B01 RFP Attachment J05 - Anadarko-CCTV-Report.pdf
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- Attached to
- Prairie Village Sewer Renovation
- Solicitation number
- 75H70122R00026
About this file
This solicitation requests proposals for construction services to renovate the existing gravity sewer system for the Prairie Village Community in Anadarko, Oklahoma. The Indian Health Service intends to award a firm fixed price contract with a period of performance of 180 calendar days from notice to proceed. The magnitude of the construction project is estimated between $500,000 and $1,000,000. The solicitation will be set aside for small businesses, with preference given to Indian Economic Enterprises. Interested parties should monitor the System for Award Management website for any amendments, with proposals due as indicated on the site. The Department of Health and Human Services Indian Health Service will evaluate proposals using the lowest price technically acceptable criteria.
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Oklahoma City Area IHS
CCTV and Visual Inspection of The Wastewater System in Support of The
Anadarko Prairie Village Sewer Replacement Project for Native American Homes
Order Number: 75H71120P00903
Inspection and Condition Assessment Report
November 6, 2020
Bai Engineers 5350 DTC Pkwy, #206
Greenwood Village, Colorado 80111 www.bai-eng.com
Inspection & Condition Assessment Report
TOC - 1 Bai Engineers | xbai@bai-eng.com
Table of Contents
Section 1 – Introduction Section 2 – Manhole Location Survey Section 3 – Manhole Condition Assessment Section 4 – Pipe Condition Assessment
4.1 Summary of CCTV Survey
4.2 CCTV Review Results
4.3 Pipe Condition Assessment Criteria
4.4 Pipe Condition Assessment Results
4.5 Pipe Condition Assessment Summary
Section 5 – Risk Assessment
5.1 Risk Assessment Evaluation Criteria
5.1.1 CoF Definition
5.1.2 LoF Definition
5.1.3 Overall Sewer System Risk
5.2 Manhole Risk Assessment
5.2.1 Manhole CoF Score
5.2.2 CoF Score by Manhole Depth
5.2.3 CoF Score by Manhole Connections Served
5.2.4 Accumulative CoF Score
5.2.5 LoF Score by Manhole Installation Year
5.2.6 LoF Score by Manhole Material
5.2.7 LoF Score by Inspection Notes
5.2.8 Accumulative LoF Score
5.2.9 Manhole Asset Management Approach
5.3 Pipe Risk Assessment
5.3.1 CoF Score by Pipe Location
5.3.2 CoF Score by Pipe Depth
5.3.3 CoF Score by Pipe Diameter
5.3.4 Accumulative CoF Score
5.3.5 LoF Score by Pipe Installation Year
5.3.6 LoF Score by Pipe Material
5.3.7 LoF Score by CCTV Condition
5.3.8 Accumulative LoF Score
5.3.7 Pipe Asset Management Approach
Section 6 – Recommendations for Repair and Maintenance
5350 DTC Pkwy, #307, Greenwood Village, CO 80111 P: 720/474-0941 Email: xbai@bai-eng.com www.bai-eng.com
Section 1 – Introduction
The purpose of this project is to present the CCTV inspection work performed for the sewer collection system at the Prairie Village (Village) of the City of Anadarko (Anadarko). The Village is located on the north end of the Anadarko. The overall sewer collection system of the Village location are shown in Figure 1.
Figure 1. Anadarko and Prairie Village Sewer Collection System Map
The report is organized into the following sections besides this Introduction section.
• Section 2. Manhole Location Survey
• Section 3. Manhole Condition Assessment
• Section 4. Pipe Condition Assessment
• Section 5. Risk Assessment
• Section 6. Recommendations for Repair and Maintenance
The report was developed based on the road map identified in the work plan (Appendix 1) and meeting records of the Pre-Construction Meeting (Appendix 2).
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Section 2 – Manhole Location Survey
The manhole location was verified through field surveys. The manhole location verification was conducted between October 13 to 16, 2020. Table 1 outlines the brief findings. Initially, there are 28 sewer manholes within the Village's sewer collection system. The initial manhole map based on the contract document is shown in Figure 2. The surveys identified two new manholes.
