Information for File # PRH

Transcription

1 Information for File # PRH Applicant Corps Contact Tom Morley Paul Hauser Address 152 Baker Drive, Redwood Falls, MN Paul.R.Hauser@usace.army.mil Phone Primary County Redwood Section 18 Township Range 112 North 36 West Latitude (NAD83) Longitude (NAD83) Information Complete On 30 November 2016 Posting Expires On 13 April 2017 Authorization Type LOP-05-MN This application is being reviewed in accordance with current practices for documenting Corps jurisdiction under Section 404 of the Clean Water Act. This application is being reviewed in accordance with current practices for documenting Corps jurisdiction under Section(s) 9 & 10 of the Rivers and Harbor Act of 1899 and Section 404 of the Clean Water Act. If an approved jurisdictional determination is completed as part of the review process for this application, a copy will be posted on the St. Paul District web page at the following link: Project Description and Purpose (per applicant): The proposed project consists of building one earthen berm measuring approximately 220 long by 180 wide by 23 high to intercept flows from two intermittent tributaries. Construction of the berm would involve the discharge of fill material below the ordinary high water mark of two unnamed tributaries for a total of 445 linear feet (0.02 acre) and into 0.14 acre of fresh wet meadow wetlands adjacent to the Redwood River. The berm would be built for the capacity to withstand a 100 year flood event with an approximate 18 hour retention time. An outlet control structure containing a 21 diameter concrete pipe would be installed through the berm to convey flow downstream to the Redwood River. Emergency overflows would be conveyed via a 30 earthen emergency spillway excavated into the southwest abutment. A riprap scour hole at the culvert outlet and riprap channel would be utilized to dissipate energy and prevent further erosion of the channel discharging into the Redwood River. The excavation of the approximate 160 long by 105 wide pond, upstream and adjacent to the berm, would be utilized as a sediment forebay and wildlife enhancement pond. The purpose of the project is to reduce peak flows and erosion of the tributary channels while improving water quality. 1

2 State Designated Trout Stream: The proposed project is not located in a designated trout stream. State Listed Impaired (Section 303(d)) Waters: The proposed project is not located in a state listed impaired water. Name, Area, and Types of Waters Subject to Loss: The project would result in the discharge of fill into 280 linear feet (0.02 acre) of two unnamed tributaries, 0.14 acre of discharge of fill into wetlands and the conversion via inundation of 0.2 acre of wetlands abutting the unnamed tributaries. These unnamed, ephemeral tributaries are tributaries to the Redwood River. Alternative Considered (per applicant): The applicant considered the No Action alternative but this would not achieve the County s Water Plan goals of reducing downstream flooding, capturing sediment from the upstream agricultural watershed and controlling erosion of the ravine. Another alternative would be to build the structure without a permanent pond. If this approach were taken, the dam would still serve the function of downstream flood and erosion reduction. However, the goal of sediment reduction would not be accomplished to the same extent, since ponding and detention have been shown to be much more effective at removing sediment from stream flows. Lastly the project could possibly be moved to another location along the same unnamed stream of some other tributary. However, the topography of the present site is most suitable for the structure, with nearly 35 feet of elevation difference between the stream and the adjacent uplands. This landscape makes the structure design possible and achieves the goals of creating a permanent pond and providing flood storage. Federally Listed Threatened and Endangered Species: The northern long-eared bat (threatened) and prairie bush clover (threatened) can be found in Redwood County, Minnesota. Historic Properties: The latest version of the National Register of Historic Places has been consulted and no listed properties (known to be eligible for inclusion, or included in the Register) are located in the project area. Compensatory Mitigation: The applicant has not proposed compensatory mitigation for the project. Drawings: Please see enclosed drawings labeled: MVP PRH Page 1 of 7 through Page 7 of 7. 2

3 MVP PRH Page 1 of 7

4 MVP PRH Page 2 of 7

5 MVP PRH Page 3 of 7

6 MVP PRH Page 4 of 7

7 MVP PRH Page 5 of 7

8 MVP PRH Page 6 of 7

9 MVP PRH Page 7 of 7