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REQUEST FOR COUNCIL ACTION Date: 10/20/2025 Item No.: 7.a. Department ApprovalCity Manager Approval Item Description:Discuss an ordinance imposing regulations on excavations within ten feet of existing foundations 1 2 Background 3 On September 8, 2025 the City Council discussed whether to impose an ordinance that 4 would allow the City to require mitigations to protect existing foundations that occur within 5 ten feet of excavations for projects constructed under the residential building code. Staff 6 provided three draft ordinance language options, but also outlined areas that needed 7 further clarification to ensure the ordinance could be fairly and uniformly applied throughout 8 the City. Those packet materials are provided in Attachment 1. Because staff lacked 9 expertise to draft an ordinance that provided regulations that would address real impacts, 10 and thus limit its overall scope, Council requested that staff seek input from a Registered 11 Design Professional before moving forward with an ordinance. Meeting minutes are 12 provided in Attachment 2. 13 14 At the Council's direction, City staff sought input from a Registered Design Professional 15 regarding adoption of a local ordinance regulating close-proximity excavations. After 16 speaking with building inspections staff in the City of Minneapolis, staff was put in contact 17 with an engineer at American Engineering Testing, Inc. (AET). AET provided technical 18 expertise in drafting the Minneapolis ordinance and has practical experience implementing 19 mitigations on various projects in Minneapolis. City staff provided AET with the City 20 Council meeting materials from the September 8, 2025 meeting, namely the presentation 21 slides that outlined the background information and specific issues that needed further 22 input or clarification and that could aid in limiting the scope of the ordinance. 23 24 Following review of those materials, staff and AET conducted a Teams meeting to discuss 25 practical regulations for close-proximity excavations. In summary, AET indicated that, in 26 their expertise, mitigation to provide vertical and/or lateral support for an adjacent 27 foundation is only necessary when excavations occur below a foundation's footing that 28 exceed one foot of depth for every one foot of horizontal separation (a standard provided in 29 the commercial building code). Meaning, in situations where there is a 10' structure 30 setback (like at The Enclave), excavations would need to exceed ten feet of depth below 31 the footing. Based on the finished grade and basement depths at The Enclave, and 32 assuming the entire 10' setback area is excavated, in order to exceed the industry- 33 accepted 1:1 ratio, a vertical excavation of 20 feet from finished grade would need to 34 occur. Any other excavation not exceeding 1:1 is generally not seen to be detrimental to an 35 adjacent foundation and, therefore, would not require mitigation such as underpinning or Page 1 of 4 Qbhf!3!pg!:29