However, Manhole 19 was not found during the survey, and after consulting with City and IHS staff, it was decided to be excluded from the sewer collection system. A total of 29 manholes were identified, as shown in Figure 6.
Table 1. Summary of Manhole Location Survey Date Manhole Location Findings Graphical Presentation
10/13/2020 27 manholes were located and surveyed. The City's as-built plans were collected and checked. MH 9 was not located due to a lack of access.
Figure 3 shows the findings as of 10/13/2020. Detailed data are provided in Appendix 3.
10/14/2020 29 manholes were located and surveyed. MH 9 was located and surveyed. A new manhole (Manhole 2A) between MH 2 and MH 3 was found and surveyed.
Figure 4 shows the findings as of 10/14/2020. Detailed data are provided in Appendix 4.
10/15/2020 MH 19 was not located. After consulting with the City and Indian Health Service (IHS) staff, MH 19 was excluded from the sewer collection system. Sewer flow from Wichita Travel Plaza was added.
Figure 5 shows the findings as of 10/15/2020. Detailed data are provided in Appendix 5.
10/16/2020 A new manhole (Manhole 15A) between MH 15 and MH 17 was found during pipe CCTV inspection. However, the manhole was not able to be located on the field for inspection.
Figure 6 shows the findings as of 10/16/2020. Detailed data are provided in Appendix 6.
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Figure 2. Anadarko’s Prairie Village Sewer Collection System Per Contract Document
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Figure 3. Anadarko’s Prairie Village Manhole Location Verification Result as of 10/13/2020
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Figure 4. Anadarko’s Prairie Village Manhole Location Verification Result as of 10/14/2020
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Figure 5. Anadarko’s Prairie Village Sewer Collection System Per Field Survey 10/15/2020
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Figure 6. Anadarko’s Prairie Village Sewer Collection System Per Field Survey 10/16/2020
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Section 3 – Manhole Condition Assessment
Field inspections and condition assessments were performed at each sewer manhole. A manhole inspection form was prepared for each manhole. All the manhole inspection forms are attached in Appendix 7. As part of the condition assessment, the manhole depth was measured and recorded in the inspection form. Then the manhole condition was rated between 0 to 10, with which 0 means the bad condition and 10 means the good condition. A summary of the manhole inspection note is documented in Table 2. A map was prepared with the manhole inspection notes and field surveyed depth, as shown in Figure 7.
Table 2. Summary of Manhole Inspection Notes
Name Depth (Feet)
Inspection Note Manhole
Rating
MH-1 8.1 Grease Accumulation 1
MH-2 7.5 Water Sag, Ponding, Iron Rust 0
MH-2A 7.2 Replacement needed, upstream has sag issues, water ponding 0
MH-3 6.5 Ponding, Seal lost, soil coming in 2
MH-4 7.0 Reverse slope, 6" of pond, grit 0
MH-5 6.4 Ponding, silt 1
MH-6 5.2 Ponding, Brick bad 2
MH-7 4.7 Ponding, Reverse Slope 1
MH-8 4.4 Dry line from West, slow flow, lateral line 5
MH-9 4.1 Reverse slope, silt, and sand 1
MH-10 3.0 Clean 5
MH-11 3.3 Dry 6
MH-12 4.5 1" Water Ponding, Soil in and root in 3
MH-13 2.6 Cleanout 18" 8
MH-14 6.0 Slope Not good, Condition is good 5
MH-15 3.6 3" water ponding, reverse slope, lose MH ring 2
MH-15A Found during CCTV, but Cannot Locate from the surface
MH-16 2.5 Dry 5
MH-17 4.8 3" water ponding, brick condition goof, silt found 3
MH-18 3.0 Dry, the dry sewer lateral is recommended to be capped 6
MH-19 Cannot Locate
MH-20 6.0 6" Water Ponding, losing Seal 1
MH-21 4.5 Ponding of Water, Soil in, two inlets 2
MH-22 6.0 6" Water Ponding, Losing Seal 1
MH-23 5.5 Good; a grease trap is recommended to be installed for sewer lateral from the Wichita Travel Plaza
MH-24 4.7 3" Ponding, silt, lost Seal 1
MH-25 6.2 Dry scum, lost Seal, dry 3
MH-26 7.2 Thick scum, lost Seal 1
MH-27 6.4 5" of scum, cannot see water 1
MH-28 4.5 5
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Figure 7. Geographical Locations of Inspected Manholes
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Using the field surveyed manhole depth and the most recent LiDAR data obtained from the United States Geological Survey (USGS), the pipe invert elevations were determined. The sewer pipe slope was then calculated. A summary of the sewer pipe slope is documented in Table 3. A map was prepared to show the sewer pipe slope (Figure 8). Four sewer mains were found to have negative (or reverse) pipe slopes (highlighted in red color in Table 3 and Figure 8).
