Hi Ice,
This looks like a Spiraea ( pronounced Spy-ree-ya), but not the attractive sort you would find at your local garden centre.
I don't know it's variety name, but, I know that it can become a very invasive nuisance. I spent hours and hours digging out a 40' long by 8' wide border of it at a garden I maintain, one winter a few years ago. A little of it still remains, but I will make sure it never reaches the epidemic proportions of before!
If your feeling energetic, and really loathe this spreading shrub, then start by cutting all stems hard back - to make the job of removing the plants easier. If the plants have formed a 'thicket', you (or a helpful male hand :huh: ) may find using a pick-axe will help break up the condensed mass of suckers. This is certainly a job to keep you warm in winter ( and the fresh air will do you the wolrd of good! ), and you may find the soil underneath remarkably dry, even at that season.
Dispose of the plants, and dig in lots of bulky compost, and then you'll have an exciting new patch at the ready for spring planting.