This is a work in progress.
From page 357 of the History of the Minnesota Valley Including the Explorers and Pioneers of Minnesota, by Rev. Edward D. Neill and History of the Sioux Massacre, by Charles S. Bryant, written in 1882, it states the following about these mounds:
...Another feature of the town site of Chaska was the existence of a number of symmetrical mounds belonging to the period of ancient mound builders. The situation and form of these mounds as well as the relics unearthed indicate that they were different from the mounds of sepulture so commonly found in this country. They were arranged in a circular form to the number of six with rising ground extending from one to the other as though the whole might at some former time have been a fort enclosed for defense. Excavations have developed bones in large numbers but in such positions as to indicate that many had been killed in some great battle and hastily gathered into some common tomb. Various implements of the usual character have also been found in them. Doubtless they must be classed among mounds of defense. A few of these have been destroyed by the improvements of settlement, but several are preserved in the public park of the village where their form and purpose can be easily observed and the archeologists can speculate on them at their leisure.