Table 3. Summary of Sewer Pipes Pipe
ID
Upstream Manhole
Downstream Manhole
Pipe Length (Feet)
Upstream Invert
Downstream Invert
Surveyed Pipe Slope
3 MH-4 MH-3 17 1180.51 1180.753 -1.44%
8 MH-8 MH-7 111 1182.845 1182.961 -0.10%
24 MH-26 MH-25 133 1180.932 1181.033 -0.08%
12 MH-14 MH-24 207 1183.072 1183.104 -0.02%
21 MH-20 MH-23 344 1182.717 1182.25 0.14%
27 MH-23 MH-22 163 1181.916 1181.657 0.16%
17 MH-17 MH-15 237 1184.762 1184.153 0.26%
19 MH-18 MH-17 177 1185.412 1184.846 0.32%
2 MH-3 MH-2A 283 1180.67 1179.724 0.33%
9 MH-9 MH-8 262 1183.926 1183.012 0.35%
26 MH-27 MH-2 130 1180.298 1179.807 0.38%
6 MH-6 MH-5 116 1181.849 1181.398 0.39%
14 MH-11 MH-12 195 1185.357 1184.486 0.45%
11 MH-24 MH-5 222 1182.938 1181.898 0.47%
18 MH-16 MH-17 161 1185.62 1184.846 0.48%
10 MH-10 MH-9 260 1184.86 1183.593 0.49%
5 MH-5 MH-4 191 1181.231 1180.26 0.51%
22 MH-21 MH-20 142 1183.785 1182.967 0.58%
25 MH-25 MH-27 77 1180.866 1180.381 0.63%
7 MH-7 MH-6 162 1183.127 1181.932 0.74%
16 MH-15 MH-14 157 1184.236 1183.072 0.74%
23 MH-22 MH-26 122 1181.99 1181.016 0.80%
4 MH-28 MH-4 194 1182.308 1180.26 1.06%
13 MH-13 MH-12 93 1185.52 1184.486 1.11%
15 MH-12 MH-14 114 1184.319 1182.656 1.46%
1 MH-2 MH-1 59 1179.557 1178.692 1.46%
27 MH2A MH2 22 1179.807 1179.474 1.55%
20 MH-19 MH-15 53 MH19 Cannot be located
The detailed manhole and pipe GIS datasets are attached in Appendix 8. A manhole survey ArcReader presentation file that contains the photos and videos taken during the field inspection was created and attached in Appendix 9. For a reference, an ArcReader presentation file for the 2016 Smoke Test was also created and attached in Appendix 10.
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Figure 8. Geographical Locations of Field Surveyed Pipe Slope
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Section 4 – Pipe Condition Assessment
Field inspection of the sewer collection pipes was conducted from October 13th through 16th via CCTV to assess the pipe conditions in Prairie Village. The following subsections will summarize the data and procedures for the assessment of pipe conditions, which will be used to make recommendations.
4.1 Summary of CCTV Survey
CCTV was performed at 30 pipe segments. The total length of the pipe surveyed is 4,098.5 feet.
A summary of the pipes surveyed with CCTV is documented in Table 4. Locations of the CCTV performed are shown in Figure 9.
