Managing Visual Impacts on Historic Sites and Districts MN State Historic Preservation Office Review and Compliance Seminar April 26, 2011 Panel Members: Mary Ann Heidemann, SHPO Matt Bartus, Pinnacle Engineering Garneth Peterson, Mn/DOT
Why are Visual Impacts Important? Part of the Assessment of Adverse Effect required by the NHPA regs (36 CFR 800.5) Visual impacts have the potential to diminish the historic property s integrity Through negative impacts on setting, feeling or association of the historic property Property integrity is key to maintaining Register eligibility
Types of Adverse Visual Impact Introduction of visual elements outside the period of significance Addition of elements that alter the design characteristics of the site Overwhelming the historic property in scale, mass or feeling Blocking or substantially altering historic vistas or views to or from the property
Examples of Adverse Visual Impact
Defining the Visual Area of Potential Effect The visual APE defines an indirect impact Different from both the archaeological APE and the direct above-ground APE Usually the largest APE in terms of land area Can be difficult to define responsibly Vague statements are not sufficient SHPO will say: Show Me
Tools to Define Visual APE & Impacts Distance guidelines Topo maps Google Earth views Visual simulations Diagrams Site photos
Presumed Visual APE from Telecommunications Nationwide PA Tower Height Visual APE Boundary Less than 200 feet Half mile 200-400 feet Three-quarter mile 400 feet and above One and a quarter mile
Other Tools: Photo Simulation Before: Existing Conditions After: Proposal in Place
Photos as a Tool: Well or Poorly Used First Submittal Second Submittal
Factors Limiting Visual APE Topography Foliage Intervening buildings Sight lines Distance Explain it to us! Document it
Sight Line Limitations
Documentation Standards 36 CFR 800.11 (a) Adequacy of documentation. The agency official shall ensure that a determination, finding or agreement in this subpart is supported by sufficient documentation to enable any reviewing party to understand its basis.
Sometimes Visual Impacts Cannot Be Avoided: Example of Knodt Farm
Univ. of MN s U-More Wind Turbine and Visual Impact on Knodt Farmstead APE for 490 Wind Turbine Adverse Effect Unavoidable Existing agricultural setting remarkably intact Open farm fields meant nothing could block the view to the turbine University had no practical site alternatives Preparation of Minnesota Historical Property Record was used as mitigation for adverse visual effect
Finding Alternatives to Avoid Adverse Visual Impacts Some Project Examples From Telecommunication Antennae Projects Matt Bartus, Pinnacle Engineering From the Lyndale Avenue Bridge Project Garneth Peterson, Mn/DOT Cultural Resources Unit
Techniques to Avoid Visual Disturbance from Antennae Utilize appropriate equipment shape Careful placement Avoid principle façade, move away from roof edge, hide among existing roof utilities Use flush mounts Paint color that blends into background Employ stealth screening devices
Assessing Visual Impact Decoy antennae used for visual assessment Integrate with existing building utilities At non-prominent location Flush mount Painted to match
Crane Test for Assessing Visual Impact
Antennae shielded from street view by equipment setback
More setback examples: Salvation Army Building
Penthouse Mounts
Chimney Mounts
Stealth Mounts
Lyndale Bridge Design Process Garneth O. Peterson, Mn/DOT CRU
On the boardwalk approaching the bridge from the east
The Original Arch
Early Replacement Options
Elliptical Arch Alternative
Round Arch Concept Design
Concrete textures for Public Advisory Committee and Public Comment
Bridge Arch Designs: Radial and Elliptical
The Final Bridge Design