Water New Zealand Web Forum

[chrisf]

Hi All,
One of our local takeaways is installing a 125L polyethylene free standing grease trap made by Plumbpak Products Hamilton. I am not familiar with this product and was wondering if anyone has any knowledge they can share. To me the capacity seems a bit small but may be OK for a takeaway business.

Cheers
Chris.

[Jared Hansen - Waipa]

125L is just too small. Period.
Waipa DC has a 500L minimum size for new GT installations or uses sizing based on the building code +25% for flushes (plus some other allowances such as +250L if a dishwasher is connected)., whichever is greater.
_________________
Jared Hansen BSc.
TRADE WASTE OFFICER
WAIPA DISTRICT COUNCIL
jared.hansen@waipadc.govt.nz
www.waipadc.govt.nz
Phone: 07 872 0030 ext 7581
Mobile: 027 478 6227
Fax: 07 872 0033

[ianhayes_rdc]

For Rotorua we have a minimum of 500 litres of water in a grease trap. We haven't got any new Plumbpak grease traps over here so can't comment on how good they may be, but suggest that the 125 lt would need to be cleaned weekly. Our experience with older model above ground traps shows that they loose shape over time and the lids don't fit properly after that, and if not cleaned regularly they leak with a terrible smell as they are not air vented. There are 500 lt plastic models. Plastic systems Ltd in Rotorua has them and they are developing a large 1000 lt model. Cheers Ian

[Jeremyhcc]

We've moved away from accepting 125L Plumbpak grease traps and now stipulate a minimise size of 500 litres. Plumbpak were advised of this.

[Craig.Rall]

Hi All we make a minimum size greasetrap of 750l and then larger sizes.
The reason we have made 750l our smallest is due to more restaurants etc using more oils than fats so have based our design on a greasetrap/oil interceptor to prevent the jumping of oils between chambers.These are made out of U.V stabilised underground polyethylene and have various venting options.And a completely sealable lid this is not a advertising ploy but just to let you know what we found when designing and testing avocado and olive oils are being used much more frequent so therefore designed accordingly.If you would like to see it it is on our website at www.devan.co.nz or you are more than welcome to contact me. Cheers Craig 021 958819

[Jared Hansen - Waipa]

The plumpak 375L and 500L GT's appear to function ok, their major failing is their outlet in the final chamber being at water level.

FOG which makes it to the final chamber can therefore discharge should they bypass the other 2 chambers. Stricter cleaning regimes are therefore required for these traps.

(Cleanouts are stipulated by WDC on an individual basis.)

I only have a handful of these traps and I am not overly happy with their design. I will be making this known to plumpak and after seeing this thread am considering making businesses with this grease trap design retrofit improved outlets.
_________________
Jared Hansen BSc.
TRADE WASTE OFFICER
WAIPA DISTRICT COUNCIL
jared.hansen@waipadc.govt.nz
www.waipadc.govt.nz
Phone: 07 872 0030 ext 7581
Mobile: 027 478 6227
Fax: 07 872 0033

[jamieWDC]

Hi there folks

For those of you with minimum requirements (apart from Waipa, spotted that one), are these limits for all types of units or not? Just wondering if there're any efficiency variations between traps & converters of similar sizes.

Ta

Jamie

[Jared Hansen - Waipa]

We use sizing for grease converters based on suppliers recommendations. They are typically much smaller than a standard grease trap because of their method of operation. In theory Oil and grease are degraded to essentially nothing (CO2 and bacteria) but in reality the process is limited to break down to fatty acids and glycerol with minimal bacterial activity. Because the oil and grease break down, the size of these devices are much smaller than standard grease traps.

For a business to install one, even second hand ones, they must be assessed by the brand (typically Dux or Simply Stainless) of converters local approved service agent.

Essentially, this gives us a guarantee that the installed device will work as it is meant to by the service agent and prevents undersizing.

The cost difference between the converters is also not huge, so it removes cost as a motivation to buy smaller.

The real risk with grease converters is how they are operated. If the automatic dosers are not kept full of liquid and excess solids are entering the converter they simply stop working.

Fitting fixed in sink screens are critical to how these devices work. You should not allow the installation of a converter without them!

I have customers who treat their converters well and they have very low cleanout frequencies (set by service agents) and those who need an occasional kick in the rear who need them pumped out every 6 months because they are full of food solids.

If you don't want to have to chase the business up, then a correctly sized passive grease trap is better. If they have no ability to install a grease trap, a converter is one of the few other options along with Big Dippers (which have their own issues.)
_________________
Jared Hansen BSc.
TRADE WASTE OFFICER
WAIPA DISTRICT COUNCIL
jared.hansen@waipadc.govt.nz
www.waipadc.govt.nz
Phone: 07 872 0030 ext 7581
Mobile: 027 478 6227
Fax: 07 872 0033

[GeorgeG]

Hi guys

Like one of the previous submitters we too were concerned by the ineffective 3rd stage of the plastic traps (and also by the price jump (they doubled) so we tracked down the actual manufacturer of them and we have had a number of discussions and I have met with them (Dennis McAulay of Rotational plastics - www.rotationalplastics.co.nz). They have since modified the trap so as the outlet of the 3rd stage is now from lower down meaning it acts as a true 3rd stage. The actual volume is also greater than the stated 375 or 500L. They have also had some issues with wholesale markups which goes some way to explaining the surprise of ourselves and drainlayers when what used to cost around $1400 jumped to $2500. They also make a range of SW retention and detention products that are quite nice.
Of specfic TW interest is that they also make a 1000L modular (could become 2000 or 3000 etc) trafficable plastic trap which they are allowed to sell direct. Customers/applicants may find it cheaper to fit a bigger trap than an agent supplied 500L.

As for the 125L plastic traps we don't let them in. Even if somehow the trap sizing complies with the provisions of G13 (most fail the twice the sink requirement) then hydraulically they fail to work as inputs tend to stir them up too much and they quickly reach a steady state where under static conditions they might look ok but they have already captured all they ever will. Cleaning them more often doesn't really solve the risk to sewer issue it merely makes the contractors more money.

We a have also recently had several of the new 1000L circular style humes concrete traps go in. These are quite nice, not overly expensive and thanks go to Rotoroa for their hand in the design and testing.

After a prolonged test period we have banned installation of new grease converters and are pursuing the fitment of screens to the few remaining of out 80 or so units without screening. The testing showed that they do not meet the claims made of them and never will and they continue to be a source of constant follow-up work for us.
thanks
GG
_________________
Gordon George
Manager, Trade Wastes Section
Hutt City Council
04-570-6819 or 027-222-5714