BECC

BORDER ENVIRONMENT COOPERATION COMMISSION

In its document "Baja California hacia la Competitividad" the state government projected the population for the year 2015 according to data obtained from official population census from 1930 to 1990 and the 1995 survey.

Currently the economy of the city of Tijuana is based on the maquiladora and service industries. The primary economic activity for the city was originally tourism, but given the transformation experienced in recent years, this is the second most active city in Mexico with regard to the number of maquiladora plants established locally.

According to information drawn from the Population and Housing census, Tijuana's population increased in the last five years from 698,752 to 966,097 residents, which provides for a 5.5% growth rate. If this same rate is considered, by the year 2000 Tijuana will have an estimated 1,200,000 residents.

The city currently enjoys the use of all utilities, including potable water with a 95% coverage rate, and sanitary sewerage, with 63% of the community households connected to it. Tijuana's potable water service can be considered one of the most efficient at the national level, since it is provided 24 hours per day 365 days per year. The sanitary sewerage service is not meeting the existing demand, and there are plans to increase coverage to 85% in the following years. Wastewater treatment does represent a major international problem due to the lack of adequate treatment facilities, even though a new 22.8 MGD binational plant located in the U.S. side has started operations. Waste collection shows a significant deficiency, specially with regard to final disposal, given the lack of technology in the execution of this service.

The project to reuse treated water for irrigation purposes is part of the outset of a whole new water culture. For each liter of potable water that can be replaced with treated water, more fresh, potable water will be available for the public, specially in areas such as this one where water is such a scarce resource and conveying it to the city represents a major investment. Although small in volume (0.18 MGD), this project can be considered a pilot project which will serve as an example of what can be achieved.

A Mediterranean type of weather is prevalent in the project's area: fair, semi-dry, steppe-like, with temperatures ranging from a low 35^oF to a high 97^oF. The annual rainfall average is 8 inches. Dominant winds from the southeast are usually northeast bound and present throughout the year.

The site's orographic configuration is a group of elevations that form small plateaus, hills and ridges that descend to sea level, and its rocky soil provides a difficult setting for agricultural activities.

Among the most predominant types of soil is regosol, with variable fertility. Its use in agriculture depends on its depth, amount of rocks in the surface, and water availability. The area where treated water generated by this project will be used, the Tijuana River area, has a sandy type of soil.

This project was initiated in 1986 by the "Colegio de la Frontera Norte, A.C. (COLEF)" and represents a model for the comprehensive use of water resources in urban areas, including water reuse for irrigation purposes and the use of native vegetation to restore hillsides and highly eroded areas of the city.

This project has received extensive support form the Tijuana Public Utilities State Commission (public state agency responsible for operating and maintaining water and wastewater services in Tijuana, B.C.) and the local authorities.

The project was developed in a 15.3 acres. plot of land given in easement to the Colegio de la Frontera Norte by the State government. The project started using the experience gained during preliminary research carried out in San Diego, California, to find a wastewater treatment system that required a minimum investment with low operation and maintenance costs. This resulted in the idea of using the aforementioned plot of land to establish a 91,200 gal/day capacity wastewater treatment system. This amount of water should be sufficient to irrigate the green areas of the land eased by the State, called Ecoparque. Inflows come from an area known as Otay Universidad (adjacent to Ecoparque), which is considered a housing development, and generates an average of 0.48 MGD. of wastewater. The park's WWTF receives wastewater from the area's intercepting sewer line.

As time went by and once the results obtained during a long testing period were observed, local authorities found appropriate to proceed to the second stage of the project, which will consist of using treated water in an area outside Ecoparque. Authorities selected the "Tijuana River 1st. Stage" area. As a first stage of the project Ecoparque will deliver 0.18 MGD which will be used to irrigate green areas in medians and traffic circles in the aforementioned area.

At the present time, authorities from both the water utility (CESPT) and the city are interested in this project, taking into account that if the treated water can be used for irrigation purposes, the equivalent amount of potable water can be used to provide the service to more families who desperately need the scarce resource. Aside from the social responsibility of the local government to provide better services to city residents, significant savings can be derived from the project, since the cost of this water will be much less than the current cost of potable water. (The agreement signed by the local government and Ecoparque established a minimum purchasing volume of 0.18 MGD at a rate that is equal to 75% of what the state applies to government organizations, which is published annually in the official state register).

Another important effect of this alternative is that given the topographic characteristics of the city and its location contiguous to the border, a need exists to treat and reuse as much wastewater as possible in order to prevent wastewater runoffs from flowing into the United States. Aside from being a nuisance, runoff water causes physical, economic, and health damages that result in protests from the United States authorities.