Table 4. Summary of Pipes Surveyed with CCTV
From
MH
To MH Survey
Length (feet) Material
Size (Inches)
Survey Notes
2 1 57.3 VCP 8
2A 2 20.5 VCP 8
3 2A 282.6 VCP 8
4 3 18.7 VCP 8
5 4 191.6 VCP 8
6 5 114.4 VCP 8
7 6 117.2 + 48.8
VCP /
DIP
Two videos found, one from upstream, one from downstream
8 7 112.5 VCP 8
9 8 263.7 VCP 8
10 9 261 VCP 8
Two videos found, one before cleaning, one after cleaning
12 11 194.2 VCP 8
Two videos found, one before cleaning, one after cleaning, sewer blockage found and survey abandoned
12 14 114.7 VCP 8
12 13 92.8 VCP 8
14 24 65 VCP 8
Pipe material changed to DIP;
downstream pipe cannot be surveyed
15 14 4 VCP 8
Pipe material changed to DIP;
downstream pipe cannot be surveyed
15 15A 118 VCP 8
17 16 80.3 VCP 8
Two videos found, one before cleaning, one after cleaning, sewer blockage found and survey abandoned
17 15A 120.1 VCP 8
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18 17 159.4 VCP 8
15 19 60.3 VCP 8
23 20 336.3 VCP 8
21 20 137.2 VCP 8
21 22 77.6 VCP 8
26 22 128.3 VCP 8
23 22 167.2 VCP 8
5 24 221.6 VCP 8
25 27 80.8 VCP 8
26 25 138.9 VCP 8
27 2 123.8 VCP 8
CCTV report shows 114 feet, the actual survey length is 123.8 feet
28 4 189.7 VCP 8
Total Length: 4,098.5 Feet
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Figure 9. Location Map of Sewer CCTV Survey
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4.2 CCTV Review Results
Upon viewing the CCTV video records, seven (7) types of the most frequent defects are identified. These seven types of pipe integration damage and leakage are summarized and illustrated in Table 5.
Table 5: Types and Examples of Pipe Integration Found in CCTV Images
Type of Damage/Leakage
Description Likelihood of Failure
Rating Example
Type 1 Sectional offset Immediate action is required
Pipe has failed or will likely fail within the next 5 years.
Type 2 Pipe damage due to corrosion Immediate repair is recommended
Pipe may fail in 5 to 10 years.
Type 3 Root Intruding Action is suggested
Pipe may fail in 10 to 20 years.
Type 4A Multiple cracks Minor defects
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Type 4B Crack - Circumferential Minor defects
Type 4C Crack - Longitudinal Minor defects
Type 5 Break-in at service tap Minor defects
Type 6 Intruding Sealing Ring Minor defects
Type 7 Debris Blockage Cleaning is recommended
Type 8 Water Level Sag Pipe may fail in 5 to 10 years.
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Type 9 Hole Soil Exposed
Pipe has failed or will likely fail within the next 5 years.
After defect identification, a GIS-based pipe condition assessment model is built and used for sewer pipe data management. The pipe defect conditions are drawn on the ArcGIS, as illustrated in Figure 10. The locations of the active and capped sewer taps or connections discovered during the CCTV survey are shown in Figure 11.
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Figure 10. Geographical Locations of Pipe Defects Found in CCTV
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Figure 11. Geographical Locations of Service Connections Found in CCTV
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4.3 Pipe Condition Assessment Criteria
The defects identified from the CCTV data are then scored by severity in terms of need for attention for repair, on a six-level scale (0-5) where “0” describes a condition that warrants no action and “5” describes the worst condition that requires immediate action as shown in Table 6.
Table 6: Scores for the Pipe Defect Conditions
Defect Condition Score
Sectional Offset
Root Intrusion 4
Cracks 3
Intruding Sealing Ring 4
Tap Break-In 2
Debris Blockage 1
Water Level Sag 4
Hole with Soil Exposed 5
The severity scores of a pipe are further aggregated as the total score for each pipe. The condition of a section of pipe is rated using the combined data of identified defects and the associated severity score. This provides a total score that prescribes a final rating based on the ranges specified in Table 7. The rating consists of six levels that describe action needed for each pipe, from “0” for no action needed to “5” for immediate action required.
