Rowlett Cottonwood Transfer Sewer: 60" RCP Sanitary Sewer Rehabilitation Project. TACWA Meeting

Transcription

1 Rowlett Cottonwood Transfer Sewer: 60" RCP Sanitary Sewer Rehabilitation Project TACWA Meeting September 25, 2009 North Texas Municipal Water District

2 Project Background 1. Rowlett-Cottonwood Transfer Sewer 2. Discharge to the Wilson Creek Wastewater Treatment Plant 3. 35,000 of 60 RCP with 54 Siphon 4. Constructed in Parallel 60 Hobas (FRP) Pipeline Constructed in Evidence of Deterioration 7. Impacts from Wet-weather Induced Rainfall (I/I)

3 Project Location

4 Condition Assessment 1. Initial Site and Condition Assessment 2. CCTV Inspection 3. Flow Monitoring

5 Initial Site and Condition Assessment 1. Alignment Review 2. Top-Side Manhole Inspection 3. Top-Side Pipe Lamping

6 CCTV Inspection Inspection Challenges: Long Pipe Segments Wet-Weather Impacts MudMaster Long, Inverted Siphon Buried Manholes

7 Flow Monitoring

8 Condition Assessment Plan 1. Develop Baseline Characteristics 2. Develop Corrosion Model 3. Evaluate Hydraulic Performance 4. Forecast Future Service Life 5. Evaluate Rehabilitation Alternatives 6. Develop Recommended Plan

9 Condition Assessment Results 100% Distribution of Condition of 60 inch RCP Pipe Segments based on the Overall Pipe Grade 60 inch RCP Pipe Segments 90% 80% Percentage of Pipe Segments 70% 60% 50% 40% 30% 20% Typical grading (rating) distribution for years old RCP 10% 0% Overall Pipe Grade (Good Condition) (Worse Condition)

10 Condition Assessment Results US MH DS MH Length (ft) In situ Factor of Safety Remaining Service Life (yrs) , , , B B 1530A A , , , (1) , , , WWTP

11 Review of Rehabilitation Alternatives Alternative Segmental sliplining Cured-in-place relning Spiral-wound pipe PVC (profile) lining Replacement Cementitious coating Epoxy coating Panel lining HDPE sliplining Final Option Yes Yes Yes Yes No* No* No* No* No* * Reason for Elimination from Further Consideration Insufficient installation experience for large-diameter applications Job conditions exceed parameters of the application Regional qualified contractor in the region Risk to adjacent buried utilities UV protection required at storage and job site Hydraulic limitations

12 Program Recommendations Project Elements: 1. Pipeline Rehabilitation 2. Manhole Rehabilitation 3. New Manhole Structures Estimate Project Cost: 1. Range: $12.9M $18.9M (based on technology) 2. Project District Budget - $6.0M

13 Phase I Construction Phase I Bid Alternate Constuction Est - $1.5M 6,600 Phase I - Base Bid Construction Est - $4.1M 10,600

14 Project Design (Ph I) 1. Supplemental Laser/Sonar Inspection 2. Surveying 3. Preliminary Plans and Specifications 4. Workshops and Review Meetings 5. Odor, Wet-weather, Noise, and Traffic Controls 6. Final Bidding Documents

15 Accessed Manhole Laser Profile Results Distance Inspected Downstream (ft) Average Horizontal ID (in) Average Vertical ID (in) Maximum ASTM Ovality* (%) Sediment Depth (in) N/A N/A N/A N/A

16 Rehabilitation Technologies Option 1 - Sliplining

17 Rehabilitation Technologies Option 1 Sliplining FRP or PVC Pros Longer Distance between Manholes Can Install with Flow in Pipe Can Push (float) 3,000+ LF Downstream (FRP) Can Push 2,000+ LF Upstream (FRP) Fewer Access Manholes Required Cons Insertion Pits are Required More Potential for Odor Problems Limit of 1.5% to 2% Deflection to Negotiate Bends Slight Reduction in Capacity due to Smaller ID Grout is Required in Annular Space High ground water at insertion pits

18 Rehabilitation Technologies Option 2 Cured in Place Pipe (CIPP)

19 Rehabilitation Technologies Option 2 Cured in Place Pipe (CIPP) Pros Increase in Capacity due to Matching Corroded ID Minimal Excavation Required Work thru Manholes Smaller Footprint for Odor Control Cons Requires By-Pass Pumping During Active Insertion and Curing Requires Higher Level of Sewer Cleaning Will Require Addition of New Access Manholes - Maximum Length of Insertion is Approximately 1,000 LF Field Wetting is Sensitive to Hot Ambient Temperatures Active I/I may require pre-rehab correction (grout, pre-lining)

20 Rehabilitation Technologies Option 3 Spiral Wound Pipe

21 Rehabilitation Technologies Option 3 Spiral Wound Pipe Pros Can Install with Flow in Pipe Minimal Excavation Required Work thru Manholes Smaller Footprint for Odor Control High ground water can be accommodated Cons Will Require Addition of New Access Manholes - Maximum Length of Winding is Approximately 800 LF Slight Reduction in Capacity due to Smaller ID Grout is Required in Annular Space

22 Project Coordination Issues Traffic control Construction permits Work in rights-of-way Odor control and management Wet-weather controls (during construction) Noise Controls Site restoration Potential contractor pool Ground water control, if necessary

23 Odor Control Strategies Reduce flow through the pipe by closing gate at Allen Control Structure Three force mains downstream of control structure will continue to flow through the pipe along with I/I. Batch or continuous treat remaining flow in pipe with chemical. Control odor at excavations Negative Pressure using mechanical ventilation Vapor phase treatment with dry media scrubber

24 Bidding and Construction

25 Engineer s Construction Estimates Length, LF Sliplining CIPP SWP Base Bid 10,612 $4,650,000 $7,220,000 $4,550,000 Alt. No. 1 1,793 $780,000 $1,200,000 $810,000 Alt. No. 2 2,120 $970,000 $1,440,000 $960,000 Alt. No. 3 1,230 $640,000 $870,000 $590,000 Alt. No. 4 1,510 $720,000 $1,030,000 $700,000 Total 17,265 $7,760,000 $11,760,000 $7,610,000 Estimated Costs include: Contractor Overhead and Profit (15%), Mobilization/Bond/Insurance (2.6%), Contingency (0%), Escalation (0.6%)

26 Bid Results Contractor Technology Bid $/lf $/ID/lf Engineer s Estimate FRP (Hobas ) $7,825,000 $453 $8.40 SJ Louis FRP+CIPP $4,428,000 $256 $4.70 Boyer FRP $5,269,000 $305 $5.65 Huff & Mitchell FRP/HDPE $5,717,000 $331 $6.10 Southwest Pipeline SWP $5,812,000 $337 $6.25 WRS Infrastructure FRP/HDPE $7,580,000 $439 $8.10 BRH-Garver FRP $7,923,000 $459 $8.50 Boring & Tunneling Co. SWP $8,038,000 $466 $8.65 Spiniello FRP+CIPP $8,130,000 $471 $8.70 RePipe Construction CIPP $8,581,000 $497 $9.20 Estimated Costs include: Contractor Overhead and Profit (15%), Mobilization/Bond/Insurance (2.6%), Contingency (0%), Escalation (0.6%)

27 Ph II - Construction

28 Rowlett Cottonwood Transfer Sewer: 60" RCP Sanitary Sewer Rehabilitation Project TACWA Meeting September 25, 2009 North Texas Municipal Water District