Appendix B: NMCA BD Existing Irrigation System Evaluation

Transcription

1 Appendix B: NMCA BD Existing Irrigation System Evaluation

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3 MEMORANDUM TO: Curt Claeys, PLA, ASLA Anderson Engineering of MN FROM: Robert W Beccard, PE Cullen Kinoshita, CLIA RE: NMCA BRIDGING DOCUMENTS EXISTING IRRIGATION SYSTEM EVALUATION As required by the NMCA Bridging Document Requirements, the existing irrigation system was evaluated to determine corrective actions that are necessary, the Phase 2 expansion project documents were reviewed to identify modifications for the bridging documents and basis of design equipment. This memorandum is to document the findings of the evaluation. Investigative Site Visit An investigative site visit was conducted on August 30, Randy Petersen provided the tour of the cemetery and reviewed the Phase 2 construction documents. The existing irrigation system is an automated drip system. There are no sprinkler irrigated burial sections. The existing water source consists of a 125 GPM groundwater well and pump, a 40,000 gallon holding tank and a 270 GPM booster pump station (three (3) at 90 GPM each). Water is treated to potable water quality. Peak season water use for the existing cemetery is 13,000 GPD. It is estimated that the master planned cemetery expansion (Phases 1-8) will increase the peak season water use by 72,000 GPD. So, at cemetery buildout, the peak season water use is 85,000 GPD. Therefore, assuming an 8 hour watering window, at cemetery build-out the required booster pump flow rate is 370 GPM. The current booster pump flow rate of 270 GPM is exceeded during Phase 4 expansion. At a flow rate of 370 GPM, the existing holding tank will be drained in 1.7 hours. The existing water source has sufficient capacity to provide water to Phases 1-3 of the expansion. At the Phase 4 expansion, the following recommended improvements should be considered: 1. Allow the drip irrigation system to operate beyond an 8 hour watering window. This is a no cost improvement but simply postpones booster pump improvement to a later phase. 2. Increase the amount of stored water by adding a 50,000 gallon holding tank. This would provide a total storage of 90,000 gallons or roughly one day of water at peak season water use at cemetery buildout. 3. Upgrade the booster pumps to provide a flow rate of 370 GPM. This could be done at Phase 4 or assuming the watering window can go beyond 8 hours, this improvement could be postponed until such time that the booster pumps need to be replaced.

4 There are four (4) points of connection and all are sized 2-inch. Each point of connection includes a backflow device, normally closed master valve and flow sensor and has a single irrigation controller. Figure 1 shows an existing point of connection installation, Figure 2 shows a master valve installation and Figure 3 show a flow sensor installation. Figure 1: Point of Connection Installation Figure 2: Master Valve Installation Figure 3: Flow Sensor Page 2

5 The existing controllers are: 1. Section A: Rain Bird ESP-LXME 2. Section B: RainMaster II 3. Section C: Weathermatic 4. Section D: ET Water Photographs of each if these installations are shown in Figure 4. Figure 4: Controller Installations (Section A, B, C, D left to right) Existing problems that require corrective action that were identified and discussed during the site visit are: 1. Controller inconsistency and management 2. Normally closed master valves 3. Drip Irrigation that has been abandoned due to removal of plant material 4. Age of the existing mainline and lateral piping As the cemetery expands, there is a concern about the number of controllers from different manufacturers, total number of stations and the ability to properly manage the entire system. The Rain Bird controller is new and is a replacement for the original controller that recently failed. The RainMaster is also a replacement and was installed several years ago. The Weathermatic controller is the original controller. The ET Water controller is a replacement that was installed in 2015 when the columbarium was expanded. Existing controllers are currently operated as stand alone irrigation controllers, i.e., independent of the other controllers on site. The Cemetery and Pacific District have discussed changing the independent controllers to a centralized irrigation control system. Preferred features of such a system include a cloud based central control system where the data is stored in the control system manufacturer s cloud database; management and data access via tablet or smart phone; flow and water use data storage and graphical reporting; and capable of receiving weather data via internet for automatic ET adjustments. Some of the existing controllers are compatible with central control. Since the existing controllers are from multiple manufacturers, some or potentially all may need to be replaced when central control is implemented depending on the central control system used. Page 3

