Code of Maine Rules › 06 - DEPARTMENT OF ENVIRONMENTAL PROTECTION › 096 - DEPARTMENT OF ENVIRONMENTAL PROTECTION - GENERAL › Chapter 500 - STORMWATER MANAGEMENT › Appendix 096-500-A - Erosion and sedimentation control

Current through 2024-29, July 17, 2024
This appendix applies to all projects.
A person who conducts, or causes to be conducted, an activity
				  that involves filling, displacing or exposing soil or other earthen materials
				  shall take measures to prevent unreasonable erosion of soil or sediment beyond
				  the project site or into a protected natural resource as defined in
				   38
				  M.R.S.§480-B. Erosion control measures
				  must be in place before the activity begins. Measures must remain in place and
				  functional until the site is permanently stabilized. Adequate and timely
				  temporary and permanent stabilization measures must be taken.
NOTE
: Other requirements may apply, including,
				  but not limited to the
Natural Resources Protection Act
38 M.R.S.
				  §480-B.
NOTE
: The Department has prepared protocols for
				  the control of erosion and sedimentation. See "Maine Erosion and Sediment
				  Control BMPs Maine Department of Environmental Protection."
1. Pollution prevention.
Minimize disturbed
				  areas and protect natural downgradient buffer areas to the extent practicable.
				  Control stormwater volume and velocity within the site to minimize soil
				  erosion. Minimize the disturbance of steep slopes. Control stormwater
				  discharges, including both peak flow rates and volume, to minimize erosion at
				  outlets. The discharge may not result in erosion of any open drainage channels,
				  swales, stream channels or stream banks, upland, or coastal or freshwater
				  wetlands off the project site.
Whenever practicable, no disturbance activities should take
				  place within 50 feet of any protected natural resource. If disturbance
				  activities take place between 30 feet and 50 feet of any protected natural
				  resource, and stormwater discharges through the disturbed areas toward the
				  protected natural resource, perimeter erosion controls must be doubled. If
				  disturbance activities take place less than 30 feet from any protected natural
				  resource, and stormwater discharges through the disturbed areas toward the
				  protected natural resource, perimeter erosion controls must be doubled and
				  disturbed areas must be temporarily or permanently stabilized within 7
				  days.
NOTE
: Buffers improve water quality by helping
				  to filter pollutants in run-off both during and after construction. Minimizing
				  disturbed areas through phasing limits the amount of exposed soil on the site
				  through retention of natural cover and by retiring areas as permanently
				  stabilized. Less exposed soil results in fewer erosion controls to install and
				  maintain. If work within an area is not anticipated to begin within two weeks'
				  time, consider leaving the area in its naturally existing cover.
NOTE
:Many construction activities within 75 feet
				  of a protected natural resource require a permit under the
Natural
				  Resources Protection Act
prior to initiation. For more information
				  regarding the applicability of the NRPA to your project, you can visit the
				  Department's website at
http://www.maine.gov/dep/land/nrpa/index.html
or contact staff of the Division of Land Resource Regulation at the nearest
				  regional office.
2. Sediment barriers.
Prior to construction,
				  properly install sediment barriers at the downgradient edge of any area to be
				  disturbed and adjacent to any drainage channels within the disturbed area.
				  Sediment barriers should be installed downgradient of soil or sediment
				  stockpiles and stormwater prevented from running onto the stockpile. Maintain
				  the sediment barriers by removing accumulated sediment, or removing and
				  replacing the barrier, until the disturbed area is permanently stabilized.
				  Where a discharge to a storm drain inlet occurs, if the storm drain carries
				  water directly to a surface water and you have authority to access the storm
				  drain inlet, you must install and maintain protection measures that remove
				  sediment from the discharge.
3. Stabilized construction entrance.
Prior to
				  construction, properly install a stabilized construction entrance (SCE) at all
				  points of egress from the site. The SCE is a stabilized pad of aggregate,
				  underlain by a geotextile filter fabric, used to prevent traffic from tracking
				  material away from the site onto public ROWs. Maintain the SCE until all
				  disturbed areas are stabilized.
