NCSPA Engineering Calculator
Water Quality System Calculator
Size corrugated steel pipe detention and retention systems using the engineering relationships and pipe data contained in the NCSPA source workbook.
System Configuration
Define the system type, elevations, and required storage volume.
System Elevations
Enter feet and inches separatelyStorage Requirement
Volume, not flow rateSite & Layout Constraints
Identify the dimension that controls the system footprint and the trench/header geometry.
Pipe Selection
Dmax limits the pipe diameters available for the system. The largest allowable diameter is selected initially, but storage and layout requirements must still be checked. Select a smaller available CSP diameter as needed.
System depth may also be affected by the project inlet pipe and other site-specific constraints.
Calculated System
Results
Enter project values and click Calculate. After the first calculation, updates will run automatically as values change.
For two-header layouts with unequal lateral lengths, the plan shows a stepped outlet manifold concept. Lateral storage uses the entered lengths; header/manifold storage continues to follow the source-workbook formula.
Selected CSP outside diameter.
Editable system layout input.
Calculated system storage.
Required design storage.
Detailed Engineering Results
Calculated values for the selected system branch.
The storage-status check preserves the source workbook logic: provided storage must be greater than the required storage. In Custom Individual Laterals mode, lateral storage is recalculated from the entered lateral lengths while the workbook header/manifold storage term is retained. The controlling dimension is reported separately so the designer can confirm the selected layout.
System Drawing
Generate a source-style CSP plan, typical trench cross section, and conceptual connection-detail sheet from the calculated system geometry.
The plan and typical cross section follow the layout conventions of the supplied NCSPA water-quality system design sketches: perimeter excavation limits, CSP headers/manifolds, parallel laterals, inlet/outlet callouts, pipe spacing, and a trench cross section. Pipe/trench geometry is drawn to the resolved engineering scale; finished cover to grade and CSP connection/fabrication details are schematic because those design inputs are not defined by this calculator. Corrugation marks are symbolic. Drawings are conceptual layout aids, not shop or construction drawings.
This calculator is an engineering aid based on the supplied NCSPA detention/retention system workbook and the NCSPA Corrugated Steel Pipe Design Manual methodology identified in that workbook. The designer remains responsible for confirming project criteria, elevations, hydraulic requirements, installation details, applicable specifications, and final design suitability.