Farm Dairy Effluent

Regional rules
Effluent publications
Compliance and Statistics
Weeping walls
Contingency storage ponds
Low application rate sprinklers
Feed pads
Useful links
For more information

Regional rules

All dairy farms must comply with Rule 16 for animal effluent disposal in the Regional Water and Soil Plan (RWSP) for Northland. These rules apply to the discharge and disposal/management of animal effluent and farm wastewater from dairies and adjacent entrance and exit races, dairy yards, holding yards, standoff pads, loafing pads, feed pads, wintering barns, calf rearing facilities, piggeries, poultry farms, stock underpasses, sale yards and transit races if used for standoff and the like.

To be a “permitted activity” the following rules must be complied with:

Key points for the Permitted Activity Rule 16.1 (Land application)

There must be no discharge to surface water:

Directly
Via overland flow
Via any tile, mole or other subsurface drain; and
No discharge directly to groundwater.

Effluent must not be discharged to land within a distance of:

20 metres of any waterway
20 metres of any drain which contains water or 10 metres of any dry drain
20 metres of any water supply bore
20 metres from neighbouring properties without the property owner's written permission
50 metres of any occupied dwelling.

These are the “Setbacks”:

Contingency measures must be in place to ensure no rules are broken due to equipment failure and when ground and/or weather conditions are unsuitable for application.
Any effluent storage or effluent treatment facilities must be sealed or lined with low permeability material to ensure there is only minor groundwater contamination through seepage.
There must be no ponding on the land surface for more than three hours after application.

Effluent must be applied in a manner that:

Evenly distributes the effluent
Does not exceed the soil's ability to assimilate the effluent
Minimises overland flow
Does not cause overland flow into setback distances from drains, watercourses etc.

NOTE: You will not consistently comply with all the above criteria if you:

Have no, or insufficient, contingency storage
Use an open hose to apply effluent
Do not keep pond levels low during dry conditions
Do not move stationery irrigators frequently.

Ponds. Effluent settlement ponds Discretionary activities

Any system which cannot consistently meet the above criteria and is not a “Prohibited Activity” is deemed a “Discretionary Activity” and requires a resource consent.

Prohibited activities

There shall be no discharge of untreated effluent to water; and
The discharge of treated animal effluent into any dune lake or any watercourse flowing into any dune lake listed in Schedule E or any river, section of river or lake deemed to have outstanding value is a Prohibited Activity.

Section 15(1)(b) of the Resource Management Act 1991 also states
“The discharge of any contaminant to water or to land in any way in which it is likely to contaminate water is an offence under the Act”.

Find Rule 16 in Part V - Rules of the Regional Water and Soil Plan

Effluent publications

From our Resource Library

A guide to managing farm dairy effluent - Northland

Farm dairy effluent – Managing stormwater

Farm dairy effluent – Managing treatment ponds

Farm dairy effluent - Storage and disposal

Managing Farm Dairy Effluent (courtesy of Dairying and the Environment Committee)

Farm Management Issues (courtesy of Dairying and the Environment Committee)

Dairy Farmer News - newsletters

Compliance and Statistics

Monitoring Programme

The Farm Dairy Effluent (FDE) monitoring programme is the council’s single largest compliance monitoring programme, accounting for almost 25 percent of the total number of activities monitored.

All Northland farms are inspected at least once per season. Follow-up inspections are also made to all farms found to have significantly non-compliant discharges.

The FDE programme is fully documented in the Farm Dairy Effluent Procedures Manual and is subject to both internal and external quality audits. The aim of the programme is to monitor the effects of the approximately 13,000 m3 of farm dairy effluent produced daily during the milking season, and to protect water quality by promoting and enforcing compliance with standards set in resource consents and regional plan rules.

FDE systems are divided into consented (MCO) or non-consented (MNC) types. Non-consented systems – currently approximately 260 farms – are visually inspected and graded depending on compliance with the criteria for “permitted activities” in the RWSP.

Consented systems – currently approximately 700 farms – are assessed against individual consent conditions and rules in the Regional Water and Soil Plan (RWSP). All farm discharges are categorised as either fully compliant, minor non-compliant or significantly non-compliant.

Our monitoring programme

All farms are monitored every year between August and December (this is the period of peak effluent loadings).
All visits are made non-notified.
Systems are checked for compliance with individual resource consent conditions and/or against the permitted activity rules.
Wherever there is a discharge to water, samples are taken. These are tested for pH, temperature, dissolved oxygen, faecal coliforms and NH4.
A 'whole of farm' approach is taken – where any non-compliance with the rules for animal effluent or silage are found on farm – these are included in the statistics.

Consented farms monitoring results

Graph - FDE consented discharges compliance trends.

Non-consented farms monitoring results

Graph - FDE permitted activity compliance trends.

Weeping walls

Northland Regional Council is promoting:

Weeping walls for solids separation
High volume contingency storage
Low application rate sprinklers for land application

Weeping wall systems

Weeping wall. Weeping walls are designed to remove solids from farm dairy effluent.

Weeping walls are used extensively in Southland and Otago where effluent application rates are strictly controlled.

The removal of solids prior to irrigation means:

Less frequent pond cleaning;
Lower pumping costs;
Better irrigator performance; and
Elimination of blockages in low application rate sprinklers.

Weeping walls get rid of the need for gravel traps, many of which do not work well and require routine cleaning.

The system consists of sludge beds which are one metre deep ponds that sit behind slatted timber walls. Two sludge beds and two weepng walls are used for each installation.

When one bed is full it is left to dry so that solids can be moved by a front end loader or excavator onto trucks or trailers and trailed onto pasture or crop paddocks.

