The document summarizes plans for the removal of Bunker Pond Dam and restoration of the stream. It provides background on the dam's construction in 1865 and deterioration over time. Removal is proposed rather than rehabilitation due to flooding risks and lack of funding for repairs. Removal is estimated to cost $180,000 and would improve habitat and allow fish passage on the Lamprey River. Sediment testing was conducted and a deconstruction plan created involving draining, concrete removal, and bank stabilization. Stream restoration designs include rock structures and plantings to reduce erosion.

1. Bunker Pond DamDam Removal and Stream Restoration Zach Boulter Andrew Smart Jake Pouliot Craig Langton Ben Inman Bill Boornazian Kyle Janco 1

3. Background

4. History

5. Rehabilitation

6. Removal

7. Natural Resources

8. Sediment

9. Hydrology

10. Stream Restoration

11. Deconstruction

12. Costing

13. Scheduling2

14. http://www.lampreyriver.org/ 3

15. Background Constructed in 1865 The dam is currently owned and operated by the NHDES since 1959 It is considered a low hazard structure by the NHDES Prone to flooding NHDES Upstream of Bunker Pond Dam 4

16. Background 15’ high 76.8 sq. mi. of drainage area Originally installed for hydropower for local mills 5

17. History 1746 - Joshua Folsom opens mill on the east side of the Lamprey. The pond is named after David Bunker, who owned a woolen mill. Historical assessment is an important part of permitting in order to identify the significance of potential historical resources. Permits can be deferred if the site contains valuable historical resources. Courtesy of Madelyn Williamson – Epping Historical Society 6

18. Original Scope Rehabilitation Sidewall cracking Sidewall expansion Seepage Groundwater flow Bank erosion Flood control West side of Bunker Pond Dam 7

19. Removal Dam no longer serves a purpose Contributes to upstream flooding More economic than rehabilitation Natural resources Marine life Plant life Water quality Downstream of Bunker Pond Dam 8

20. Funding Repair Annual Cost to Operate: $3,800/yr. Average Dam Restoration Cost: $800,000 Little to no Funding Provided for Repair Removal Estimated Removal Cost: $180,000 More Funding Provided Because of Effect on Ecology 9

21. Natural Resources Lamprey River as the most significant coastal river for anadromous fish. Lamprey is a National Wild & Scenic River NH Fish and Game Commission 10

22. Restoration Potential for Anadromous Fish www.nh.des.gov 11

23. Spawning Habitat Reservoir - Decreased Water Quality (decreased circulation) - Pollutants Accumulate (concentrate) - Oxygen Depletion (may become anoxic) - Reservoir Stratifies(loss of turbulent flow) Downstream - Water Quality is Reduced - Altered Flow Regime - Traps Sediment - Traps Debris - Blocks Nutrient Transport - Algae Blooms - Temperatures modified - Sediment Starved - Riverbed Degrades - Increased Temperatures - Blocks Fish Passage Increased Evaporation - Nutrient Starved Debris Jam epilimnion metalimnion hypolimnion Habitat/Substrate Buried by Sediment Original Bed Profile Free Flowing River at Dynamic Equilibrium Dam Courtesy of Laura Wildman – American Rivers 12

25. Samples taken at 5’ intervals closest to dam

26. 10’ intervals farther away

27. Approx. 5250 ft3of sediment.13

29. Gradually drawing down the dam,14

30. Hydrology Hec-Ras (Hydraulic Engineering Centers River Analysis System) Bridge upstream is still concern for flooding 15

31. HEC-RAS http://www.lampreyriver.org/ 16

32. Cross-Sections 17

33. 3-D Cross-Sections Bunker Pond Dam 2-GEL Plan: Plan 02 4/18/2010 Legend WS 100 yr Ground 10 Bank Sta 9.95 9.6 9.8 9.9 9.5 9.4 9.3 Figure : 3-D Cross-Section 18

34. Bridge Pre-Removal Bunker Pond Dam 2-GEL Plan: Plan 02 4/18/2010 Route 27 Bridge .1 .045 .1 155 Legend 150 EG 100 yr WS 100 yr 145 Elevation (ft) Crit 100 yr 140 Ground 135 Bank Sta 130 125 0 200 400 600 800 1000 1200 1400 Station (ft) Figure : Route 27 with Bunker Pond Dam 19

36. 4,930 cfs 100 year flood used in HEC-RAS modeling

37. Approximate 80 year Flood 3,800 cfs

38. New Market Stream Gauge used peak flow of 8,970 cfs20

39. Bridge Post-Removal Bunker Pond Dam 2-GEL Plan: Plan 04 4/18/2010 Route 27 Bridge .1 .045 .1 155 Legend 150 EG 100 yr WS 100 yr 145 Elevation (ft) Crit 100 yr 140 Ground 135 Bank Sta 130 125 0 200 400 600 800 1000 1200 1400 Station (ft) 21

40. Proposed Stream Restoration Geomorphic Stream Rock Structures to reduce bank erosion Planting of wild flowers and slope seeding Monitoring will be required in the months post removal The Cross-Vane, W-Weir, and K-Hook Vane by David Rosgen 22

41. Proposed Stream Restoration The Cross-Vane is a grade control structure that decreases near-bank shear stress, velocity and stream power. Structures locations will be determined post removal Possible locations Before Route 27 Bridge channel River bends within Bunker Pond 23

42. Proposed Stream Restoration Approximately 50 cubic yards of rip rap removed from the dam site Can be used to create cross- vanes 24

43. Predicted Planting Area 25

44. Deconstruction Plan Dewatering Draining via flood gate Bedrock at approx. 4’ Portadam will be put in place Any water remaining will be pumped out From Portadam brochure 26

45. Deconstruction Plan Removal of Concrete Removal will begin at the east abutment and progress to the west abutment Approx. 270 tons of concrete Concrete will be recycled for $35/ton at ERRCO in Epping, NH 27

46. Deconstruction Plan Post-Removal Rip-rap removal Seeding and jute mats on banks Portadam will be removed and reinstalled to divert water back to original stream flow http://www.gregsindigenouslandscapes.com.au/images/JuteMat.JPG 28

47. Deconstruction Plan 29

48. Winnicut Dam: October 2009 http://www.earthcam.com/winnicut/ 30

49. Winnicut Dam: October 2009 http://www.earthcam.com/winnicut/ 31

50. Winnicut Dam: November 2009 http://www.earthcam.com/winnicut/ 32

51. Winnicut Dam: March 2010 http://www.earthcam.com/winnicut/ 33

52. Cost Breakdown 34

53. Scheduling 35

54. Advisors Grace Levergood (NHDES) Dr. Thomas Ballestero Dr. Kevin Gardner Dr. David Gress Dr. Pedro de Alba 36

55. THANK YOU QUESTIONS? 37