Water Reuse Case Studies in No. 3 Universidad Politécnica de Cataluña

STORAGE OF RECLAIMED WATER April 2007

Introduction de et al., 1995) as a coordinated response to the water demands of urban, This study case describes the initiatives industrial, and agricultural users in the taken in Vitoria-Gasteiz, Spain by several Vitoria region. The main objectives of the Irrigation Districts and the Álava Regional plan were 1) to improve water supply Government to build the Azúa Valley reliability, 2) to decrease flooding risks, Lake for storing reclaimed water and 3) to ensure the environmental produced during the winter season as to protection of tributary streams. be able to use it for agricultural and landscape irrigation during the summer The main objective of this case study is to season. This text is an excerpt of the present the role of the Azúa Valley Lake paper presented at the International as an essential component of the IWRR Symposium on Dams in the Societies of Plan of Vitoria-Gasteiz, with particular the XXI Century, Barcelona, 18 June emphasis on: 1) the quality of the 2006 (Mujeriego and López, 2006). reclaimed water that will be stored in it, 2) the environmental and economic Scope and Purpose benefits that will be derived for the region, 3) the improvement in water The city of Vitoria-Gasteiz is the capital of supply reliability that will provide to the both the Álava Foral Territory and the current water supply system, 4) the Regional Government of the Basque reduction of flooding risks associated Country in Spain. With a population of with current management policies for 220,000 inhabitants, it includes a very surface water supply reservoirs, and 5) diverse industrial activity that contributes the definition of those water quality about 30% of its wastewater flows. The management strategies to be followed city of Vitoria-Gasteiz shares its water for maintaining the aesthetic and supply system with the city and the environmental status of the reclaimed regional area of , with a water stored in the lake. population close to 1 million inhabitants, through the conjunctive use of the water Water Resources and Water Uses reservoirs of the Zadorra River, with a total useful capacity of 180 hm3. Table CS3-1 summarizes the storage capacity of the Zadorra river reservoirs The urban water supply requirements of and the water demands of the Bilbao and Vitoria-Gasteiz have been surrounding populated areas. Table CS3- exceeding the storage capacity of the 1 clearly shows two basic and important existing reservoirs in a steady increasing facts: 1) the flows provided by the manner during the last decades. This reservoirs are devoted exclusively to situation has prompted the need for the urban water supply and to preservation current water users to provide additional of the rivers’ environmental conditions, water resources, particularly by Vitoria- and 2) the annual water demands Gasteiz, the user with the largest deficit. corresponding to those two uses exceed An Integrated Water Reclamation and the useful capacity of the reservoirs. Reuse (IWRR) Plan for Vitoria-Gasteiz was prepared by the Álava Regional This inadequate water supply reliability, Government in 1992 (Diputación Foral historically estimated at a minimum Water reuse case studies in Spain, No. 3 2

deficit of 20 hm3 per year, has resulted in supply dams, using the pumping serious coordination difficulties over the stations and the pipelines of the last decades for the Inter-regional existing irrigation network. Watershed Agency (Confederación 3. To use reclaimed water for Hidrográfica del , CHE), the Regional landscape irrigation of parks and Governments of Álava and Vizcaya, the public gardens in the city of Vitoria- City Councils affected, and the Irrigation Gasteiz. Table CS3-2 shows that Districts in the area. landscape irrigation in Vitoria- Gasteiz represents more than 10% of the city’s surface water supply. Table CS3-1. Available water resources and water When the currently proposed new allocations from the Zadorra River reservoirs. landscape areas become active in Reservoir capacity the forthcoming years, that fraction 3 Urrunaga 67 hm will reach an estimated 15% value. Ullibarri 139 hm3 3 Total 206 hm Water Reclamation Authorized maximum volume 180 hm3

