ADDENDA B Hydrologic and Hydraulic (H&H) Study Guidance 2019

09/25/2018 DRAFT FEMA Region I PA H&H Study ADDENDA B Hydrologic and Hydraulic (H&H) Study Guidance 2019 Region I Federal Emergency Management Agency (FEMA) Public Assistance Hydrologic and Hydraulic (H&H) Study Guidance 1

09/25/2018 DRAFT FEMA Region I PA H&H Study Table of Contents Contents 1. BACKGROUND...3 2. HYDROLOGIC AND HYDRAULIC (H&H) STUDY... 4 3. THREE OPTIONS FOR H&H STUDY REQUIREMENTS...5 4. H&H STUDY PERFORMANCE AND COMPONENTS... 7 Appendices Appendix A Appendix B Examples H&H Comments and Conditions for EHP Project Review Appendix C Regulatory Citations Appendix D Related FEMA Categorical Exclusions from NEPA 2

Region I Federal Emergency Management Agency (FEMA) Hydrologic and Hydraulic (H&H) Study Guidance 1. BACKGROUND FEMA's July 9, 2018 Policy Clarification for Public Assistance Hydrologic and Hydraulic Study Requirements for Drainage Structures and Culverts clarified the April 26, 2018 Public Assistance Program and Policy Guide (PAPPG) Appendix J requirement for a watershed Hydrology and Hydraulics (H&H) study for projects involving replacing or upsizing drainage structures or culverts, in compliance with 44 CFR Part 9 (E011988 Floodplains and E011990 Wetlands) and Part 60 (NFIP). The Policy Clarification directed Public Assistance staff to work with Environmental and Historic Preservation (EHP) and Mitigation field staff to determine when projects require an H&H study. This document provides guidance on when H&H studies are required in FEMA Region 1 and addresses common types of Public Assistance (PA) projects, i.e., upsizing culverts and bridges. The guidance may also be applied to new culverts being installed as a mitigation measure. Other types of projects and/or those in complex hydrologic or highly developed settings should be discussed with EHP and NFIP staff to determine H&H requirements. Requirements of 44 CFR Part 9 (E011988 Floodplains and E011990 Wetlands) and Part 60 (NFIP) related to H&H studies are outlined below. Note that projects eligible for FEMA Public Assistance grants without Mitigation are not necessarily exempt from H&H study requirements and other elements of Environmental and Historic Preservation review. Even if upgrades are a result of codes and standards improvements, the following requirements and guidance apply to the project. In addition, culvert and bridge construction projects are subject to any other local, state and federal requirements that may require H&H studies../ 44 CFR Part 9 Floodplain Management and Protection of Wetlands has the following requirements (paraphrased): 9.11(d)(4) No encroachments within a floodway that would result in any increase in flood levels, no increase in water surface elevation of the base flood more than one foot within the community. 9.11(d)(5) In a floodway or coastal high hazard area, additional standards... must be the only practicable alternative, not inconsistent with NFIP or more restrictive state or local standards, elevated in coastal high hazard areas. 9.11(f) Restore and Preserve-if the action will result in harm to or within the floodplain or wetland, the agency shall design or modify the action to preserve as much of the natural and beneficial floodplain and wetland values as is possible../ 44 CFR Part 60 NFIP contains the following (paraphrased): 60.3(b)(7)-Assure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained. 60.3(c)(10)--Cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the 3

