July 23, Mr. Richard Miller, Vice President Lake Arrowhead Property Owners Association 7065 Arrowroot Trail Gaylord, Michigan 49735

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1 Mr. Richard Miller, Vice President Lake Arrowhead Property Owners Association 7065 Arrowroot Trail Gaylord, Michigan Re: Task No. 3 Report of Findings Section 32, Township 30 North, Range 4 West Hayes Township, Otsego County, Michigan Dear Mr. Miller: In accordance with your request, Applied Geotechnical Services, Inc. (AGS) has completed Task 3 of the Strategic Lake Dredging Hydrogeologic Investigation presented in AGS Proposal No dated June 8, AGS was authorized to perform this work on June 30, This letter presents a summary of the field and laboratory exploration and the results of our hydrogeologic analysis and evaluation. PROJECT BACKGROUND INFORMATION & PURPOSE OF STUDY AGS performed a Lake Level Augmentation Evaluation study for Lake Arrowhead during March and April of The findings of the Lake Level Augmentation Evaluation report (AGS Report No dated April 12, 2012), indicates that under the present conditions Lake Arrowhead is recharging at a slower rate than it discharges into the groundwater and Pencil Lake on its down stream side. Also, our study indicates that augmentation of the lake level by installation of pumping wells will not be feasible. However, the findings suggested that it may be possible to raise the lake level by implementing a properly designed dredging program. It was pointed out that additional studies will be required to confirm the preliminary conclusions of the previous studies. Furthermore, once the conclusions, scope and limitations of the additional studies are confirmed and understood by the Association, a dredging plan could be developed. In accordance with the provisions of Part 301 of P.A. 451 of 1994 (the Natural Resource and Environmental Protection Act), a dredging plan must be approved by the Michigan Department of Natural Resources and Environment (MDNRE) and a permit obtained prior to implementing a dredging program. AGS representatives visited the subject site on June 14 and 15, 2012 to collect data regarding historic lake levels previous investigations. On June 15, 2012 gave a presentation to the Lake Arrowhead Property Owners Association (LAPOA) summarizing the findings of our Lake Level Augmentation Evaluation report. During our visit, we were also informed that the LAPOA had previously investigated the feasibility of conducting a mass dredging program of the lake

2 Page 2 between 2003 and This information was photocopied and transmitted to AGS on June 21, AGS has completed a review of this information. TASK 3 SCOPE OF SERVICES As presented in AGS Proposal No dated June 8, 2012, Task 3 included the following scope of services: 1) Clearance of the boring/well locations with the MISS DIG system prior to drilling. 2) Performance of approximately five (5) soil borings extending to an estimated depth of 30 feet below the existing ground surface and installation of 2-inch PVC observation wells within each of the borings. The wells were to be installed with appropriate screened interval, filter sand pack, bentonite seal, and locking protective cover concreted into the ground. 3) Obtain at least two sets of groundwater level measurements for the wells at intervals of approximately one to two weeks. 4) Perform a laboratory test program to characterize the engineering and groundwater flow properties of the subsoils surrounding the lake. Laboratory testing to include visual engineering classifications, mechancial sieve analysis grain size distribution and permeability testing. No surveying or report preparation services were included as part of the Task 3 scope of work authorized by the LAPOA on June 30, FIELD EXPLORATION PROCEDURES The present investigation included the performance of five (5) Geoprobe soil borings and the installation of four (4) groundwater observations. The wells have been designated as OW-1 through OW-4 and were performed at the locations shown on Schematic Observation Well Location Plan appended to this letter report. Logs of the soil borings/observation wells area also attached. The soil borings were extended to a depths of 35 to 65 feet below the existing ground surface. The bottom of the observations well screens were typically installed at a depth of approximately 5 feet below the groundwater level encountered while drilling. At the location of GP-5, groundwater was not encountered within the 65-foot maximum possible explorable depth. Therefore, a well was not installed within this boring. The borings/monitoring wells were performed by Pearson Drilling Company of Lake City, Michigan.