Current allocations Water supply to Bilbao 145 hm3 The water reclamation facility of Vitoria- Water supply to Vitoria 25 hm3 Gasteiz began operating in 1995, and has a capacity of 35,000 m3/day, In-stream flows of the Zadorra y Santa 3 30 hm 3 Engracia Rivers equivalent to 12 hm /year. That water Total 200 hm3 volume is sufficient to irrigate 10,000 ha of agricultural land during the summer season. The edaphic characteristics of the Planned Water Reuse and Integrated agricultural areas of the Vitoria region Water Resources Management render summer irrigation a suitable practice under a schedule of once every The Irrigation Districts affected, in three consecutive years. This practical cooperation with the CHE and the Álava requirement results in an agricultural Regional Government, have been surface area actually irrigated during a implementing since 1996 an Integrated summer season close to 3,300 ha, just Water Reclamation and Reuse Plan, with about one third of the 10,000 ha the following main objectives: available to the Irrigation Districts. 1. To use reclaimed water for irrigation of 10,000 ha of several Table CS3-2. Surface water consumption for urban food crops, including orchards and water supply and landscape irrigation in the city of raw eaten vegetables. Irrigation Vitoria-Gasteiz. Urban started in 1996, and covered Landscape Urban 3 Year 3 irrigation, hm area, ha supply, hm initially a surface area of 4,000 ha. (% total use) The additional 6,000 ha began 2003 460 24.6 3.1 (13) irrigation with surface water during 2002 437 24.6 2.5 (10) the summer of 2005, waiting for 2001 402 25.2 2.8 (11) the corresponding volumes of 2000 402 24.8 2.5 (10) reclaimed water that would be stored in the Azúa Valley Lake, by 1999 400 24.5 2.4 (10)

the end of 2006. 1998 380 25.3 2.0 (7,9) 2. To replace a fraction of the in- stream ecological flows currently provided from the surface water The water reclamation plant of Vitoria- reservoirs by the corresponding Gasteiz was designed according to the flows of reclaimed water, with the quality criteria for reclaimed water quality level required for included in the Title 22 of the California supporting fish life, namely Water Code (Asano, 1998, Asano et al. salmonid and cyprinid waters 1991). Planned water reuse for (European Council, 1978). Those agricultural irrigation was designed replacement flows would be according to the guidelines and technical introduced just below the water criteria included in the Guidance Manual 3 Storage of reclaimed water

prepared by the California State Water off-stream storage reservoir, shaped by Resources Control Board (Pettygrove and two earth dams that form an artificial Asano, 1984; Mujeriego, 1990). lake with a capacity of 7 hm3. The lake has been designed and built according The optimal operation of the water to the environmental requirements reclamation plant was limited by the applicable to a high value natural ability of the irrigation system to store the landscape environment. The lake is reclaimed water produced during the located 75 m over the water level of the fall-winter-spring seasons. The flow nearby surface water reservoirs of the capacity of the water reclamation plant Zadorra River, and just about 2 km from allows irrigation of a maximum of 4,000 them. This topographic situation offers a ha (1,300 ha effective) under continuous unique condition to contemplate the operation during the summer season. possibility for future water contributions However, storing the reclaimed water from the Azúa Valley Lake to the Ullibarri produced during the rest of the year reservoir, after applying the water would provide enough water to irrigate purification processes that may be up to 10,000 ha (3,300 ha effective). To considered necessary at that time. achieve that objective, the IWRR Plan of Vitoria-Gasteiz included the construction of an off-stream reservoir, where Table CS3-4. Physico-chemical quality of reclaimed reclaimed water could be stored during water produced at the water reclamation plant of Vitoria-Gasteiz, from 1996 to 2006. the fall-winter-spring season, and Turbidity < 2 NTU Boron < 1.50 mg/l subsequently used for irrigation during Electrical < 1,000 µS/cm Cadmium ND the summer season. Table CS3-3 conductivity summarizes the water flow provisions Ammonia 1.5-19 mg N/l Chromium < 0.02 mg/l included in the IWRR Plan of Vitoria- nitrogen

