Seven Oaks Irrigation System Analysis Report

Seven Oaks Irrigation System Analysis Report

SEVEN OAKS COUNTRY CLUB BAKERSFIELD, CALIFORNIA

Introduction The purpose of this report is to present an assessment of the current condition and expected remaining service life of the irrigation system at Seven Oaks Country Club. The information in this report is based on an analysis of record drawings of the irrigation system, discussions with the maintenance staff, visual observations during a site visit and catch can testing performed to evaluate the distribution uniformity of the sprinklers. Background The irrigation system covered in this report was completed in two phases. The original 18 holes were opened in 1990. This course covers approximately 133 acres of irrigated turf. The west 9 was opened around 2000 / 2001 and covers about 100 acres of irrigated turf. Depending on the design, the quality of the materials used, the quality of the installation and how the system has been operated, an irrigation system generally last between 15 and 30 years, with 20 being the average, before major upgrades or complete replacement are required. Because the overall irrigation system is made up of component parts and sub-systems, some parts or sub-systems wear out sooner than others. These components and sub-systems will be discussed in more detail in this report. Water Source and Water Requirement The primary water source for the entire 27 holes is supplied by a well that is located immediately adjacent to the pump stations. The reported capacity of the well is 3000 gpm however when the pump was started during our visit, it only registered 1500 gpm on the flow meter. We presume the well was dug during the original construction in 1990. It was upgraded in 2014 with a new well casing and a deeper set. There is also a backup supply from a city water meter adjacent to the maintenance yard that has a 6” backflow preventer. Although we do not know the exact meter size, based on the backflow size, we estimate that this source should be able to provide up to 1000 gpm. The city water meter has not been used for at least the last 5 years.

We prepared an estimated water requirement by month for each course. This is included at the back of this report as Attachment 1.

PO Box 2949

PO Box 2243

Newport Beach, CA 92659

Leander, TX 78646

Bryant Taylor Gordon Golf

11/27/19

The average peak water requirement for the original 18 holes is approximately 850,000 gallons per day (gpd) and the average peak water requirement for the west 9 is approximately 640,000 gpd for a total of just under 1.5 million gallons on an average peak day. It should be noted that absolute peak requirements may exceed this on extremely hot days. At the observed flow of 1500 gpm from the well, it can deliver a maximum of just over 2 million gallons per day which should be adequate for the anticipated average peak requirement, but on an absolute maximum day this may fall short, and it has been reported that from time to time the well cannot keep up with the irrigation demand resulting in the main irrigation lake level dropping. From past discussions with well pump professionals, we have been told that a well pump should not be run for more than 23 hours in any given 24-hour period, so at 1500 gpm, you should not expect to get much more than 2,070,000 gpd from the well. This is intended to protect the pump motor and allow the well to recover. Pumping Stations There are two pump stations that supply the irrigation systems for Seven Oaks. One station was installed with the original 18 holes, and the second station was installed to supply the west 9 holes. These pump stations are not interconnected to the best of our knowledge. Both pump stations are located in the maintenance yard. They both appear to be Flowtronex/PSI stations and are both pretty much original equipment dating back to the original installations. Both are located out in the open without any protection from the elements. At an estimated 30 years old, the pump station for the original 18 has considerably exceeded its expected life span of 15-20 years (See Attachment 2). The station has an upgraded control panel which was installed in 2017 and it was reported that two of the pump motors have been either repaired or rewound in the past (one was replaced in 2015, the other in 2017). The upgraded control panel included a new Variable Frequency Drive (VFD) that controls the pump speed. Undoubtedly, these repairs and upgrades have allowed the station to survive as long as it has. The pump station configuration for the original 18 has (3) 75 hp motors and (1) 40 hp motor for a total of 265 hp. The discharge pressure is set to 115 psi. Generally, the 75 hp motors are intended to run during the night time irrigation cycle and the 40 hp motor is intended to provide the ability to water during the day without starting a larger horsepower motor. The 40 hp motor may also run during night time irrigation as well. By our calculations, this station should be able to produce approximately 2800 gpm. If the 40 hp motor is excluded from the mix, the total may be somewhere around 2300 gpm.

