What is it?
The General Permit for the Discharge of Stormwater and Dewatering Wastewaters from Construction Activities (Construction General Permit) is designed for developers and builders throughout the state. It requires implementation of a Stormwater Pollution Control Plan (SWPCP) for construction activity sites to prevent and mitigate the effects of erosion and sedimentation both during and after construction in order to lessen the impacts of stormwater pollution.
Why is it needed?
Throughout construction, disturbances to the land can cause erosion and sedimentation. Erosion is caused by the removal of protective natural vegetation, as well as the addition of impermeable surfaces being placed on top of the soil. As it rains, sedimentation occurs, with sediments entering storm runoff and being deposited into local waterways. These processes can cause great damage to water quality, aquatic life and habitats, wetlands, and have other environmental consequences.
Even after construction is finished, other pollutants, such as fertilizers, pesticides, or metals, may still be present and runoff into waterways during storms, making it increasingly important to address the possible pollutants both during and after construction. For more information, check out our Stormwater Basics page.
Frequently Asked Questions
Since when has this General Permit been in place?
The effective date for this General Permit is Dec. 31st, 2020.
Who needs a permit?
This permit is required for any construction sites which disturb a total of one or more acres.
However, any sites between one and five acres do not require registration under the Construction General Permit if the activity is reviewed and approved by a local land-use commission. This could be planning and zoning, wetlands, conservation commission, etc. The reviewing commission must also be following regulations pursuant to the CT Soil Erosion and Sediment Control Act.
How do I register?
Registration can be done through DEEP’s ezFile instructions. All registrations and accompanying documents must be electronic. Both Locally Approved and Locally Exempt projects must submit registrations and pay the registration fee what aligns with their project. Information of the specifics of what is required within the registration form can be found on pages 23-27 of the Construction General Permit. With your registration, you must provide a Stormwater Pollution Control Plan (SWPCP) addressing erosion and sediment control, as well as post-constructions measures.
Existing permittees have 120 days to submit a re-registration.
What is the difference between Locally Approved vs. Locally Exempt?
Locally Approved: construction activity for which the registration is not for a municipal, state, or federal project and is required to obtain municipal approval for the project.
As a locally approved project, you will still need to register under the permit and provide your SWPCP completed by a qualified professional. This SWPCP must also be reviewed and certified by a qualified professional of one of the five Soil Conservations Districts. Make sure you have a present contractor sign a certification stating that they are familiar with and will follow the SWPCP and the Construction General Permit. The registration for locally approved projects must be submitted at least 60 days before commencing any projects.
Locally Exempt: construction activity for which a registration is required under the general permit and which is not a locally approvable project
As a locally exempt project, you will still need to register under the permit and provide your SWPCP completed by a qualified professional. Make sure you have a present contractor sign a certification stating that they are familiar with and will follow the SWPCP and the Construction General Permit. The registration for locally exempt projects must be submitted at least 60 days before commencing projects under 15 acres and 90 days before commencing projects over 15 acres, discharges to a tidal wetland, or discharges to an impaired waters.
What if my construction activity discharges directly to an impaired water?
To confirm if your activity discharges directly to an impaired water, check with the Impaired Waters Table.
If this is the case, take note of the provisions which must take place:
You may not disturb more than 3 acres at any one time and you must provide temporary stabilization measures implemented within 3 days of a temporary suspension of over 14 days in the construction period, as well as permanent stabilization 30 days before disturbance; OR
Document the measures being taken to ensure there is no discharge to impaired waters during rain events of up to 2-year, 24-hour event during construction within you SWPCP; OR
If the impaired water has a TMDL, your SWPCP must show that there is remaining Waste Load Allocation (WLA) in the TMDL to allow for the discharge, ensure the WLA will not be exceeded, AND monitor the discharge for any indicator pollutant identified in the TMDL in the rain events where discharges are present.
What is needed for inspections?
All registrants must have a Plan Implementation checklist, schedule, and identification of the qualified professional who will be conducting inspections within their SWPCP. The plan must also keep track of any findings, actions, and results of all site inspections conducted.
These routine inspections must be conducted at the beginning of construction, at the end of every phase of construction, as well as weekly.
What if my construction site is a Solar Arrays site?
While solar arrays are a great source of renewable, clean energy, the construction process can pose a great threat to water quality if not properly managed. Construction for solar arrays pose a great threat for runoff, erosion, and sedimentation. Therefore, solar array construction sites, along with the general conditions of the permit, have further conditions to follow in order to prevent and minimize stormwater pollution. Examples of these conditions are the establishment of roadways, gravel paths, and transformers to be considered as effective impervious cover for the purposes of calculating Water Quality Volume (WQV). The solar panels themselves are considered to be effective impervious cover depending on the slope of the site as well. Specific setbacks and buffers are also required around the construction site depending on the surrounding environment. More information on Solar Arrays construction sites can be found within Appendix I of the Construction General Permit.
What do I do once construction is over?
Once the construction activity is complete, a Notice of Termination (Word docs can be found here for Non-Solar Projects and Solar Projects) can be submitted. However, the Notice of Termination can only be submitted once the activity site has achieved final stabilization for one full growing season (April to October). The termination form can be filed at the following address:
CENTRAL PERMITS PROCESSING UNIT
BUREAU OF MATERIALS MANAGEMENT & COMPLIANCE ASSURANCE DEPARTMENT OF ENERGY & ENVIRONMENTAL PROTECTION
79 ELM STREET
HARTFORD, CT 06106-5127
Stormwater Pollution Control Plan (SWPCP)
The boxes below will provide information on each aspect required in the SWPCP. The SWPCP must be developed and maintained on-site for the duration of the construction activity. An example SWPCP can be found here.
