Here is a Link that I have found very helpful:
https://www.surveymonkey.com/r/shore...Ny%2fvn3hrM%3d
It helps define your project as related to the shore Land protection Act.
This is the NH Subsurface page:
http://des.nh.gov/organization/divis.../ssb/index.htm
but what is also helpful are the two links on this page, it takes a bit to figure out how the searches work but you can look up properties near you and see who did the work or see how many jobs a designer or installer have done.
http://www2.des.state.nh.us/SSBOneStop/
Also I sent you a PM.