base flood more than one foot at any point within the community. 60.3(d)(3)-Prohibit encroachments within the floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during occurrence of the base flood discharge. 60.6(a)(7) Variances may be issued for new construction, substantial improvements and for other development necessary for the conduct of a functionally dependent use (without any increase in base flood discharge levels in the floodway, or if it would not result in increased flood heights, additional threats to public safety, extraordinary public expense, nuisance... ) and the structure or development is protected by methods that minimize flood damage during the base flood and create no additional threats to public safety. 2. HYDROLOGIC AND HYDRAULIC (H&H) STUDY A Hydrologic and Hydraulic (H&H) Study is the study of movement of water, including the volume and rate of flow as it moves through a watershed, basin, channel, or man-made structure. Typically the analysis includes an evaluation of the upstream watershed area and expected flood flows so that culverts can be appropriately sized. A complete H&H study also evaluates upstream and downstream water surface elevations for the proposed water crossing at flood flows consistent with Base Flood Elevations (BFE), to assure that BFE in the community's Special Flood Hazard Area (SFHA) does not increase more than one foot, as a result of the new water conveyance. The standard for a regulatory floodway (a mapped area of the main channel carrying the majority of river flow) is no rise in BFE. The 1% annual flood discharge is used in the analysis. If the project is a critical action, the more restrictive 0.2% annual flood discharge is used in the analysis. H&H studies are necessary to protect against future flood loss. In addition, culvert and bridge replacement projects may require H&H studies for low flows to assure aquatic organism passage in accordance with other state or federal requirements. H&H Studies may also be required for projects that are in a wetland outside of the SFHA. Situations where this could arise are perennial streams with surrounding wetlands in a mountainous area, or where an undersized culvert has created ponding and a wetland. While this latter category are "manmade" wetlands, they may support wetland communities, and maintaining them may be environmentally beneficial. Region 1 comprises six states with varying requirements (Codes and Standards) for stream road crossing design and permitting. All six states have their own Clean Water Act (CWA) General Permits regulated by the U.S. Army Corps of Engineers (USAGE). Most replacement-in-kind projects are exempted from Clean Water Act requirements. Minor alterations are covered by the CWA General Permits in New England as long as General Conditions are met, with varying reporting requirements. Projects that alter the size or configuration of stream road crossings may require a higher level of permitting under the CWA. State and federal agency contact information is included on the "Green Sheet" developed for each disaster declaration; the information is intended to assist project proponents in determining project permitting requirements. Applicants must comply with current regulatory requirements for their projects. 4

3. THREE OPTIONS FOR H&H STUDY REQUIREMENTS OPTION 1: AN H&H STUDY IS til2i REQUIRED If any one of the following criteria are met, an H&H Study is NOT required in Region 1. 1. Project is completed as PA Category B (Emergency Protective Measures), needed to maintain public safety access; or 2. Project cost is less than $5,000 and exempt from E011988 and E019990 review; or 3. Return back to exact pre-disaster condition (length, diameter, number of culverts) or the only change is in material type; or 4. Project is a stormwater-only drainage or conveyance structure, where water does not flow regularly or seasonally (i.e., a "road crossing," "cross culvert," or "equalization culvert"). This only applies to locations that are NOT mapped as riverine or other wetlands on the US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html and must be verified by regional EHP staff; or 5. Culvert or bridge size increases for projects: a. outside of Special Flood Hazard Areas (SFHA) and b. the new cross sectional open area is within 160% of the structure opening(s) being replaced (an of increase of no more than one circular culvert size in accordance with the following list of diameters in inches): 8"-10"-12"-15"-18"-21"-24"-30"-36"-42"-48" Circular culverts with diameters greater than 48 inches or others with crosssectional open areas above 12.56 square feet would be subject to H&H study requirements, Options 2 and 3 below. Examples illustrating projects meeting Option 1 are provided in Appendix A.1 and A.2. OPTION 2: LIMITED H&H STUDY If a project does not meet the Option 1 criteria but is of a small enough scale relative to the SFHA, a limited H&H study is adequate. For projects within or upstream of SFHA, where an H&H study is required, the downstream analysis can be limited to an assessment of the proportion of the site's drainage area to the SFHA drainage area. In cases where the drainage area to the project is less than 10% of the drainage area to the nearest point of the next downstream SFHA, it is presumed that the project will not have a significant impact on the downstream BFE. The Limited H&H study only requires calculation of the upstream flows and analysis to properly size the water conveyance opening. EHP staff can assist in determining when the Limited Downstream H&H Analysis is applicable. Steps to verify the applicability of the Limited H&H Study: 1. Using the National Flood Hazard Layer (NFHL) viewer available at: https://hazardsfema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa 5

