Before I start, I’d like to point out that this investigation was conducted by two people – myself and [Howmuch?]. We are both sensible (well, usually) adults and have experience of, and training for, confined spaces. Entering such environments – and storm drains in particular – is a dangerous thing to do. I advise nobody to do it. Water can enter at a moments notice, there can be sudden drops, trips and gas hazards. What we did here, we undertook at our own risk, and in the full knowledge that we were trespassing and could well get into difficulty. Doing so without training, the correct equipment or suitable permission is dangerous, stupid and nobody should do it.
Since this blog started, there’s been a huge interest in Chasewater, and it’s dam. The reservoir was built as Norton Pool in the late 1700′s to feed the canal network. It’s worth thinking about this for a while, as it’s quite a concept, and one often lost on the casual observer. The canal system through the towns of the northern Black Country is almost exclusively fed by the 144m O.D. level of the Wolverhampton canal network, which runs from Horseley Junction, all the way through the suburbs of Worverhampton eastwards to Bloxwich and Brownhills in the form of the Wyrley and Essington canal. There is no canal linked to this that is higher – so where this contour canal transitioned to other waterways, downhill locks were employed. There were 30 alone on the Lichfield and Hatherton, for a start. Then there are locks at Longwood, Aldridge, At Birchills in Walsall, and several complex series at Wolverhapton. Every time a boat uses a lock, water is lost downhill. A busy canal, operating as the freight motorway of it’s day, would see huge water consumption.
Water was precious, and Norton Pool was built to feed the canal’s voracious thirst. Over the years, the reservoir has been fed by the Crane Brook from the north (as it always has been), and has seen some water pumped into it from nearby mines. Water also seems to have been recovered from the canal at times when the level was high, and following an enquiry rom fellow Brownhills historian Dave Fellows, Chasewater Wildlife Group head honcho Graham Evans has discussed the nature of the pumping and feed arrangement last year. I’m now fairly sure water was being pumped from the coal mines on Brownhills Common into the Slough Arm. I think a mine owner may even have charged for this supply, although I can’t place where I got that impression. Together with other such sources of what would certainly have been very foul water, these contributed to the general canal supply. When the water was at a high level, it appears to have been pumped back from the canal into the Nine Foot Pool (so called because of the measuring scale erected in it). The Nine Foot is the pool on the Canal side of the dam, at the beginning of the spillway basin, designed to take the flow should the reservoir overflow. The spillway in general seems certainly to be as old as Chasewater itself, although alterations and strengthening seem to have taken place in the late Victorian period.
On Sunday last, after talking about the site for months previously, myself and top local history ferret [Howmuch?] decided to investigate the spillway, and it’s interesting drainage arrangements. To do this, we decided to enter the culverts to see where they went. On the way, we noticed some intriguing things about the civil engineering, and some pointers to the history. Much of this has already been suggested by the wonderful Andy Dennis.
- The current state of the spillway basin between Nine-Foot and the old sluice gates is stepped in profile on one side rather than a plain trough shape. We think this may be due to sediment dredging.
- In Google Earth, and on the ground, the land within is darker. We’re thinking this is due to sedimentation from the filthy canal water it would have contained.
- We’re wondering if the canal water was pumped into the basin to settle out before possibly being allowed to flow back into the main body of Norton Pool.
- We have no direct evidence of that, just a hunch.
- The top of the sluice seems to have had lock-style gates. We feel that water probably was retained by them, and they therefore sealed like lock gates.
- The culverts on either side acted as a level control for the basin, but maybe a drain, too, depending on the location of the upper portals which are now buried.
- The new storm drain seems to have been built any time from mid-1960′s to the late 1970′s. It’s a classic Reinforced Concrete Pipe (RCP) design.
- The storm drain runs under the brickwork sluice, under the canal and heath, and emerges on the north of the new bypass as the continuation of the Crane Brook.
- We think it was built to avoid possibly contaminated washdown or runoff water from the old spillway basin contaminating the then improving canal water.
- The above seems daft but it’s all we can think.
- We’re wondering how it was all constructed, and if anyone has dates or photos. In places the brickwork in the sluice seems to have been disturbed and regrouted.
- The brick sluice is probably now redundant, although in heavy flow conditions I wonder if the basin would backfill as a buffer?