Farm Effluent Code of Practice

July 2011

A new code of practice and design standards for dairy farm effluent

A new code of practice and design standards for farm dairy effluent has recently been published. It is intended for designers of farm dairy effluent collection, storage and land application systems so that they have an agreed standard design criteria for new systems. There is also a system of training and accreditation for designers and suppliers. The Code is voluntary and does not affect existing systems, but where farmers are planning new systems they now have the option of engaging accredited people and using accredited equipment suppliers to give them greater assurance that the systems they put in will do what is required.

Along with the Code is a guide for farmers so that they know what questions to ask designers and what information to give them, as well as information on choosing the right contractors.

Featherston dairy farmer Keith Dennis says that the Code has been a long time coming, and he welcomes it because of the assurance it gives him that the $180,000 or so that he is planning to invest in a new effluent treatment system will do the job he wants it to in a way that will meet all known industry and regional council requirements.

Dairy farmers invest hundreds of thousands of dollars in effluent treatment systems that sometimes prove inadequate. One reason for this is that there has been no definitive set of performance criteria that designers and suppliers of equipment and systems could aim for and no accreditation system for identifying designers and suppliers who are trained and/or have the experience to meet regulatory requirements for effluent treatment.

In the past few years there has been an extensive consultation process throughout the industry and the result is a comprehensive Code of Practice that has recently been released.

Logan Bowler, environmental extension specialist with DairyNZ, says that the code is a guide to take designers through the process of developing a new farm dairy effluent (FDE) system.

“It covers the initial site investigation through to commissioning the final system and provides a general design approach, listing factors that designers must take into account and performance standards that every new FDE system must achieve,” he says.

“The Code and standards are voluntary at this stage and don’t have any effect on existing installations. Those will continue to be monitored by regional councils and the industry.”

Logan is one of a number of extension specialists whose job it is to make sure farmers are aware of all the issues and options open to them and the benefits and risks of each option. There is usually a variety of means of doing a particular job whether it be diverting stormwater or handling effluent and if farmers know what they are, they can get the answers they need from equipment suppliers.

“The message to farmers is that the Code has been developed for the farmers to ensure that they get what they pay for and the system will do what they require. If the job is done by an accredited supplier then the design should be fit for purpose because it has to meet the Code e.g. they have had to take into account soil type and rainfall etc,” says Logan.

“Farmers are spending considerable amounts of money and they need to spend wisely and just once. They may pay a little more for people who follow the Code but they will get the assurance that it provides. However, it is not compulsory and they can still hire whoever they like.”

As well as the Code there is a guide for farmers so that they can ask the right questions of suppliers. Logan says it means that suppliers will inevitably understand more about a farmer’s particular situation and will be able to take into account their unique circumstances and consider all the potential issues that may arise.

Keith Dennis, a dairy farmer near Featherston in the Wairarapa, says he has been waiting a long time for the Code and the farmers’ guide and is pleased it is finally out.

“One of the good things about the Code is that there is also a planning process because every farm is a little bit different and farming philosophies are different. It will help those wanting to design something new to get a system that will suit them,” says Keith.

“And the other thing that I’m pleased about is that there will there are training programmes for the people involved in advising farmers so that they can be qualified and accredited. That avoids farmers putting a lot of money into a system and then being told by the council that it is not good enough. It provides a bit more of a safeguard because farmers don’t have to figure out what gear to use on their own and rely on someone who is selling a product and may have some expertise but not a broad range of knowledge.”

Keith milks about 500 cows on a 180 ha milking platform of reasonably free draining stony alluvial soil, all of which is irrigated with artesian water using a long lateral irrigation system. Each day his staff shift about 370 irrigators using two four-wheel-drive vehicles.

At present for effluent he has a consented spray irrigation system. The effluent is collected in a sump and spread over a fixed 30 ha of land on a rotational basis using a travelling irrigator. Keith says that the design was inadequate right from the start and despite his early intervention it has never worked properly. Their consent allowed them to irrigate over just 21ha, but this caused excessive build-up of nutrients, notably potash, so he extended the area of coverage to 30ha. This was still unsatisfactory.

“In the last two years we have been investigating various options for a new system. The goal is to harvest all the effluent and develop it into a useful material that we can put over the whole farm. We have started preparations that have involved demolishing an old cowshed to clear an area where the new system will go. This cost $6500,” says Keith.

“It is now set up so that we can gravity feed to the ponds that we are going to build for the system, which we envisage building over three years and could cost around $180,000.”

The first part will be the primary collection area and sand trap made from prefabricated concrete slabs. A tractor will be able to drive in and pick up the sand, sediment and stones, which could be stockpiled and re-used on farm tracks etc. From there the effluent will gravity flow into a 40,000 L concrete primary settling pond. A separator will remove all the solids, which will be augured onto a bunded concrete pad. Once dried it will be removed with a front-end loader and potentially can be used for things like calf bedding, Keith says.

The liquid will then be moved to a secondary holding pond of between 500,000 and 1,000,000 L, and the treated nutrient will be pumped through the irrigation system over large parts of the farm. Measured amounts of this nutrient will replace the usual irrigation water and some of the fertiliser.

“We will be able to cover about 140 ha of the farm and on the remaining 40 ha we will be able to spread the dry product a couple of times a year using a fertiliser truck. We will measure its nutrient value in terms of phosphate, potash and sulphur, and put on a measured amount consistent with nutrient budgeting.”

That’s the long-term goal. For now Keith is in the middle of the planning process and he is delighted that the Code and farmers’ guide have become available.

“My comment on the Code of Practice is that it is long overdue. What was the best practice system five years ago is now out of date, and in the last 10 years the pressure on dairy farms to change has been great and it continues,” he says.

“We want to do something that will work and will show the general public that we are serious about what we are doing and that we care about our land. We live in the country and so we have to live with our system and in our environment. We like to swim in the rivers, eat fish out of the streams and use the water, so its quality impacts on our lives and we are actively doing what we can to improve the situation.

The Code will help farmers to do this.”