Gasteiz. BOD5 < 5 mg/l Copper < 0.05 mg/l

NO3 2-15 mg/l Mercury ND COD < 20 mg/l Nickel < 0.40 mg/l Table CS3-3. Integrated Water Reclamation and Reuse Oxygen Plan for Vitoria-Gasteiz. < 7 mg/l Lead ND demand Capacity and Uses Objectives Selenium ND Reclamation capacity (2003) 12.00 hm3/year Agricultural uses (2003) 2.40 hm3/year Zinc < 0.40 mg/l 3 Agricultural uses (2006) 7.00 hm /year ND : non detectable, lower than 0.01 mg/l Storage capacity 7.00 hm3/year Existing irrigation network 350 km pipelines Table CS3-5. Organic and microbiological quality of reclaimed water produced at the water reclamation plant of Vitoria-Gasteiz, from 1996 to 2006. Tables CS3-4 and CS3-5 show the water Bromodichloromethane < 5 µg/cm quality achieved by the water Bromoform 1 µg/l reclamation plant of Vitoria-Gasteiz since Chloroform < 30 µg/l 1996, when it became operational. Dibromochloromethane < 1.0 µg/l Reclaimed water satisfies the quality Chlorophenols Non detectable Total coliforms Absence/100 ml criteria specified by the Title 22 of the Helminth eggs Absence/500 ml California Water Code (Asano et al. Giardia lamblia Absence/500 ml 1991), the health guidelines Crypt osporidium Absence/500 ml recommended by the World Health Legionella Absence/litre Organization (1998) y and the water Salmonella Absence/100 ml reuse criteria proposed by the US Environmental Protection Agency (2004). The Azúa Valley Lake is an essential component of the IWRR Plan of Vitoria- Azúa Valley Lake Gasteiz, for the following reasons: 1. It provides the reclaimed water The Azúa Valley Lake is the final volumes required for in-stream flow significant construction work included in substitution in the Zadorra River, in the IWRR Plan of Vitoria-Gasteiz. Is it an case of a prolonged failure of the Water reuse case studies in Spain, No. 3 4

biological treatment processes of production of an additional amount of the municipal wastewater hydroelectric energy, generated by that treatment plant of Vitoria-Gasteiz, same flow when descending the 300 m or the physico-chemical processes altitude difference existing between the of the water reclamation facility of surface water reservoirs and the Vitoria-Gasteiz. hydroelectric power station in the Bilbao 2. It ensures the water flows region. The hydroelectric energy necessary for agricultural and generated by those flows will be close to landscape irrigation of the regional 2 million kWh annually. and the urban areas of Vitoria- Gasteiz during the summer season. Reclaimed water discharged into the 3. It provides a mechanism for Azúa Valley Lake will be of excellent nutrients removal from the physico-chemical and microbiological reclaimed water stored in the lake. quality (see Tables CS3-4, and CS3-5). This will be achieved by alternating However, it contains significant anoxic and aerobic conditions in concentrations of nutrients (ammonia the water column, and the addition nitrogen, nitrates and phosphorous). of atmospheric oxygen through a Those nutrient concentrations need to deep aeration system. Compressed be controlled, as to prevent development air will be generated by of anoxic conditions during ammonia photovoltaic energy panels located nitrogen oxidation, and thus to ensure in the inside slopes of the earth suitable biological and aesthetic dams. conditions in the lake. An ammonia nitrogen limit of 0.5 mg N/l (equivalent The reclaimed water storage reservoir to 2.3 mg/l of dissolved oxygen) has was considered a basic element of the been adopted to ensure that the IWRR Plan of Vitoria-Gasteiz, after biological quality of the water in the evaluating similar water resources reservoir and its potential to maintain management initiatives adopted in aerobic conditions remain acceptable at Southern California (Mujeriego, 2004, all times in the lake. To achieve that 2005). The Azúa Valley Lake promotes a objective, the Azúa Valley Lake design more sustainable use of the hydroelectric project incorporates a deep aeration energy generated with the surface water system, using compressed air diffusers stored in the Zadorra river reservoirs, and located 1 m above the bottom of the results in an overall lower emission of lake, with a capacity to maintain a carbon dioxide due to lower energy dissolved oxygen concentration higher consumption (Sala & Serra, 2004, than 3 mg/l. Mujeriego, 2005). The considerable amount of compressed The water reclamation plant of Vitoria- air that will be required to satisfy the Gasteiz has a design capacity able to oxygen demand of lake water makes satisfy the water required for agricultural necessary to consider an inexpensive and landscape irrigation, and to energy source, with a low carbon dioxide contribute a flow of up to 0.4 m3/s for emission rate. A large surface area of substitution of the in-stream (ecological) photovoltaic plates will be installed on flows discharged from surface water the inside slopes of the earth dams, reservoirs. That flow contribution preventing any undesirable aesthetic represents just 40% of the 1 m3/s in- impact from the outside. The top line of stream flow currently established by the earth dams has a length of 900 m, regulatory requirements. which allows for a total surface area of photovoltaic plates of 1,800 m2, with a The indirect benefits of this flow power capacity of up to 150 kW. The substitution are: 1) the availability of the direct current produced by the plates will corresponding 0.4 m3/s of surface water, be stored and subsequently converted to which can be diverted from the alternate current, which will be used for reservoirs and used for urban water running the air compressors. supply in the Bilbao region, and 2) the 5 Storage of reclaimed water

