THE OF IN TREA- AND - Pollution Prevention Regional ...infohouse.p2ric.org/ref/30/29529.pdf · - Current Arizona Water Law ... recreationail reuse as well as recharge for future ...

THE FUTURE OF WASTEWATER IN OOODYEARv ARIPONA TREA- AND USE

Norm Fain, P.E. Burgess & Niple, Inc.

Lynn Kartchner, P.E.

Sam Barnes Wastewater Operations, City of Goodyear

Director of Public Works, City of Goodyear

OUTLINE

- Abstract - Current Arizona Water Law - Arizona Regulatory Requirements - Reuse Potential in Goodyear - Treatment Required for Reuse in Goodyear

ABSTRACT

The City of Goodyear is a community of just under 10,000 people located in the western reaches of the Phoenix metropolitan area. Developers and community planners have identified Goodyear as having a high potential for growth as the economy in Arizona continues to improve.

Due to current water laws in Arizona, strict management of this valuable resource is dictated by our legal and regulatory communities. To promote com”mnity growth in a responsible and economicallty feasible manner, Goodyear is actively pursuing the use of wastewater to augment their water resources. The use of reclaimed effluent will enable growth in the community while reducing reliance on surface and groundwaters. The potential uses of this resource in the community include urban, industrial, agricultural and recreationail reuse as well as recharge for future recovery.

This paper focuses on the effluent quality to use this resource and treatment to meet the quality requirements for various types of effluent reuse. The effluent uses that are available to the community today will change as the community grows, wastewater flows increase, and land uses change. The treatment system built today must be readily conducive to cost effective modifications with demands for changing effluent quality due to

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changing uses. The nature of the current uses I*

will permit lower levels of treatment initially. Future uses, required as the community grows, dictate a higher effluent quality to mjtnimize risk to the public. This requires modiEication of treatment processes to meet the evolving quality requirements.

The treatment plant expansion currently in progress is an extended aeration facility. Flexibility is designed into the facility to provide biological nutrient removal in the future as effluent uses require. Provisions are included to convert disinfection methods to ultraviolet radiation to minimize the potential for total trihalomethane formation as aquifer recharge is pursued. Hydraulics are set to permit the inclusion of advanced chemical treatment processes if required in the future.

In summary, Goodyear intends to augment their water supply using wastewater. To1 keep this aggressive effort affordable to the community, the City will exhaust the least expense ef Eluent reuse applications first. The goal is to utilize this resource to the maximum extent possible within the communities ability to pay for it.

CURRENT ARIZONA WATER L A W

W-

Throughout history man has settled in areas that contain sufficient supplies of water to sustain life. Evidence of this dates back to the Hohokam Indians who settled in the low deserts of what is now known as central Arizona. Water has long been the most valuable resource of any civilization because it is absolutely necessary t.o all life. Over time, the changes man has made to nature and its natural water cycles has affected the supplies and quality of water in the environment. These changes have included containment behind dams redirecting the eventual destination of the water, and changes in the way water is used affecting the eventual quality of the water. A major result of these changes is growth and more comfortable lifestyles.

During the past several decades Arizona has recorded declining groundwater surf ace levels in some aquifers of the State. As the groundwater levels receded, water quality has also declined. This is due in part to the man-made chianges in the

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natural water cycles of mother nature. The resultant changes are not all bad; however, left unchecked the potential for serious environmental problems exists in some areas of the State. Consumer protection legislation during the late 1960's and early 1970's resulted in the Assured and Adequate Water Supply programs. These programs are intended to function in concert with Clean Water Act programs resulting in a safe water supply that will meet the needs and demands for support of life in the future.

The Arizona assured water supply program was borne out of land fraud where buyers were purchasing essentially worthless land that had no water or water rights. To minimize the fraud, legislation was passed that required sellers of land to submit water plans to be evaluated for adequacy. Under the original 1973 law three criteria were developed for determining whether a water supply was adequate for a proposed development. The seller had to demonstrate:

1) 100-years of water supply is available. 2) Annual declines in the groundwater levels

would not exceed 10-feet per year, and 3) The depth of groundwater after 100-years

would inot be more than 1,200-feet below the ground surface.

If the water supply was found to be insufficient to meet these criteria, that finding had to be made known to all potential buyers of that land. A public report had to be prepared and included in all marketing materials and contracts for sale of the land in question.

