The grease pit should be cleaned twice a year. More if there is an emergency like water backing up into the kitchen and/or horrible smells coming up from the floor drains in kitchen. Observe the photos:
The panel for the grease pit is directly in front of the big windows in the kitchen.
This is what it looks like after a full 6 months of collecting the grease and waste of the kitchen drains. Preferably you would not let any grease or food waste go down the drains, but as it is with cleaning dishes, more of it gets down the sink than you can imagine.
[I use the word "dishes" lightly, it mostly reflects pots, pans, trays, utensils...not actual plates.]
It stinks like...well, like real sewage!
To clean it dress yourself with a double apron (front and back) and cover yourself like with the biggest trash bag and then cut holes for your arms and head. Use the good latex gloves and bring a few more sets with you. Also you want to have one of those face masks like at the hospital or when painting. You can buy them cheap at Home Depot and keep a few around. The smell could make you vomit.
I use a slotted spoon or spatula to scrap all the solid chunks of grease and waste off the top and fill up a "tea pitcher" with the waste. I use the hand-truck to carry the second largest pot on it. I line the pot with the largest and thickest garbage bag. This is what I fill up as I scoop waste out...you can scoop it straight to the pot, or fill up the pitcher first and then dump in the pot.
The pitcher you can keep closer to the actual work. And later you may want to use the pitcher for skimming off the top then pouring into the pot.
When the bag is full close to the top of the pot STOP because you want to tie a knot in the bag and roll the pot up the hill to the trash. When you do this, the pot rolls uphill at a slant so you don't want that stuff bouncing back or pouring out on you or the ground.
Then use the pot handles to pick it up and dump into the trash dumpster. Then repeat this process as many times as necessary. Usually 2 to four times. When I get done I throw everything away: Gloves, pitcher, garbage bags I have used, even the slotted spoon and/or spatula...Everything can be replaced relatively cheap from Sam's Club or Webstaurant.com. Throw the aprons in the bag of dirty laundry.
Doing it yourself is a difference of $20 or $30 dollars in supplies versus $600 a year. Now if cleaning it is not an option then call the local Roto-Rooter Plumbing Service and get a quote. My first quote I got in 2012 was almost $300.00 (Three Hundred Dollars) so I would imagine it would be more than that now. And you need to get it done twice a year.
This is how it should look when your done. Or pretty close to this.
Probably the two best times to do this is end of the school year when VFCA is done and before summer camp has started AND during Fall or Christmas Break when the VFCA is not in session. During the day it's best to do it between 1pm and 230pm so you leave enough time on either side for lunch to be over and before parents start coming regularly to pick up their children from LVA. Because LVA is all year around. Bring a change of work shirt or chef jacket in case of splatter and/or smell permeates clothes.