Economic Indicators full operation is expected by late 2006, once the required safety and operation The total investment required for an protocols are completed and approved. annual production of 12.5 hm3 of The lake has been designed to store the reclaimed water was 3.25 M€, which winter-spring excess of reclaimed water represents a specific investment of 0.26 produced at the Vitoria-Gasteiz water €/m3 of annual capacity, in 1995. The reclamation plant, so it can be used for unit cost of reclaimed water at the plant agricultural and landscape irrigation site, including investment costs and during the summer, and also for in- operation and maintenance costs, was stream ecological flow substitution. The 0.065 €/m3 in 2006. Azúa Valley Lake is a unique infrastructure in Spain, but similar to The total investment required to convey, others built in Southern California and store and distribute 12.5 hm3 of Israel to store reclaimed water for reclaimed water for irrigation of 10,000 multiple uses. ha of agricultural land was 28 M€, which represents a specific investment of 2.25 Operation of the Azúa Valley Lake will €/m3 of reclaimed water available. In serve the following main objectives: particular, the investment required to 1. To provide the reclaimed water built the off-stream Azúa Valley Lake, flows necessary for substitution of with 7 hm3 storage capacity, was 11,8 the in-stream (ecological) flows of M€, which represents a specific the Zadorra River, especially during investment of 1.70 €/m3 of storage the summer season. capacity. 2. To provide the reclaimed water flows necessary for agricultural and Based on that information, the following landscape irrigation in both the economic indicators can be estimated for Vitoria region and the city of the Vitoria-Gasteiz water reclamation Vitoria-Gasteiz during the summer and reuse project for agricultural months. irrigation: 3. To promote nutrient removal from stored reclaimed water, mainly in 1. Reclamation: the form of ammonia nitrogen and Reclaimed water index: 0.065 nitrates. euros/m3 produced (2006). 4. To provide a future option for complete recycling of a fraction of Reclamation investment index: 0.26 the reclaimed water produced by €/m3 annual capacity. the city of Vitoria-Gasteiz.