9cd or another method, find the project location; 2. Compute the size of the drainage area to the project site using the USGS StreamStats Application: https://streamstats.usgs.gov/ss/. 3. Using the National Flood Hazard Layer (NFHL) viewer or another method, determine the location of the nearest downstream SFHA that drainage from the project would flow into; 4. Compute the size of the drainage area to the nearest downstream SFHA determined in Step 3 using the StreamStats Application; 5. Calculate the proportion of the drainage area of the project site to that of the nearest downstream SFHA: Drainage Area of Step 2 divided by Drainage Area of Step 4. If the result is less than 0.10, the project is eligible for the Limited H&H option and does not require further downstream analysis. If the result is greater than 0.10, a complete H&H study (Option 3), including downstream analysis is needed for the project. An example illustrating Option 2 is provided in Appendix A.3. OPTION 3: A COMPLETE H&H STUDY IS REQUIRED If any of the following conditions apply, a Complete H&H study is required in Region 1. Other cases may also require complete H&H studies based upon professional judgment of EHP, NFIP staff or a Professional Engineer to assure the requirements of 44 CFR Part 9 and Part 60 can be confidently achieved. 1. Permanent PA Category C Projects that are located: a. In a mapped floodplain (SFHA on the FEMA Map Service Center or Printed FIRM) and b. Carries a surface water feature mapped on US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html; or 2. 8-Step Analysis Required: An 8-step analysis by EHP staff demonstrating the need for the project, its lack of impacts on base flood levels and wetland resources, and the lack of practicable alternatives is required in addition to the complete H&H study if project: a. Carries a wetland or surface water feature mapped on US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html and b. Project cost is more than $100,000; or 3. Wetland and large increase: a. Carries a mapped riverine wetland or supports a non-riverine wetland feature on US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html: and S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 6

b. Is new construction or alterations (mitigation) of bridges and culverts, that alters the diameter of the culvert, or the number of culverts such that the total open area at the project location is an increase of more than 160% of the prior structure's open area (more than one circular culvert size increase in accordance with the following list of diameters in inches): 8"-10"-12"-15"-18"-21"-24"-30"-36"-42"-48" (Circular culverts with diameters greater than 48 inches or others with cross-sectional open areas above 12.56 square feet would be subject to complete H&H study requirements, unless the location meets the Limited H&H Study (Option 2) allowance); or 4. Projects that could be reasonably expected to impact base flood elevations in SFHA due to the magnitude of the size increase, proximity to the SFHA, proximity to public infrastructure or other structures, or in areas where multiple projects affecting the waterway are under development: or 5. Presence of aquatic endangered species; or 6. H&H Study is required by another local, state, or federal jurisdiction. An example of a project that requires a complete H&H study is provided in Appendix A. 3. 4. H&H STUDY PERFORMANCE AND COMPONENTS Applicant may utilize its own qualified staff or services of a company that has licensed professional civil, environmental, or hydrologic engineers for assistance. FEMA Region 1 will accept complete H&H studies by qualified public agency staff offering technical assistance to applicants, provided they meet minimum requirements of evaluating appropriate flood flows and downstream impacts (as needed). Analysis shall be performed in accordance with standard current engineering practice. Information required in an H&H Study: Limited and Complete H&H Studies: Watershed area computation and flood flow estimates Design of appropriate flood conveyance structure(s) Complete H&H Studies: Water surface elevations and water surface profiles at proposed project relative to BFE Development of appropriate and effective mitigation measures to avoid, minimize, and mitigate potential impacts to floodplain storage and physical habitat provided within a floodplain system Any other requirements imposed by local, state or federal agencies. S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 7

General guidance for Complete H&H Studies (as eligible/required): 1) The H&H study should be a standalone document prepared and signed by an Engineer Licensed in the State and qualified to perform such work. The report should have a narrative portion including but not limited to: a. A description of the pre-disaster site conditions, an overview of the damages and a description of the proposed installation. b. Identification of the exact location of the site using latitude and longitude including the verbal names of the stream/drainage (if there is one) and the name of the facility (or road). c. A description of the methodology used to analyze the basin and the input parameters used in the calculations. The description should also include the conditions at the drainage crossing (e.g. size/slope/length of pipe and height of roadway above pipe invert elevation/top of stream bed/shape, slope and roughness values used for tailwater conditions). d. A statement should be included that indicates why the selected storm frequency was chosen for the analysis (e.g. local/state standards or unique site conditions). e. Discussion of other considerations such as bottom embedment (counter-sinking the pipe) or use of baffles to allow for fish passage, changing culvert type from a RCP to a CMP, or installation of an arch culvert as necessary because of permit requirements. f. A summary statement that provides an overview of the analysis and signed/stamped by a Professional Engineer. 2) FEMA funding for upsizing of culverts/water crossings is conditional on an evaluation of upstream/downstream impacts in accordance with the options provided in this guidance document. If the increased conveyance will not negatively affect upstream or downstream structures/properties, the summary statement should state that there are "no negative upstream or downstream impacts to structures or property". If the applicant/engineer is unable to determine the effects of upsizing a conveyance. the proposed conveyance structure may be considered "not technically feasible". 3) The H&H study should include calculations and reference material used to perform the analysis (specifically tables, charts, maps, & graphs). Resources should be appropriately cited. 8

