Leakage Detection of Buried Water Carrying Services Affecting

Leakage Detection of Buried Water Carrying Services Affecting Slope Speakers: Miss Carman Lam Ir Dr. King Wong Date: 26 Feb, 2011 Ref: HKIUS-GEN-018 BWCS 1

Hong Kong is also full of • Slopes (斜坡) And • Many of Us Live next to the slopes Ref: HKIUS-GEN-018 BWCS 2

Why detect leakage of BWCS? • Water loss(流失) from leakage(滲漏) takes up nearly a quarter of total water consumption( 用量) in HK. (around 230, 000 m 3 of water lost) • Leak water erode (侵蝕) the soil and create void(空隙) underground. This destroys(破壞) the soil structure and the soundness(完整性) of the ground. Ref: HKIUS-GEN-018 BWCS 3

Why detect leakage of BWCS? • Leakage of BWCS affecting slope can cause landslide without notable(明顯) signs(徵兆). • Kwun Lung Lau Landslide (觀龍樓事件) in 1994 caused 5 fatalities and 3 injuries. • There about 5, 7000 sizeable man-made slopes in Hong Kong Ref: HKIUS-GEN-018 BWCS 4

1994年 7月 觀龍樓事件 “Three die in landslip due to drain problem” July 1994 Ref: HKIUS-GEN-018 BWCS (Source: SCMP 23 July 1994) 5

Kwun Lung Lau Event On 23. 7. 94 Professor Morgenstern Lead Investigation Morgenstern’s Report Concluded That: 調查結論 • Leakage of Nearby Buried Drains Was a Key Factor Contributing To The Tragedy 鄰近被埋水渠洩漏是引致這水慘劇的主要原因 • A Program of Direct Monitoring and Repair of Buried Services Where Leakage Might Impact On Slope Stability Should Be Developed. • 應建立機制直接監察帶水道因洩漏引致影響斜 坡的穩定性 Ref: HKIUS-GEN-018 BWCS 6

Why detect leakage of BWCS? • Causes(原因) of Kwun Lung Lau Landslide Intense Rainfall A. Leakage from BWCS weakened(削 弱) the structure and stability(穩定性) of slope in long term Ref: HKIUS-GEN-018 BWCS B. Intense(密集) heavy rainfall and leakage saturate( 浸透) the soil C. Ground movement and landslide (山泥 傾瀉) 7

Why detect leakage of BWCS? • After the incident, Professor Morgenstern recommended in the report that ü Government should develop a programme for direct monitoring and repair of buried services affecting slope. ü Buried services at hazardous locations should become mandatory in a 5 -year interval. Ref: HKIUS-GEN-018 BWCS 8

Code of Practice • Code of Practice on Inspection and Maintenance of Water Carrying Services Affecting Slopes • published by the Works Branch in 1996 in correspondence of the Kwun Lung Lau Incident Ref: HKIUS-GEN-018 BWCS 9

Code of Practice • Code of Practice on Monitoring and Maintenance of Water Carrying Service Affecting Slopes • Second Edition published by the ETWB in Nov. 2006 Ref: HKIUS-GEN-018 BWCS 10

Objective & Scope of COP • Give guidance on the inspection and maintenance of buried water-carrying service affecting slopes • To present procedures and practice to prevent leakage of buried services affecting slopes *Code of Practice on Inspection & Maintenance of water Carrying Services Affecting Slopes Ref: HKIUS-GEN-018 BWCS 11

Key issues in the Co. P • Planning for monitoring and maintenance • Methods of inspection and maintenance • Specification for CCTV Survey, Manhole Internal Condition Survey and Leak Detection for Water Mains • Record Keeping Ref: HKIUS-GEN-018 BWCS 12

Inspection & Investigation of Buried Water-Carrying Services • Leakage investigation – Fresh Water Supply System – Salt Water Supply System • Closed Circuit Television Survey for Sewers & Drains • Man-entry Inspection for Sewers & Drains *Code of Practice on Inspection & Maintenance of water Carrying Services Affecting Slopes Ref: HKIUS-GEN-018 BWCS 13

Purposes of Leakage Detection • To identify potential leaks from water mains or drains(給、排水查漏) • To prevent landslip due to leakage (避免因漏水而引起的斜坡倒塌) • To save lives(拯救生命) • To save costs for damage repairs (減少維修支出) • To improve living standards(提高生活水平 ) Ref: HKIUS-GEN-018 BWCS 14

