With some exceptions, when a temporary BMP (Best Management Practice) is no longer needed on a construction site, most often after final stabilization has occurred, it must be removed by the contractor. However, some BMPs, such as temporary sediment basins, may be converted to permanent BMPs after construction is complete. It is also generally acceptable for BMPs made of natural materials (such as fiber logs/rolls, natural fiber erosion control mats, etc.) to be left on the site to decompose. Erosion prevention practices constructed from degradable materials represent the most common class of stormwater construction BMPs that are left in place after construction is complete and the site is stabilized. perimeter control BMPs constructed from degradable materials may also be left on site in some cases. However, temporary perimeter controls constructed from materials that do not readily decompose, such as silt fences, filter socks, straw bale barriers, sandbag barriers, metal stakes and reinforcement fencing, and other relatively low cost BMPs must be removed.
In general, whether a construction stormwater BMP is removed after the completion of construction and stabilization of the work site primarily depends on (1) the conditions of the contract and applicable permit(s), (2) the intended function and lifespan of the BMP, and (3) the nature of the materials used to construct the BMP. MPCA’s 2018 Stormwater Construction Inspection Guide states that “all temporary synthetic and structural erosion prevention and sediment control BMPs (such as silt fence) must be removed on the portions of the site for which the Permittee is responsible”, and that BMPs “designed to decompose on site (such as some compost logs) may be left in place.”
Whether they are to be removed or left in place, all BMPs should still be cleaned of excess sediment and other accumulated debris at the completion of construction and final stabilization when they are no longer needed. However, depending on the expected rate of decomposition and intended use of the site, a contractor or site owner may wish to remove and dispose of some BMPs or BMP components in lieu of leaving them in place to decompose. The guidance in this BMP chapter pertains primarily to sites where the standard regulatory procedures for determining whether a temporary construction stormwater BMP should be removed, left in place, or converted to a permanent stormwater management feature apply.
The table below provides general recommendations for categories and types of temporary BMPs regarding whether they are typically removed or left in place on a construction site after final stabilization.
Typical recommendations for BMP removal for common construction stormwater BMPs.
Link to this table
|BMP category/type||Standard procedure||Applicability and special considerations|
|Erosion prevention practices (stabilization practices)|
|Temporary/permanent seeding||Left in place||Mulch or other natural temporary cover to protect seeded areas should also be left in place.|
|Mulches||Left in place||Mulch, hydraulic mulch, and any anchoring materials must be degradable.|
|Tackifiers/soil stabilizers||Left in place||If using tackifiers and stabilizers (e.g., polyacrylamide or PAM), ensure they are nontoxic to aquatic life (i.e., not cationic).|
|Erosion control blankets (ECBs)||Left in place||Installed ECBs with emergent vegetation are left in place. May be removed and reused when used as temporary cover without seed on short-duration projects.|
|Turf reinforcement mats (TRMs)||Left in place||Left in place to provide permanent armoring and vegetation support.|
|Erosion prevention practices (other)|
|Riprap||Left in place||Typically serves a permanent function for armoring, stabilizing, and protecting soil against erosion.|
|Sediment control practices|
|Vehicle tracking BMPs||Removed||Removed after final site stabilization or after no longer needed (e.g., vehicles no longer entering or existing site).|
|Perimeter controls||Varies; most are removed||May be left in place if constructed from degradable materials (e.g., fiber rolls/logs).
Silt fencing must be removed after upslope areas are stabilized.
|Check dams||Varies||May be left in place if constructed from degradable materials (e.g., fiber rolls/logs).
Check post-construction stormwater management plan for applicability.
|Diversion barrier controls||Varies; most are removed||In general, all are removed after stabilization. In special cases, such as where removal may damage structures or foundation soils, cofferdams may be left in place.|
|Inlet protection||Removed||Must be removed after stabilization.|
|Outlet energy dissipation||Varies||Devices designed for temporary, short-term (e.g., less than one year) use must be removed after stabilization.
Whether they are left in place as permanent BMPs depends on function and desired aesthetics. Check post-construction stormwater management plan for applicability.
|Sediment traps/basins||Varies||Temporary sediment traps are removed after stabilization.
