prep for xypex application question

question is in caps below:
realizing that waterproofing can be tricky i wasn't going to trust myself to diagnos the troubles in my basement. didn't want to remodel and find out during rainy season i was wrong. so i called in a company here in the San Francisco Bay area to consult. This company only does waterproofing. They recommended xypex concentrate for my problem. (I'm on a hill with part of the basement below grade. I have some seepage and moisture in the rainy months. the runoff is good around the house, but apparently hydrostatic pressure is forcing water up through the holes left from forms. yes, they didn't fill these and they go right down into earth)
$800 in consulting fees later, i'm now in the prep stage. xypex requires a porous surface free of non-concrete materials. apparently it seeps into the porous exposed concrete and forms crystals. unfortunately i discovered that parts of the 18" foundation wall were covered with plaster.
ITS SEEMS I NEED TO FIGURE OUT HOW TO REMOVE THE PLASTER FROM THE ROUGH CEMENT. IT HAS PLENTY OF LITTLE CAVITIES. ITS ABOUT 60 SQ FT. ANY IDEAS?
i've thought about sandblasters (until i started reading about the dangers) and grinding wheels with wire brush attachments.
much thanks
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Chris Porro Email List wrote:

Assuming the plaster was simply screed onto the unfinished concrete wall, it may be possible to bash it with a hammer and use a hammer and putty knife to remove it from the wall. When the bulk is removed brush down the wall, and vacuum it .
Pressure wash or sand blast to provide a very clean surface.
I assume you have somehow plugged the holes left from the forms. If thats where the water was coming in then thats what has to be sealed. Depending on the size a hydrostatic cement might be appropriate. Thats a type of cement which expands when it dries.
I would call a cement contractor for a quote.
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that's what i was kinda afraid of. maybe i can do a sandblaster, but the pressure washer seem impossible. i've used one before and i'd need a pump to remove the water from the basement afterwards. not to mention all the drywall that would be warped.
i'm going to put my faith in this consultant. all they do is waterproofing, they are well known in this area, and my first contractor recommended them. i can't see bringing in a concrete guy for maybe 8 holes that are less are about 1/2" diameter.
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