Pits
Inflow Hydrograph (user-provided hydrograph) property sheet
This window enables you to enter a user-provided hydrograph at a pit. You have a choice of applying this above the inlet at the surface, or inside the pit. You need to specify the duration of this hydrograph and the time step between ordinates. This ...
Surcharge Pits and Converters
A surcharge pit is one that is intended to overflow. It may have an outlet pipe that is smaller in diameter than its inlet pipe(s), or it may have no outlet pipe at all. The latter situation occurs in localised pipe systems that are intended to carry ...
Sealed pit, bolt-down pit
This is a pit with a bolted-down lid, which can pressurise so that the hydraulic grade line can rise above the ground surface. This can be quite complicated when there are branches and flows must be distributed among the pipes leading into a pit so ...
Regional pit types
The examples and pit data base files supplied with DRAINS contains pit inlet capacity relationships for a number of types of pits used in various regions of Australia. More pit types can be added as reliable information on pit inlet is obtained. ...
QUDM pipe system design procedures
The Queensland Urban Drainage Manual (QUDM) sets out detailed pipe design procedures that include the estimation of pit pressure changes using a set of charts that includes the Missouri Charts (Sangster et al., 1958) and graphs developed by Hare ...
Ponding volumes at sag pits
For sag pits, in the Pit property sheet, DRAINS offers two choices regarding storage volumes: an inverted pyramid assumption and an elevation - surface area table: With the first option, in the Lite hydraulic model, DRAINS considers ponding at sag ...
Ponding depths
At many places in drainage systems, including commonly occurring sag pits, surface water can form ponds due to obstructions or barriers. Some of these may be intended, such as detention basins, while many are unintentional and may only operate in ...
Pits (manholes, gullies, inlets, catchbasins)
In piped stormwater drainage systems pits serve several purposes. They act as inlets for stormwater, points where pipes can conveniently change their size, slope or direction, and inspection and maintenance openings. An important distinction is ...
Pit drawing tool
This tool, with the symbol , allows you to draw a drainage pit on the Main Window. When you select it, the arrow cursor changes to a pencil. Click the point of the pencil where you wish to locate the pit and the pit symbol and a name will appear. ...
Pit property sheet
This sheet appears as: (Layouts that apply in earlier versions of DRAINS are described later in this topic.) (a) Inputs With the latest sheet, it is necessary to enter the following information in the main Pit Properties page: a pit name of up to 10 ...
Pit energy losses and pressure changes
At pits there will be changes to the positions of the hydraulic grade line and the energy grade line, caused by energy losses due to turbulence in the pit. The information below applies to pits with inlet and outlet pipes flowing full. The head loss ...
Pit Data Base property sheet
This window allows you to set up a data base of inlet capacity relationships for common pit types or families, with different sizes in each type. This format is required for the design method used in DRAINS. The Add and Properties buttons in the top ...
Pit alignment and pressure change coefficient charts
Procedures for determining pit pressure change coefficients involve the alignment of the outgoing pipe to the incoming flows. With the QUDM Charts procedure, orientations and relative angles of pipes are determined from the system drawing, which is ...
ILLUDAS pit (superseded)
This type of pit is no longer available in DRAINS, but may be encountered in old DRAINS models. In the older form of the Pit property sheet, it is selected as a simple sag pit (as per ILLUDAS) in the first set of radio buttons. This has no ...
HEC22 wizard
This is a procedure for determining the capacity of on-grade pits from geometric data, using methods presented in U.S. Federal Highway Administration Hydraulic Engineering Circular 22, Urban Drainage Design Manual, 3rd Edition, 2009 (available from ...
Falls and drops in pits
In Australia the term 'fall' is used to define a loss in level along a pipe or channel, and through a pit, as shown below: The word 'drop' is used to describe a difference in invert levels of pipes entering and leaving a pit, where the invert of an ...
Blocking factors
In DRAINS you can specify a factor at each pit to represent the reduction in capacity due to blockage by debris that may be washed into a pit during a storm, or be present beforehand because of poor maintenance. This is an uncertain factor and little ...