HIGHWAY DESIGN MANUAL Chapter 8 Highway Drainage

1 HIGHWAY DESIGN MANUAL Chapter 8 HIGHWAY Drainage Revision 97 (Limited Revision) June 9, 2021 Issued by Engineering Bulletin 21-030 Effective with DESIGN Approval on or after September 1, 2021 HIGHWAY Drainage 8-2 EB 21-030 09/01/2021 Section Changes Throughout Reformatted Chapter for legibility, updated document references, removed obsolete references, and incorporated hyperlinks. Exhibits renumbered to accommodate new exhibits in revised Section Allowable Headwater Section has been updated to meet guidance from the New York State Flood Risk Management Guidance for Implementation of the Community Risk and Resiliency Act.

2 Exhibit 8-3 (formerly Table 8-2) DESIGN Flood Frequencies (in years) for Drainage Structures and Channels table has been revised to reflect community risk and resiliency standards for local roads. Appendix 8B Appendix renamed to remove SPDES Permit number. Updated document references, removed obsolete references, and updated hyperlinks. Appendix 8B, Exhibit 1 Removed Streambank restoration projects as an example since they are no longer included in the SPDES Permit list of routine maintenance activities. Appendix 8B, Exhibit 3 Values revised to reflect 2015 Stormwater DESIGN MANUAL updates.

3 Appendix 8B Kinderhook Lake watershed added to list of Phosphorus Restricted Watersheds Appendix 8B Stormwater Management DESIGN MANUAL page references corrected. Appendix 8B Removed reference to inspections after rain events to reflect the current SPDES Permit and NYSDOT MURK 6 forms. Appendix 8B (22) Removed reference to Draft NYSDOT Stormwater Management Practices Operation & Maintenance MANUAL (no longer on NYSDOT website) and replaced with reference to NYSDEC Maintenance Guidance for Stormwater Management Practices.

4 Appendix 8B Section updated to include NYSDEC s electronic NOI submission process. HIGHWAY Drainage 8-3 EB 21-030 09/01/2021 TABLE OF CONTENTS INTRODUCTION .. 6 LEGAL ASPECTS OF HIGHWAY Drainage .. 7 State Drainage Law .. 7 Connections to State Drainage Facilities .. 15 HYDROLOGY .. 18 Type of Project vs Extent of Hydrologic Analysis .. 18 Hydrologic Analysis .. 19 HYDRAULIC principles .. 30 Types of Open Channel Flow .. 30 Energy of Flow .. 33 OPEN CHANNELS .. 34 Types of Open Channels .. 34 Channel DESIGN Criteria.

5 36 Hydraulics - DESIGN and Analysis .. 38 Maintenance .. 41 CULVERTS .. 42 Hydraulic DESIGN Criteria .. 42 Pipe DESIGN Criteria .. 51 Culvert DESIGN - Overview .. 59 Site Considerations .. 67 Maintenance .. 69 Safety - Roadside DESIGN .. 70 Rehabilitation of Culverts and Storm Drains .. 71 STORM Drainage SYSTEMS .. 84 Planning and Coordination .. 84 Hydrologic Analysis .. 85 Gutters .. 86 Inlets .. 87 Storm Drains .. 94 Drainage Structures .. 104 Storage Facilities .. 110 Shared Costs .. 110 Maintenance .. 112 EROSION AND SEDIMENT CONTROL AND STORMWATER MANAGEMENT.

6 113 Determining the Need for an Erosion and Sediment Control Plan and SPDES/NPDES Stormwater Permits .. 113 Erosion and Sediment Control .. 115 SPDES General Permit for Stormwater Discharges from Construction Activity .. 120 NPDES Construction General Permit .. 121 MS4 Stormwater Outfall Inventory Mapping .. 122 Drainage REPORT .. 123 Introduction .. 123 Hydrology .. 123 Open Channels .. 123 Culverts .. 124 Storm Drainage Systems .. 124 Erosion and Sediment Control and Stormwater Management .. 124 Special Considerations.

7 125 References .. 125 PLANS AND SPECIFICATIONS .. 126 Plans .. 126 Specifications .. 128 Special Notes .. 129 HIGHWAY Drainage 8-4 EB 21-030 09/01/2021 Drainage SOFTWARE .. 130 REFERENCES .. 131 References for Chapter 8 .. 131 Topics Presented in the " HIGHWAY Drainage Guidelines" and the "AASHTO Drainage MANUAL " .. 134 Appendix A Structural Materials for Various Pipe Materials and Shapes Appendix B NYSDOT DESIGN Requirements and Guidance for State Pollutant Discharge Elimination System (SPDES) General Permit for Construction Activity HIGHWAY Drainage 8-5 EB 21-030 09/01/2021 LIST OF EXHIBITS Exhibit 8-1 Areas of Environmental Concern.

8 9 Exhibit 8-2 Flood Hazard Area .. 13 Exhibit 8-3 DESIGN Flood Frequencies (in years) For Drainage Structures and Channels .. 24 Exhibit 8-4 Values of Runoff Coefficient (C) for Use in the Rational Method .. 26 Exhibit 8-5 k Values for Various Land Covers and Flow Regimes .. 27 Exhibit 8-6 Specific Energy Diagram .. 32 Exhibit 8-7 Total Energy in Open Channels .. 33 Exhibit 8-8 Culvert Allowable Headwater .. 42 Exhibit 8-9 Methodology for Estimating DESIGN Discharge Based on Drainage Area .. 43 Exhibit 8-10 DESIGN Discharges Multipliers by County.

9 44 Exhibit 8-11 The Effect of Backwater Based on Terrain Upstream of the Culvert .. 45 Exhibit 8-12 Flood Risk Management Guidelines for Culverts .. 47 Exhibit 8-13 Culverts on Regulated Floodways vs. Other Streams .. 48 Exhibit 8-14 Projected Sea-level Rise .. 50 Exhibit 8-15 DESIGN Lives .. 52 Exhibit 8-16 Metal Loss Rates for Steel by Geographic Location .. 53 Exhibit 8-17 Anticipated Service Life, in years, for Steel (with and without additional coating) .. 54 Exhibit 8-18 Additional Coating Options .. 55 Exhibit 8-19 Typical Anchor Bolt Details.

10 58 Exhibit 8-20 Factors Influencing Culvert Performance in Inlet and Outlet Control .. 59 Exhibit 8-21 Flow Profiles for Culverts in Inlet Control .. 62 Exhibit 8-22 Flow Profiles for Culverts in Outlet Control .. 66 Exhibit 8-23 Anticipated Service Life, in years, for Steel (with and without additional coating) .. 96 Exhibit 8-24 Headloss Coefficients .. 99 Exhibit 8-25 Correction Factors for Bench Types .. 102 Exhibit 8-26 Drainage Structure Pipe Entrance .. 106 Exhibit 8-27 Inside Dimensions of Drainage Structures (Types A Through U).