NY Rising Reconstruction Program Project Update

Size: px

Start display at page:

Download "NY Rising Reconstruction Program Project Update"

Dale Webb
6 years ago
Views:

1 NY Rising Reconstruction Program Project Update Rye City Council Monthly Meeting PRESENTERS: Bradley Cantor Kate Seely-Kirk Peter Johantgen Brian Platt Governor s Office of Storm Recovery (GOSR) Regional Lead Dormitory Authority of the State of New York (DASNY) Director Construction Administration Dormitory Authority of the State of New York (DASNY) Project Manager O Brien & Gere Engineers, Inc. (OBG) Engineer

2 PRESENTATION OUTLINE Bowman Dam Automation - Benefit-Cost-Analysis (BCA) Results Summary Milton Road Drainage Improvements Results Summary 2

PREVIOUS STUDY - ANALYSIS OF UPPER POND RESIZING Objective #1: Expansion of Upper Pond Refinement to match available funding ($2 million) Bowman Dam

3 PREVIOUS STUDY - ANALYSIS OF UPPER POND RESIZING Objective #1: Expansion of Upper Pond Refinement to match available funding ($2 million) Bowman Dam Objective #2: Sluice Gate Operation Assess effectiveness of previously proposed operating algorithm when combined with work performed in Objective #1 3

4 Approx. ~0.7 ft. PREVIOUS BowmanDamProject STUDY Plan: 1) RESULTS OBG_exist-10y 11/30/2016 COMPARISON 2) OBG-Plan-13KCUT -10y 11/30/2016 3) POND OBG-Plan-13KCUTEXPANSION 12/1/2016 VS. SLUICE GATE Legend OPERATION I-95 Conclusion: The benefits associated with Upper Pond resizing are an order of magnitude less than the benefits from utilizing a gate operation strategy. I-287 WS Max WS - OBG_exist-10y WS Max WS - OBG-Plan-13KCUT-10y WS Max WS - OBG-Plan-13KCUT-10y-PB@I-287-new Ground 10-YEAR FLOOD Existing WSE 13.5K EXCAV. EXCAVATION + SLUICE GATE Stream Bed 13.5k CY Excavation + Sluice Gate Highland Rd. Purchase St Main Channel Distance (ft) 4

5 2-Year Year Year Year Year Year Water Surface Elevation Reduction (ft) PREVIOUS 1.50 STUDY RESULTS COMPARISON PB ALGORITM BY CONTROL LOCATION 2-year 5-year 10-year 25-year 50-year 100-year PB@Indian Village PB@l-287 Locations ( ) Conclusions: The gate should remain open for events < 5-year return frequency Selection of algorithm control location may influence observed WSE reductions Majority of reduction is attributed to sluice gate control 5

6 SLUICE GATE AT BOWMAN DAM Gate installed: 2013 EXISTING CONDITION The dam in fixed closed position Previously developed operational algorithms not implemented Need for additional stream monitoring stations and system integration 6

7 BENEFIT COST ANALYSIS STUDY OBJECTIVES Compare the following: Costs of stream gauge construction and sluice gate operation Benefits associated with avoided property damage if stream gauges were constructed and integrated with existing sluice gate Comparison is made by calculating a Benefit Cost Ratio 7

8 BENEFIT COST RATIO FEMA Benefit-Cost Analysis (BCA) Toolkit The outcome is a Benefit-Cost Ratio (BCR) BCR > 1 A project is economically viable 8

9 CONCEPTUAL DESIGN PROCESS STREAM GAUGES Site visit performed to identify potential gauge locations. Radio survey performed to assess data transmission options Due to terrain and vegetation, cellular technology is proposed Modeling performed to estimate potential water surface elevation reduction Conceptual gauge and instrumentation design performed Conceptual capital cost estimation Operation and maintenance cost estimation 9

10 COST ESTIMATION Components: Stream gauge and gate control system design, construction, and operation Stream monitoring system design Means of gauge communication Data storage and access Existing infrastructure integration Model & algorithm calibration Implementation Operation & maintenance 10

11 PROPOSED GAUGE LOCATION BROOKSIDE WAY (UPSTREAM) GAUGE 11

12 PROPOSED GAUGE LOCATION PURCHASE ST. (DOWNSTREAM) GAUGE 12

13 EXISTING PROPOSED BENEFIT ESTIMATION Benefit Component: Potentially avoided property damage If flood elevations are reduced by approximately 1 foot, how would residential flood damage be reduced? Estimate number of residences affected by reduction Estimate avoided damage costs 13

14 BENEFIT COST ANALYSIS SUMMARY APPROXIMATE BENEFITS AVOIDED PROPERTY DAMAGE: $8,800,000 APPROXIMATE COSTS INITIAL COST: $398,000 SOCIAL BENEFITS: $2,000,000 ANNUAL MAINTENANCE: $25,000 TOTAL ESTIMATED BENEFITS: $10,800,000 TOTAL ESTIMATED COST: $630,000 Notes: 1. Mental stress and anxiety includes treatment cost per person 2. Values are expressed in 2017 dollars Benefit cost ratio (BCR) is 14 Notes: 1. Values are expressed in 2017 dollars 2. Annual maintenance portion of the total estimated cost is expressed in 2017 dollars assuming 7% annual discount rate. Annual maintenance would not be funded with NY Rising Project funding. 3. Project life assumed to be 15 years (i.e., instrumentation and controls are assumed to require updating after 15 years of use). BCR is greater than 1, therefore the project is economically viable 14

