Cleaning up Kambah

About 5 years ago a waterline was bolted down at Kambah Rocks using 12mm Dynabolts (non-stainless). The bolts have been slowly rusting since, as they end up under water whenever the river floods. I've been intending to replace them with stainless glue ins when time and budget allows, and when I can be sure it won't be used for a day or so while the glue sets. The plan was to do it at the end of this past summer.

Sadly someone beat me to it, but did so in the most half hearted, incompetent way possible. Clearly someone that hadn't bolted before, and hadn't really done any research. They drilled new holes rather than pulling the originals, and drilled very close to the original bolts. The bolts stuck out from the rock a good 40mm, and the glue was an eyesore. On top of that, they had bolted the wrong anchors on the far side, placing them near an old set that were never used because they form a dangerous line, a few rocks come into play a little closer to the line than was first considered.

Before I found them they had clearly been used by someone without a good idea of how to use them, the bolts were bent 15+ degrees. I don't know how that happened, even with the long bolts, if the hanger had been tightened down properly there is no way this could occur. The way I see it, there are 2 possibilities - there was excess glue on these threads as well, and the hanger only went down to 15-20mm above the rock;
or, they didn't have/use hangers, and somehow though it was a good idea to just wrap the bolts with a sling or something. While this might explain why they were so long, it seems like a long shot.

Regardless, given the condition of the bolts and the general quality of the work it was clear that they had to come out as well, adding another few hours to the job.

Removing the Stainless glue-ins 

Given the lack of skill evident from the surface, I figured it was unlikely that the bolter had done proper preparation to their bolts, so I first tried to unscrew them. By locking two nuts together I was able to create a bolt head that could be used to unscrew the bolt. Sure enough the bolt started to move as soon as I applied some torque. As the bolt came out it required the leverage of the large shifter, and some serious muscle as a vacuum formed under the bolt and made things harder. I was surprised by the length of the bolts, whoever did them put some serious effort into drilling the holes, especially given the corners cut elsewhere, they were ~100mm deep, with 40mm above the surface. Knowing this now, had they not been bent I would have considered leaving them in, as they weren't inherently unsafe, just ugly.

The mistakes:

• Bolts were too long above the rock
• Glue was ugly and not cleaned up
• Bottom bolt end was not cut at an angle - allows an air bubble, and key to my method of removal
• No cuts/texture on the bolt - again key to my method of removal
• They were probably not washed with soapy water, I don't think the glue<->bolt bond was as strong as it could have been - if true, also essential to how I removed them
• glue and bolts weren't camouflaged at all

Removing the old Dynabolts

These have actually proved far more difficult to remove, partially due to attempts with poor tools that damaged the threads before I worked out a process. The weather has also been unkind this Autum and Winter, with the river flooding several weekends that I would otherwise have finished the job on, On one occasion we were pulling bolts from on or below the water level in May or June, it was more than a little cold.

Adding the new bolts

The new glue-ins are similar to the bad ones I removed - M12 stainless threaded rod - I'm using 316, glued in with Ramset 801

These were prepared in accordance with the above points, and placed as unobtrusively as I could manage.