Construction work on the Brandywine Project began in mid-    August 1999.  The watershed was experiencing a significant drought.  The project was started right after the Maier site.

Site De-Watering

The Brandywine project was constructed by the same contractor as the Maier site, therefore the same dewatering equipment was used.  A 12" diesel pump was placed at the top of the project and the upstream flow was piped over 1,100 feet to an area with multiple old stream channels.  After construction of the uppermost  meanders, the pump was moved down lower in the project and used to pump around the lowest meander. Sediment and erosion control were addressed by trapping all turbid water at the lowest point in the project reach and then using a 10" electric pump and 6" pipelines to pump the turbid water to the grassy floodplain. 

Stream Channel Excavation

The project required the movement of tens of thousands of yards of material to create the new stream channel.  The main planform is excavated by a number of large dozers working closely with the GCSWCD to minimize the pushing distance of the materials. The GCSWCD found these projects work best when the District and the Contractor are in constant communication regarding staging and sequencing of the work.

The Brandywine site presented the first instance where the District had to exercise a bid item for over excavation of clay materials. In the upper half of the project, Lacustrine clays were found in the thalwag excavations.  The Contractor was required to over excavate the clay to a depth of 3' below the design elevation. The clay excavation was backfilled with clean gravel materials, and the clays buried in the adjacent floodplain.

The Contractor constructed the rock structures after the channel was established using rock averaging 3x4x6 feet in size.  The structure arms were constructed on slopes between 4% and 7% and they were keyed 10-12 feet into the streambank.  Rock vanes were used on the meander bends, with cross vanes installed at the head of all the riffles.

When the structures were completed, the Contractor transplanted large willow clumps to the head of all rock structures. Then the entire site was hydroseeded with conservation seed mix.

Nine days after the seeding was completed and the machinery moved out, Tropical Storm Floyd made a visit to the watershed. The newly completed work took the brunt of the largest flood the valley had experienced to date.  The flood hit before the bio-engineering components were installed causing some minor damages. Due to the lateness in the season, a decision was made to put the repairs off until 2000.