Blasting and groundwater

[ptmoss]

I'm designing a small subdivision where there will clearly be a need to blast several locations for road and house construction. Off the top of my head, I would expect the most depth from ground surface to be removed will be about 8 feet. That would be for some of the house foundations. The bedrock is typical NH granite.

One issue that is developing is a very vocal lake association for a lake that is approximately 2000 feet away. A letter has been circulated claiming that extensive blasting and re-direction of numerous streams threatens quality and quantity of run-off coming from this property and worries about potential damage to the lake ecology.

Now, no streams are going to be re-directed. That's a big no-no in NH and our stormwater plan is going to great lengths to maintain existing hydrologic patterns as best as can be accomplished.

My question is whether blasting can have any impact on subsurface water that passes beneath the property, obviously directed towards the lake, and whether there can be any water quality problems associated with it.

A second question is how far a typical pre-blast survey might extend to. There is one neighbors house 100' from a couple areas that will need blasting, the property owners house and barn are 200' and 100' away from some of the blast areas, and a few other neighbors would be somewhere in excess of 300'. It's not a survey I would ever be qualified to perform, but I expect the question to arise during upcoming Planning Board meetings.

Thanks!

 

[Dirtmaster]

You have asked a lot of questions in a very short post.

I had a project in the the early '70s where we dried up

wells within a half mile of of the project.

The streams, rivers, springs, etc., must be studied

prior to any blasting activity. I would STRONGLY

recommend that you employ a Geotichnical engineer

to surey the site and moitor any blasting activity.

You already have a group of people who want to nail you

for their problems, make sure the problems you pay

for, are ones you you create.

 

[exploengineer]

It will be highly unlikely to cause any problems from blasting in this type of situation. Its extremely shallow and wouldn't be any different then excavating without blasting.

I also live in New England and work in the explosives engineering industry. New Englanders can be very litigiuos and have the "not in my backyard" mentality. Remember, preblast surveys are not just for homeowner protection, they are for your protection too. Usually, the fire marshal will dictate the distance, but a rule of thumb is a minimum of 250 feet. Do not do these surveys based on price. Make sure they are not the quick 30 - 45 minute variety, but very thourough.

Good luck!

Frank Lucca M.I.Exp.E.

http://www.terradinamica.com

 

[dicksewerrat]

Take many, many pictures. Use message board with date time direction from camera toward bldg. Make sure all property owners see this being done. That alone will stop 75% of the claims. Video with audio, also. any cracks in existing bldgs. Should be measured for width and depth.

 

[ptmoss]

Thank-you all!