1. (a) In addition to meeting the applicable conditions established in Env-Wt 300, the department shall not approve a hard-scape stabilization proposal such as rip-rap or a retaining wall unless the applicant demonstrates that the bank or shoreline in that location cannot be stabilized by preserving or restoring natural vegetation, landscaping, or bioengineering.

2. (b) Bank/shoreline stabilization shall:

   1. (1) Be designed to be the least intrusive practicable method in accordance with Chapter 8 of the A/M BMPs, available as noted in Appendix B;
   2. (2) Conform to the natural alignment of the bank/shoreline;
   3. (3) Not adversely affect the stream course such that water flow will be transported by the stream channel in a manner that the stream maintains its dimensions, general pattern, and slope with no unnatural raising or lowering of the channel bed elevation along the stream bed profile;
   4. (4) Not adversely affect the physical stream forms or alter the local channel hydraulics, natural stream bank stability, or floodplain connectivity;
   5. (5) Avoid and minimize impacts to shoreline resource functions as described in Env-Wt 514.01 and Chapter 8 of the A/M BMPs, available as noted in Appendix B;
   6. (6) If the project is a wall on a great pond or other surface water where the state holds fee simple ownership of the bed, locate the wall on the shoreward side of the normal high water line; and
   7. (7) If the project is to install rip-rap, locate the rip-rap shoreward of the normal high water line, where practicable, and extend it not more than 2 feet lakeward of that line at any point.

3. (c) The hierarchy of bank stabilization practices shall be as follows:

   1. (1) Soft vegetative bank stabilization, including regrading and replanting of slopes, in which all work occurs above ordinary high water or normal high water;
   2. (2) Bioengineered bank stabilization or naturalized design techniques that uses a combination of live vegetation, woody material, or geotextile matting and may include regrading and replanting of slopes;
   3. (3) Semi-natural form design shall be allowed only where the applicant demonstrates that anticipated turbulence, flows, restricted space, or similar factors, render vegetative or soft stabilization methods, bioengineering, and natural process design stabilization methods physically impractical;
   4. (4) Hard-scape or rip-rap design shall be allowed only where anticipated turbulence, flows, restricted space, or similar factors render vegetative, bio-engineering, semi-natural form design and diversion methods physically impractical and where necessary to protect existing infrastructure; and
   5. (5) Wall construction shall be allowed as the last available option, only where lack of space or other limitations of the site make alternative stabilization methods of bioengineering, semi-natural, and rip-rap impractical. Wherever sufficient room exists, slopes shall be cut back to eliminate the requirement for a wall.

4. (d) Stream bank-stabilization project plans shall be developed in accordance with the following techniques, as applicable:

   1. (1) Naturalized and semi-natural design techniques where practicable in accordance with “Guidelines for Naturalized River Channel Design and Bank Stabilization” dated February 2007, R. Schiff, J.G. MacBroom, and J. Armstrong Bonin, available as noted in Appendix B and at https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/2020-01/r-wd-06-37.pdf;
   2. (2) For bioengineering projects, National Engineering Handbook Part 654 (NEH 654), Technical Supplement 141, Streambank Soil Bioengineering, dated August 2007, NRCS, available as noted in Appendix B and at https://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=17818.wba; and
   3. (3) For stream restoration projects, NEH 654, Stream Restoration Design, dated August 2007, NRCS, available as noted in Appendix B and at https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/water/manage/restoration/?cid=stelprdb1044707.

Source. #12805, eff 12-15-19; amd by #13124, eff 10-23-20