6 Normally closed master valves are an operational problem because the Flower Water Stations (FWS) are connected to the irrigation system. If the irrigation controller is not operating the master valves are closed so there is no water to the FWS. Currently, to provide water to the FWS, a station on each controller must be turned on during visiting hours. If there is an empty station on a controller, this station is used. If there is not an empty station on a controller, Cemetery staff must identify a zone or zones that can be watered during the day. Operating four controllers in this manner daily is a problem. When the control system is replaced, the intent would be to replace the normally closed master valves with normally open master valves. Replacement is being suggested instead of reconfiguring the valves due to the age of the valves. The normally open master valves would allow water to the FWS without having to turn on the controllers. If a high flow condition were sensed, the master valves would close just like the normally closed master valves. The high flow threshold would be set to allow for FWS operation but to close the master valve if there were a mainline break. Over time, some plant material that was planted in the 1998 construction has been removed due to either plant attrition or the plant material blocked equipment access to the burial sections for second interments. Backhoes used to excavate burials have a turning radius that allows the backhoe to access the burial sections & graves. However, the dumpers that haul dirt away from a specific grave for a second interment and bring it back do not have short turning radius. The dumpers can only drive down the rows of graves with tires in the aisle over the burials between the monuments. Figure 5 shows an area of where the plant material has not been removed. Figure 6 shows an area where shrubs have been removed to allow maintenance access. Figure 5: Example of Original Plant Material Installation Page 4

7 Figure 6: Example of Plant Material Removed for Maintenance Access Where the plant material has been removed, some of the drip emitter tubing has been capped and in other locations it has not. At the locations where the tubing has not been capped, water is being wasted because no plant material is being irrigated. However, in some locations the water may be beneficially used by other plant material such as the remaining trees. It is unknown how many locations where the tubing has not been capped or where the capped tubing might be leaking. As shown in Figure 7, at locations where the drip tubing has not been capped, wet spots appear on the surface. However, Cemetery staff noted that due to soil conditions, there are locations where the water does not surface making it difficult to find the uncapped ends. Figure 8 shows a drip tubing capped end that is leaking due to the tubing splitting upstream the cap. Figure 7: Water Surfacing at Drip Tubing Uncapped Ends Page 5

8 Figure 8: Drip Tubing Capped End Leaking Although this water wastage problem requires corrective action, Cemetery staff would prefer to leave this as an in-house project because the cemetery also has an on-going beautification project. The beautification project strategically replaces plant material that has been removed while allowing maintenance access to burial sections and caps drip tubing where plants will be permanently left out. This project requires an understanding of how each burial section is accessed, the types of plants being used and allows the cemetery to utilize existing staff during the winter. Therefore, continuing this as an in-house project is preferred. Some of the existing PVC mainline and drip lateral piping has begun to fail. Mainline failure has been attributed to pressure surges since the pump was relocated and the VFD controls failed. When the VFD controls are replaced, the mainline breakage issues should be resolved. The Cemetery and a Contractor are currently in discussion regarding replacement of the VFD controls. It is unknown as to what is causing the failure of the PVC drip laterals. Drip lateral is approaching 20 years old and theoretically should have a 25 to 30 year economic life. The future concern is at what point in time will the PVC drip lateral need to be replaced. Review of Phase 2 Construction Documents Irrigation construction documents for the NMCA Gravesite Expansion and Cemetery Improvements Project 914CM3009 were reviewed with Cemetery staff and the following observations are noted: 1. Sheet LI-101: Backflow Preventer Model/Notes say Sized to Demand. Backflow should be sized 2-inch to match tap and future demand. 2. Sheet LI-101-Controller is a Rain Bird ESP-LXMEF: Cemetery noted and irrigation study recommends a Rain Bird ESP-LXD controller to allow all zones in the expansion to be on one controller and to easier facilitate future expansion. 3. Sheet LI-101: Mainline Model/Notes say 2 Class 315: Due to the smaller ID of Class 315 pipe, mainline pipe should be sized 2 ½-inch so that the velocity does not exceed 5 FPS when the 2-inch tap is operated at 70 GPM. 4. LI-102, LI-103, LI-104: Remote Control Valve (RCV) flow rates are less than the minimum flow rate recommended by the manufacturer. Minimum flow for Irritrol 700 Page 6