Drawings which display the structural and environmental layout of the area of construction. Make sure locations of where stormwater discharges to any surface waters during and after construction are noted as well. Also included must be:
- Areas of soil disturbance
- Location of structural and non-structural controls
- Areas where stabilization practices will oxer
- Areas with vegetation acter construction
Estimated timetable and phases of the construction activity, including the erosion and sediment disturbance for each phase and for the activity as a whole. Where practicable, avoid disturbances of over 5 acres at a time and implement stormwater control measures in early phases of construction.
Runoff Reduction and LID information
Information on surrounding environmental layout and infiltration ability, locations and narratives of post-construction management measures, runoff reduction practices, and LID designs, calculations of water quality volume and proposed impervious cover. See page 31 for details. Make sure the following is included:
- Layout / locations of surrounding environmental areas (streams, floodplains, wetlands, etc)
- Drainage patterns
- Soils with suitable infiltration
- Soils with unsuitable infiltration for building
- Location and narrative of post-construction stormwater management measures, runoff reduction practices, and LID design measures
- Areas suitable for infiltration of stormwater runoff
- Calculations of retention of water quality volume as applicable
- Description of site constraints preventing retention of water quality volume
- Calculations of proposed effective impervious cover for site
Identification of all contractors and subcontractors, their individual activities, and their signed certifications. Any subdivisions within the construction activity must also comply with the Construction General Permit, have a copy of the SWPCP, and have signed certifications of all contractors.
Provide a description, sizing, and impact of the construction activity. You can access the National Stormwater Calculator here to find the average runoff coefficient of post-construction
Description and drawings of all control measures planned for implementation to minimize pollutant discharges. Make sure to include the calculations of the design of sediment and floatables removal controls and calculations of the design of the velocity dissipation controls.
All registrants must have a Plan Implementation checklist, schedule, and identification of the qualified professional who will be conducting inspections within their SWPCP. The plan must also keep track of any findings, actions, and results of all site inspections conducted. These routine inspections must be conducted at the beginning of construction, at the end of every phase of construction, as well as weekly. An example check list can be found here.
Description of provisions for controlling possible discharges both during and after construction to any impaired waters.
Stormwater Control Measures
Below is more information on each of the stormwater control measures covered by the Construction General Permit.
Erosion and Sediment Controls
Soil stabilization and protection
The plan must have a narrative, drawings, and schedule for implementing soil stabilization practices and ensure that the existing vegetation is preserved to the maximum extent practicable. Disturbed portions must be minimized and stabilized throughout construction. Any slopes on site which are greater than or equal to 8% must have two rows of erosion control barriers installed.
Stabilization and protection practices must begin within 7 days of when the construction activity has permanently finished. Areas which remain disturbed beyond the seeding season will receive long-term, non-vegetative stabilization and protection sufficient to protect the site through the winter. Temporary or permanent vegetation must be maintained on the site at all times. There can be no use of pesticides, herbicides, or fertilizers on the vegetation.
In place must also be a reverse slope bench of any slope steeper than 3:1 (horizontal: vertical) and exceeds 15 ft vertically unless slope stabilizing structures are properly put in place or soil stability has been verified.
Include descriptions and drawings within SWPCP of structural measures to divert flows away from exposed soils, store flows or otherwise limit runoff and minimize pollutant discharges. Set up a temporary sediment trap or basin for points of discharge with drainage area of between 2 to 5 acres
Disturbances within 50 ft require installation of double row of sediment barrier
Include maintenance procedures and operating conditions for erosion and sediment control measures in SWPCP
- Dewatering wastewaters should not cause scouring or erosion or contain suspended solids in amounts that could reasonably be expected to cause pollution of surface waters
- Discharged in a manner that minimizes the discoloration of receiving waters
- Include maintenance procedures and operating conditions for dewatering wastewaters measures in SWPCP
Post-Construction Stormwater Management
Post-Construction Performance Standards
- Is a site is currently developed with an effective impervious cover total of 40% or more, design site to retain on-site half the water quality volume
- Provide additional stormwater treatment which cannot be retained for discharges up to the full water quality volume for sediment, floatables, and nutrients
- When half of the water quality volume cannot be retained, retain to the maximum extent practicable and treat for sediment, floatable, and nutrients
- Same retention and treatment scenario as redevelopment
- OR if the redevelopment will not increase effective impervious cover, additional stormwater control measures to treat the water is required, but the permittees will not have to retain the water quality volume
- All sites currently undeveloped or contain less than 40% effective impervious cover
- Retain water quality volume for site, document if this is not possible
- Retain to the maximum extent practicable and treat for sediment, floatable, and nutrient
Post-Construction Control Measures
Incorporate runoff reduction and LID control measures, measures to minimize suspended solids and removes floatable (80% removal goal annually), and place velocity dissipation devices at discharge locations and at the lengths of any outfall channels.
Implement best management practices to minimize the amount of litter, debris, building materials and other waste from being discharged
Post-construction stormwater measures must be properly cleaned of sedimentation. Remaining silt fences must be removed once the area is stabilized.
Have designed washout areas for any cleaning of equipment, applicators, vehicles, and containers. These washout areas must be:
- Outside buffers and at least 50 ft away from streams or wetlands
- Inspected once a week
Storage of Chemical and Petroleum Products
All chemical and petroleum products must be stored in an impermeable containment system without any cracks or leaks of any kind. The containment system must hold at least 110% of the volume of the largest container being stored
Off-Site Vehicle Tracking and Dust Suppression
Minimize the off-site tracking of sediment caused by vehicles and the generation of dust
Cold Water Stream Habitat
Any construction within a Cold Water Stream Habitat must implement an 100 ft undisturbed buffer to be verified post-construction with any additional plantings to maintain the stream cover