AOUIFER MANAGEMENT

In 1980, thte Groundwater code was passed which added the goals of controlling groundwater overdraft and providing a means to allocate the State's limited groundwater resources to meet the changing neleds of the State. This established different levels of management to compensate for the varying degrees of potential environmental and economic damage. Areas with the lowest potential for damage are required to demonstrate water adequacy under the three criteria described in the original legislation. Areas deemed to have the highest potential of groundwater overdraft have been classified as Active Management Areas (AMA).

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An AMA has been historically defined as an aquifer basin that has or is currently experiencing a substantial annual decline in the water surface elevation. The fact that an aquifer has been classified as an AMA does not mean that the entire aquifer fits this model. In Arizona there are four Active Management areas that have exhibited an aquifer decline across portions of the aquifer basin. These areas are designated as the Phoenix, Pinal, Prescott, and Tucson AMAs and are shown in Figure 1. Each of these AMAs contain areas that are not experiencing declining aquifer conditions. In fact, some areas within these AMAs are considered to be waterlogged. Reasons for these disparities in aquifer conditions include the following:

- Surface water percolating into aquifer effectively recharging the immediate area, - Variations in the geologic strata within the aquifer basin changing porosity, transmissivity and conductivity, - Inter-basin flows, and - Vertical flows from deep water bearing strata beyond the acknowledged basin limits.

The Arizona Department of Water Resources (ADWR) established the AMA boundaries based on the estimated aquifer basin limits. They did not consider those areas in a basin that were not exhibiting overdraft conditions any differently that the rest OP the estimated basin. Today they recognize these areas, but have yet to develop criteria for saPe yield that is representative of the actual conditions. The City of Goodyear is within the Phoenix AMA but is not experiencing overdraft conditions. However, the fact that they have been included in the AMA requj.res them to conform to the goals of the management area.

within an AMA there are five criteria for demonstration of an assured water supply. These criteria are as follows:

1) 100-years of water supply is available. 2) The water supply must be of adequate quality

meeting the aquifer water quality standards established by the Arizona Department of Environmental Quality (ADEQ).

3) The proposed water use must be consistent with the management goal of the AMA,

4) The proposed use must be consistent with the management plan of the AMA, and

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ARIZONA ACTIVE MANAGEMENT AREAS

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5) The applicant for assured water supply must have the financial capability to construct any necessary delivery systems and treatment works.

Of these criteria, demonstration that t.he proposed water use is consistent with the management goal will have the largest economic impact. The management goal in all four m s includes limiting groundwater use. This requires a demonstration that alternative water supplies can and will be used. These water supplies include surface supplies from the Central Arizona Prloject (CAP) water, Salt River Project (SRP) water systems and treated wastewater effluent. Since (Goodyear is within the Phoenix AMA the City must comply with these requirements even though the clommunity is not in a groundwater mining condition.

aTERNATIVE WATER SUPPLIES

CAP water is Colorado River water that is delivered to the Phoenix metropolitan area in the Central Arizona Canal. Goodyear has a CAP allocation but getting it to the City and preparing it for its eventual use is very expensive. Costs of attaining this water include CAP delivery costs plus construction of additional conveyance and treatment systems. If the water is to be used for potable purposes it must: be treated to drinking water standards. Goodyear is not located within any of the Salt River Project service areas and does not have any water rights to that surface water source.

Effluent is a water supply that is; currently generated in the community. The Clean Water Act currently requires treatment of this water before it can be disposed of to protect the e!nvironment. At similar costs of treatment for discharge effluent can be treated for reuse or recharge. The additional benefit is a water supply available for use in the community.

ARISONA REGULATORY REQUIREMENTS

All operating wastewater treatment plants in Arizona are required to operate within guidelines that define the quality of effluent discharge from the facility. The guidelines are d'escribed in permits that define water quality parameters for treated effluent that is intended for a specific

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I use. The currently accepted disposition for

Discbarge to a regulated water of the United State,s. This includes unregulated tributaries to the regulated water such as a dry w<ash.

Reuse of the effluent for beneficial purposes. This includes irrigation, recreational impoundments, and industrial applications.

Direct or indirect recharge of effluent to an aquifer for storage, future recovery, or replenishment.

Currently, there are five permits that wastewater treatment plants may be required to comply with in Arizona.

treated effluent include the following:

State Permits:

Aquifer Protection Permit (APP) Reuse Permit Recharge and Recovery Permit

Federal Permits:

National Pollutant Discharge Elimination System

503 Sludge Regulations Permit (NPDES)

Of these permits the APP is required with all effluent dispositions and is written to regulate in concert with reuse, recharge, or discharge permits. Reuse permits will always be required in Arizona when an effluent is reused. When aquifer recharge is included in the reuse plan Recharge and Recovery permits will be required. The exception to this is Indian reservations , the State has no jurisdiction; therefore, only federal permits are required. Currently there are no federal permits required for the reuse or recharge of effluent..