2. Reuse Furthermore, operation of the Azúa Reuse investment index: 2.25 €/m3 Valley Lake will satisfy the following annually available. secondary objectives: 1. To gradually restore the water Storage investment index: 1.70 €/m3 allocations of the Bilbao region, storage capacity. which have been increasingly used for drinking water supply in the 3. Reclamation and reuse Vitoria Region. Reclamation and reuse investment 2. To allow for a more sensible index: 2.51 €/m3 annually available. management protocols for the water levels in the surface water Summary reservoirs, as to ensure a higher protection level with respect to The Azúa Valley Lake is the most flooding episodes in the Vitoria emblematic element of the ambitious region. Integrated Water Reclamation and Reuse 3. To produce an additional 2 million Plan of Vitoria-Gasteiz that began in kWh annually of hydroelectric 1992. Construction of the Azúa Valley energy. Lake was completed in June 2004, and Water reuse case studies in Spain, No. 3 6

References Mujeriego, R. (2004). La gestión del agua en el sur de California. Ambienta, no. Asano, T. (Editor) (1998). Wastewater 38, pág. 31-38. Ministry of the Reclamation and Reuse. Water quality Environment, Madrid. management library, Vol. 10. www.mma.es/publicacion/ambienta/ Technomic Publishing Co. Inc. Mujeriego, R. (Editor) 1990. Guidance Lancaster, PA, USA. Manual on Irrigation with Reclaimed Asano, T., Richard, D., Crites, R.W. & Municipal Wastewater (in Spanish). Tchobanoglous, G. (1991). Evolution Universidad Politécnica de Cataluña, of tertiary treatment requirements in Barcelona. California. Water Environment and Pettygrove, G.S. & Asano, T. (1984), Technology. vol. 4, no. 2. Irrigation with Reclaimed Municipal Council of the European Communities Wastewater: a Guidance Manual. (1978). Council Directive 78/659/EEC Report no. 84-1 wr. California State of 18 July 1978 on the quality of fresh Water Resources Control Board, waters needing protection or Sacramento, California. improvement in order to support fish Sala, L. & Serra, M. (2004). Towards life. Official Journal L222, pp. 0001- sustainability in water recycling, Water 0010. Science and Technology, vol. 50, no. Diputación Foral de Álava, Gobierno 2, 1-8. Vasco y Aguas Municipales de Vitoria United States Environmental Protection (1995). Plan de Recuperación y Agency (USEPA) and United States Reutilización Integral de las Aguas Agency for International Residuales de Vitoria-Gasteiz. Development (USAID) (2004). Diputación Foral de Álava, Vitoria. Guidelines for Water Reuse. Mujeriego, R. & López, J. (2006). Azúa EPA/625/R-04/108, September 2004. Valley Lake and Integrated Water Office of Water, Washington, D.C., y Resources Management in Vitoria- Office of Research and Development, Gasteiz. Dams and Reservoirs, Cincinnati, Ohio. Societies and Environment in the 21st World Health Organization (WHO) Century, Berga et al. (Editors). Taylor (1989). Health Guidelines for the Use and Francis Group, London, ISBN: of Wastewater in Agriculture and 0415 404231. Vol. 1, pp: 117-124. Aquaculture. Technical Report Series Mujeriego, R. (2005). La reutilización, la 778. Geneva, Switzerland. regulación y la desalación de agua. Ingeniería y Territorio, No. 72. ISSN: 1695-9647. Spanish Civil Engineering Association. Madrid. www.ciccp.es/revistait/

Acknowledgments

This document was prepared with the support of the Regional Office for Europe of the World Health Organization and the Mediterranean Action Plan, and is included in the report “Promoting the use of reclaimed water in Mediterranean countries”, submitted in April 2006.

The preparation of this document has been possible thanks to the enthusiastic assistance of Mr. Julio López from Técnicas y Técnicos, S.A. (TYTSA), the valuable comments of Mr. Lluís Sala from Consorci de la Costa Brava, and the continuous support of the Department of Agriculture of the Álava Regional Government.

This document was revised and updated in April 2007. 7 Storage of reclaimed water

Edited by

Rafael Mujeriego, PhD Prof. of Environmental Engineering Universidad Politécnica de Cataluña

ETS de Ingenieros de Caminos Jordi Girona, 1-3, Building D1 08034 Barcelona, Spain [email protected]