Appendix A Examples 9

A.1 Example Site where H&H Study NOT Required: Mclaren Hill Rd Culvert #2 Site location coordinates: 44.30611, -72.099444 Category C, 30-inch diameter CMP culvert replaced with 36-inch diameter CMP culvert OPTION 1: AN H&H STUDY IS NOT REQUIRED If any one of the following criteria are met, an H&H Study is NOT required in Region 1. 1. Project is completed as PA Category B (Emergency Protective Measures}, needed to maintain public safety access; (NO-was Category C so DOES NOT MEET); or 2. Project cost is less than $5,000 and exempt from E011988 and E019990 review; (NOwas Category C so DOES NOT MEET) or 3. Return back to exact pre-disaster condition (length, diameter, number of culverts) or the only change is in material type; (NO-was increased size so DOES NOT MEET) or 4. Project is a stormwater-only drainage or conveyance structure, where water does not flow regularly or seasonally (i.e., an intermittent stream or "road crossing"). This only applies to locations that are NOT mapped as riverine or other wetlands on the US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html ; (NO-carries a mapped unnamed tributary to Stevens River so DOES NOT MEET) or 5. Culvert or bridge size increases for projects: a. outside of Special Flood Hazard Areas (SFHA) (YES-Project is outside SFHA so MEETS) and b. the new cross sectional open area is within 160% of the structure opening(s) being replaced (an of increase of no more than one circular culvert size in accordance with the following list of diameters in inches): 8"-10"-12"-15"-18"-21"-24"-30"-36"-42"-48" (YES-Culvert is one size increase on list so MEETS) (PROJECT MEETS BOTH CRITERIA #Sa and #Sb so MEETS and NO H&H STUDY REQUIRED) S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 10

A.2 Example Site where H&H Study NOT Required: McLaren Hill Rd Culvert #3 Site location coordinates: 44.307778, -72.097500 Category C, No Original Culvert; Adding 36-inch diameter culvert OPTION 1: AN H&H STUDY IS NOT REQUIRED If any one of the following criteria are met, an H&H Study is NOT required in Region 1. 1. Project is completed as PA Category B (Emergency Protective Measures), needed to maintain public safety access; (NO-is Category C so DOES NOT MEET); or 2. Project cost is less than $5,000 and exempt from E011988 and E019990 review; (NO- DOES NOT MEET) or 3. Return back to exact pre-disaster condition (length, diameter, number of culverts) or the only change is in material type; (NO-no culvert present pre-disaster so DOES NOT MEET) or 4. Project is a stormwater-only drainage or conveyance structure, where water does not flow regularly or seasonally (i.e., an intermittent stream or "road crossing"). This only applies to locations that are NOT mapped as riverine or other wetlands on the US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html ; (YES; MEETS SO H&H IS NOT REQUIRED) or 5. Culvert or bridge size increases for projects: a. outside of Special Flood Hazard Areas (SFHA) (YES-project is outside of Sf HA so MEETS) and b. the new cross sectional open area is within 160% of the structure opening(s) being replaced (an of increase of no more than one circular culvert size in accordance with the following list of diameters in inches): 8"-10"-12"-15"-18"-21"-24"-30"-36"-42" (NO-new culvert project so more than 160% increased open area--does NOT MEET) (Both required conditions in Item 5 were not met, so DOES NOT MEET) 11