Table 7: Pipe Rating Based on Distribution
Pipe Total Score Rating Action
>25 5 Immediate Attention
16-25
Moderately Immediate Attention
11-15 3 Action recommended 6-10 2 Intermediate Defect 1-5 1 Minor Defect 0 0 No Action Needed
4.4 Pipe Condition Assessment Results
Each of the pipes surveyed in Prairie Village with CCTV is assigned a condition rate per the procedures explained in Section 4.2 and summarized in Table 8. The resulting condition assessment is shown graphically in Figure 12. “Total score” is the sum of all the defect ratings of a pipe, while “rank” is the final condition rating for each pipe based on the total score.
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Table 8. Results of Pipe Condition Rating
Pipe ID Total Score
Condition Rank
MH-27 to MH-2 3 1
MH-25 to MH-27 13 3
MH-26 to MH-25 6 2
MH-22 to MH-26 20 4
MH-23 to MH-22 11 3
MH-20 to MH-23 51 5
MH-21 to MH-20 12 3
MH-3 to MH-2A 39 5
MH-4 to MH-3 11 3
MH-28 to MH-4 5 1
MH-5 to MH-4 34 5
MH-7 to MH-6 6 2
MH-8 to MH-7 18 4
MH-9 to MH-8 56 5
MH-10 to MH-9 43 5
MH-24 to MH-5 58 5
MH-14 to MH-24 (1) 9 2
MH-13 to MH-12 40 5
MH-11 to MH-12 52 5
MH-12 to MH-14 16 4
MH-15 to MH-14 (1) 1 1
MH-19 to MH-15 10 2
MH-17 to MH-15 45 5
MH-18 to MH-17 22 4
MH-16 to MH-17 28 5
MH-2 to MH-1 8 2
MH-6 to MH-5 18 4
MH2A to MH2 3 1
MH21 to MH22 35 5
Notes: (1). Sections of the pipes from MH-14 to MH-24 and from MH-15 to MH-14 were found to be ductile iron pipes (DIPs). The DIPs were corroded down to less than 5 inches. The CCTV cannot access for cleaning and inspection. Refer to Figure 9 for the DIPs locations.
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Figure 12. Graphical View of Pipe Condition Assessment Results
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4.5 Pipe Condition Assessment Summary
In summary, a total of 2239.8 feet of pipe, over 50% of the total pipe length of 4098.5 feet, were ranked as 5 (Table 9), requiring immediate maintenance or repair action.
Table 9. Pipe Length Results
Pipe Condition Rating Total Length (Feet)
5 2239.8
4 629.3
3 403.9
2 487.5
1 338
Total 4098.5
A CCTV pipe condition assessment ArcReader presentation file was created and attached in Appendix 12.
Section 5 – Risk Assessment
Based on the field inspection and survey, a total of 30 pipes and 30 manholes (including one missing manhole, MH#19) were recorded for the Village’s sewer collection system. A detailed risk assessment was performed for the 30 pipes and 29 manholes. An asset register was created to include all the manholes and pipe datasets.
5.1 Risk Assessment Evaluation Criteria
Each sewer manhole and pipe segment in the asset register was evaluated using two risk factors:
Consequence of Failure (CoF) and Likelihood of Failure (LoF). A risk score from 1 (low risk) to 5 (high risk) was assigned to each CoF and LoF factor. The risk scores are shown in Table 10.
Table 10. Risk Score Ranking for CoF and LoF
Score CoF/LoF Definition
1 Low
2 Low-Medium
3 Medium
4 Medium-High
5 High
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5.1.1 CoF Definition
The Consequence of Failure, or the criticality of an asset, measures the direct and indirect implications and costs in case of the asset failure. For instance, the maintenance and repair of deeply buried infrastructures or infrastructures that are close to major roads will be more difficult and most likely cost more. Therefore, the CoF factors are primarily associated with the location of the sewer infrastructure and its proximity to other infrastructures (such as road, school, hospital, and other facilities) and natural resources (such as surface water and groundwater). In addition, repair of manholes that serve more customer taps will increase the cost of sewer bypass and the cost for replacing a pipe changes with its diameter. Three CoF factors were evaluated for each manhole and pipe, including infrastructure locations, depth, and the number of taps served by a manhole or the diameter for a pipe. Their risk scoring criteria are shown in Table 11.