9 Series valve is 0.1 GPM. Flows less than 0.1 GPM are shown on the plans. Cemetery prefers flows in the 5 10 GPM range per RCV to minimize number of RCVs. 5. LI-103, LI-104: No mainline pipe or control wire stub-outs are provided for the future development. 6. LI-103, LI-104: No spare control wires are specified. Cemetery typically has three (3) spare wires from the controller to each RCV box. 7. LI Flower Water Station (Detail 1): Pressure regulating valve (PRV) is shown upstream the shut-off valve. PRV should be downstream of shut-off valve so that if the PRV fails, it can be worked on without shutting down the entire irrigation system. Cemetery noted and irrigation study recommends a curb stop valve instead of a regular ball valve for the shut-off valve. Cemetery noted and irrigation study recommends that all pipe between valving and faucet be copper. 8. LI-108 Pipe Sleeving at Pavement (Detail 4) Pipe depths should be to top of the pipe. 9. LI-109 P.O.C. Schematic (Detail 2) Manual drain valve is not needed. Size should be shown as 2-inch. 10. Specifications Section 1.8 Testing No mainline test is shown. Cemetery noted and irrigation study recommends the mainline to be tested to 140 PSI due to the pressure surges that are occurring. 11. Specifications Section 2.5 Mainline Components No specifications for the backflow device, master valve and flow sensor are provided. 12. Specifications Section 2.7 Control System No remote is specified. Cemetery noted and irrigation study recommends a hand held remote that is compatible with the Rain Bird controller specified. (Note: If central control system recommendations are implemented, this recommendation can be ignored.) Components for Design/Build Expansion Cemetery maintenance staff noted and irrigation study recommends that the irrigation system for any cemetery expansion be configured like the existing system. Point-of-Connection components should be sized 2-inch. All plant material throughout the site will be drip irrigated. No sprinklers or bubblers. Shrubs and trees must be irrigated on separate zones and where possible each RCV should have a flow of 5 to 10 GPM to minimize the number of RCVs. The following basis of design irrigation equipment is recommended by the irrigation study to remain consistent with the irrigation equipment currently used in the cemetery. Irrigation Satellite Controllers: o Compatible with potential future central control system o Controller enclosure equipped with internal cooling fan to prevent buildup of heat inside the enclosure o Painted desert tan to match the decomposed granite o Located on north side of structures (shade) wherever possible Backflow Prevention Page 7

10 o Reduced pressure backflow device, sized 2-inch o Model: Febco 825YA or equal o Include wye strainer o Include pressure gauge upstream of backflow device o Enclosures to be painted desert tan Master Valve o Normally open, sized 2-inch o Griswold 2230 to match existing Flow Sensing o Compatible with irrigation control system o Sized appropriately for design flows Piping o Schedule 40 PVC mainline and lateral pipe Valves: o Remote control valves Irritrol 700 Series to match existing Quarter turn plastic ball valves for isolation o Quick coupling valves Rain Bird 44NP to match existing Non-potable purple locking rubber covers Drip Irrigation o Multi-outlet and single-outlet drip emitters Bowsmith to match existing o Y-strainers with ball valve for flushing Flower Water Station o Haws Model #6252EHLF Summary of Recommended Improvements For the existing Cemetery, the irrigation study recommends the following corrective actions: 1. Replace existing controllers and enclosures. Replace existing controllers with controllers that are compatible with a central control system. Basis of design is Rain Bird ESP- LXMEF. Replace existing enclosures with enclosures that have an internal cooling fan. Basis of design is Strong Box. 2. Implement a cloud based central control system. Basis of design is Rain Bird IQ-Cloud Version 3.0 control system. One satellite controller will be designated as the Server satellite and communicate to the cloud via cellular cartridge. All other satellite controllers will be designated as Client satellites. Communication between the Server satellite and Client satellites will be via radio. For the NMCA Gravesite Expansion and Cemetery Improvements Project 914CM3009, the irrigation study recommends the following changes: 1. Size Point-of-Connection components as 2-inch 2. Size mainline pipe as 2 ½-inch 3. Redesign laterals for sufficient flow so that RCV operate properly and to reduce the number of RCVs. 4. Provide mainline pipe and control wire stub-out to future development sections. Page 8

11 5. Provide a controller with sufficient capacity for current and future development sections. This could be achieved by redesigning the laterals to reduce the number of laterals and/or changing the type of controller being used. 6. Provide spare wires if a traditional type of controller is used. For future Cemetery expansion projects, the irrigation study recommends: 1. Use an approach and equipment consistent with the existing drip irrigation approach and equipment currently used in the cemetery and listed above. Page 9

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