Work Based Diploma -Unit 223 Manage Drainage Systems

Work based diploma -Unit 223 Manage Drainage systems

Notes and examples of documents to help you complete the unit

Which soil types will most likely require drainage systems and why.

Clay and slits will be in most need or drainage systems due to lack of soil pore space and slow movement of water through the soil profile. This is due to the small particles sizes in the soil meaning then can fit together closely and this makes it hard for water to move through them. Sandy soils have large spaces between particles and therefore drain quickly.

Soil Texture and soil structure

Soil texture refers to the particles the soil is made up of

Soil structure refers to how these are arranged and fit together in the soil

It is hard to alter the texture but very easy the damage the structure of soil.

Good soil structure is important as it

Ensures water flow into soil

Ensures air flow into and out of the soil

It provides space, and a protected home, for roots, germinating seeds as well as soil organisms (bacteria etc.)

Cranfield University – A guide to better soil structure – National Soil Resources Institute.

Drainage operations can damage soil structure. Driving heavy machinery very soil when it is wet will compress the soil particles damaging the structure. This will make the surface areas around the drains compacted and slow to drain. Where possible drainage should take place in dry soil conditions and if possible boards used to transport heavy tractors and trailers

The benefits of drainage to the playing surface and plant health quality.

Although drainage is expensive to install in does provides a number of benefits that include

Firm playing surface- a dryer surface is a firmer surface
Less damage to playing surface- drier surfaces are less easily damaged
Reduced disease problems- dry surfaces reduce fugal activity (most fungi need moisture to spread from plant to plant)
Improved root depth- if water can move quickly through the soil plant roots develop by reaching deeper into the soil to reach the water. This makes them more resistant to drought conditions and more resistant to stresses such as heat, cold and wear.
Improved plant health- in a well-drained soil oxygen levels are increased and this allows for better grass growth.
Reduction in course closures- a dry soil can be played on a poorly drained soil may flood and prevent play.
Increased revenue from all year play. Continued on next page:
Increased use from playing surface
Keeps the soil air space free of water, enabling plant growth to take place
Extended growing season and playing season- a dry soil is a warm soil so well drained soils warm up quickly in the spring providing better playing surfaces earlier in the year.
Raises soil temperature- as above

Why install drains?

Drains remove excess water from the playing surface; this means the surface is available for play more often and is of a higher quality.
Drains control the height of the water table in the soil.
Drains lower the water table, this promotes deeper turf grass root systems
Drains remove excess water that would other wise fill the air pores in the soil (poorly drained soils lack oxygen and this reduces bacterial and other microbe activity in the soil leading to increased thatch layers etc.)

How to identify blocked drains

Look for the following indicators

Wet spots in areas over drainage pipes indicating a blocked drain
Depressions along drainage lines (indicates a possible collapse of drain)
Water lying over pipe lines the day after heavy rain (may indicate drainage pipe or soil problems)
Observe the drain out fall several hours after heavy rainfall (pipes should be running well)

The causes of drain malfunction and explain how to deal with each.

Typical drainage problems that can occur include

Problem / Solution
Leaves / rod to remove, keep ditches clear
Soil compaction over drain / aerate affected area
Silt in pipe / rod to remove
Collapsed drain / dig out section and replace
Blocked out let (end of pipe) / Clear debris
Blocked pipe / Rod pipe to clear
Overgrown vegetation in drainage ditch / Clear vegetation (strim and rake out)
Drainage ditch silted up / Dig out silt
Drain blocked by tree roots / Remove tree/s if this is not possible or desired then use a sleeved pipe in the sections of drain affected
Water lies over drained areas / Check drain is not blocked, then check water is reaching the drain as soil compaction may be the cause if so aerate area.
Blocked silt trap / Clear silt from trap

Factors affecting water flow rates through pipes

The main factors that will affect the flow rate through a pipe are as follows

Size of pipe the larger the pipe the less drag their will be on water moving through it.
Smoothens of the inside walls of the pipe (the smoother the wall the faster the water flow.
The degree of fall on a pipe (the steeper the fall the faster the water flow will be).

Principles of drainage design

Use an accepted lay out such as grid or herring bone
Ensure drains are placed deep enough to avoid aeration equipment
Drain spacing should be as follows

1.5 to 1.8m (5 to 6 feet) – used on flat areas in heavy soils

1.8m to 2.4 (6 to 8 feet) - used on gentle slopes and lighter soils

2.4m (8) feet and more- used on steeper ground and course textured soils

Ensure you have a good outlet at the end of the drainage pipe
If end of pipe is in a ditch, ensure the end of a pipe is at least 30cm (1 foot) above water level of ditch.