Table 11. Risk Score Criteria for CoF
CoF Score by Infrastructure Location
Sub - Category Criteria Risk Score
Proximity to Major Road
Infrastructure is further than 100 ft from major road 1
Infrastructure is 75-100 ft from major road 2
Infrastructure is 50-75 ft from major road 3
Infrastructure is 25-50 ft from major road 4
Infrastructure is less than 25 ft from major road 5
Sub - Category Criteria Risk Score
Proximity to Water
(Streams, rivers, reservoirs, water bodies)
Infrastructure is further than 250 ft from water body 1
Infrastructure is 100-250 ft from water body 2
Infrastructure is 50-100 ft from water body 3
Infrastructure is 25-50 ft from water body 4
Infrastructure is less than 25 ft from water body 5
CoF Score by Infrastructure Depth
Sub - Category Criteria Risk Score
Depth to Inverts
<= 4 ft 1
4 - 5 ft 2
5 - 6 ft 3
6 - 7 ft 4
>7 ft 5
CoF Score by Number of Taps Served by Manhole
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Sub-Category Criteria Risk Score
Number of Customers Served
<= 10 1
10 - 20 2
20 - 40 3
40 - 60 4
>60 5
CoF Score by Pipe Diameter
Sub - Category Criteria Risk Score
Pipe Diameter <= 8 in 3
A risk score from each of the three CoF categories was generated based on the surveyed conditions of manholes and pipes. For the CoF score by infrastructure location, the highest risk score from all sub-categories was used. An accumulative CoF score was obtained from all the three CoF categories with a weighting factor (%) for each category. s. The formula of the accumulative CoF score is:
Accumulative CoF Score for Manhole = 40% CoF by Infrastructure Location + 30% CoF by Infrastructure Depth + 30% CoF by Number of Taps Served by Manhole
Accumulative CoF Score for Pipe = 40% CoF by Infrastructure Location + 30% CoF by
Infrastructure Depth + 30% CoF by Pipe Diameter
5.1.2 LoF Definition
Likelihood of Failure (LoF) measures an asset’s likelihood of, or timing to, failure. LoF is primarily associated with the physical conditions of the existing asset, such as installation age, material, field condition (manhole), and CCTV condition (pipe). The following LoF factors listed in Table 12 were evaluated for this project.
Table 12. Risk Score Criteria for LoF
LoF Score by Infrastructure Installation Year
Installation Year Risk Score
1980-present 1
1960-1980 3
<1960 5
LoF Score by Pipe Material
Pipe Material Risk Score
PVC / HDPE 1
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VCP 3
RCP / DIP / CIP 5
LoF Score by Manhole Material
Manhole Material Risk Score
Concrete 1
Steel 3
Brick 5
LoF Score by Pipe CCTV condition
Pipe CCTV Condition Rating Risk Score
Score = 1 1
Score = 2 2
Score = 3 3
Score = 4 4
Score = 5 5
LoF Score by Manhole Field Condition
Manhole Condition Rating Risk Score
Score = 10 - 8 1
Score = 7-6 2
Score = 5-4 3
Score = 3-2 4
Score = 1-0 5
A risk score from each of the LoF categories was generated based on the survey results of a manhole and a pipe segment. A weighting factor (%) was applied to each category to obtain the accumulative LoF score. The formula of the accumulative LoF score is:
Accumulative Pipe LoF Score = 20% LoF by Pipe Installation Year + 20% LoF by Pipe Material
+ 60% LoF by Pipe CCTV Condition
Accumulative Manhole LoF Score = 20% LoF by Manhole Installation Year + 20% LoF by Manhole Material + 60% LoF by Manhole Field Condition
5.1.3 Overall Sewer System Risk
The ultimate goal of the CoF and LoF risk assessment is to determine the appropriate asset management measure(s) needed and the prioritization of the measure(s). Business Risk Exposure
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(BRE), or simply risk, is a calculated measurement used to determine the course of action needed for managing an asset. BRE is calculated as the product of the LoF and the CoF. The BRE score is used to help support the prioritization of asset improvement actions. The BRE score is plotted in a matrix, and each BRE score is assigned to a management approach. The illustration is shown in Figure 13.
