In science ... we use mean sea level ...
en.wikipedia.org
"A common and relatively straightforward mean sea-level standard is instead the midpoint between a
mean low and mean high tide at a particular location." ...
stupid ************ ...
Hard to believe that Crick has a science degree but then again, I remember along with my fellow Irrigation Specialist having to school a Civil Engineers overt reliance on Pressure data to point out that
flow is what rules the day in irrigation designs since Pressure was already reliable above 60 PSI in the city water distribution system. and some of it gets lost when it goes through the Water Meter/doublecheck/valves set up which all has to be accounted for in the irrigation design.
He was putting in too small valve sizes oversized zones and undersized main lines which was why so many large parks were having these dry spots in parks and even coverage gaps because there wasn't enough water brought into the part itself to keep the pressure up.
A Park named
Lynnwood Loop a 10.9-acre park with 99% of it grass had a 3" mainline/Water Meter/ Doublecheck (it was 2" water meter at the start!) which I inherited back in 1998 when I took over someone else's job because he was incompetent discovered that the reason WHY Pressure was between 35-40 psi was because there were TWO 2" valves running at a time it was actually designed that way by a civil engineer because he neglected to bring in enough water to support the pressure rate which should be around 55 psi in the zones but that would have been troublesome with a three inch water supply.
I ended up breaking the two valves set to single valve runs at a time which brought the pressure up to around 60-65 PSI range but being a big park, I run two valves just the fence line valves to reduce the run time on the clock as it was from 9:00 pm to around 10:00 am which was a bit long but then when I realized the 1955 Well which was right there in the park was no longer being used for drinking water consumption because of high Sulphur and nitrate levels was able to convince the Engineers to install a 25 HP pump rated at 200 GPM which was set in about 50" deep then it was heavenly ran the double set up again with around 60 PSI levels in each zone with oversize nozzles in some of the 21's rainbirds then started irrigating at 10:00 pm end around 6:00 am.
I built the overflow valve set up in the pump building by the pump to protect the system and a primary 2" air relief at the Flow meter area in the now 4" line installed to accommodate the increased pump flow rate and with a Variable Drive system for control of the system.
I loved the job in those days.