Pillsbury “A” Mill
Water Power Tunnel
(1882)
Minneapolis, Minnesota

Pillsbury “A” Mill Water Power Tunnel (1882) Minneapolis, Minnesota

preservation-alliance-of-mn-logo2016 Impact Award Winner!

The Pillsbury “A” Mill is one of the most recognizable historic structures on the Minneapolis riverfront and one of only 25 National Historic Landmarks in Minnesota. The mill’s nineteenth-century water power system is comprised of three main portions: 1) the headrace tunnel that channels water from the Mississippi River to the “A” Mill’s two turbine shafts, 2) the turbine shafts themselves, and 3) two tailrace tunnels that return water to the river.

The City of Minneapolis, Dominium (the building owner/developer), and the St. Anthony Falls Heritage Board and the Minnesota Historical and Cultural Heritage Grant program financed a study to help preserve the tunnel system and find ways to explain its historical significance to the public. The study, which included documentation for the Historic American Buildings Survey (HABS MN-29-5-A) ) and the Minnesota Historic Property Record (MHPR HE-MPC-9995), was performed by Mead & Hunt, Inc. in partnership with CNA Consulting Engineers, 10,000 Lakes Archaeology, Inc., and ARCH3, LLC. A 3D visualization of the tunnel was also created by Artificial Natures, LLC.

Large format photography of the water power system required view camera setups in moving water and confined spaces, the use of hand-held strobe “painting” to illuminate tunnel walls, and work in sub-zero temperature environments.

ARCH3, LLC received one of four 2016 Impact Awards from the Preservation Alliance of Minnesota for the photographic documentation of the tunnel system.

 Pillsbury headrace tunnel inlet structure - MHPR HE-MPC-9995-01 (Please credit Daniel R. Pratt and the Historic American Buildings Survey)

Interior concrete wall of intake structure - MHPR HE-MPC-9995-02 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Curved masonry tunnel northeast of intake structure - MHPR HE-MPC-9995-03 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Headrace tunnel looking southeast from intake end - MHPR HE-MPC-9995-05 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Tunnel to Phoenix Mill in headrace wall - MHRP HE-MPC-9995-06 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Detached iron gate from Phoenix Mill tunnel - MHPR HE-MPC-9995-08 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Headrace tunnel, looking southeast towards forebay and trash rack - MHPR HE-MPC-9995-11 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Drill holes in headrace tunnel floor - HABS MN-29-5-A-25 (Please credit Daniel R. Pratt and the Historic American Buildings Survey)

Headrace tunnel, looking northwest from near forebay - MHPR HE-MPC-9995-09 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Headrace tunnel arch profile near forebay - MHPR HE-MPC-9995-12 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Manhole access tunnel opposite forbay - MHPR HE-MPC-9995-13 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Cast iron trash rack adjacent to forebay - MHPR HE-MPC-9995-14 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Headrace tunnel terminus behind trash rack - HABS MN-29-5-A-27 (Please credit Daniel R. Pratt and the Historic American Buildings Survey)

Forebay arch at headrace tunnel terminus - MHRP HE-MPC-9995-16 (Please credit Daniel R. Pratt and the Historic American Buildings Survey)

Detail of brick forebay pillar - MHPR HE-MPC-9995-17 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Forebay showing upstream (r) and downstream (l) turbine gates - HABS MN-29-5-A-29 (Please credit Daniel R. Pratt and the Historic American Buildings Survey)

Upstream turbine sluice gates - HABS MN-29-5-A-30 (Please credit Daniel R. Pratt and the Historic Aerican Buildings Survey)

Downstream turbine sluice gates - MHPR HE-MPC-9995-20 (Please credit Daniel R. Pratt and the Historic American Buildings Survey)

Downstream turbine sluice gate control mechanism - MHPR HE-MPC-9995-21 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

View from above downstream turbine pit - MHPR HE-MPC-9995-23 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Detail view from above downstream turbine - MHPR HE-MPC-9995-22 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Upstream (l) and downstream (r) turbine tailrace exits below A Mill - MHPR HE-MPC-9995-24 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Upstream turbine tailrace exit at Mississippi River level - MHPR HE-MPC-9995-26 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Downstream turbine tailrace exit at Mississippi River level - MHPR HE-MPC-9995-27 (Please credit Daniel R. Pratt and the Minnesota Historic Property Record)

Turner columns in adjacent Pillsbury "C" Mill (Please credit Daniel R. Pratt and the Historic American Buildings Survey)