3 Page 3 The groundwater observation wells consisted of 2-inch schedule 40, flush joint, PVC materials installed within 3½-inch I.D.driven steel casing. Each of the wells included a 5-foot section of No. 10 slot screen and vented well cap. A filter sand pack was placed above the screen. A two-foot thick layer of bentonite chips were placed above the filter sand pack and the remaining portion of the annular well space was backfilled by allowing the native soils to cave-in around the well casing to a depth of approximately 2½ feet below the ground surface. A locking protective cover was then concreted into the ground. The wells were developed by bailing until the water bailed from the well became relatively clear. The well coordinates and top of PVC standpipe elevations for the observation wells were determined by Diffin-Umlor Consultants, Inc. of Wixom, Michigan (Michigan registered land surveyor). During the field operations, Jeff Anagnostou, P.E., C.P.G. of AGS maintained the logs of the subsurface conditions, including changes in stratigraphy and observed groundwater levels. LABORATORY TESTING The soil samples were placed in sealed containers in the field and brought to the AGS soil and materials laboratory for geotechnical testing and classification. A geotechnical engineer classified the samples in general conformance with the Unified Soil Classification System (ASTM D 2487). The geotechnical/hydrogeological laboratory testing program also included performing mechanical grain size distribution analyses (sieve analysis, ASTM D 422 ) and falling head permeability testing (ASTM D 2434) on a total of four Geoprobe soil samples obtained from the soil borings. Table 1 presents a list of the analyzed soil samples. The grain size distribution and falling head permeability test results are appended to this report. Table 1: List of Sieve Analysis/Falling Head Permeability Composite Samples Boring No. Sample No. Strata Depth (feet) Vertical Hydraulic Conductivity(feet/day) OW to OW to OW to OW to Ave.: The laboratory testing indicates the sands have a relatively high hydraulic conductivity. The sieve analysis results indicate the above samples from OW-1 through OW-4 typically consist of fine to medium sands with trace amounts of gravel, coarse sand, and silt. The samples possess a Unified Soil Classification System designation of SP.

4 Page 4 We will hold the soil samples for 90 days from the date of this report. If you would like the samples please contact us within this time frame. SOIL AND GROUNDWATER CONDITIONS Approximately 3 to 4 inches of sandy topsoil was typically encountered at the Geoprobe boring locations. The subsoils typically consisted of fine to medium sands with trace amounts of gravel, coarse sand, and silt. The driller looked for indications of groundwater seepage in the boreholes both during drilling and upon completion. Groundwater seepage was reported in the borings at a depths of 16 to 53 feet below the existing ground surface during drilling. Upon completion of the borings, groundwater was also reported at depths of 16 to 53 feet. Groundwater level readings for each of the wells were obtained on June 30 and July 20, The results are shown on Table 2 Groundwater Level Readings. As shown on Table 2, the groundwater levels encountered within the observations wells are generally higher than the water level of Lake Arrowhead. The groundwater level encountered in Observation Well OW-4 was below the lake level. However, OW-4 is situated downstream from the lake. Table 2 Groundwater Level & Lake Level Readings Well No. OW-1 OW-2 OW-3 OW-4 T.O.C. Elev. (ft) G.S. Elev. (ft) /30/12 GW Elev. (ft) /20/12 GW Elev. (ft) Lake Arrowhead (ft) Lake Arrowhead (ft) Lake Arrowhead (ft) At Public Swimming Dock At Boat Launch Dock West End of Lake Little Bear Lake (ft) Adjacent to Lake Arrowhead Boat Launch Note: Depth measured from T.O.C. (top of casing) We believe that in consideration of the low snowfall during the winter of and the hot spring/summer experienced in the site area, groundwater levels are likely to be near a historic low at the present time. The NOAA long range forecasts of precipitation levels for the Gaylord, Michigan area indicate an "equal chance" of precipitation levels to be at, above, or below

