TH 53 Project & MPCA’s Construction Stormwater Permit

Responsibilities - General Permit  Owner & Operator are Co-Permittees:  Owner- responsible for compliance with entire permit  Operator (contractor)- responsible for the construction related portions  Permit issued to discharge clean stormwater

Items covered: 1.Knowledgeable person/Chain of Responsibility (Part III.A.2) 2.Temporary sediment basins (Part III.C.) 3.Permanent stormwater management system (Part III.D.) 4.Training Requirements (Part III.F.) 5.Stabilization timeframes (Part IV.B.2.) 6.Ditch stabilization (Part IV.B.4.) 7.Pipe energy dissipation (Part IV.B.5.) 8.Sediment control practices (Part IV.C.) 9.Buffer Zones (Part IV.C.9.) 10. Dewatering (Part IV.D.) 11. Inspection and Maintenance (Part IV.E.5.) 12.Concrete washout (Part IV.F.4.) 13.Duty to Notify (MN Stat ) 14.MPCA observations

Knowledgeable person / Chain of Responsibility (Part III.A.2) The owner must identify a person knowledgeable and experienced in the application, installation, inspection and maintenance of erosion prevention and sediment control BMPs who will oversee the implementation of the SWPPP. The owner shall include in the SWPPP a chain of responsibility with all operators on the site……to ensure that the SWPPP will be implemented and stay in effect until….Final Stabilization.

Temporary sediment basins (Part III.C.) Required when runoff from 10 acres or more of disturbed soil drain to a common location. Basin constructed prior to runoff draining 10 acres draining to it. Live storage for a 2-year, 24 hour storm (2.44” at the Site) except cannot be less than 1800 cubic feet/acre drained to the basin. Outlet must have floating inlet, must be designed for complete drawdown and maintenance. Exception if a temp sed basin if “Infeasible”

Temporary Sedimentation Basins Outlets Must Discharge from Surface >10 acres of disturbance draining to 1 point Or required if dewatering turbid water Permit PG

Permanent Storm Water Management III.D. 1” WQ volume from the new impervious must be retained on site unless prohibited (see Part III.D.1.j.) If prohibited, other volume reduction practices such as Wet Sedimentation basin, Filtration, Regional Ponds prior to discharge. Linear Projects – lack of ROW must maximize treatment w/grasses swales, filtration, small ponds, etc. See “Linear Permanent Stormwater Management Design Flow Chart” at: Permit PG

Infiltration System Guidelines Constructed last (unless rigorous erosion and sediment controls provided) Minimum 3 feet of separation between the bottom of the basin and saturated soils/bedrock Stabilize soils around basin Area around basin protected from compaction and sedimentation

Protecting Infiltration Systems

Infiltration (and filtration) practices must be designed to drain within 48 hours

Who must be trained?  Individual(s);  preparing the SWPPP.  amending the SWPPP.  performing inspections.  performing or supervising the installation and maintenance of BMPs.  Training content –must be commensurate with individual’s job responsibility.  Training refresher required every three years. Permit PG

Stabilization must be initiated immediately when construction has ceased on any portion of the Site and will not resume for 14 days. Stabilization Timeframes Permit PG

Definition of “initiated immediately” (Appendix B. 12.) means taking an action to commence stabilization as soon as practicable, but no later than the end of the work day, following the day when the earth‐disturbing activities have temporarily or permanently ceased. Initiate Stabilization Immediately Permit PG. 31

Initiate Stabilization Immediately The following activities can be taken to initiate stabilization: 1. preparing the soil for stabilization BMPs; 2. applying mulch or other non‐vegetative product; 3. seeding or planting; 4. starting any of the activities in # 1 – 3 on a portion of the area to be stabilized; 5. finalizing arrangements to have stabilization product fully installed Document these efforts in the SWPPP!