A.3 Example Site where Complete H&H Study Required: Wardsboro Newell Hill Rd Culvert #15 Site Location Coordinates: 43.03885, -72.87053 Category C, Replacing 36-inch diameter culvert with 12-ft wide x 6-ft high box culvert OPTION 1: AN H&H STUDY IS NOT REQUIRED If any one of the following criteria are met, an H&H Study is NOT required in Region 1. 1. Project is completed as PA Category B (Emergency Protective Measures), needed to maintain public safety access; (NO-is Category C so DOES NOT MEET); or 2. Project cost is less than $5,000 and exempt from E011988 and E019990 review (NO- DOES NOT MEET); or 3. Return back to exact pre-disaster condition (length, diameter, number of culverts) or the only change is in material type; (NO-new culvert configuration/size so DOES NOT MEET) or 4. Project is a stormwater-only drainage or conveyance structure, where water does not flow regularly or seasonally (i.e., an intermittent stream or "road crossing"). This only applies to locations that are NOT mapped as riverine or other wetlands on the US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html; (NO-culvert carries a mapped tributary to Wardsboro Brook so DOES NOT MEET) or 5. Culvert or bridge size increases for projects: a. outside of Special Flood Hazard Areas (SFHA) (YES-project is outside of the SFHA so MEETS) and b. the new cross sectional open area is within 160% of the structure opening(s) being replaced (an of increase of no more than one circular culvert size in accordance with the following list of diameters in inches): 8"-10"-12"-15"-18"-21"-24"-30"-36"-42"-48" Original 36-inch diameter culvert open area= 1,018 square inches= 7.1 square feet Replacement 12-ft x 6-ft box culvert open area = 10,368 square inches = 72 square feet Open area size increase= 10,368/1,018 X 100 = 1,018 percent (NO--new open area greater than 12.56 square feet and increase of more than 160%, so DOES NOT MEET) (Only one of the two conditions required under item 5 were met, so DOES NOT MEET) CONTINUE TO OPTION 2 (NEXT PAGE) 12

Example A.3 (Continued) OPTION 2: LIMITED DOWNSTREAM H&H ANALYSIS: Site coordinates: 43.03885, -72.87053 Drainage Area to site= 0.54 square miles (Stream Stats) Nearest downstream river SFHA: Wardsboro Brook near intersection of Cross Rd/Newell Hill Rd/Smead Rd 43.02983, -72.85184 Drainage Area to nearest downstream river SFHA: 8.02 sq miles 0.54 square miles/8.02 square miles= 0.067 x 100 = 6.7% Percent Project Drainage Area to Downstream SFHA = 6.7% Percent Project Drainage Area less than 10% of Downstream SFHA MEETS CRITERIA FOR LIMITED DS H&H STUDY,+ H&H analysis only needed for culvert sizing,+ No further analysis of downstream impacts needed Unless Project meets criteria for Complete H&H Required CONTINUE TO OPTION 3 (NEXT PAGE) TO VERIFY 13

Example A.3 (Continued) OPTION 3: COMPLETE H&H REQUIRED CRITERIA: If any one of the following conditions apply, a complete H&H study is required in Region 1. 1. Permanent PA Category C Projects that are located: a. In a mapped floodplain (SFHA on the FEMA Map Service Center or Printed FIRM) (NO- Project is not in a SFHA so DOES NOT MEET) and b. Carries a surface water feature mapped on US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.htm l; (YES--Project carries a mapped tributary to Wardsboro Brook so MEETS) or (Both conditions in Item 1 are not met, so DOES NOT MEET) 2. 8-Step Analysis Required: An 8-step analysis by EHP staff demonstrating the need for the project, its lack of impacts on base flood levels and wetland resources, and the lack of practicable alternatives is required in addition to the complete H&H study if project: a. Carries a wetland or surface water feature mapped on US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands/data/mapper.html (YES--Project carries a mapped tributary to Wardsboro Brook so MEETS) and b. Project cost is more than $100,000 (YES-Project Cost> $100,000: MEETS) (Both conditions in Item 2 are met, so Complete H&H Needed); or 3. Wetland and large increase: a. Carries a mapped riverine wetland or supports a non-riverine wetland feature on US Fish and Wildlife Service National Wetland Inventory map, accessible at the Wetlands Mapper: https://www.fws.gov/wetlands /Data/Mapper.html: (YES--Project carries a mapped tributary to Wardsboro Brook so MEETS) and b. Is new construction or alterations (mitigation) of bridges and culverts, that alters the diameter of the culvert, or the number of culverts such that the total open area at the project location is an increase of more than 160% of the prior structure's cross sectional open area (more than one circular culvert size increase in accordance with the following list of diameters in inches): 8"-10"-12"-15"-18"-21"-24"-30"-36"-42"-48" (Circular culverts with diameters greater than 48 inches or others with cross-sectional S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 14

