Orchard Beach State Park Erosion Control and Geotechnical Study

Client

    Michigan Department of Technology, Management & Budget (MDTMB)

Location

    Manistee, Michigan

Key Elements

    Geotechnical Field Explorations
  • Laboratory Testing and Analysis
  • Alternatives Analysis for Slope Stability Improvements
  • Conceptual Level Remedial Recommendation Measures to Reduce Slope Erosion

Located on the East shore of Lake Michigan, this historic state park encompasses 211 acres and has 3,000 feet of shoreline with a steep bluff and includes historical limestone structures  constructed in the 1930s and 1940s as well as various other buildings and amenities that were added throughout the years, including restrooms and showers, contact station, administrative and maintenance building, manager’s residence, and garage. There is also a campground and day area.

Due to continuing erosion at the toe of the bluff as result of record high water levels in Lake Michigan, the shoreline of the park has experienced significant slope instability. Erosion has also been exacerbated by groundwater seepage at the face of the slope and an increase in the intensity of rain events. Significant erosion and slope failures have occurred since 2017 and have resulted in risk to the stability of several park structures and underground utilities. Of particular concern are the historic shelter building, the historic sanitary pump station, associated underground infrastructure including a bathroom located within 50 feet of the bluff face, and components of the stormwater system, including the outfall discharge pipe. In addition, a set of gabion baskets supporting a riprap-protected section of the bluff was undermined and collapsed, leading to loss of the toe and destabilization of that area, which currently supports the only pedestrian access to the beach via a set of stairs.

The Michigan Department of Natural Resources (MDNR) and MDTMB selected GEI in 2017 initially to study the bluff, better understand the risks posed to the historic shelter building and develop conceptual level mitigation alternatives. GEI’s services were expanded to include a comprehensive evaluation of the park’s coastline, complete a vulnerability study of all park structures near the shoreline and develop a complete design and construction bid package to implement the recommended improvements to reduce vulnerability. GEI will also provide contractor bid evaluation and selection, construction oversight and construction management services. In addition to design and construction services, MDNR has also engaged GEI to provide vulnerability assessment training to their Parks and Recreation Division staff to be used throughout the organization with the goal of becoming more proactive in dealing with highwater impacts at their various park, harbor, marina, boat launch and other facilities statewide.

GEI developed the final design and construction bid documents on time and under budget on an expedited schedule due to project shutdowns related to COVID-19 and inflexible funding schedules. This was possible due to the strong relationship between DTMB/DNR and GEI staff and GEI’s specific understanding of the DNR’s capital improvements projects funding process. Additionally, high water levels in the Great Lakes in 2019 and 2020 caused a shortage of shore protection stone and marine contractors to place the stone. Because of high estimated costs, GEI revised our plans to reduce the length of shore protection, and moving the historical structures, reducing overall cost to the State of Michigan. Multiple presentations were made by GEI staff to DNR leadership to aid in communication of the project’s details, importance of taking action quickly before a disastrous slope failure occurs and to better understand the agency’s hurdles to overcome.

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