Managing Visual Impacts on Historic Sites and Districts

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1 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

2 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

3 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

4 Examples of Adverse Visual Impact

5 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

6 Tools to Define Visual APE & Impacts Distance guidelines Topo maps Google Earth views Visual simulations Diagrams Site photos

7 Presumed Visual APE from Telecommunications Nationwide PA Tower Height Visual APE Boundary Less than 200 feet Half mile feet Three-quarter mile 400 feet and above One and a quarter mile

8 Other Tools: Photo Simulation Before: Existing Conditions After: Proposal in Place

9 Photos as a Tool: Well or Poorly Used First Submittal Second Submittal

10 Factors Limiting Visual APE Topography Foliage Intervening buildings Sight lines Distance Explain it to us! Document it

11 Sight Line Limitations

12 Documentation Standards 36 CFR (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.

13 Sometimes Visual Impacts Cannot Be Avoided: Example of Knodt Farm

14 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

15 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

16 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

17 Assessing Visual Impact Decoy antennae used for visual assessment Integrate with existing building utilities At non-prominent location Flush mount Painted to match

18 Crane Test for Assessing Visual Impact

19 Antennae shielded from street view by equipment setback

20 More setback examples: Salvation Army Building

21 Penthouse Mounts

22 Chimney Mounts

23 Stealth Mounts

24 Lyndale Bridge Design Process Garneth O. Peterson, Mn/DOT CRU

25 On the boardwalk approaching the bridge from the east

26 The Original Arch

27 Early Replacement Options

28 Elliptical Arch Alternative

29 Round Arch Concept Design

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32 Concrete textures for Public Advisory Committee and Public Comment

33 Bridge Arch Designs: Radial and Elliptical

34 The Final Bridge Design