open areas above 12.56 square feet would be subject to complete H&H study requirements, unless the location meets the Limited H&H Study (Option 2) allowance); Original 36-inch diameter culvert open area= 1,018 square inches= 7.1 square feet Replacement 12-ft x 6-ft box culvert open area = 10,368 square inches = 72 square feet Open area size increase = 10,368/1,018 X 100 = 1,018 percent and new opening greater than 12.56 square feet (YES-- Upsizing greater than 160% increase in open area-meets) (But MEETS Option 2 Limited H&H Study-so overall DOES NOT MEET Item #3) or 4. Presence of aquatic endangered species; (NO-DOES NOT MEET) or 5. Projects that could be reasonably expected to impact base flood elevations in SFHA due to the magnitude of the size increase, proximity to the SFHA, proximity to public infrastructure or other structures, or in areas where multiple projects affecting the waterway are under development (NO-DOES NOT MEET) Or 6. H&H Study is required by another local, state, or federal jurisdiction (NO-DOES NOT MEET). S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 15

A.4 Example Site where Complete H&H Study Required: Example site with a wetland impoundmenuundersized culvert or upland wetland OPTION 1: AN H&H STUDY IS NOT REQUIRED 16

Appendix B Regulatory Citations 17

Appendix B Regulatory Citations 44 CFR Part 9 Floodplain Management and Protection of Wetlands (8-Step Analysis requirements ) 9.11(d)(4) No encroachments within a floodway that would result in any increase in flood levels, no increase in water surface elevation of the base flood more than one foot within the community. 9.11(d)(S) In a floodway or coastal high hazard area, additional standards... only practicable alternative, not inconsistent with NFIP or more restrictive state or local standards, elevated in coastal high hazard areas, 9.11(f) Restore and Preserve-if the action will result in harm to or within the floodplain or wetland, the agency shall design or modify the action to preserve as much of the natural and beneficial floodplain and wetland values as is possible. 44 CFR Part 60 NFIP 60.3(b)(6)-Notify adjacent communities and the State Coordinating Office prior to any alteration or relocation of a watercourse, and submit copies of such notifications to the Federal Insurance Administrator. 60.3(b)(7)-Assure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained (The Policy should be consistent with this minimum standard that applies to communities) 60.3(c)(10)-Cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot at any point within the community. 60.3(d)(3)-Prohibit encroachments within the floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during occurrence of the base flood discharge. 60.6(a)(7) Variances may be issued for new construction and substantial improvements and for other development necessary for the conduct of a functionally dependent use (without any increase in base flood discharge levels in the floodway, or if it would not result in increased flood heights, additional threats to public safety, extraordinary public expense, nuisance... ) and the structure or development is protected by methods that minimize flood damage during the base flood and create no additional threats to public safety. 18

Appendix C Related FEMA Categorical Exclusions from NEPA 19

AppendixC Related FEMA Categorical Exclusions from NEPA CATEX N4-Stream work, modifications, floodways Do not result in adverse flood risk effects to downstream communities, Do not result in any increase of flood levels within the community during the occurrence of the base flood discharge if the action takes place within the regulatory floodway, and Where the effect of the proposed project when combined with other existing or reasonably foreseeable development will not increase water surface elevation of the base flood more than one foot at any point within the community if the action takes place in a floodplain with no regulatory floodway. N6--Relocation/Realignment of Structures and Facilities Does not apply to: realignment actions affecting a regulatory floodway if they result in any increase in flood levels during the base flood discharge; actions occurring seaward of the limit of moderate wave action (or within V zones when the limit of moderate wave action has not been identified). N9--Flood Hazard Reduction Actions Do not result in adverse flood risk effects to downstream communities, Do not result in any increase of flood levels within the community during the occurrence of the base flood discharge if the action takes place within the regulatory floodway, and Where the effect of the proposed project when combined with other existing or reasonably foreseeable development will not increase water surface elevation of the base flood more than one foot at any point within the community if the action takes place in a floodplain with no regulatory floodway. This CATEX captures some standards for minimization of floodplain impacts such as avoidance of flood risk effects, encroachment prohibitions, and minimization of impacts to floodplain values. OHS intends to encourage practices that avoid, minimize, or mitigate impacts to environmental and historic resources and wetlands or floodplain functions such as their conveyance capacity, moderation of flow velocity, groundwater recharge, improvement of water quality, habitat characteristics, and flood moderation. Compensatory mitigation actions are acceptable mitigation measures if they are agreed to by the applicable governmental entity that has regulatory oversight over the affected resource. 20

