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   <br />   <br />  <br /> <br /> <br /> <br /> <br />October 13, 2025 <br /> <br /> <br /> <br />Marco Vincent <br />Takka Day Design <br />Submitted by email: marco@takkadesign.com <br /> <br /> <br />RE: Limestone Retaining Wall Typical Section <br />Project Location: 865 Partenwood Avenue, Orono, Minnesota <br /> Project No. 25-1339 <br /> <br />Dear Mr. Vincent: <br />This letter includes important details regarding the attached design for the typical engineered section of <br />the stone retaining wall at the above location. This design is based on wall layout information provided by <br />you in an email dated October 9, 2025, and subsequent dates including Site Drawings & Documents, <br />Architectural House Plans, and a Variance Submittal prepared by Takka Day Design dated October 7, <br />2025. <br /> <br />The attached typical section(s) should be referenced for construction details. Special note should be <br />made of the wall embedment depth and the geosynthetic fabric (geogrid) length as measured from the <br />front face of the wall, if applicable. <br /> <br />Refer to industry standard practice references for installation information, specifications, and details. <br />- Boulders shall be placed to avoid continuous joint planes in vertical directions. <br />- Each stone shall bear on two or more rocks below it with good flat-to-flat contact. <br />- Compact any structural fill place behind the drainage zone to 95% standard proctor. <br />- Install non-woven landscape fabric behind the stone to limit soil migration through the wall face. <br />- Drainage stone shall consist of clean sand or 3/4” to 1.5” crushed stone. <br /> <br />The design of the wall system is specific to the following parameters: <br /> Location: Replacement of the deteriorated existing retaining wall and necessary improvements to <br />the grading on the east side of the house as stated in your Variance Submittal. <br /> Maximum exposed height(s): 5.5 feet <br /> Minimum embedment depth = 6“, or as noted <br /> Soil conditions: Silty/clayey sand, friction angle = 30.0 degrees, unit weight of 120.0 lb/ft3 <br /> Required soil bearing capacity = 1500 psf <br /> Surcharge load behind the wall: 50 psf <br /> 5:1 maximum slope at top of wall; 5:1 maximum slope at bottom of wall <br /> Boulder sizes: see cross section drawing <br /> Geosynthetic Reinforcement Fabric Type: Not required <br /> Drainage pipe: Required <br /> <br />This wall system has not been designed for ground water surcharge loads. Direct all surface drainage <br />away from the wall. Methods to do so include but are not limited to the following: drainage swale, site <br />grading, retention ponds, etc. Details of water control are left to the wall contractor. Additional information <br />requested by Criterium-Twin Cities Engineers but not available includes: geotechnical site survey and soil <br />data. Please contact Criterium-Twin Cities to provide additional site assessment services if desired. <br />188