中華民國內政部建築研究所中華民國內政部建築研究所

一、研究緣起
面對氣候變遷對水資源的影響，各區域水資源經理基本計畫，主要透過開源、節流、調度、備援等策略多管齊下辦理各項水資源建設及管理工作。其中「開源」係多元水資源開發提高供水能力，尤其109年氣候異常，國內首次發生豐水期無颱風侵臺所帶來的降雨，面對嚴峻枯水挑戰，除落實各項節水及水源調度措施外，更採取增加抗旱水井、埤塘利用、伏流水利用、移動式淨水設備及緊急海淡機組等多元水源使用，以減緩旱象衝擊；然在110年初水情仍持續嚴峻，尤其以台灣中、南部地區的情況最為緊迫，台中市首以新建案建築工地點井地下水做為緊急抗旱水源之一，大幅減緩水庫的供水壓力。
由於建築工地開發在地基基礎開挖時，為平衡地基通常會進行排降地下水工程，而其抽取的量體依工地規模平均一天可達數千噸甚至上萬噸，且整體地下水抽排時程通常需持續8至12個月，可見其量體驚人，然而建築工地所抽取的地下水多係以排入管溝系統放流處置，未針對其作妥適的運用規劃，使得水資源浪費。鑒於建築工地所需用水量較大，每月自來水費通常需耗費數萬元，若能透過抽取的地下水做為工地臨時用水，尤其一般地下水源若非受自然或人為嚴重污染的地區，其水質通常僅需簡易淨水處理即可直接作為非接觸用水利用(如建築工地機械用水、清掃、灑水、沖廁及消防用水等)，不僅可大幅降低建築工地開發所需的用水成本，更可達到水資源永續利用之目的。為協助有效運用建築工地地下水資源，考量目前國內尚無建築工地施工過程地下水再利用之相關衡量方法與基準，本計畫蒐集調查現行建築工地施工過程之地下水利用之案例，並針對建築工地排降地下水量與工地臨時用水量進行評析，同時就該地下水之貯集與多元利用提供規劃建議，據以研提建築工地臨時用水計畫書需求項目與內容綱要，以作為纳入綠建築評估系統之參考。
本研究案執行期程為十個半月，爰引本所協同研究計畫需求說明，研究計畫之研究旨在研議建築工地施工過程地下水再利用納入綠建築評估系統之可行性。本計劃將蒐集彙整建築相關法規(含水利法)與相關政策規範與現行建築工地施工過程具地下水利用之相關案例，進而評析施工過程排降地下水量與工地臨時用水量，並研提建築工地臨時用水計畫書之需求項目與內容綱要，針對建築工地地下水貯集及其他多元利用提出規劃建議，期能有效提高國內建築工地地下水再利用的規劃意願，使其成為產業常態用水的來源之一。
二、研究方法及過程
研究內容初步之5項研究內容，研究案之工作項目如下：
1.蒐集彙整建築相關法規(含水利法)與相關政策規範。
2.現行建築工地施工過程之地下水利用案例蒐集與分析。
3.施工過程排降地下水量與工地臨時用水量之評析。
4.研提建築工地臨時用水計畫書之需求項目與內容綱要。
5.針對建築工地地下水貯集及其他多元利用提出規劃建議，並研議地下水之貯集與多元利用納入綠建築評估系統之可行性分析。
本計畫蒐集彙整建築工地排降地下水之相關法規與相關政策規範，針對現行新建建築工地施工過程之地下水再利用的案例蒐集與分析，並透過建築工地的抽排地下水或袪排水計畫書進行蒐集彙整，探討施工過程排降地下水量與工地臨時用水量，並提出多元利用之建議，進而研提建築工地地下水袪水工程與臨時用水計畫書之需求項目與內容綱要，最後匯集研究成果而研議地下水之貯集與多元利用納入綠建築評估系統之可行性分析，預計本計劃之研究內容將對未來綠建築體系發展與其推廣應用上具重要參考價值。
三、重要發現
國內針對排降地下水常以袪水、縮水或束水等名詞稱呼，然僅內政部營建署、行政院農委會水土保持局及各政府的工務局的施工規範第02240章具有袪水之定義與工法說明；而建築工地地下水的袪水作業的鑿井工程，惟有經濟部水利署施工規範第02243章中針對鑿井工程進行說明，然常聽到的工地點井作業，目前尚未有相關法規或規範進行詳細說明。因此，本計畫在建築工地地下水袪水工程的相關文獻蒐集，將鑿井工程簡易分為集水坑袪水工法、點井袪水工法及深井袪水工法，經案例彙整成果，發現國內建築工地排降地下水作業，反而係深井袪水工法較為多數，且臺中因地質特性，則多以人工的方式進行鑿井，其他地區則多以機具鑽鑿的方式進行。
民國110年在國內水情持續嚴峻的情況下，行政院核定「緊急抗旱水源應變計畫2.0」，其中包括建築工地地下水再利用，此為國內首次將其作為緊急備援水使用，由於建築工地地下水的抽取量豐沛，當時舒緩水庫與多處地區的枯水問題；然旱災過後，直至今日僅臺中市將建築工地地下水再利用之規定增訂於建築物施工管制辦法中，且各新建工程的地下水袪水計畫書中僅以簡易條列的方式針對地下水再利用計畫進行說明，使得實際設置應用上較欠缺地下水再利用的供水標的之方針，且多數地下水仍為直接放流至公共排水溝。透過國內十大地下水分區的污染物監測成果顯示，僅濁水溪沖積扇與嘉南平原平均合格率僅有79.3及81.4分，其他八大地下水分區合格率皆在90分以上；統計每年的地下水抽用量，僅濁水溪沖積扇、嘉南平原及屏東平原三區屬於超抽的情況，而其他七大地下水分區每年的地下水補助量皆大於抽用量，因此國內在地下水的開發利用應極具潛力。
四、主要建議事項
建議一
建築工地施工過程地下水再利用案例進行綠建築評估系統之試評與驗證之研究：立即可行建議
主辦機關：內政部建築研究所
協辦機關：財團法人台灣建築中心
由於本年度完成建築工地施工過程地下水再利用納入綠建築評估系統之方案研擬，但考量國內建築工地各地區地質與現地條件，以及擋土工程、地下水袪水時程與袪水計畫內容之不同，其評估比例與方式應針對前述不同限制條件而進行調整，故建議後續應針對國內相關縣市的建築工程案例進行蒐集彙整，並藉用水計畫書草稿進行綠建築評估系統之試評，驗證其評估參數與審核標準並進行用水計畫書草稿增修訂，進而研議建築工程地下水袪水管理及再利用在綠建築評估系統之標準與方法，作為未來綠建築體系發展與推廣應用上之重要參考。
建議二
建築工地施工過程地下水再利用與袪水管理之相關法規制度檢討與增修訂：短中期可行建議
主辦機關：內政部建築研究所
協辦機關：內政部營建署、經濟部水利署、地方政府
國內針對建築工地施工過程地下水再利用，目前僅台中市的建築施工管制要點與辦法中規定建築工地有抽排水者，應設置地下水資源再利用裝置，其計畫內容則納入該市建築工地的地下水袪水計畫書中，然地下水袪水再利用計畫之內容並未詳述建築工地整體的用水規劃與其再利用之比例，故造成許多再利用裝置未能有水資源永續利用之實質效益；另外，國內建築工地地下室開挖進行地下水袪水作業，其計畫書名稱與需求內容依主辦機關而有所差異，未有標準化的相關規定。建議各主管機關應一致化地下水袪水計畫書名稱並定義內容相關名詞，統整計畫書內容架構與編列方式，且為促進水資源永續利用應統一增加「地下水袪水再利用計畫」，進而針對建築工地施工過程地下水再利用與袪水管理進行相關法規制度之檢討與增修訂，作為未來建築工地相關政策發展與永續水資源利用之參考。