4. Temporary stabilization.
Within 7 days of the
				  cessation of construction activities in an area that will not be worked for
				  more than 7 days, stabilize any exposed soil with mulch, or other non-erodible
				  cover. Stabilize areas within 75 feet of a wetland or waterbody within 48 hours
				  of the initial disturbance of the soil or prior to any storm event, whichever
				  comes first.
5. Removal of temporary measures.
Remove any
				  temporary control measures, such as silt fence, within 30 days after permanent
				  stabilization is attained. Remove any accumulated sediments and stabilize.
NOTE
: It is recommended that silt fences be
				  removed by cutting the fence materials at ground level to avoid additional soil
				  disturbance.
6. Permanent stabilization.
If the area will not
				  be worked for more than one year or has been brought to final grade, then
				  permanently stabilize the area within 7 days by planting vegetation, seeding,
				  sod, or through the use of permanent mulch, or riprap, or road sub-base. If
				  using vegetation for stabilization, select the proper vegetation for the light,
				  moisture, and soil conditions; amend areas of disturbed subsoils with topsoil,
				  compost, or fertilizers; protect seeded areas with mulch or, if necessary,
				  erosion control blankets; and schedule sodding, planting, and seeding so to
				  avoid die-off from summer drought and fall frosts. Newly seeded or sodded areas
				  must be protected from vehicle traffic, excessive pedestrian traffic, and
				  concentrated runoff until the vegetation is well-established with 90% cover by
				  healthy vegetation. If necessary, areas must be reworked and restabilized if
				  germination is sparse, plant coverage is spotty, or topsoil erosion is evident.
				  One or more of the following may apply to a particular site.
(a) Seeded areas. For seeded areas, permanent stabilization
				  means a 90% cover of the disturbed area with mature, healthy plants with no
				  evidence of washing or rilling of the topsoil.
(b) Sodded areas. For sodded areas, permanent stabilization
				  means the complete binding of the sod roots into the underlying soil with no
				  slumping of the sod or die-off.
(c) Permanent Mulch
.
For mulched areas,
				  permanent mulching means total coverage of the exposed area with an approved
				  mulch material. Erosion Control Mix may be used as mulch for permanent
				  stabilization according to the approved application rates and limitations.
(d) Riprap
.
For areas stabilized with riprap,
				  permanent stabilization means that slopes stabilized with riprap have an
				  appropriate backing of a well-graded gravel or approved geotextile to prevent
				  soil movement from behind the riprap. Stone must be sized appropriately. It is
				  recommended that angular stone be used.
(e) Agricultural use. For construction projects on land used
				  for agricultural purposes (e.g., pipelines across crop land), permanent
				  stabilization may be accomplished by returning the disturbed land to
				  agricultural use.
(f) Paved areas. For paved areas, permanent stabilization
				  means the placement of the compacted gravel subbase is completed, provided it
				  is free of fine materials that may runoff with a rain event
(g) Ditches, channels, and swales. For open channels,
				  permanent stabilization means the channel is stabilized with a 90% cover of
				  healthy vegetation, with a well-graded riprap lining, turf reinforcement mat,
				  or with another non-erosive lining such as concrete or asphalt pavement. There
				  must be no evidence of slumping of the channel lining, undercutting of the
				  channel banks, or down-cutting of the channel.
7. Winter Construction.
"Winter construction" is
				  construction activity performed during the period from November 1 through April
				  15. If disturbed areas are not stabilized with permanent measures by November 1
				  or new soil disturbance occurs after November 1, but before April 15, then
				  these areas must be protected and runoff from them must be controlled by
				  additional measures and restrictions.
(a) Site Stabilization. For winter stabilization, hay mulch
				  is applied at twice the standard temporary stabilization rate. At the end of
				  each construction day, areas that have been brought to final grade must be
				  stabilized. Mulch may not be spread on top of snow.
(b) Sediment Barriers. All areas within 75 feet of a
				  protected natural resource must be protected with a double row of sediment
				  barriers.
(c) Ditch. All vegetated ditch lines that have not been
				  stabilized by November 1, or will be worked during the winter construction
				  period, must be stabilized with an appropriate stone lining backed by an
				  appropriate gravel bed or geotextile unless specifically released from this
				  standard by the Department.
(d) Slopes. Mulch netting must be used to anchor mulch on all
				  slopes greater than 8% unless erosion control blankets or erosion control mix
				  is being used on these slopes.