.. Appendix D H&H Comments and Conditions for EHP Project Review S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 21

Appendix D H&H Comments and Conditions for EHP Project Review Draft Standard REC text for H&H studies SOW should list for each project culvert or bridge, the name of the stream it carries, e.g., "Cold River" (if applicable), or "unnamed tributary to Cold River" or "stormwater only" in addition to coordinates, diameter or opening size, material, and length. H&H Study NOT Required: If multiple culverts, use as many comments needed and select appropriate comment for each and list which ones the statement applies to. Work completed as Category B Emergency Protective Measures: Comment: SOW: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project because [culvert(s)/bridge replacement] was completed as Category B (Emergency Protective Measures) work. SOW is restoring to pre-disaster condition: Comment: SOW: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project because [culvert(s)/bridge replacement] project is to restore pre-disaster condition. No change in size; material type change only: Comment: SOW: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project because the only change in [culvert(s)/bridge replacement] project is material type. Culvert conveys stormwater only: Comment: SOW: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project because the culvert(s) [is/are] stormwater-only conveyance. Culvert/bridge outside of SFHA and increase in opening is <160% Comment: SOW: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project because the work is outside of Special Flood Hazard Areas (SFHA) and the new culvert/bridge opening area is within 160% of the original structure opening(s) being replaced. 22

Culvert or bridge upsize, Limited H&H Study Required Condition: SOW: In accordance with Region 1 H&H Study guidance, a limited H&H study to properly size [culvert/bridge] opening(s) is required for this project. Culvert or bridge upsize, Complete H&H Study Required Condition: SOW: In accordance with Region 1 H&H Study guidance, a complete H&H study to properly size [culvert/bridge] opening(s) and evaluate downstream impacts to the BFE in SFHA is required for this project. E011988 Floodplain E011988: If located in a Floodplain H&H Study Not Required: Comment: E011988: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project. See SOW. Limited H&H Study: Condition: E0 11988: In accordance with Region 1 H&H Study guidance, a Limited H&H study to assure proper engineering design of the facility is required for this project. The project drainage area is less than ten percent of the drainage area to the nearest downstream SFHA and therefore it is presumed that the project will not have a significant impact on the downstream BFE. Complete H&H Study: Condition: E011988: In accordance with Region 1 H&H Study guidance, a Complete H&H study is required for this project to assure proper engineering design of the facility and to assure the project will not have detrimental effects to SFHA, to comply with 44 CFR Parts 9 and 60. Condition: E011988: A complete H&H study is required for this project in accordance with Region 1 H&H Study Guidance dated [mm/dd/yyyy], to comply with 44 CFR Parts 9 and 60. S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 23

E011990: If located in a Wetland H&H Study Not Required: Comment: E011990: In accordance with Region 1 H&H Study guidance, an H&H study is not required for this project. See SOW. Limited H&H Study: Condition: E011990: In accordance with Region 1 H&H Study guidance, a Limited H&H study to assure proper engineering design of the facility is required for this project. The project drainage area is less than ten percent of the drainage area to the nearest downstream SFHA and therefore it is presumed that the project will not have a significant impact on the downstream BFE. Complete H&H Study: Comment: E011990: In accordance with Region 1 H&H Study guidance, a Complete H&H study is needed to assure proper engineering design of the facility and to assure the project will not have detrimental effects to SFHA or a wetland, to comply with 44 CFR Parts 9 and 60. Condition: E011990: A complete H&H study is required for this project in accordance with Region 1 H&H Study Guidance, to comply with 44 CFR Parts 9 and 60. S:\4. Mitigation Division\_EHP Branch\EHP MASTER\011 b) Streams\H&H Studies\FEMA H&H Policy\Draft FEMA R1 HH 24