Figure 13. Illustration of BRE Score Matrix and Management Approach
5.2 Manhole Risk Assessment
The CoF and LoF scores for each of the manholes were summarized in the following sections.
5.2.1 Manhole CoF Score
The location of major road and water body near the Village area is shown in Figure 14. As shown, the closest water body to the Village area is the Washita River.
The higher CoF score from the proximity to the major road and water body was determined and then selected as a final score for the location. The CoF score by the manhole location was presented in Figure 15.
5.2.2 CoF Score by Manhole Depth
The CoF score by manhole depth was presented in Figure 16.
5.2.3 CoF Score by Manhole Connections Served
Based on the number of houses served by a manhole, the CoF score at each manhole was determined. The CoF score by the number of connections served by the manholes was presented in Figure 17.
5.2.4 Accumulative CoF Score
Using the formula in Section 5.1.1, the accumulative CoF score was determined for each manhole. The accumulative CoF score was presented in Figure 18.
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Figure 14. Locations of Major Roads and Water Body
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Figure 15. Manhole CoF Score by Manhole Location
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Figure 16. Manhole CoF Score by Manhole Depth
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Figure 17. Manhole CoF Score by Number of Connections Served by the Manhole
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Figure 18. Accumulative CoF Score of Manholes
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5.2.5 LoF Score by Manhole Installation Year
The LoF score based on the installation year was shown in Figure 19.
5.2.6 LoF Score by Manhole Material
The LoF score based on the manhole material was shown in Figure 20.
5.2.7 LoF Score by Inspection Notes
The LoF score based on the manhole field inspection notes and rating was shown in Figure 21.
5.2.8 Accumulative LoF Score
The accumulative LoF score was determined using the formula in Section 5.1.2. The accumulative manhole LoF score was shown in Figure 22.
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Figure 19. Manhole LoF Score by Installation Year
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Figure 20. Manhole LoF Score by Material
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Figure 21. Manhole LoF Score by Field Inspection Notes and Rating
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Figure 22. Accumulative LoF Score of Manholes
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5.2.9 Manhole Asset Management Approach
Based on the accumulative CoF and LoF scores, the sewer manhole BRE risk score Matrix is shown in Figure 23. The summary of the number of manholes for each BRE risk category is shown in Table 13. A total of 15 manholes were identified at the high risk, requiring immediate action or high priority renewal. The graphical presentation of the sewer manhole BRE risk is shown in Figure 24.
Figure 23. Sewer Manhole BRE Score Matrix
Table 13. Summary of Sewer Manhole BRE Risk Score Matrix
Asset Management Approach
# of Manholes
Immediate Action 1
High Priority Renewal 14
Mid Priority Renewal 7
Frequent Assessment 0
Regular Monitoring 0
Sample Assessment 4
Total Number of Manholes 26
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Figure 24. Graphical Illustration of Sewer Manhole BRE Score Matrix
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5.3 Pipe Risk Assessment
The CoF and LoF scores for each of the pipes were summarized in the following sections.
5.3.1 CoF Score by Pipe Location
The higher CoF score from the proximity to the major road and the water body was determined and selected as a final score. The CoF score by pipe location was presented in Figure 25.
5.3.2 CoF Score by Pipe Depth
The CoF score by the pipe depth was presented in Figure 26.
5.3.3 CoF Score by Pipe Diameter
The CoF score by the pipe diameter was presented in Figure 27.
5.3.4 Accumulative CoF Score
Using the formula in Section 5.1.1, the accumulative CoF score of a pipe segment was determined for each sewer pipe. The accumulative pipe CoF scores were presented in Figure 28.
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Figure 25. Pipe CoF Score by Pipe Location
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Figure 26. Pipe CoF Score by Pipe Depth
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Figure 27. Pipe CoF Score by Pipe Diameter
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Figure 28. Accumulative CoF Scores of the Pipes
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5.3.5 LoF Score by Pipe Installation Year
The LoF score based on the installation year was shown in Figure 29.
5.3.6 LoF Score by Pipe Material
The LoF score based on the Pipe material was shown in Figure 30.