The capacity of the station for the original 18 is currently set to 2000 gpm in the irrigation control system computer program. Based on the average peak irrigation

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requirement, this should be capable of completing an irrigation cycle in approximately 9.5 hours. At 2300 gpm, the water window could potentially be reduced to around 8.5 hours and at 2800 gpm, the water window should be just over 7 hours. Due to its age, the pump station may not currently be capable of producing the originally designed 2800 gpm capacity at the designed pressure point. The design point for the west 9 pump station is 2400 gpm at 100 psi as is indicated on the Serial Number plate on the front of the station control panel. Currently the pump station is set to operate at 1500 gpm in the control system computer and the discharge pressure has been increased to 110 psi in the pump control software. The 1500 gpm setting should allow an average peak irrigation cycle to be completed in about 10 hours. At the full station capacity of 2400 gpm, the average peak irrigation cycle should be able to be completed in about 7 hours. We presume the increase in the discharge pressure was done in an attempt to resolve some perceived pressure issues at the furthest points end of this course; holes 3 and 4 Islands. It should be noted that an increase in the discharge pressure of a pump will typically result in a decrease in the total gpm the station can produce. However, in this case, with the (3) 75 hp motors, the station may still be able to produce 2400 gpm even with the 10 psi increase in the set point. We will discuss this in more detail later in the report. Each pump station has a single Amiad ABF filter (Automatic Brush Filter). The design of this particular filter model has proven to be problematic due to its inability to self-clean sufficiently. The brush basically imbeds debris deeper into the filter mesh rather than removing it. Over time the filter becomes inefficient and can cause excessive pressure loss across the filter element. Additionally, a single filter is never a good choice since it does not allow for adequate filtration or flow if the filter needs to be taken off line for service. This may have been a budgetary decision rather than the best recommendation of the designer. Hydraulic Design The golf course elevations range from a high of about 360’ at maintenance, to a low of about 345’ at various locations around the course. Static pressures on the original 18 holes should be between 115 and 121 psi. Static pressures on the west holes should be between 110 and 115 psi. This should be more than adequate to allow for normal friction losses through the piping system and valves assuming the main lines have been sized appropriately and the flow rates in the computer hydraulic tables are set correctly for the designed piping sizes. That being said, it is our opinion that many sections of the main line pipe are undersized for the existing pump station capacities. Much of the 8” pipe should actually be 10” or 12” to evenly distribute the water around the course. Although it was common practice to use at least some 4” pipe for main lines when the original 18 holes were installed, it is more common today to use nothing smaller than 6” pipe

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for main lines. This is partially because of the increased flexibility of modern irrigation computer systems over those that were available 30 or even 20 years ago.

The under sizing of the main line pipe is evidenced by the excessive flows we noted in the irrigation computer hydraulic tree as past irrigation managers attempted to provide adequate flow to various areas of the course. Industry design standards are to not exceed a flow velocity of 5 feet per second in the piping system. In several areas, flow rates have been set to exceed this by as much as 40%. There are long ranging implications of doing this that we will discuss in more detail in the following sections. High flow rates are also associated with high friction losses in the pipe. If there is too much friction loss due to high flow rates, pressures will be affected as you get further away from the pump station. In Attachment 3 we present friction loss calculations and the resulting dynamic pressures at two locations on the course, one for each pump station. Because of the high flow rates and long distance from the pump station out to 4 Islands tee, you will note that the resulting dynamic pressure is between 58 and 68 psi. This is below the base operating pressure for the sprinklers. As a result, the performance of the sprinklers in that area will most likely be adversely affected. Note that this is a worst-case example and may not occur daily depending upon how the irrigation computer schedules stations in that area. Losses on the original 18 out to 5-Oaks are acceptable even with the excessive flow rates in at least one section of main line. We could not calculate the friction losses out to 3- Lakes because of problems with the irrigation computer hydraulic >Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22-23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34

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