The wall is constructed by installing posts at one metre centres and fastening 50mm x 50mm slats to the posts. There are specific width gaps between the timbers depending on the effluent source, e.g. dairy yards or feedpads etc.

The top side of each of the slats is tapered so the liquid effluent flows more efficiently through the wall.

Click the image below to open a larger version in pdf format

Sludge beds

Each sludge bed should have 30m3 of volume for every 100 cows
The sludge bed is one metre deep
The sludge bed has an internal batter of 2:1
The floor of the sludge bed should be level
The concrete apron under the weeping wall must be slightly lower than the bottom of the sludge bed

Weeping wall design

Click the image below to open a larger version in pdf format

The required wall area is typically one square metre for every 100 cows but with a minimum of five square metres for each wall.
The recommended gap between slats for effluent from the dairy is 6mm.
It may be necessary to increase the gap to around 8mm on farms where maize silage is fed or pastures contain a proportion of high fibre grass such as kikuyu.
The recommended gap between slats for feedpads is 18mm.
The slats must be fastened to the posts when they are saturated as dry slats will expand when they get wet and close the gap. If this happens, chainsaw work will be required.
The bottom of the wall and the concrete apron must be above the level of the liquid in the pond to allow the sludge to dry.
There must be rip rap or a concrete channel to carry effluent to the pond to prevent erosion below the weeping wall.

Weeping walls and feedpads

Weeping walls are also ideal for separating effluent solids off feedpads.

The required size of the sludge beds is dependent on how much the pad is used
The gap between the timbers is also wider

Weeping wall maintenance

Sludge beds require cleaning annually
Weeping walls should be pressure washed while the sludge beds are empty
Any broken slats or knot holes can be repaired using plywood strips

Contingency storage ponds

Effluent should not be applied to pasture when soils are at or near saturation.

Northland's soils are often saturated from May through to October.

Research has proven that effluent applied to saturated soils will result in up to 80 percent of the effluent running off to surface or ground water.

Dairy industry guidelines state that with spring calving herds in Northland there should be a minimum storage volume of 5m3/cow. This is for effluent from the dairy and yard only and assumes that stormwater is diverted when the yard is clean. It also assumes that the ponds are emptied in autumn and the only input over winter is rainfall on the ponds.

If there is winter milking or the yard is used for standoff over winter, or if there is an open standoff or feedpad the storage volume must be increased.

Regional rules require that:

There must be no ponding on the land surface for more than three hours after application.

Effluent must be applied in a manner that:

Evenly distributes the effluent;
Does not exceed the soil's ability to assimilate the effluent;
Minimises overland flow; and
Does not cause overland flow into setback distances from drains, watercourses etc.

Note: you will not consistently comply with all the above criteria if you:

Have no, or insufficient, contingency storage;
Use an open hose to apply effluent;
Do not keep pond levels low during dry conditions; and/or
Do not move stationary irrigators frequently.

Contingency storage is now mandatory.

Low application rate sprinklers

Low application rate sprinklers can cover a large application area with a low application rate (approximately 4 mm/hr) of effluent.

Low application rate sprinklers have traditionally created management problems because small diameter nozzles repeatedly block up.

A low application-rate sprinkler is now available which has a choice of nozzle sizes at 8, 9 and 10mm.

At 20 PSI with a 9mm nozzle they can spread as much as 3700 lires/hour over 850m2 at an application rate of 4.43 mm/ hour.

The sprinklers are fitted to PODS and up to eight can be connected to a single mainline depending on pump capacity and the size of the mains.

Volumes and wetted areas increase with pump capacity and pressure. The PODS can operate at up to 100psi.

A number of Northland farmers are operating pods from their ponds using gravity with good results.

Feed pads

Feed pads and stand-off areas

The Regional Rules for effluent disposal from feed/stand-off pads, wintering barns, herd homes etc are the same as those for effluent from the dairy.

When considering the construction of a feed/stand-off facility it is important to consider all options and design the effluent disposal system at the same time.

Design of pads

The design of the pad and the infrastructure around is – stock races, silage and supplementary feed storage bunkers – should allow for the effective collection and treatment/disposal of all effluent (including silage leachate).

Effluent characteristics

The major differences between effluent from a feed/stand-off pad and that from the dairy are:

Higher solids content
Higher volume
Higher nutrient content

Effluent volume

The volume discharged from the pad:

Is directly related to stock numbers and the length of time animals are on the pad;
Varies depending on the construction material of the pad;
Is increased by lost feed solids when supplements are fed;
Is directly related to cleaning method, e.g. scraping versus washing;
Can be much higher than from the dairy alone; and
Is greatly increased during rain.

Covered feed pad. Covering pads greatly decrease the effluent volume.

Stormwater

Effluent application systems must be designed to handle stormwater volumes.

Stormwater from the pad cannot be diverted:

When stock are on the pad
When the pad is not clean

In Northland rainfall events with intensities of 10mm/hr occur frequently and falls of 3-60 mm/hr are common. Ten millimetres falling on a 1000 m2 pad will generate an additional 10m3. This is the same as the total daily effluent volume from a dairy milking 200 cows.

Some Northland farmers have fitted roofs to existing pads to improve cow comfort and reduce effluent volumes by decreasing stormwater on to the pads.

Solids removal and treatment

Solids can be:

Retained in a separate pond
Retained behind a “weeping wall”
Mechanically separated

Feed pad. Feed pad with effluent system.

Retained solids can be dried and then spread on land provided that the criteria for permitted activities of the Regional Rules for Northland are complied with.

For more information on the design of feed pads see the DairyNZ website