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HomeMy WebLinkAbout11-05-18 City Commission Packet Materials - C13. Mod 2 to Agreement with US Forest Service for Mystic Lake Beaver Dam Commission Memorandum REPORT TO: Honorable Mayor and City Commission FROM: Brian Heaston, Project Engineer Shawn Kohtz, Interim Director of Public Works SUBJECT: Ratify the City Manager’s signature for Modification No. 2 to the Challenge Cost Share Agreement between the City of Bozeman and U.S. Forest Service Gallatin Custer National Forest for the Mystic Lake Beaver Dam Removal Project. MEETING DATE: November 5, 2018 AGENDA ITEM TYPE: Consent RECOMMENDATION: Ratify the City Manager’s signature for Modification No. 2 to the Challenge Cost Share Agreement between the City of Bozeman and U.S. Forest Service Gallatin Custer National Forest for the Mystic Lake Beaver Dam Removal Project. BACKGROUND: In late August of 2017 a mountain biker notified the City via email that a large beaver dam had plugged the outlet of Mystic Lake. The dam was sizeable, approximately 7’ tall and 20’ wide at its crest, impounding an estimated 150 acre-feet, or nearly 49 million gallons, of water behind it. Coordination between the City and USFS Bozeman District Ranger staff immediately ensued to formulate a plan of action to remove the beaver dam and eliminate flooding risk. Mystic Lake is located at the headwaters of Bozeman Creek on U.S. Forest Service lands. Sudden failure of the beaver dam would have presented an unacceptable risk to life safety, downstream property, and infrastructure along Bozeman Creek. The City and USFS entered the attached challenge cost share agreement. The agreement splits the costs to remove the beaver dam approximately 50/50 between the City and USFS. Due to the emergency nature of the work, the agreement was not brought to the Commission for signature authorization of the City Manager. Modification No. 1 to the agreement, also attached, was signed soon after to amend the scope of work and cost. The beaver dam was removed in November 2017 after the lake level behind the dam was slowly drawn down over a period of 2 weeks by a siphon installed to lower the lake level to a point where it was safe to remove the beaver dam. The siphon piping presently remains at the outlet of Mystic Lake. By this memo, Modification No. 2 to the agreement is presented to the Commission for authorization for the City Manager to sign. Modification No. 2 extends the date of project completion to December 31, 2019. Additional work is planned at Mystic Lake to repurpose the existing siphon pipe at the lake outlet into a beaver deceiver device. A beaver deceiver device 186 allows water to flow through the device (ie the siphon piping), rendering the storage ability of the beaver dam inoperable since water continues to flow through the piping, instead of being impounded by the dam. Permanent installation of a beaver deceiver requires permits from MT FWP and the U.S. Army Corps of Engineers. Permits were not issued by the agencies in time for the beaver deceiver work to occur this fall. Thus, Modification No. 2 to the cost share agreement extends the project completion date by one year to give time to complete components of the project next summer that the USFS has already agreed reimburse through the cost share agreement. The City is responsible for costs associated with the beaver deceiver installation. The beaver deceiver install was not contemplated in the original cost share agreement as the original agreement focused on eliminating the immediate flooding threat by removing the dam. The beaver deceiver is new component to the project to mitigate risk and ease in maintenance should another beaver dam be built at the outlet of the lake. A CIP project is planned for the proposed FY20 water fund CIP at $35,000 for the beaver deceiver. The cost share agreement, as modified, includes an agreed cost share for site rehabilitation work. By approving Modification No. 2, the city will be reimbursed for this component of the project. Note, the permanent installation of the beaver deceiver device is beyond the scope of the original cost share agreement, hence why the City is responsible for funding the installation at 100%. FISCAL EFFECTS: Total cost for the project as contained in the cost share agreement as amended is $61,300 which will be split equally between the USFS and City. The City’s share will debit from the Water Enterprise Fund. An additional $35,000 expenditure is planned in the FY20 water fund CIP to install the beaver deceiver next summer. ATTACHMENTS: Challenge Cost Share Agreement Modification No. 1 to Agreement Modification No. 2 to Agreement 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230