Meeting the needs of the Tijuana residents under the provisions of the agreement requires the expansion of the existing treatment facility. Given that this facility was initially conceived as a modular project, it requires the construction of:

The total cost of the project is estimated at 1.4 million pesos (177,000 dollars).

Completion of the works requires 4 months, as explained in the following table.

1. Under the minimum permissible criteria, foundation studies are recommended, including exploration, sampling and laboratory analysis, to finalize the development of a final report.

Under the current use of land standards and regulations, this project complies with the Tijuana urban development program published in the state official register on February 3, 1995, which is based on:

The quality of water to be treated is as follows:

The wastewater treatment technology proposed is the process currently used, that is, a treatment process consisting of:

Treatment is given through a settling basin at the inflow desilting channel, which is used to separate objects that can obstruct the units.

A fine screen or microscreen with capacity that exceeds 0.25 MGD and a 50% instant overflow capacity, which is used to control odors and increase dissolved oxygen.

Biological leakage filter (biofilter) consisting of two sections to provide greater operating flexibility. The biological filter is composed of two 8 X 8 ft. towers, the first of which extends 12 ft. high with packaging (also called filtering media). The second tower is 18 ft. high, and jointly they provide a large surface area for wastewater contact. These work by removing dissolved organic matter and producing sludge that is later flocculated. Water is distributed by a series of sprinklers placed in a tube header on each of the towers. Both units can be operated in a parallel or serial fashion, with a 68,000 - 182,400 gal/day broad flow range, depending on the degree of treatment desired.

A smaller than conventional modular unit, whose appearance resembles that of a spinning top or a cylinder over a cone. The goal is to provide a passive solid extraction system that does not require energy input or mechanical dragging. Organic sludge is drained through an outlet tube placed in the lower part of the device by hydrostatic pressure in the water tank. Water in the upper portion is drained to a spillway that conveys it to the sprinklers installed in the Ecoparque green areas. All the treated water produced with this system is used only to irrigate the hillside and green areas of the park. When treated water is not used for irrigation purposes, it is returned to the local sewage system. Solids are being currently discharged to the city's sewerage system.

With the proposed expansion from 91,200 gal/day to 273,600 gal/day, the excess will be used to irrigate a municipal green area known as "Tijuana River 1st. stage." The city will build a 4.8 miles. conveyance line to be integrated to the system. The conveyance project was developed by the Tijuana Public Utilities State Commission (CESPT) as part of their contribution to the project.

The quality of treated water is specified in the "particular discharge conditions" established by CNA and contained in their Technical Resolution No. DAR 001/97 issued by the regional management office of the Baja California peninsula, which establishes the following parameters:

Note.- Fecal coliforms have not been determined because all treated water is used inside Ecoparque, where no disinfection facilities exist. The expansion project addresses the need of a chlorine contact chamber for disinfecting purposes.

WASTEWATER TREATMENT PLANT:

With over 8 years of experience at the wastewater treatment facilities for Tijuana's Otay Universidad residential area, and considering that the source of inflow will be the same, the same treatment system has been considered for the expansion with some adjustments, such as the biological filter and a contact chamber to disinfect treated water to bring it to compliance with CNA's discharge conditions.

Consists of a screening chamber at the inlet desilting channel. No modifications are needed because the required capacity is met.

A fine screen or microscreen with capacity that exceeds 0.27 MGD and a maximum 0.50 MGD instant overflow capacity is already in place. No modifications are required for this unit, since its capacity is sufficient to receive the flows programmed with the expansion.

The flexibility of this component is greater than that of the microscreen with regard to design flow; its size can vary. The proposed system includes the construction of a 16 X 16 X 18 ft. biological filter (4.88 X 4.88 m. in the base X 5.48 m. height). A minimum 50% reflow is required to obtain CNA's established quality.

An existing tank is currently operating. The tank was designed by Ecoparque staff and has a 0.11 MGD treatment capacity. Its design has been proven effective since no problems have arisen during its operation. Therefore, the construction of two other similar tanks is being considered to meet the new demand.

The disinfection process consists of injecting chlorine to the water to be delivered to the city of Tijuana to ensure it meets the bacteriological quality standards set by CNA. The recommended chlorine concentration is 0.15 mg/l, with 30 minutes of contact time. Considering the volume to be disinfected, an 4,750 gal tank is required for the operation, including baffles to prevent short circuits during the flow.

Since the beginning of this project, the option of treating only household wastewater was considered. This premise is still effective because the portion of the city whose wastewater is discharged to the interceptor that conveys these waters to Ecoparque has been saturated, and industrial facilities are not allowed in the area under the Tijuana Master Plan.

