High, for homeowners comfortable with basic excavation and understanding fundamental drainage principles. Professional consultation is recommended for extensive systems, complex site conditions, or if connecting to existing public stormwater infrastructure.
Basic excavation and drainage project. Primarily focused on proper grading, material selection, and adherence to setback and frost depth regulations. Generally does not involve complex structural or utility systems.
Project Guidelines & Rules
I. Permits, Planning & Site Considerations
4 Rules
Local Permit Requirements
Consult with your local municipality's building department to determine if a permit is required for underground storm drainage modifications. Requirements may vary based on the scope of work and local ordinances within DuPage County.
Utility Locates (JULIE)
Prior to any excavation, contact JULIE (Joint Utility Locating Information for Excavators) at least 48 hours (excluding weekends and holidays) before digging to identify and mark all underground utilities. This is a critical safety and legal requirement in Illinois. (Illinois Underground Utility Facilities Damage Prevention Act)
Property Line Setbacks
Maintain minimum setbacks from property lines as required by your local municipality's zoning ordinances to prevent drainage issues or impacts on adjacent properties.
General Site Drainage
The finished grade shall slope a minimum of 6 inches in the first 10 feet away from the foundation. The underground gutter extension system must maintain positive drainage away from the structure and prevent water accumulation near the building foundation. (2024 IRC R401.3)
II. Excavation & Trenching Standards
4 Rules
Frost Protection Depth
All underground piping and components that could be affected by frost heave must be buried below the local frost line. For DuPage County, the minimum frost depth is 42 inches (1067 mm) below finished grade. (2024 IRC R403.1.3, DuPage County Building Standard)
Separation from Electrical Lines
Maintain adequate separation between the trench for the gutter extension and any existing or new underground electrical lines. Consult the 2023 NEC for specific separation requirements and minimum cover depths for conductors and cables. (2023 NEC 300.5)
Trench Stability & Safety
Trenches deeper than 5 feet (1524 mm) or otherwise deemed unsafe may require shoring or sloping to prevent collapse. All excavation work must adhere to recognized safety standards. (Referenced: OSHA 29 CFR 1926 Subpart P for excavation safety best practices)
Backfill & Compaction
Trenches shall be backfilled with suitable material, free of large rocks or debris that could damage the pipe, and compacted to prevent settling, protecting the integrity of the pipe and the finished grade. (Illinois Plumbing Code Section 890.200)
III. Materials & System Installation
4 Rules
Pipe Material
Use durable, non-corrosive piping suitable for underground storm drainage, such as PVC (SDR 35 or Schedule 40) or corrugated HDPE pipe. Ensure materials meet applicable ASTM standards and are approved for underground use. (Illinois Plumbing Code Section 890.130)
Connection to Downspout
Ensure a watertight and secure connection between the downspout and the underground extension pipe. This typically involves an approved adapter and appropriate sealants to prevent leaks and erosion at the foundation. (Illinois Plumbing Code Section 890.1430)
Pipe Sizing
The pipe size must be adequate to handle the anticipated volume of stormwater from the connected downspout(s) to prevent backup and overflow. For residential applications, typically 3-inch or 4-inch diameter pipe is sufficient, but larger roof areas or multiple downspouts may require larger sizing per Illinois Plumbing Code tables. (Illinois Plumbing Code Section 890.1450)
Slope/Gradient
Maintain a minimum continuous slope of 1/8 inch per foot (1%) for effective gravity drainage throughout the entire length of the underground extension to prevent standing water, debris accumulation, and freezing within the pipe.
IV. Discharge & Stormwater Management
4 Rules
Positive Drainage at Discharge Point
The discharge point of the underground extension must release water to a location that provides positive drainage away from all structures and property lines, and does not create standing water, erosion, or nuisance conditions on your property or adjoining properties. (2024 IRC R401.3)
Discharge Location Restrictions
Stormwater shall not be discharged onto public sidewalks, streets (unless specifically designed and approved as part of a public stormwater system), or directly onto adjacent private property without specific easements or agreements. Discharge must remain within the owner's property or into an approved storm sewer system. (Local Stormwater Management Ordinance, Illinois Plumbing Code Section 890.1490)
Erosion Control
Implement measures at the discharge point to prevent erosion, such as splash blocks, pop-up emitters, or rock beds, to disperse water flow and protect the landscape. (Best Management Practice, implied by 2024 IRC R401.3)
Connection to Other Drainage Systems
If connecting to an existing storm sewer, a private storm drainage system, or a sump pump discharge, ensure compliance with Illinois Plumbing Code Section 890.1490 and obtain approval from the local building department or utility authority. Connection to sanitary sewers is strictly prohibited. (Illinois Plumbing Code Section 890.130, 890.1490)
