brandon Johnson

FROM: JD Leonard, CID

RE: Fort Mitchell National Cemetery Sprinkler Assessment

A site visit was made to the Fort Mitchell National Cemetery on July 18, 2018 to observe the existing cemetery irrigation and interview the staff. This report will document the existing condition of the cemetery irrigation system and make recommendations in the summary according the level of importance.

Water Source:

The existing irrigation water source is two wells which each produce 300 GPM feeding into a 100,000 gallon tank. The tank gravity feeds an adjacent booster pump station consisting of two 40 HP centrifugal pumps and one 5 HP centrifugal pressure maintenance pumps The booster pump station alternates pump starts and produces 400 GPM at 100 PSI. The booster pump discharge is a 6-inch pipe feeding the 6-inch loop around the inside of Fort Mitchell Circle Road. The controls for the pumps are in the pump control building adjacent to the storage tank and are relatively new and in working order.

Storage Tank with Booster Pump In Foreground

It is estimated that the wells take two to four hours by the cemetery staff to fill the 100,000 gallon tank. The calculated peak season daily use is 104,000 gallons. This is acceptable considering the calculated time to fill the tank with each pump delivering 300 GPM is 2.7 hours, therefore the tanks can be filled at a slightly lower rate than the

Memorandum – Fort Mitchell Irrigation Investigation December 19, 2018 booster pump discharge. It is noted that pump #2 is not as deep as pump #1 and delivers iron which is causing staining on the headstones.

Water Use:

Based on the cemetery master plan, it is estimated that a total of approximately 14 acres will be permanently irrigated when the expansion is built-out. The existing cemetery has an irrigated area of 12 acres and the expansion is estimated to have 2 total irrigated acres.

Auburn University has published “Pan Evaporation in Alabama” which includes mean pan evapotranspiration, which can be used with rainfall data from U.S. Climate Data to calculate net irrigation requirement. Net irrigation requirement is the amount of water that must be supplied to meet warm season turfgrass consumptive demands. The data shows that the seasonal rainfall is 33.6-inches, and pan evapotranspiration is 49.2-inches. It should be noted that no irrigation is required in January, February, November and December.

The net irrigation requirement calculation does not include losses that occur due to evaporation, percolation and runoff. To calculate peak season and annual water use, an assumed irrigation operational efficiency of 75% is used. This implies that the irrigation system must apply 39.3-inches annually.

Monthly and annual water use estimates were prepared for the existing and expansion area assuming an annual irrigation application of 39.3-inches. These calculations show that annually the existing area will use approximately 9.61 MG and the expansion area will use 1.87 MG. Total annual water use when the expansion is completed is 11.48

MG.

At peak season in June, the combined cemeteries will require 3.15 MG or 105,000

GPD.

Irrigation pumping systems for cemeteries are typically designed to apply the amount of water required in an 8-hour watering window to minimize conflicts with maintenance operations and visitation. To meet an 8-hour watering window, an instantaneous flow of approximately 340 GPM is required for the combined cemeteries at build-out. The current 400 GPM pump station is adequate for the current and expansion irrigation needs.

Irrigation water use calculations are included in Appendix A.

Irrigation Equipment Mainline pipe. The irrigation mainline pipe is a mix of class 200 PVC and C-900 pipe rated to 150 PSI. The maintenance staff have noted that there have been many pipe repairs from burst pipe and fittings, especially solvent weld fittings. There are no air vacuum relief valves or pressure relief valves noted on the drawings and none were found during the site investigation. As the cemetery staff repairs mainline breaks they are replacing the solvent weld fittings with MJ ductile iron fittings and the pipe is being replaced with C-900 PVC.

Recent Six-Inch Mainline Break With Solvent Weld Fittings

Lateral pipe is believed to be sch 40 with no chronic problems reported.

Mainline Valves There are currently 21 isolation ductile iron gate valves in the system and it is reported that none of them work and are all stuck in the open position. This makes it difficult for the cemetery staff to isolate sections of mainline for repairs resulting in draining the entire system for mainline or valve repairs and long downtime for repairs.

Flower water stations are currently eight self draining yard hydrants on PVC pipe risers attached to the mainline pipe.

Flower water Station

Quick coupling valves are Toro and there were no reported issues.

Irrigation Controller The current system is a Toro Osmac system with one central touch net computer and 5 Osmac satellite controllers. All the satellite controllers have spare capacity, and only two have radio communication with the central control computer at the time of the site visit.

The satellite controllers use conventional wiring consisting of a common ground and individual low voltage control wires to each solenoid valve. The cemetery staff has reported lightning strikes on all the controllers in the past and the grounding and surge protection have not been tested after the lightning strikes.

Satellite Controller

Sprinkler Equipment Toro P-220 solenoid valves are used for remote control valves and do not have individual shut offs.

Sprinklers used are Toro T7P large radius rotary sprinklers spaced at 48’ irrigation aisle spacing x 62’ lateral spacing.

Recommendations in order of importance to provide the new irrigation addition a working infrastructure.

1. Replace the 21 gate valves that do not work.

2. Provide a manual 3-inch drain off the existing mainline at section 12 to drain to daylight above the creek.

3. Provide two 2-inch continuous acting air vacuum relief valves at the high and low points of the system and one 1-inch pressure relief valve at the low point of the system

4. Replace the existing central control system with an updated central control and satellite controllers making easier for the staff to use.

5. If the existing controllers cannot be replaced, we recommend the 5 existing satellite controllers have new grounding rods and surge protectors installed.

The following impact the current cemetery irrigation system operation but will not impact the planned expansion.

1. Replace the existing flower water station hydrants to match the new ADA compliant Haws faucet.

2. Upgrade the remote control system with new radios, this would automatically happen if the central control system were upgraded.

3. Replace the existing irrigation mainline pipe with new CL 200 PVC, ductile iron fittings and joint restraints.

Appendix A