The importance of outfalls for a drain

When installing a drain, it is important that the water can exit the drain quickly and effectively. The end of a drain is known as an outfall. The best types of outfall will be

A clear ditch that flows out of the golf course
A large lake able to cope with the water flow
A river
A stream
A soak-away that drains into a free draining surrounding soil

The most commonly used drainage layouts

The most commonly used lay outs are herring bone and grid systems that are shown in the diagrams below.

Below- Herring bone system in use on a golf green

Note the drain around the edge of the green, this is sometimes referred to as a “smile” drain

Installing land-drains

Cross section of a typical land-drain installation

Calculating the fall of a drain

The fall of a drain refers to how steeply it drops downwards. For example, a fall of 1 in 100 means it would drop down wards by 1 metre over a distance of 100 metres (the end would be 1 m lower than the start point)

To find depth of the fall the calculation is as follows

Distance divided by the required fall

So if we wanted a fall of 1 in 200 over a distance of 100 meters would be worked out as follows

100 divided by 200 = 0.5 meters, so the out fall is 0.5m deep, to which you need to add the depth at which you set the start of the drain (you would not start the drain at ground level)

Example

Ground level Ditch

Start of drain is 30 cm

below ground level

Fall of drain is 1 in 200 Depth of outfall is 0.8 m

Length of drain is 100m long

Distance 100m divided by fall 200 = 0.5 metres plus the start depth of 0.3 metres makes the outfall 0.8m deep

What drainage records should be kept and why?

It is important that records of the system layout, any works carried out on the system, and any changes to it are kept. This will allow you to locate drains easily when repairs are needed and also to avoid damaging them when carrying out other works.

How often should drainage systems be inspected

This depends on the age of the drains, type of soil on the site, type of drainpipe used, amount of trees near drains etc. However it would be wise to check all drainage systems prior to winter to ensure they are functioning correctly before the winter rains arrive and then at reasonable frequencies (e.g. monthly) during the winter.

Possible adverse environmental impacts from drainage works

Clearing of ditches should be avoided during bird nesting season to avoid disturbance to nesting birds and other breeding wildlife. Clearing of silt from drains, ditches etc. should not be carried out in periods of low water flow as large amounts of silt flushed into shallow streams etc. may result in damage to aquatic life.

Try not to work on drainage systems during periods of high soil moisture as the moving around of heavy machinery and materials may result in serious damage to the soil structure and turf areas.

Possible wastes arising from drainage works and how to avoid them

Recycle soil etc. removed from drainage trenches (e.g. organic materials such as leaves etc. can be composted.

Measure the required amount of pipe to avoid purchasing more than you need.

Health and safety implications of drainage works

Working on drainage system presents a number of hazards i.e.

Open trenches – people tripping, falling in etc. (Health and Safety at Work at). Open trenches should be roped off to help avoid risks to the public.

Working in drains could bring you into contact with rat urine, which can cause serious diseases (Personal Protective Equipment regulations and Control of Substances Hazardous to Health Regulations).

Ditch banks can present serious slip hazards and working too close to deep ditches with tractors and trailers presents a risk of the sides of the ditch collapsing under the weight and possible injury to staff.

Managing waste from drainage operations

Organic waste such as silt, leaves etc can be composted on site for use in future works.
Inorganic waste such as old plastic piping may recycled at a local authority waste disposal site. It should not be burned as this will generate toxins and causes pollution.

Drainage records

This unit requires you to complete an irrigation checklist. The checklist must have a date and cover the work that is to be completed. An example of such a checklist might look is shown below.

Sundown Golf Club Drainage system monthly checklist- Date: 16.10.17

Checks carried out by: Peter Pennywise
For the attention of :Roger Smith Course Manager
Hole / Green /

Bunkers

/ Fairways / Ditches / Comments
1 / OK / OK / OK / problem / Ditch needs strimming
2 / OK / NA / OK / OK
3 / OK / OK / OK / NA
4 / OK / OK / OK / problem / Pipe under bridge needs clearing
5 / OK / OK / OK / OK
6 / OK / NA / OK / NA
7 / OK / NA / OK / NA
8 / OK / NA / OK / NA
9 / OK / NA / OK / NA
10 / OK / NA / OK / NA
11 / OK / NA / OK / NA
12 / OK / OK / OK / OK
13 / OK / Problem / OK / OK / Water lying in left fairway bunker (still full from last weeks rain)
14 / OK / OK / OK / OK
15 / OK / OK / OK / NA
16 / OK / OK / OK / NA
17 / Problem / OK / OK / NA / Outlet in ditch full of debris (needs rodding)
18 / OK / OK / OK / OK
PG / OK / OK / OK / OK

Other comments

Pipe under bridge on the 4th hole will need a lot of work, stuffed with mud and leaves etc.

