I am getting ready to replace my utility tub, and I would like to correct the plumbing problem while I do it. When the kitchen sink upstairs is running, the utility tub gurgles sometimes. The kitchen sink drains horizontally before dropping vertically to the basement where the washing machine and utility tub are located. They drain to the vertical pipe coming down from the kitchen, but there is no separate vent pipes for the washer or tub. I have attached a picture showing how it is now. How should I change it to avoid the gurgling?