Conservation & Ecology
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Typical stainless steel well heads
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The EA will always adopt the
presumption for renewal stance, so long as it can be demonstrated that there is still a need for the groundwater
Groundwater filling 20,000m3 irrigation storage lagoon
showstoppers. If, after that, everything seems to look okay, then you can move forward and have a detailed feasibility report compiled that identifies all of those contributory factors in greater detail. This would not just be a geological report. It should be so much more involved than that. It should include the geology/hydrogeology, capital cost expectations, operating cost expectations, maintenance requirements and all Environment Agency (EA) requirements for the well drilled at the location etc. Ultimately, the report should cover enough detail and provide the conclusions that can be presented to a board of directors, where applicable, for a decision to be made. So, with the above said, let’s start with the
business case. If you spend a reasonable amount of money on buying in water via the mains, and it is in excess of say £5,000 per year, then I would suggest that a groundwater source may well be worth looking at. That doesn’t mean it might not stack up for those paying less through using less water, it just means the probability of a benefit might be limited. But don’t forget, some wells only need to be really shallow and, therefore, pretty cheap in comparison. If you are a larger irrigator using say 15,000-20,000m3
per annum, then it will
There are some really good drillers out there, but there are also some very poor ones; and I mean really poor!
almost certainly be worth considering a well. At these volumes, and therefore paying perhaps £18,000 - £40,000 per year, then even a deeper, larger and therefore more costly well would still be a strong contender. Remember the enormous cost difference between groundwater and mains water? It is this gulf that strengthens the business case. Even if the whole well system costs £100,000, the return on the capital investment might only be two or three years, after which it’s a huge annual saving year on year.
I will always remember a startling statistic
that applied to a well I drilled for a paint factory in East London back in the mid 1990s. Annually, they used around 135,000m3
of mains water for their process to manufacture 128 I PC AUGUST/SEPTEMBER 2017
paint. The site, in Woolwich, was located straight into chalk and the well didn’t have to be very deep - around 70m as I recall. The cost of the whole process for installing, equipping and licensing the well was recouped in under four months and, as mains water gets more expensive, so the business case for groundwater takes another step in the right direction.
Okay, so you have told us about all the good things about wells; what are the drawbacks?
Any drawbacks with installing and operating your own well will usually be identified at the feasibility report stage. The biggest one may be the uncertainty of gaining the water demanded of it, but this risk should be quantified so the client can make an informed decision about proceeding. One way of coming to certain conclusions
will be interpreting historical records. If the target site is marked as point “X” on a map, and it was discovered during the local surveys that there was a well drilled fifty years ago 600m north of the target site that yielded, for example, 4l/sec and another drilled ninety years ago about 450m south east that yielded 2l/sec, and finally another drilled twenty years ago 1000m to the west that yielded 8 l/sec then, assuming the geology is fairly uniform across these sites, it would not be unreasonable to assume that a new well, drilled with greater design skills and modern techniques, might be somewhere in between those yields - so diligent risk assessment is a high priority. Where there is uncertainty towards yield
availability, there may be a case to drill a small diameter pilot hole first to assess yields and open up that well if yields are adequate. This would be another risk management technique. It is the consultant’s target to do as much diligent desk top investigation prior to having a rig on site. It should be a case of the actual well drilling validating what all of the upfront work has determined, and not necessarily a Eureka moment with drill crews high-fiving each other when water is blown
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