Permitting Presentation

Permitting Presentation

Michigan Bridge Scour WorkshopLand and Water ManagementDivisionMarch 10, 2009Department of Environmental Quality

Transportation and Flood Hazard Unit►Funded by an MOU between MDEQand MDOT►Staff work directly with PublicTransportation Agencies (PTA(s))

Scour Protection will requirepermits under one or both ofthe following Statutes:►Part 301, Inland Lakes and Streams, ofthe Natural Resources andEnvironmental Protection Act, 1994 PA451, as amended (NREPA)►Part 31, Floodplain RegulatoryAuthority, NREPA

A permit is needed under Part301 for the following:►Dredge or fill the bottomland►Construct, enlarge, extend, remove or placea structure on bottomland►Structurally interfere with the natural flow ofan inland lake or stream

Definition of a Stream in Part 301:► “…a river, stream, or creek which may or may not beserving as a drain…or any other body of water that hasdefinite banks, a bed, and visible evidence of a continuedflow or continued occurrence of water…”

This meets the definition of a stream►DefiniteBanks►A Bed►Visibleevidence ofa continuedflow oroccurrenceof water

This is not a Stream:► No Definite Banks► No Bed► Visibleevidence ofoccurrenceof water butnot ofcontinuedflow

Part 301Inland Lakes and Streams► “The department shallissue a permit if it findsthat the structure orproject will notadversely affect thepublic trust or riparianrights … the departmentshall consider the possibleeffects of the proposedaction upon the inland lakeor stream … and the usesof all such waters,including uses forrecreation, fish andwildlife, aesthetics….”

► A permit is required the placement of riprapin the streamBankfull ChannelOrdinary High Water Mark WidthBaseflow Channel

A Permit is required under Part31 for the following activities►Any Occupation,►Any Filling,►Any Grade Changeswithin the floodplain of a river/drain► With a drainage area of 2 square miles orgreater

Floodway vs. Floodway Fringe► The floodway is the river channel and theportions of the floodplain that are reasonablerequired to carry and discharge a 100 yearfloodFloodwayFloodway Fringe

FloodwayAn engineering analysis may be requiredto showResidentialthat proposedconstruction,non-residentialincludingstructural additions, is prohibiteddevelopmentwithinwillthenotFloodwayrestrict flood flowand cause a harmful increase in floodelevationsFloodway Fringe• Areas of active flow

Projects can not cause a harmfulinterference:Causing an increased stageor change in direction offlow that causes, or islikely to cause:1. Damage to property2. A threat to life3. A threat of personalinjury4. Pollution, impairment,or destruction of water orother natural resources.

Adding riprap to prevent scour mayreduce your current end area.

Riprap placed below natural channelbottom

Scour protection needed at footings

Avoid placing grout over the riprapor block

Provide a stream crossing that hasminimal impact to the environmentas possible► Use riprap/articulating block in scoured out areasto match the original stream invert► - or bury the ripap/block to match the streaminvert. Fill voids with smaller stone► Leave part of the natural stream in placewhenever possible► Randomly place some larger rock over the block► Go to a larger structure size, so that the velocitiesare reduced and the amount of protection isreduced or eliminated

Consider cross vanes to reducelocalized scour/ersosion

Questions are always welcome!When in doubt, please ask.►►

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