MS4 MappingBy

Sacha Mkheidze&

Aaron Hebert

What is an MS4? And what

does it do?

• Municipal Separate Storm Sewer System.

• A series of interconnected stormwater features that collect and transport stormwater from communities to the waterways.

• Phase I, issued in 1990, requires medium and large cities or certain counties with populations of 100,000 or more to obtain NPDES permit coverage for their stormwater discharges.

• Phase II, issued in 1999, requires regulated small MS4s in urbanized areas, as well as small MS4s outside the urbanized areas that are designated by the permitting authority, to obtain NPDES permit coverage for their stormwater discharges.

• MS4’s are mapped in two ways:I. From plans (as builds)II. Field verification

How and why are MS4’s mapped

Plans Typically Include:• Catch basin information

such as location, depth and flow direction.

• Pipe information including size, depth, materials and flow direction.

Plans

Limitations of plans:• They may be difficult to

track down and obtain.

• They may not represent the truth on the ground.

Plans Typically Include:• Catch basin information

such as location, depth and flow direction.

• Pipe information including size, depth, materials and flow direction.

Plans

Limitations of plans:• They may be difficult to

track down and obtain.

• They may not represent the truth on the ground.

How the data is collected• GPS data loggers are utilized

to collect information for each specific feature.• Catch basins (CB), manhole, MS4

outfall, pipe inlet, crossover outlet, point generic, septic system and BMP’s.

• Each feature has specific measurements that are collected (size, depth and flow direction).

• Collected data is downloaded and processed, quality checked and then turned over to county engineer.

Field verification

• Very accurate data.

• Relatively easy to obtain.

• Can pick up any problem areas within the system (illicit discharges, excessive trash, failing structures and blockages).

• A more complete picture of the MS4.

Benefits of field verification

Before and after field verification

Lincoln Park, Prairie Township in Franklin County

Ohio

Lincoln Park MS4 (County data)

Lincoln Park MS4 based on field

verification

• Data is entered into GIS.

• Data is quality checked.

• Data is given to County Engineer.

What happens next?

Questions?