Pond Construction

As we wind down construction for this season, the rainy weather continues to limit progress. The pond dredging is complete, all 30,500 cubic yards of it. On some days, the mud was so thick that the excavator had to push the dump trucks to get them moving forward.

More than half of the sediment has been transported off-site but the rest is spread out in the future wetland area to dry. With the cooler, cloudier weather, this process has slowed considerably. As a result, sediment hauling to the landfill has virtually stopped. Hauling may continue in November, but it is unlikely that this task will be completed this fall. Hauling may start again in the winter when the material freezes.

Some of the earthwork in the new pond has begun, but again the weather is a factor. Clay soil needs some moisture to compact correctly, but for much of the last month, the pond area has been flooded. The embankment for the upstream pond - designed to capture phosphorus, sediment and other pollutants - has been completed. The embankment is capped with pre-cast concrete blankets.

Some poured concrete work has begun. The footings for the pedestrian bridge in the middle of the site have been poured. The carpenters should be out again in the next few days to build the forms for the remaining concrete work on the bridge and outlet.

Pre-cast concrete blankets that will cover the main dam will be delivered to the site in the next few days. These blankets have void spaces that will be seeded. Once vegetated, the concrete will not be visible.

Some additional work will be required to stabilize the site for the winter, insure that it drains, and still functions for flood control. We won’t be seeding or installing any permanent vegetation this year as planned, so none of the site will resemble a finished product as the end of this season. We can only do our best to make up for lost time next year. There is still plenty of room in the project schedule to complete the work by next August, however, we will have to have a very dry spring if we are to get everything completed and seeded/planted on time.

Lastly, I’ll mention that Birch Hollow road was not always free of construction sediment. We did our absolute best to keep eroded soil from being tracked off the site, but there was about a two week period there where that was difficult. We received several complaints and an inquiry from the City of Ann Arbor Soil Erosion Control Officer. Several improvements were made to the entryway to minimize the problem. Additionally, the street was swept once per day, whenever hauling occurred. I apologize to the residents of this neighborhood for the trouble. I can only hope that you are very satisfied with Ann Arbor’s newest park when complete.