Generated sludge will be returned to the local sewerage system because only 0.5% of the local wastewater will be treated.

ECOPARQUE, TIJUANA , BAJA CALIFORNIA.

BUDGET PROPOSAL

JANUARY,1997 (U.S. DOLLARS)

At the present time a head chemist, one assistant and two operators are in charge of the Ecoparque wastewater treatment facility. However, with the expansion, this staff will not be sufficient to manage the plant, specially given the responsibility of delivering the volume and quality agreed to with the City of Tijuana. Thus, new personnel should be hired to meet the project's requirements.

When the mechanisms considered in the project start operating, the line to convey treated water from the plant to the reuse point will also be completed. Construction and maintenance of the conveyance line is a commitment made by the local authorities. The only test period will be the one required to stabilize the process, which is a normal operation to start up a plant of this nature, with the additional advantage of having a module already operating in the plant.

The necessary recommendations for starting up and testing installed equipment will be made at project start up time.

Following are the main operation, conservation, and maintenance actions for the proposed works:

To support the implementation of these operation, conservation and maintenance programs, the necessary recommendations regarding operation and maintenance personnel will be made.

Annual operation and maintenance costs are estimated at $40,000 USD. Estimated administrative costs are an annual $ 10,000 USD.

The total cost of the project is $ 1.4 million pesos (US $177,000 with an 8 to 1 peso to dollar exchange rate). Although initially the applicant considered the possibility of obtaining 50% of the cost from a financial institution such as NADBank, negotiations have been initiated to procure the total investment from various U.S. and Mexican financial sources such as foundations and other private organizations.

2.- Commercial, industrial and government use.

Tijuana households with meters will cover monthly user fees for each cubic meter of water used, according to the following levels of consumption:

* ccu = 100 cuft

The aforementioned Agreement executed by the City of Tijuana, CESPT and Ecoparque stipulates that the fee paid to Ecoparque shall be "25% below the approved official rate, as a minimum" . Such fee is established in the State Revenue Code, which in this case is 75% of $3.78/ccu, equal to an $2.83/ccu sale price, effective during 1997. The Agreement further establishes that the minimum volume to be bought by CESPT to Ecoparque will be 0.18 MGD, guaranteeing thus an annual $250,000 (two hundred and fifty thousand dollars) gross income. This minimum volume may be increased in following years with amendments to the Agreement.

The project is currently being managed by the COLEF Foundation, whose organization consists of one director, two assistants, a head chemist and chemical assistant, and two plant operators. New personnel needs are projected once the project starts its commercial operation. Specialized personnel will be required to operate and maintain the equipment, as well as to form an accounting and administrative area responsible for the commercial function.

The project's contributions to sustainable development in the proposed area can be summarized as follows:

An outstanding feature of the project is a component to educate residents with respect to treated wastewater reuse, which in the long term will have a positive impact, as natural resources such as water will be more effectively utilized.

Moreover, the following issues have been identified as integral parts of the project:

Academic and research project started in July, 1986 at Tijuana, Baja California by the COLEGIO DE LA FRONTERA NORTE. Its fundamental premise is considering wastewater as a reclaimable resource instead of an unsolvable problem. Thus the need to develop the concept of a decentralized wastewater collection and treatment system to manage city flows separately. This alternative to the conventional treatment system takes advantage of a compact facility design with capacity for modular growth, a simple process, and a minimum amount of parts for a reliable and inexpensive operation. The project proposes technologies available to society, that permit a better use and management of urban resources.

The ECOPARQUE proposal intends to manage city flows separately and distribute the resource within the urban area, and instead of looking at wastewater as a problem to be solved, it considers it a valuable urban resource which must be reclaimed to cover local needs, such as irrigation for the city's green areas, especially under the region's water scarce conditions.

The project intends to promote and strengthen the capacity of local institutions. Being an applied research project, it relates the academic with the administrative sector, and trains administrative and operating personnel with ability to work under local supervision in water reuse projects.

By presenting a comprehensive approach for the use of resources, ECOPARQUE is being based on sustainability principles, since it considers the use of treated wastewater to irrigate local green areas. This characteristic renders the project ideal to be incorporated into the local conservation and development plans.

Furthermore, being a decentralized facility, part of the wastewater is not discharged to the Punta Banderas wastewater treatment plant but rather recharged to underground water tables.

Furthermore, as a green section of an urban area, the project serves as a shelter for small animals that become another component of the community's environment.

Furthermore, environmental education provided at ECOPARQUE is aimed at reconciling individuals with their surroundings. In this manner, the community can become aware of the present situation of the environment at the local and regional level, and they can have access to alternatives that could be implemented at the domestic level.