1.Purpose of the research
Facing the impact of climate change on water resources, the basic plan and management of regional water resource systems are mainly by using water resources development, conservation, scheduling and backup strategies. Among them, "development " refers to the development of multiple water resources to improve the water supply capacity. In year 2020, there was no typhoon visiting Taiwan in the wet season due to climate change. In the face of severe water shortage, multiple water resources such as drought-resistant wells, pit ponds, stagnant water, mobile water purification equipment and emergency desalination units have been adopted to mitigate the water shortage due to drought. The drought condition continued and was not improved especially in middle and southern Taiwan. For the first time in Taichung city, the groundwater dewatering from the building construction sites was used as emergency drought-relief water sources which greatly reduced the water supply pressure of the reservoir.
For constructing the foundation of the buildings, the groundwater dewatering is needed if groundwater level is high during the foundation excavation. The amount of the groundwater pumped may reach thousands of tons or even tens of thousands of tons per day depending on the scale and groundwater condition at the construction site. And the time period of groundwater dewatering usually lasts for 8 to 12 months.   Also, groundwater dewatering from the construction sites is mostly discharged into drainage system without reuse as water resources. Due to large amount of water consumption at construction sites, the monthly water fee usually costs tens of thousands New Taiwan Dollars. In areas without groundwater pollution, this water can be reused with simple water purification systems for non-contact water use. This can reduce the cost of water fee at construction site but also achieve the goal of sustainable utilization of water resources. In order to promote the efficient of groundwater reuse and establish relevant measurement methods and benchmarks at construction sites for groundwater reuse in Taiwan, this project collects and investigates selected cases for construction site of buildings with groundwater dewatering. And the amount of groundwater withdrawal and the water consumption at construction sites were evaluated and analyzed.  Recommended and suggestions fort the storage and multiple utilization of the groundwater were made. Based on these information, the water demand for each water use unit and contents of the temporary water consumption plan for the construction site are recommended and developed as a reference for consideration in the Green Building Evaluation System.
