Wetland Mitigation
Wetland Mitigation
(OP)
How do you create a wetland? There is a site where we are required to do mitigation and it has to be of like-kind. Is it as simple as lowering the grade and planting like-kind plant species there? I searched several websites including the EPA and have been having a difficult time finding specific, cut and dry standards for creating wetlands. This particular site is in MD.
I would just like to know where I could go to find out this information. Thank you
I would just like to know where I could go to find out this information. Thank you





RE: Wetland Mitigation
The Pennsylvania BMP Handbook (January 2005, Draft), Section 6.13 Constructed Wetlands provides details and construction information. The book can be obtained in PDF format at the following link:
http:/
Let us all know if you have any additional questions. Good luck!
RE: Wetland Mitigation
RE: Wetland Mitigation
The design standards for Virginia, Maryland, and D.C. are very similar. Additionally, the Pennsylvania handbook is heavily based on the Virginina and Maryland BMP books.
http://ww
This link is for the Maryland Stormwater Design Manual, which has sections for constructed wetlands.
RE: Wetland Mitigation
Good luck,
h.
RE: Wetland Mitigation
The wetland's biologist end goal is to provide wetlands, yours is to maximize your client's land use. The design team's objective is to provide the best combination.
The law only requires replacement in-kind, so only replace in-kind. That means 0.1 acre remedial for 0.1 destroyed...no safety factor.
Women and cats will do as they please; men and dogs should just learn to live with that - Steve
RE: Wetland Mitigation
You need to have hydrologic connectivity. It's no good having a pool if it only gets the water that lands on it.
Also, if you're obligated to do water quality, you can send your site runoff through the wetland and you're assured* of getting sufficient flow through the wetland to keep it wet and also your water is being treated by the vegetation.
*Well, only if your site is big enough.
RE: Wetland Mitigation
H.
RE: Wetland Mitigation
I agree that you need to work closely with the biologist.Be aware that someone(local authority,government agency,etc.)will have to sign off on your plan and wetland mitigation,wetland restoration,wetland enhancement,& wetland creation are dual discipline conservation practices.
You may want to check out C of Engineers and Natural Resources Conservation Service websites.You can start at these websites and then fineturn your search for your local state or district office.You are looking for practice codes and standards.
Hope I didn't complicate matters.It's not complicated,you just need to know who your audience is.
RE: Wetland Mitigation
Based on my past experience, typical roles on the team are as follows (this is a quick brain-dump, these may or may not apply to your situation):
Permit coordination: often led by an environmental-type or the landscape architect, works with agencies to ensure the correct type of wetland is created and the right amount of that wetland is created. Relies on input from the rest of the project team to fill our permit info.
Landscape architect: develops concept/preliminary grading plan for use by civil; develops planting plan; specifies nature of soil improvement and subgrade preparation; responsible for planting & plant establishment procedures (specifications and plant establishment plan)
Civil engineer: provide hydrologic and hydraulic analysis/modeling; develop water budget for wetland to ensure proper seasonal water levels & volumes; provide the landscape designer with typical water levels for their use in delineating plant communities relative to the pond surface eleveation; assess need for pond liner (with input from geotech); design & detail pond liner; develop constructable grading plan for the plan set based on the LA's concept plan, including horizontal and vertical control points (how will it be staked?); detail for hydraulic features such as weirs or drop structures; ensure flotable habitat features (e.g. logs) are anchored (details); assess scour potential at inlet/outlet and address through design; provide quantities of cut/fill for permit purposes; develop erosion and sedimentation control plan; determine if/how to temporarily bypass existing flows during the construction.
Biologist: provide input to permit coordinator and landscape designer to ensure the biological/ecological design criteria are met; assist with plant selection; identify additional habitat features (logs, "snag" trees, etc.)
Geotechnical engineer: assess native soils and imported soils for seepage/infiltation potential; advise on pond liner need & options; provide bearing capacity under structures (e.g. weirs); advise on groundwater elevation relative to the proposed water surface elevations and implications thereof; advise on constructability.
I'm sure I forgot some items but the issues indicated above should at least be considered during the design process, and responsibilities assigned so that plants won't be mis-matched to the water regime, and the plan set is constructible. It's also good for the civil to provide some operational control of water amounts/routing, if possible, for example by providing an adjustable weir so water levels can be adjusted post-construction if needed.
Good luck!
RE: Wetland Mitigation
Many states and the EPA often see wetlands as waters of the US or State and do not allow treatment within them. The new wetland would be considered this way since it should be comparable to the old wetland it is replacing. This is why you sometimes see wetland mitigations doubled even if not required, so you can claim treatment in the treatment portion and mitigation for the rest.
Otherwise, unless you have a park in the development you may want to just buy the necessary wetland credits from someone else, if allowed, and move forward. Most urban wetland mitigations are pretty useless for maintaining species diversity for both plants and animals so a large off site bank that is managed by a someone like the Nature Conservancy actually provides the "species" benefit of wetlands.
RE: Wetland Mitigation