History of Leakage Detection Industry in Hong Kong (香港查漏行業-歷史) • Before 80 s, Mainly carried out by WSD(水務署). • Early 80 s, First CCTV Inspection contract awarded. (首個合 約) by HKHA (房屋署) • 80 -90, Term contracts for CCTV Inspection from DSD(渠務 署) and HKHA. • 1994 -Kwun Lung Lau Event. (觀龍樓事件) • 1995 -First Contract for Leakage Detection on buried watercarrying services Affecting Slopes by HKHA. (房屋署發出首個主要斜坡查漏合約) • 1996 -Publication of the Code of Practice for Leakage Detection Affecting Slopes by Works Branch. (香港政府 務局頒發首個斜坡查漏 作實務守則) Ref: HKIUS-GEN-018 BWCS 15

History of Leakage Detection Industry in Hong Kong(con’t) (香港查漏行業-歷史) • 1997 -2000, first round of contracts were awarded from WSD, DSD & Highways Department and HKHA as Term contracts for Leakage detection affecting slopes • 2002, second round of contracts were awarded from WSD, DSD & Highways Department and ASD as term contracts or work orders. • 2002, Leakage detection contract from HKHA were awarded under slope maintenance contractors. Ref: HKIUS-GEN-018 BWCS 16

History of Leakage Detection Industry in Hong Kong(con’t) • July, 2002, the formation of Hong Kong Institute of Utility Surveyors, HKIUS. (香港地下管線測量師學會成立 ) • · 31 March, 2003, the final of the Constitution(憲 章 ) of HKIUS. • · 1 April, 2003, the formation of the first executive committee of HKIUS. (第一屆行政委員會成立) 1 April, 2005, the formation of the second executive committee of HKIUS. Ref: HKIUS-GEN-018 BWCS 17

Scope of inspection Affecting slope means… • A strip of land adjacent (鄰接) to the crest (頂點) of the slope with a width equal to the maximum vertical height of the slope However, the scope should extent depends on… • Hydrogeological(水文地質) conditions of the ground • Nature(性質) of slope • Type & age of pipe • Any structures(建築物) on the slope Ref: HKIUS-GEN-018 BWCS 18

Methods for detection • Visual inspection (觀察) • For drains - CCTV Survey & ME Survey - Manhole Internal Condition Survey • For Water Mains - Leak Noise Correlation - Acoustic leak detection (MLD/ELD) - Noise Loggers - Hydrogen Gas Detection Ref: HKIUS-GEN-018 BWCS 19

Planning for inspection Identify the alignment of the pipes/drains to be surveyed • Check past records • Utility Survey/ Mapping • Ground Penetrating Radar Survey (GPRS) Ref: HKIUS-GEN-018 BWCS 20

Check past records • For private assets/properties (私人資產) - The asset owners (資產擁有者)should provide the information • For public utilities (公共設施) - Information can be found from various government departments Ref: HKIUS-GEN-018 BWCS 21

Check past records Public Utilities Slopes Geotechnical Engineering Office (土力 程處)of Civil Engineering and Development Bureau (CEDD) (土木 程署) (http: //hkss. cedd. gov. hk) contains updated information on 57, 000 registered man-made slopes Drainage Services Department Water Mains Water Supplies Department Ref: HKIUS-GEN-018 BWCS 22

Work Procedures • Calibration and preparation • Checking past record. • 翻查紀錄。 • For private services, collect all information available regarding the assets from the client (asset owner). • 若是私用設施，向客戶/ 資產擁有者索取所有相關資料。 • For public services, information can be obtained from various relevant Government Departments. • 若是公用設施，可從相關政府部門獲取相關資料。 Ref: HKIUS-GEN-018 BWCS 23

Work Procedures • Reconnaissance survey • 初步勘查 • The full extent of assets (manholes, pipes, catchpits and other ancillaries) located within the survey extents. • 搜尋檢測範圍的所有相關結構（沙井、管道、截留井及其 他有關結構）。 • Any other manholes and additional features not shown on the base mapping or layout plans, and/or revisions to match existing conditions on site. • 有否其他圖則遺漏了的沙井及其他結構，及有甚麼需要按 現況作修改 Ref: HKIUS-GEN-018 BWCS 24

Work Procedures • Safety precautions include Permit-to-work (PTW), Temporary Traffic Arrangement (TTA), Personal Protective Equipment (PPE), etc. • 執行安全措施，包括 作許可証(PTW)、臨 時交通安排、個人保護措施等。 Ref: HKIUS-GEN-018 BWCS 25

