Several blasting sessions were done in our neighborhood at a
construction site, about 1/4 mile from my house. My close neighbors
who were home during weekday blasting sessions felt definite shaking
of there houses. When inspecting my foundation (in basement) I found
numerous thin cracks along 3 sides of the structure. All above-ground
cracks start at the foundation top and "stair-step" down along mortar
joints. Our foundation and basement had always been very tight and
dry. My wife and I saw no cracks in 11 years of ownership, including
accompanying the pest control person in annual foundation inspections.
The previous owner certifies there were no foundation cracks or
By phone, several repair contractors and people with basic knowledge
of blasting all asked if we had any previous cracking, and if new
cracks were horizontal or stair-step in appearance. All said
stair-step cracking is characteristic of blasting. And,lateral
cracking is characteristic of outside soil and water pressure on a
The measured level of blasting recorded by a small engineering group
shows lower levels at their few monitored locations.
This posting is a query to experienced engineering, legal,
home-owning, or other people knowledgeable in reference sources. I
need documentation for:
(1) Stair-step type cracking in foundations being characteristic of
(2) Typical damage appearance from low-level (fringe area) blasting
in above and below-ground, previously intact foundations.
(3) Good practice requirements for geotechnical surveys before
(4) Good practice requirements for placement and density of
seismometers in residential environments.
(5) Higher damage probability in certain types of soil, faults and
(6) Higher damage probability during rainy periods.
(7) Other documentation which can help a homeowner understand and
realistically deal with this situation.
As a very troubled homeowner, I will greatly appreciate consideration
and responses from anyone with experience.