NOTE
: The Department has prepared protocols for
				  the control of erosion and sedimentation during the winter months. See "Maine
				  Erosion and Sediment Control BMPs Maine Department of Environmental
				  Protection."
8. Stormwater channels.
Ditches, swales, and
				  other open stormwater channels must be designed, constructed, and stabilized
				  using measures that achieve long-term erosion control. Ditches, swales and
				  other open stormwater channels must be sized to handle, at a minimum, the
				  expected volume run-off. Each channel should be constructed in sections so that
				  the section's grading, shaping, and installation of the permanent lining can be
				  completed the same day. If a channel's final grading or lining installation
				  must be delayed, then diversion berms must be used to divert stormwater away
				  from the channel, properly-spaced check dams must be installed in the channel
				  to slow the water velocity, and a temporary lining installed along the channel
				  to prevent scouring. Permanent stabilization for channels is addressed under
				  Appendix A(5)(g) above.
(a) The channel should receive adequate routine maintenance
				  to maintain capacity and prevent or correct any erosion of the channel's bottom
				  or side slopes.
(b) When the watershed draining to a ditch or swale is less
				  than 1 acre of total drainage and less than ¼ acre of impervious area,
				  diversion of runoff to adjacent wooded or otherwise vegetated buffer areas is
				  encouraged where the opportunity exists.
9. Sediment basins.
Sediment basins must be
				  designed to provide storage for either the calculated runoff from a 2-year,
				  24-hour storm or provide for 3,600 cubic feet of capacity per acre draining to
				  the basin. Outlet structures must discharge water from the surface of the basin
				  whenever possible. Erosion controls and velocity dissipation devices must be
				  used if the discharging waters are likely to create erosion. Accumulated
				  sediment must be removed as needed from the basin to maintain at least ½
				  of the design capacity of the basin.
The use of cationic treatment chemicals, such as polymers,
				  flocculants, or other chemicals that contain an overall positive charge
				  designed to reduce turbidity in stormwater must receive prior approval from the
				  Department. When requesting approval to use cationic treatment chemicals, you
				  must describe appropriate controls and implementation procedures to ensure the
				  use will not lead to a violation of water quality standards. In addition, you
				  must specify the type(s) of soil likely to be treated on the site, chemicals to
				  be used and how they are to be applied and in what quantity, any manufacturer's
				  recommendations, and any training had by personnel who will handle and apply
				  the chemicals.
10. Roads.
Gravel and paved roads must be
				  designed and constructed with crowns or other measures, such as water bars, to
				  ensure that stormwater is delivered immediately to adjacent stable ditches,
				  vegetated buffer areas, catch basin inlets, or street gutters.
NOTE
: (1) Gravel and paved roads should be
				  maintained so that they continue to conform to this standard in order to
				  prevent erosion problems. (2) The Department recommends that impervious
				  surfaces, including roads, be designed and constructed so that stormwater is
				  distributed in sheet flow to natural vegetated buffer areas wherever such areas
				  are available. Road ditches should be designed so that stormwater is frequently
				  (at least every 100 to 200 feet) discharged via ditch turnouts in sheet flow to
				  adjacent natural buffer areas wherever possible.
11. Culverts.
Culverts must be sized to avoid
				  unintended flooding of upstream areas or frequent overtopping of roadways.
				  Culvert inlets must be protected with appropriate materials for the expected
				  entrance velocity, and protection must extend at least as high as the expected
				  maximum elevation of storage behind the culvert. Culvert outlet design must
				  incorporate measures, such as aprons, to prevent scour of the stream channel.
				  Outlet protection measures must be designed to stay within the channel limits.
				  The design must take account of tailwater depth.
12. Parking areas
. Parking areas must be
				  constructed to ensure runoff is delivered to adjacent swales, catch basins,
				  curb gutters, or buffer areas without eroding areas downslope. The parking
				  area's subbase compaction and grading must be done to ensure runoff is evenly
				  distributed to adjacent buffers or side slopes. Catch basins must be located
				  and set to provide enough storage depth at the inlet to allow inflow of peak
				  runoff rates without by-pass of runoff to other areas.
13. Additional requirements.
Additional
				  requirements may be applied on a site-specific
				  basis
.