Storm Drainage

Plumbing Systems

CNST 305 Environmental Systems 1Dr. Berryman

2bc Waste Water Disposal and Storm Drainage

Chapter 4, 7; Appendix A (Wentz) and 8.6 -8.7 (Toa)

4.11 Analysis and Design of Construction Systems - Mechanical (3 hrs)

Why Storm Drains (rainwater systems)?

Design Principles Install piping large enough to handle

rainfall in a reasonable amount of time

Size system based on rate of rainfall

RainfallRate Map

Omaha, NECode design -

6” Rainfall per hour

Source: National Standard Plumbing Code

Source: National Weather Service

Mmmhhhh? Only 3.8 inches per hour

Roof Drains Four Types

Flat Roof – Drains

Flat Roofs – Flow Control

Overflow Drains

Site Drains

Catch BasinLocations

Types of Pipe for Site Drains

Plastic Vitrified Clay Cast Iron Corrugated Galvanized

Manhole Placement

Engineering Design Determine Rainfall

Determine Area Determine Number of Drains Determine Slope Available

Sizing Roof Drains

80’Location: East Kansas

Slope: 1/8” per ft

40’c.o.

Allowable Flow Rate Table

Flow Rate for Conductors/Leaders

Sizing Roof Drains (cont.)

80’Location: East Kansas

Slope: 1/8” per ft

Rainfall Rate: 6”/hr

40’c.o.

Sizing Site Drains Formula

Flow (CFS) – CIA• • •

Chart Mannings chart for concrete pipe

Sizing Site Drains

Location: Western Colorado

Slope = 1.0” / 100’ Design for 100 year

rain

3 acres

½ bituminous

½ grass

CB Rim El. 99.6

200’

36” SS Main

Coefficients of Runoff

Sizing Site Drains (cont.)

FORMULA Flow = CIA

CFS =

size pipe…go to Manning

Manning Pipe Flow Chart

Checking Velocity and Time

Next Time

3abc

Water System Chapter 8; Appendix B (Wentz) and 8.1-  8.3 (Toa)

4.11 Analysis and Design of Construction Systems - Mechanical (6 hrs)

WATER SYSTEMS