5 Page 5 normal precipitation levels. The longrangeweather.com 12-mouth outlook for precipitation levels indicates the Gaylord, Michigan area may experience higher than normal precipitation levels. This information is attached. ANALYSES & EVALUATION As shown in Table 2, the groundwater levels obtained in the up-gradient and side-gradient observation wells (i.e., OW-1 through OW-3) are higher than the water level of Lake Arrowhead. As expected, the groundwater level within OW-4, downgradient of Lake Arrowhead, is lower than the water level of the lake. Therefore, dredging of the muck sediments from the lake bottom within the spring areas underlying the east side of the lake would promote increased groundwater recharge into the lake. The amount of rise of the lake water level in response to the improved recharge would depend on the future elevation of the groundwater level surrounding the lake. At present, it appears the groundwater level surrounding the lake on the up-gradient (east side of the lake) and side-gradient (north and south sides of the lake) is approximately 2 feet higher than the water level. The water level of Little Bear Lake adjacent to the Lake Arrowhead boat launch area is also approximately 2 feet highter than Lake Arrowhead. Little Bear Lake is up-gradient with respect to Lake Arrowhead. The groundwater level near the lake will depend on several factors including, future precipitation and evapotranspiration rates and man-made groundwater withdrawls from the aquifer. In addition, it appears the muck sediments blanketing the bottom and sides of the lake are impacting the lake level by acting as a relatively impermeable liner. Where sands are present along the sides of the lake, the lake water would be expected to rapidly seep out of the lake once the lake level rises above the groundwater level. However, where the muck sediments blanket the shoreline of the lake above the present lake level, it appears the muck would reduce the rate of seepage through the sides of the lake and allow a slightly higher lake level to be acheived. The attached Lake Arrowhead Dredging Plan was prepared by Mr. David Cunningham, former LAPOA board member, based on muck sediment soundings he performed in October of As shown int the Dredging Plan, muck sediments within the eastern portions of the lake typically ranged from 3 to 5 feet in thickness. Sediments within the western portions of the lake were generally 2 feet or less in thickness. Based on our visual obserations and limited probing of the lake, it appears the thickness of the muck has increased since Computer modeling and empirical data indicate for lakes that are significantly wider than the thickness of the permeable soils underlying the lake, such as is the case for Lake Arrowhead, the groundwater recharge to the lake and and discharge from the lake to the groundwater predominantly occurs near the shoreline of the lake. A review of the Lake Arrowhead Dredging Plan reveals the greatest muck sediment thickness occurs along the eastern shoreline of the lake in the areas where the springs are attempting to flow into the lake. A strategic dreding plan aimed at maximizing the lake water level would target the spring areas for muck removal.

6 Task No.3 Report of Findings AGS Project No Page 6 Based on the above considerations, we estimate that under present conditions a strategic dredging of the spring areas may permit a rise in the lake level of up to approximately 2 feet. However, if precipitation levels increase in the future as expected, the strategic dredging would take advantage of the resulting higher groundwater levels by promoting higher flow rates into the lakes at the springs. Additional probing of the lake bottom within this areas will help determine whether the dredging can be performed by drag-line (excavation using a crane or back-hoe) or hydraulic methods or a combination of the two. Another option to increase groundwater recharge to the lake includes the excavation of coarse aggregate-filled trenches ("french drains") parallel to the shoreline along east sides of the lake within the LAPOA picnic pavillion and boat launch areas. Additional aggregate-filled trenches would then be constructed perpendicularto the shoreline. These trenches would extend through the muck sediments blanketing the sides of the lake and allow the groundwater to flow into the lake relatively unimpeded. Based on the available data, it appears the shoreline along the east side of the lake should be dredged at this time to "open" the principal springs. To maintain the health of the lake, additional dredging will be required in the future remove the deep accumulations of muck sediments. We hope this information is sufficient for your present needs. regarding this letter, please contact us. If there are any questions Respectfully. APPLIED GEOTECHNCIAL SERVICES, INC. r~~ e e T. Anagnostou, P.E., C.P.G. Geotechnical Engineer/Principal ~Encl: Schematic Observation Well Location Plan, Log of Borings OW-1 through OW-4, and GP-5, Grain Size Distribution Test Results, Permeability Test Results, Lake Arrowhead Dredging Plan, NOAA Long Range Precipitation Outlook for Gaylord, Michigan, Longrangeweather.com 12-Month PreCipitation Forecasts for Gaylord, Michigan 1 pc: encl. 1 pc: LAPOA Board Members (pdf via ) Applied Geotechnical Services, Inc Riverside, Livonia, MI48154