Drainage systems are crucial to landscape health by preventing erosion and protecting plants. They work through an outlet, main and submain ditches to convey water, and lateral drains to remove water from soil. Main drains draw water into pools or spas but require safety features to prevent entrapment. Properly installed and maintained subsurface drains can provide drainage solutions depending on soil type by removing water from below ground level.

1. Drainage is a vital part of landscape design. It helps prevent soil erosion and protects plants and
animals. It’s often out of sight, but it’s crucial to your property’s health.
The components of drainage systems include an outlet at the lower end; a main and submain
ditches that collect water and convey it to outlets; and lateral drains, which remove water from
the soil. Laterals can be arranged in either a uniform or random pattern.
Main Drains
Located in the deepest part of the pool or spa, main drains are designed to draw water into the
recirculating pump. When working properly, this is a simple and effective way to provide
drainage solutions.
Pool main drains work off of the suction created by the recirculating pump to suck water through
them and into the PVC piping that leads to the skimmers and the pool or spa’s circulation
system. Unfortunately, main drains have also been the cause of a fair share of tragedies in
swimming pools and hot tubs, including human and animal entrapment deaths.
Because of this, main drains are required to comply with VGB regulations aimed at reducing the
risk of entrapment. To do so, they must feature dual suction outlets, a safety vacuum release
system, or a suction limiting venting system to break the pressure buildup or limit the amount of
suction that can be created when the drain is blocked.
A main sewer line, which is sometimes referred to as a sewage line, is the large-diameter pipe
that all your smaller drain lines connect to. Wastewater from your showers, sinks, garbage
disposal, and toilets all make their way down these lines to the sewer system or septic tank
outside your home. If the main line becomes clogged, all the fixtures within your home will be
affected. Often, this is the most obvious sign of a major problem that will require professional
plumbing services to resolve.
Mud Drains
A mud drain, or area drain, can be used to help mitigate a muddy paddock problem by
channeling surface and subsurface water to another location. They consist of a small
underground catch basin with one or more drain pipes. A metal or plastic grate covers the drain
in the ground, and the pipe(s) carry runoff water to some termination point-typically a street
curb, municipal storm drain, or retaining area.
If a mud drain is not maintained properly, the piping can be blocked by sludge and other
materials, which will reduce its efficiency in mitigating muddy conditions. Blocked drains can be
flushed using a rubber drain bladder that attaches to a garden hose and when turned on shoots
a blast of water into the pipe to dislodge any obstructions.

2. When constructing your drainage system be sure that the trench has good slope (1% grade or
better) to ensure gravity does all of the work of channeling water away. Also be sure to use
proper drain fill material. 1-1/2" clean natural round gravel provides the best permeability to
allow water to flow freely and minimize blockages.
Be sure to check with your local utilities before starting any digging projects. The locations of
buried electrical, telephone and TV cables and gas piping may influence your drainage plan. If
you cannot get clearance, consider other drainage solutions such as trenching with Lighthoof.
Inclined Pipes
The inclined pipe is a common particle-conveying structure and is widely used in many
industries such as boiler combustion, oil refining and solar thermal power generation. In these
systems, the inclined pipe is often equipped with a valve that regulates the particle mass flow
rate. During the conveying process, the descending particles oppose gravity by either creating
lift and entraining the bubbles (dilute phase) or by sliding friction against the pipe wall (solids
phase).
The different characteristics of the flow phenomenon in an inclined pipe-valve system can cause
significant pressure fluctuations and severe vibration of the system. The aim of this study was to
experimentally investigate the dynamic pressure and displacement features in an inclined pipe
under varying particle mass flow rates with different valve positions. The results showed that the
downward gas-solid two-phase flow in an inclined pipe could be characterized by three distinct
flow patterns: creeping stratified flow, upward channeling flow and dense phase fluidization flow.
Statistical analysis of the interface wave type map reveals that the wavy interface shape is
significantly dependent on the inclination and azimuthal angle of the inclined pipe. The interface
wave height distribution and the liquid film thickness decrease with increasing inclination angle,
while the interfacial waves attain higher amplitudes and lower propagation velocities with
inclination. It is also shown that the Limit of Stationary Deposit Velocity increases with the
inclination angle.
Subsurface Drains
Drains can provide drainage solutions for a wide range of conditions. The type of drain to use
depends largely on the soils in the area being drained. Refer to soil maps available from natural
resources or Cooperative Extension Service offices, and dig test pits where necessary.
A properly designed system will provide years of trouble-free operation as long as it is properly
planned, constructed, and maintained. The design should be based on the water table level
desired and a drainage coefficient, or rate of removal, selected for the field.

3. The location and spacing of drains depend on the soil types and conditions. In sandy soils, for
example, drains should be spaced about 200 to 300 feet apart. In moderately permeable or clay
soils, they may be spaced closer together, depending on the drainage coefficient selected.
Each drain should have a proper surface-water inlet, which can be a metal cone grate or a
metal mesh, to float debris and protect the bottom of the drain. Inlets should be located on
grades sloped away from the field to prevent silt and other materials from building up around
them. A sediment trap should be used where water flows into a drain from above.
Each drain should be blinded and backfilled before work is suspended for a day, to protect the
drain from damage during the construction process. The drain should be backfilled to a grade
that is determined to give it the capacity required for the area being drained. Breathers should
be provided to vent the drain and to assure maximum flow.