• Operation • • • Work Procedures Locating buried water-carrying services 探測地下帶水管道位置 。 Observe surface installations. 觀察與管綫相關的地面設施。 Carry out utility survey. Electromagnetic method (PCL) for metallic pipes. GPR for non-metallic pipes 進行管綫測量。 以電磁法(管綫探測儀)探測金屬電纜 。 以探地雷達探測非金屬電纜 。 Ref: HKIUS-GEN-018 BWCS 26

Work Procedures • Visual inspection to find out clues of leakage like water spots and seepage. • 觀察地面有否水漬或滲水。 Ref: HKIUS-GEN-018 BWCS 27

Work Procedures • • Inspection of drains 檢測水渠 High pressure water jetting if found suitable. 如有需要，先進行高壓清洗。 CCTV survey / Man-entry survey if necessary. 閉路電視檢測 / 人員進入管內檢測(如有需要)。 Manhole internal condition survey. 沙井內部狀況評估 。 Ref: HKIUS-GEN-018 BWCS 28

Work Procedures Inspection for water mains. 水管檢測 。 Leak Noise Correlation Survey. 噪聲相關檢測 。 Mechanical Leak Detection/ Electronic Leak Detection. • 使用機械測漏儀/電子測漏儀 。 • • • Ref: HKIUS-GEN-018 BWCS 29

Data processing • Due to the potential danger of landslip caused by water leakage, the urgency of rehabiliatation work is higher. • In the grading system of CCTV survey, defects of conduit on slopes should deserve a higher grade, that is a more serious condition. Ref: HKIUS-GEN-018 BWCS 30

Structural Performance Grade (SPG) in CCTV Survey • Supplementary information about the surrounding is considered SPG = ICG + V • V is a variable adjusting the ICG by considering the addition information affecting the grade Year of Installation: On slope Not on slope Ref: HKIUS-GEN-018 BWCS Less than 30 years +1 0 Between 30 and 50 years +2 +1 More than 50 years +2 +2 31

Work Procedures • Reporting • Reconnaissance (事前勘查) Survey Report 1. Location plan showing survey extent and assets in the region in A 3 size. 2. Location photographs showing the slopes to be surveyed. Ref: HKIUS-GEN-018 BWCS 32

Reports of BWCS • Slope report Title Page List of assets Drawing of Slope Ref: HKIUS-GEN-018 BWCS • Location • Date of survey • Details from GEO Catalogue • List of all manholes and pipes investigated • Summary of the problems found • Survey extent • Base map details • Details of manholes surveyed 33

Reports of BWCS Other information • Special circumstances • Emergency works List of survey • Various surveys carried out within the survey extent Appendix • Survey Reports for various surveys carried out *The report shall have the SLOPE REFERECE NUMBER clearly displayed in the COVER and EACH PAGE of the report Ref: HKIUS-GEN-018 BWCS 34

Record keeping • Results of inspection shall be documented and well-kept for late retrieval and reference • All records shall be kept by the owner • Duplicate copies shall be made and kept by - Owner’s corporations - Maintenance agents - Property managers Ref: HKIUS-GEN-018 BWCS 35

Training and Accreditation of Personnel (操作員要求) Type of Personnel Role Minimum Training Requirement Minimum Years of Experience Project Leader Contractual arrangement, check and certify reports Training courses for relevant survey/detection methods and data management 10 years in contract administration, preferably in relevant disciplines Team Leader Works arrangement, check data quality and consistency Training courses for relevant survey/detection methods and data management 5 years in works of relevant disciplines Crew Leader Supervision of field works and site safety Training course and valid training certificate for relevant discipline 3 years in works of relevant disciplines On site inspection Training course and operation of equipment valid training certificate for relevant discipline 2 years in works of relevant disciplines Operator Ref: HKIUS-GEN-018 BWCS 36

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Guide to Leakage Detection of Buried Water-carrying Services • Planning and preparation • Surveying methods -Utility Survey - CCTV Survey - WLD Survey • Procedures • Personnel Requirement • Reporting • Sample photos and forms Ref: HKIUS-GEN-018 BWCS 38

BWCS pamphlet • A brief introduction to BWCS survey Ref: HKIUS-GEN-018 BWCS 39

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Q&A Ref: HKIUS-GEN-018 BWCS 43