This research project takes ten months. Based on the requirements of the project, it aims to study the feasibility of incorporating groundwater reuse into the green building assessment system during the construction process at construction sites. This project collects relevant building regulations and relevant policies and norms and relevant cases of groundwater utilization in the construction process of current building sites. Then, the amount of groundwater dewatering during the construction process and the temporary water consumption items at constructions sites were studied. Hence, draft of the temporary water use plan was proposed which included water demand items and water consumption requirement and contents of the water use plan. Major expectations of this project are to effectively improve the groundwater reuse at construction sites of buildings and treat this water resource as source of industry.
2.Methodology and procedures
Research methodology and procedures include following five items:
●Collect and compile relevant building regulations (water conservancy law) and related policy specifications.
●Collection and analysis of groundwater utilization cases in the construction process of current building sites.
●Evaluation and analysis the amount of groundwater dewatering during the construction process and the temporary water consumption of the building sites.
●Clarify the water demand items and develop the draft outline of the temporary water use plan at construction sites of building.
●Propose suggestions for groundwater storage and multiple utilizations of groundwater withdrawal at construction sites of buildings.Study the feasibility of incorporating groundwater storage and multiple utilization into the green building assessment system.
3.Major findings
The definition of “groundwater dewatering” is generally found in the Construction and Planning Agency, MOI, the Soil and Water Conservation Bureau, Council of Agriculture, Executive Yuan, and the public works bureaus of various levels of governments in the Chapter 02240. The well-sinking project for the drainage of groundwater in the building sites is only explained in the Chapter 02243 of the Construction Regulations of the Water Resources Agency, MOEA. However, the definition of “well point dewatering” at construction sites of buildings is no relevant regulations or regulations. Specifications are detailed. Therefore, this project collects relevant literature on groundwater dewatering at construction sites of buildings. Dig well engineering can be roughly divided into sump excavation method, point well excavation method and deep well excavation method. The data from the collected cases show that the groundwater dewatering at the construction site is mostly by the deep well excavation method. Due to the geological characteristics in Taichung areas, well drilling is mostly carried out manually but other areas are mostly carried out by machine drilling.
The Executive Yuan had approved the "Emergency Drought Relief Water Source Response Plan 2.0", which reused the groundwater dewatering at construction sites of building. Groundwater dewatering was used as emergency backup water for the first time in Taiwan. Due to adequate amount of water extraction, drought condition had been relieved in many areas. However, Taichung City has added the regulations on the reuse of groundwater in construction sites of buildings to the building construction regulations but with short and simple paragraph and not reasonable reuse of groundwater. From the pollutant monitoring results of the top ten groundwater zones in Taiwan, the Zhuoshuixi alluvial fan and the Jianan Plain have an average grade of 79.3 and 81.4 points, separately. Other eight groundwater zones have the grade greater than 90 points. From the statistics of the annual groundwater withdrawal, Zhuoshuixi alluvial fan, Jianan Plain and Pingtung Plain are all belong to over-pumping areas and groundwater recharge is larger than groundwater withdrawal for other seven groundwater regions. Therefore, development and utilization of groundwater in Taiwan are available in the future.
4.Major recommendation items
Through this research, following two recommendations are made for immediate- and short- to middle- term period:
Recommendation 1
Research on the trial evaluation and verification to the green building evaluation system based on the cases of groundwater reuse in the construction process of the building sites: immediate
Organizer: Architecture and Building Research Institute, MOI
Co-organizers: Taiwan Architecture & Building Center
The results of research in this year have developed the programs for incorporating groundwater reuse into the green building evaluation system during construction process at the building sites. For considering the geological and local conditions of various regions of construction sites as well as the differences contents for the earth retaining works, groundwater dewatering schedule and the content of the dewatering plan. The assessment ratio and method should be adjusted according to the above-mentioned different constraints. Therefore, it is recommended that the more construction projects of buildings at different counties and cities should be collected. Then, the draft temporary water use plan should be evaluated and verified for green building assessment system. Furthermore, the evaluation parameters and audit standards are added and revised in the draft temporary water use plan, and the standards and methods for the management and reuse of groundwater in construction sites in the green building evaluation system are discussed. They are important for the development and promotion of the green building rating system in the future.
Recommendation 2
Review and amendment of relevant laws and regulations for groundwater reuse and dewatering management at construction sites of building: short- to middle- term
Organizer: Architecture and Building Research Institute, MOI
C0-organizer: Construction and Planning Agency, MOI; Water Resources Agency, MOEA; Local Governments
At present, the construction control regulations and measures in Taichung City stipulate that if there is pumping and drainage in construction sites of building, groundwater resource reuse devices should be installed which is included in the city's construction sites of building in the groundwater dewatering plan. However, the content of the groundwater dewatering reuse plan does not in detail about the overall water reuse plan and the percentage of reuse. Hence, water reuse devices cannot achieve the substantial benefits of sustainable water resource utilization. In addition, for groundwater dewatering operations, the name of the plan and the content of the requirements do not have standardization. Therefore, it is suggested that all central/local governments should unify the name of the groundwater dewatering plan, define the terms related to the content of temporary water use plan at construction sites of buildings, summarize the content structure and arrangement of the plan, review and amend relevant laws and regulations for groundwater dewatering and reuse and management during building construction period. These will provide as the reference for policy development of future groundwater dewatering at construction sites of building and sustainable water resources utilization.