2 Buildings Below Street Level and Water Table
2 Buildings Below Street Level and Water Table
(OP)
I am thinking about raising a 3/4 acre existing parking lot up about 3 feet. This would require all the entrances to have steps down into the 2 buildings that were built on piles around 50 fifty years ago. The entire 2 acre property and roadways flood around 30 inches deep in heavy rainstorms. Would a large perforated ADS pipe detention system under the parking lot be feasible to store some of the water and then discharge it to daylight as the tide lowers. Any tips on how to resolve this matter would be appreciated.





RE: 2 Buildings Below Street Level and Water Table
I don't know about costs but money spent solving the wrong problem is money washed away ( pun intended ).
good luck
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
"The Elevations are as follows. Main Street El. 9.0, Parking Lot and Building Slab El. 7.0, 100 year High Water Mark El.9.50."
Are these elevations above mean sea level ?
By "high water mark do you mean the Base Flood Elevation (BFE)as established by a detailed flood study of the Hackensack River adopted by FEMA?
Why does the subject of your original post mention the "water table" ?
Are you aware that the "100 year" flood level has nothing to do with 100 years ?
Are you aware that the "100 Year flood level" is usually considered only accurate to within plus or minus 1 foot ?
Are you certain that flood waters cannot inundate your buildings via some other indirect route even if you raise the parking lot ?
Is flooding caused by high flows in the river, high tides, or some combination of both ?
During flood conditions, what is the velocity of flow near your site?
If your buildings are not residential, have you considered flood proofing them ?
Are they now, or can they be insured through the National Flood Insurance Program (NFIP)?
What local, City or County, tegulations apply to your property?
Answer these questions for yourself and your client. The answers may suggest possible alternatives to "raising" ( filling?) the parking lot.
Good luck
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
Isn't the average tide always zero ? Isn't that the definition of Mean Sea Level ? Or are you using some other datum such as MLLW ?
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
In New Jersey, I believe from a quick Google search, that the tide range is about 1.5 meters or about 5 feet.
I am not a licensed Surveyor and I live in Salem, Oregon far away from your project. I have worked with flood plains and various datums for 47 years, however. If you have questions about how these elevations are established any good Surveying textbook should answer them better than I can. Also, you could post them in the Surveying Forum on this website.
Back to your original question:
Please visit the websites provided in previous posts. FEMA has a wealth of very detailed information (FREE!) and the NOAA website will give you very good weather data.
Also, get the maps AND the Flood Study for the Hackensack River. Without it you cannot make any informed decision or even compile a list of practical alternatives.
Good luck
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
RE: 2 Buildings Below Street Level and Water Table
You can give it a go with SWMM5 or Stormnet. Both have great GUI and are easy to learn.
Good luck
Teddy
RE: 2 Buildings Below Street Level and Water Table