14 days for all waters (7 days if drain to special or impaired water)

Mulch application rates 90% coverage 60% coverage Want 90% coverage if Hay/Straw 100% coverage if Hydromulch

Normal Wetted Perimeter Stabilize drainage ditches/swales within 200 feet from the property edge or from point of discharge to any surface water. Stabilization must be completed within 24 hours after connecting to surface water or property edge. Complete stabilization of the remaining portions ditches/swales within 14 days after connecting to a surface water or property edge and construction in that portion of the ditch has temporarily/ permanently ceased. Permit PG. 17

Normal Wetted Perimeter 200’ wetland Ditch Stabilization - Normal Wetted Perimeter

200’ stream Mulch is not compliant stabilization in ditches Ditch Stabilization - Normal Wetted Perimeter

200’ Ditch Stabilization - Normal Wetted Perimeter

(2-yr, 24-hr storm; 2.44” at Site)

Pipe outlets must have temporary or permanent energy dissipation within 24 hours of connection to a surface water

Sediment control practices (Part IV.C.) The Permittee(s) must employ Sediment control practices as necessary to minimize sediment from entering surface waters,….. Sediment control practices must be established on all down gradient perimeters before any upgradient land‐disturbing activities begin. These practices shall remain in place until Final Stabilization has been established….. A floating silt curtain can be used as a perimeter sediment control if the floating silt curtain is installed as close to shore as possible. Immediately after rip rap installation is complete, an upland perimeter control practice must be installed….

Ditches can be used as Sediment Containment System During Construction

Concrete Washout: Wash water must not contact the ground. Liquid & Solid wastes must be disposed of in compliance with MPCA rules. A wash out sign must be installed adjacent to each washout facility. Slip form machines (no trucks) may be washed off onto the compacted road bed if paving over next day. Permit PG. 23

Recover and recycle back into truck

Dewatering Must discharge sediment laden water to a sedimentation basin or treated with appropriate BMPs on site so as to not cause nuisance conditions Permit PG

Must direct discharges to vegetated areas, unless infeasible. Permit PG. 19 & 31 Dewatering

Discharge of site dewatering water

Permittee’s Inspections The ENTIRE site must be inspected; 1. Every 7 days; 2. Within 24 hours of a 0.5” rain event 3.Portions of Site with permanent cover, inspections can be relaxed to 1/month 4.Record and Photograph all points of discharge, if observed. Document these efforts in the SWPPP! (including findings and corrective actions taken)

Buffers (within 50’ of water bodies) Preserve a 50 foot natural buffer, or, if a buffer is infeasible… Provide redundant sediment controls when working within 50 feet of a surface water. Natural buffers are not required adjacent to ditches, storm drain inlets, and sediment basins.

Buffers (within 50’ of surface waters) Silt Fence Bioroll Stabilized soils Redundant BMPs More Redundancy Nice Work!

Buffers (within 50’ of surface waters) Provides two areas for sediment capture

MN Statute DUTY TO NOTIFY AND AVOID WATER POLLUTION. …..it is the duty of every person to notify the agency immediately of the discharge, accidental or otherwise, of any substance or material under its control which, if not recovered, may cause pollution of waters of the state, and the responsible person shall recover as rapidly and as thoroughly as possible such substance or material and take immediately such other action as may be reasonably possible to minimize or abate pollution of waters of the state caused thereby. Three parts: 1.Notify the MPCA 2.Recover - rapidly, thoroughly 3.Minimize the pollution

MPCA Enforcement - Common Violations  Top 5 NPDES Violations (Statewide)  1. Failure to Stabilize Disturbed Soils  2. No Perimeter Sediment Controls  3. Maintenance of Erosion & Sediment Control BMPs  4. Vehicle Tracking  5. Inlet Protection

MPCA Enforcement - Common Violations  No (or Inadequate) SWPPP  No (or Inadequate) Inspections or Inspection Documentation  Dewatering (permit section IV.D.)  MN Rule subp. 2 “Nuisance Conditions Prohibited” No…wastes shall be discharged…into any waters of the state…(pollution examples), visible oil film, excessive suspended solids, material discoloration, aquatic habitat degradation,…

MPCA Observations  Erosion control is far more effective than sediment control !!!  BMP selection & installation is critical  BMP maintenance  Too much reliance on silt fence

Mulch application rates 90% coverage 60% coverage Want 90% coverage if Hay/Straw 100% coverage if Hydromulch

MPCA Observations  A significant part of nearly all MPCA enforcement cases is due to a poor erosion control effort, or dewatering/nuisance cond.  A great SWPPP is worthless if not implemented.  Communication breakdown during construction.

Construction Stormwater Web Site

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