5.3.7 LoF Score by CCTV Condition
The LoF score based on the Pipe field inspection notes and rating was shown in Figure 31.
5.3.8 Accumulative LoF Score
The accumulative LoF score of a pipe was determined using the formula in Section 5.1.2. The accumulative pipe LoF scores were shown in Figure 32.
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Figure 29. Pipe LoF Score by Installation Year
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Figure 30. Pipe LoF Score by Material
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Figure 31. Pipe LoF Score by CCTV Condition
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Figure 32. Accumulative LoF Scores of Pipes
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5.3.7 Pipe Asset Management Approach
Based on the accumulative CoF and LoF score, the sewer pipe BRE risk score Matrix is shown in Figure 33. The summary of the number of pipes for each BRE risk category is shown in Table 14.
A total of 14 pipe segments were identified at the high risk, requiring high priority renewal. The graphical presentation of the sewer pipe BRE risk is shown in Figure 34.
Figure 33. Sewer Pipe BRE Score Matrix
Table 14. Summary of Sewer Pipe BRE Risk Score Matrix
Asset Management Approach
# of Pipes
Immediate Action 0
High Priority Renewal 14
Mid Priority Renewal 7
Frequent Assessment 1
Regular Monitoring 7
Sample Assessment 2
Total Pipe Segments 31
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Figure 34. Graphical Illustration of Sewer Pipe BRE Score Matrix
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Section 6 – Recommendations for Repair and Maintenance
Based on the manhole and pipe condition assessment, the following recommendations were proposed:
1. In-service sewer lateral rehabilitations are recommended. Non-use service laterals are suggested to be capped. For example, use a concrete block to cap the dry sewer lateral located on the East side of Manhole MH8.
2. Replace the pipe segment from MH14 to MH15, which has a corroded cast-iron-pipe.
3. Replace the pipe segment from MH3 to MH 4, which has a negative slope.
4. Replace all pipe segments with less than 0.14% slope. They include (1) pipe between MH
14 & MH 24, (2) pipe between MH 26 & MH 25, and (3) pipe between MH 7 & MH 8.
5. Install a new grease trap at MH 23 to intercept the flow from Wichita Travel Plaza and perform routine cleaning at this location.
Besides the above recommendations, we have identified additional manholes and pipes at high risk by the BRE risk assessment. A total of 15 manholes and 14 pipe segments require immediate actions and high priority renewal (Table 15 and Figure 35).
In some cases where a pipe and associated manholes are all ranked at a high risk, which warrants a high priority for an asset improvement. For example, pipe segment #5 was ranked as the high priority renewal, and both associated manholes #4 and #5 are also ranked as the high priority renewal. By improving the pipe and manholes together, it could yield a greater benefit by reducing the costs for repair and avoiding risks caused by interference between the manhole and pipe failures.
It should be noted here that this assessment did not account for the costs for repair or replacement and funds available for such improvement, which might alter the priority of the asset improvement.
Table 15. Pipes and Manholes at High Risk
Pipe
ID
Upstream Manhole
Downstream Manhole
Pipe Length (Feet)
Improvement
1 MH-2 MH-1 59 Two Manholes
2 MH-3 MH-2A 283 Pipe and one manhole
5 MH-5 MH-4 191 Pipe and two manholes
6 MH-6 MH-5 116 Pipe and two manholes
7 MH-7 MH-6 162 Pipe and two manholes (CIP Pipe)
9 MH-9 MH-8 262 Pipe and one manhole
10 MH-10 MH-9 260 Pipe and one manhole
11 MH-24 MH-5 222 Pipe and two manholes
13 MH-13 MH-12 93 Pipe only
14 MH-11 MH-12 195 Pipe only
17A MH-17 MH-15A 120 Pipe only
17B MH-15A MH-15 118 Pipe and one manhole
18 MH-16 MH-17 161 Pipe only
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21 MH-20 MH-23 344 Pipe and one manhole
23 MH-22 MH-26 122 Manhole only
25 MH-25 MH-27 77 Manhole only
A S MH-21 78 Pipe only
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Figure 35. Graphical Illustration of Sewer and Manhole with High Risk for Replacement
File details come from the government source that posted it. Updated .