15 Milton Road Drainage Improvements Study 15

16 MILTON HARBOR HOUSE AREA MANHOLE OUTLET CATCH BASIN 16

17 MODEL INPUTS SYSTEM OUTFALL Flow generating rainfall Tidal conditions in the bay Average High Tide: 3.4 ft (NAVD88) DRAINAGE AREA 17

18 MODELED CONDITIONS: TIDE: 3.4 ft WITH CHECK VALVE AT SYSTEM OUTFALL RAINFALL EVENT: 10-YEAR STORM MODEL VIEW: PLAN VIEW MODEL VIEW: PROFILE EXISTING CONDITIONS: CURRENT STORMWATER SYSTEM CONFIGURATION 18

19 EXISTING CONDITIONS TIDE ELEVATION: 3.4 FT WITH CHECK VALVE AT OUTFALL RAINFALL EVENT: 10-YEAR STORM REPLACE WITH 24 PIPE REPLACE WITH 24 PIPE REPLACE WITH 24 PIPE PROPOSED IMPROVEMENTS: REPLACE EXISTING PIPES 19

20 PROPOSED CONDITIONS TIDE ELEVATION: 3.4 FT WITH CHECK VALVE AT OUTFALL RAINFALL EVENT: 10-YEAR STORM REPLACE WITH 24 PIPE REPLACE WITH 24 PIPE REPLACE WITH 24 PIPE PROPOSED IMPROVEMENTS: REPLACE EXISTING PIPES 20

21 MODELED CONDITIONS: TIDE: 3.4 ft WITH CHECK VALVE AT SYSTEM OUTFALL RAINFALL EVENT: 10-YEAR STORM PROFILE VIEW: EXISTING CONDITIONS PROFILE VIEW: PROPOSED IMPROVEMENTS (INCREASE PIPE SIZES) PROPOSED IMPROVEMENTS: REPLACE EXISTING PIPES 21

22 NYS DEC SEA-LEVEL RISE PROJECTION REGULATION 22

23 2050 CONDITIONS TIDE ELEVATION: 4.7 FT WITH CHECK VALVE AT OUTFALL RAINFALL EVENT: 10-YEAR STORM REPLACE WITH 24 PIPE REPLACE WITH 24 PIPE REPLACE WITH 24 PIPE PROPOSED IMPROVEMENTS: REPLACE EXISTING PIPES 23

24 PROPOSED CONDITIONS TIDE ELEVATION: 4.7 FT WITH CHECK VALVE AT OUTFALL RAINFALL EVENT: 25-YEAR STORM REPLACED WITH 24 PIPE REPLACED WITH 24 PIPE REPLACED WITH 24 PIPE PROPOSED IMPROVEMENTS: REPLACE EXISTING PIPES 24

25 MODEL CONDITIONS TIDE ELEVATION: 4.7 FT WITH CHECK VALVE AT OUTFALL RAINFALL EVENT: 25-YEAR STORM DIVERTING WATER BY CONNECTING DRAINAGE SYSTEMS OUTLET MANHOLE CATCH BASIN EXISTING DRAINAGE SYSTEM PROPOSED CONNECTION OUTLET 25

26 MILTON HARBOR HOUSE AREA SUMMARY Replacing existing pipes would reduce flooding on Milton Harbor House property during a 10-year storm event Flooding would be reduced for both the current high tide of 3.4 feet and projected 2050 high tide of 4.7 feet In addition to replacing existing pipes, constructing a pipe to divert water to an adjacent storm sewer system would provide additional capacity to manage larger storms 26

27 Hewlett Street Area 27

28 HEWLETT STREET SYSTEM CONFIGURATION RECOMMEND INSTALLING CHECK VALVE LOCATION OF PERIODIC FLOODING 28

29 HEWLETT STREET PROPOSED IMPROVEMENTS Prevents water and sediment from entering the pipe Creates additional storage for storm water Slightly reduces flooding at Hewlett Street and Milton Road intersection 29

30 COST ANALYSIS SUMMARY STORM SEWER IMPROVEMENT CONCEPTUAL CONSTRUCTION COST Replace Existing Pipes (Milton Harbor House Area) $310,000 Replace Existing Pipes & Divert Water (Milton Harbor House Area) $647,000 Check Valve (Hewlett Street & Milton Road Intersection) $55,000 Note: Construction costs do not include engineering and construction oversight costs. 30

31 NY Rising Reconstruction Program Project Update Rye City Council Monthly Meeting QUESTIONS? 31

Model Results Operation and Maintenance (O& M) Results Cost-Benefit Analysis Results Conclusions

BMP Performance and Outline Background Model Results Operation and Maintenance (O& M) Results Results Conclusions Melissa Baker, Water Resource Technician Capitol Region Watershed District, St. Paul, MN