Health and Safety Legislation affecting drainage operations

Acronym / In full / Brief description of the legislation etc.
COSHH / Control of Substances Hazardous to Health 2002 / Requires employers to protect employees and other persons from the hazards of substances used at work by risk assessment, control of exposure, health surveillance and incident. This will result in a written COSHH assessment.
PUWER / Provision and Use of Work Equipment Regulations 1998 / Requires that equipment provided for use at work is suitable for use, maintained in a safe condition, only used by people who have received adequate information, instruction and training in its use.
RIDDOR / Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013
(Some reportable diseases may caught be staff working in contaminated water e.g. Weil’s disease) / Requires the employer to record and report any serious injuries, accidents or near misses.
HASAWA / Health and Safety at Work act 1974
(the need to keep yourself and other safe during drainage works) / Requires employers to protect staff and other people in the workplace from harm.
Requires workers to protect themselves and others from harm in the workplace.
PPEAWR / Personal Protective Equipment at Work Regulations 1992
(PPE to protect from water-borne diseases e.g. rubber gloves etc.) / Requires the employer to provide free of charge any PPE required for activities carried out in the work place where a risk has been identified e.g. steel toe capped boot if there is a risk of injury to feet from mower blades etc.
MHOR / The Manual Handling Operations Regulations 1992
(Lifting heavy loads of soil etc. when working in drainage ditches) / Requires employers to assess the risks involved in lifting, moving items in the workplace and to provide training in safe lifting and handling.
NAWR / Noise at Work Regulations 1990 (noise when strimming ditches etc). / Requires employers to assess risk from noise to workers hearing and if required provide hearing protection (see below)

WBD L3 Unit 223 (Further knowledge)

Hydraulic Conductivity

This can be calculated by setting up a small experiment using a long glass tube having a bung with a glass tube set in it at the lower end with a small amount of porous material topped by a set amount of top soil from the area to be drained. The tube is then filled with water and the time taken for the water level to drop a given amount is recorded. The following calculation is then made:

F = fall in inches
D = depth of soil layer
H = Average between starting and finishing head of water
T = time taken in seconds

Hooghout's Drain Spacing Equation

S = drain spacing (CMS)
h = depth to impermeable layer
K = hydraulic conductivity of permeable layer
V = design rate (CM/hr) at which rain is to be cleared from surface.

Example

Soil has a 30cm layer of top soil: hydraulic conductivity is 40 cm per hour. Rain to be cleared from surface at 0.125cm per hour (i.e. 3cm per day).

S = 10.72m distance apart from laterals

From web page

Problems associated with poor drainage

The main problems with poor drainage are

Soil is more prone to compaction

Root depth is reduced

The lack of oxygen in the soil may lead to problems such as black layer.

Why poor drainage causes black layer

Water from rain and irrigation build up in the soil filling the pore spaces in the soil. This will result in a reduction of oxygen loving bacteria as they begin to die off.

These are the replaced by bacteria that do not require oxygen to operate. These produce a gas called Hydrogen sulphide which is toxic to grass roots.

This gas will react with metals in the soil particularly iron and will cause layers of metal sulphides that will severely restrict grass growth and root formation.

Movement of water in the soil

Water flows down into soil under the force of gravity. If this downward movement is stopped by compaction layers etc. or if the downwards movement of water is to slow due the soil type. If this water is not then drained away it will slowly begin to fill the soil and fill the air spaces between the soil particles and in doing so remove oxygenvital for plant growth.

Water moving downwards under gravity

Maintenance of open ditches

The main problems of an open ditch are

Excessive weed growth can speed up silting- ensure regular strimming of banks and bases of ditches. The use of specialised herbicides for use in water may be considered.

Debris (branches etc.) collecting near culverts, pipes etc. Check on a regular basis and remove as required.

Bank slips, the cause of bank slippage are

Water erosion of bank – reinforce bank by using stones sandbags filled with concrete.

Blocked pipe entering ditch, water will build up pressure in the blocked pipe causing bank damage. Check area for pipes and clear as required.

Blocked pipe resulting in pressure build up in the soil around the outlet and bank slippage

Silt build up

Ditches containing slow moving water will silt up quickly the will occasionally need digging out to ensure pipe out let is not buried.