Temporary sediment basins may be converted to permanent stormwater management basins after stabilization.
|Stabilized earth/soil berm||Varies||Typically removed after stabilization. In some cases, may be left in place if permanently stabilized with vegetation. Check post-construction stormwater management plan for applicability.|
|Surface water protection practices|
|Buffer zones||Left in place||Always preserved on site|
|Construction stormwater treatment practices|
|Dewatering (including chemical treatment and sediment filtration)||Removed||Dewatering practices are operated during construction activity and may be removed after construction ceases and site is stabilized.|
|Practices to minimize sediment discharge|
|Diversion and working in the dry||Removed||Removed after construction is complete and stream channel and site are stabilized.|
|Temporary stream crossing||Removed||Removed after construction is complete and stream channel and site are stabilized.|
|Stabilized construction exit||Removed||Removed after construction is complete and construction equipment/materials have been removed. Grade and stabilize area after removal.|
Final stabilization and removal of applicable temporary BMPs must be completing prior to closing out the project permit. At project completion, a Notice of Termination (NOT) will need to be submitted to terminate coverage under the MPCA Construction Stormwater General Permit. The NOT must be submitted within 30 days of completing final stabilization at the project site. The following must be completed (MnDOT, 2006).
Section 13 of the MPCA Construction Stormwater General Permit describes conditions for permit termination (submission of the NOT), which includes BMP removal. Regarding the removal of temporary BMPs, Section 13.5 states: “Permittees must remove all temporary synthetic erosion prevention and sediment control BMPs prior to submitting the NOT. Permittees may leave BMPs designed to decompose on-site in place.”
See Costs for information on payment for temporary sediment control devices by MnDOT, including the schedule of payment following BMP removal.
It is important to consider the cost and time required for BMP removal and disposal when planning the overall project cost and schedule. The MnDOT Standard Specifications for Construction (2018 Edition) Section 2573.3 Part A.1 delegates responsibility of erosion and sediment control BMP removal to the Erosion Control Supervisor, stating: “The following list describes the duties of the Erosion Control Supervisor:
The removal of temporary erosion and sediment control BMPs is not considered a standalone construction stormwater practice; therefore, there are no specific design recommendations for BMP removal, only recommended procedures. In all cases, the removal of devices intended for temporary use shall be performed in accordance with the terms of the contract or as directed by the Engineer.
The following information provides general recommendations on sequencing for several common erosion prevention and sediment control BMPs that are removed from construction sites after final stabilization, when they are no longer needed.
Temporary sediment basins and fiber rolls or logs can be left on site, but should be modified.
Fiber rolls or logs
Final inspection and closeout of a construction site requires cleanup of all materials related to construction activities, final stabilization to prevent erosion from disturbed areas, and removal of temporary erosion prevention and sediment control BMPs.
Section 1407 (Final Cleanup) of the MnDOT Standard Specifications for Construction (2018 Edition) states: “Before requesting final inspection in accordance with 1516.2, “Project Acceptance,” the Contractor shall remove the following from the Project Site and other locations outside of the Project Site used in performing the Work:
The Contractor shall also leave the Project Site, including borrow pits, in a condition acceptable to the Engineer. The cost of final cleanup is included in the Contract Unit Prices of the Contract Items.”
As discussed above in Applicability, MPCA’s 2018 Stormwater Construction Inspection Guide provides guidelines on conducting final inspection of the site for meeting final stabilization requirements. Regarding BMP removal, the guidance states:
Once vegetation has been established and applicable temporary erosion and sediment control BMPs have been removed, the Notice of Termination will need to be submitted to formally close out the project.
Costs for removal of larger BMPs are typically included in bid pricing. Section 2573.5 (Basis of Payment) of the MnDOT Standard Specifications for Construction (2018 Edition) states: “The contract pay items for stormwater management will include the material, equipment, installation, maintenance, and removal as required by the contract to complete the work. For items of work not included in the schedule of Contract Pay Items, the Department will pay Unit Prices for the relevant items of work.
The Department will provide partial payment of temporary sediment control devices properly installed at no greater than 50 percent of the contract unit price for each relevant pay item unless otherwise required by the contract. The Department will pay the remaining partial payment after proper maintenance and removal of the device.” These terms provide an incentive for the contractor to ensure that BMPs are properly removed after the completion of construction.
Except where more stringent requirements are presented in this guidance, BMPs shall comply with MnDOT and other state requirements. Primary design references include the following.