AOUIFER PROdECTION PERMIT

The APP, adlopted in 1989, replaced the groundwater quality protection permit. The permit was established to fulfill the requirements of the Environmental Quality Act adopted by legislation into Title 49 of the Arizona Revised Statutes. The APP is .intended to assure treated effluent and

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solids do not contribute to the degradation of , aquifer water quality. It provides the State with the ability to control minimum standards for wastewater treatment for both state and federal permit criteria.

In general terms, the APP requires that the applicant make two demonstrations intended to assure that the aquifers of the State are protected from contamination. The first demonstration must show that the wastewater treatment plant is designed , constructed , and operated to achieve the greatest degree of discharge pollutant reduction. This is achieved through the application of the best available demonstrated control technology (BADCT:) processes, operation methods, and other acceptable alternatives. The second demonstration must show that the discharge will not cause or contribute to a violation of an aquifer water quality standard at the point of compliance. The point of compliance is typically located at the water surface of the aquifer. However, in most cases it is acceptable to comply with aquifer water quality standards at any location prior to contact with the aquifer.

The exception to the APP demonstration requirements for showing BADCT, is when aquifer recharge or underground storage and recovery is pursued. These projects do not require compliance with BADCT. However, applicants must show there will be no cause or contribution to the violation at the aquifer quality standard. Thi.s exception exists because surface waters that currently meet the aquifer water quality standards are eligible for recharge projects.

The aquifer water quality standards were adopted to establish acceptable pollutant levels based on the protection of human health. The numeric Aquifer Water Quality Standards for Arizona are shown in Table 1.

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Table 1 Aquifer Water Quality Standards for Arisona

INORGANIC CXEMICALS : CONTAMINANT

POLLUTANT LIMIT lmu/ll

Arsenic Barium Cadmium Chromium Lead Mercury Nitrate (as N) Nitrite (as N) Total Nitrate 61 Nitrite [as N) Selenium Fluoride

ORGANIC CHEMICALS:

POLLUTANT

Benzenle Carbon Tetrachloride o-Dichlorobenzene para-Dichlorobenzene lI2-Di~chloroethane 1,l-Diichloroethylene cis-l,:2-Dichloroethylene trans-.l,2-Dichloroethylene 1,2-Dichloropropane Ethylbt, Snzene Monochlorobenzene Styrene Tetrachloroethylene Toluene Trihalomethanes (Total) 1, 1,l-Trichloroethane Trichloroethylene Vinyl Chloride Xylenes (Total)

PESTICIDES IUD PCBs :

POLLIITANT

Alachlor Atrazine Carbof w a n Chlordaine 1,2-Dibromo-3 -Chloropropane Ethylene Dibromide (EDB) Heptachdor

0 .05 1.0 0.01 0 . 0 5 0 .05 0.002 10.0 1.0 10.0 0.01 4.0

CONTAMINANT GIMIT (mu/ 11

0 .005 0 .005 0 . 6 0 .075 0 .005 0 .007 0.07 0.1 0.005 0 . 7 0.1 0.1 0.005 1.0 0.10 0.20 0.005 0.002 10.0

CONTAMINANT LIMIT [mu/ 1)

0.002 0.003 0.04 0.002

0.00005 0.0004

(DBCP) 0.0002

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T a b l e 1 (cont.)

POLLUTANT CONTAMINANT LIMIT (ma / 12.

Heptachlor Epoxide 0.0002 0.0002 Endrin 0.0002 Lindane

Methoxychlor 0.04 Polychlorinated Biphenols (PCBs) 0.0005 Toxaphene 0.003 2,4-Dichlorophenoxyacetic Acid (2,4-D) 0.07 2,4,5-Trichlorophenoxypropionic Acid 0 .05

(2,4,5-TP or Silvex)

RADIONUCLIDES:

POLLUTANT CONTAMINANT

- LIMIT (DCi/TI

Gross Alpha (Excluding radon & 15.0

Combined Radium 226 & 228 5 . 0 Average Annual Beta & Photon 4.0

uranium)

Radioactivity mi 11 irem/ year

MICROBIOLOGICAL POLLUTANTS:

Based on the presents or absence! of total coliforms in a 1oo-ml sample. Any two positive samples in a two week period is a violation of aquifer water quality standards.

TURBIDITY

Monthly Average I Two Consecutive Day Average

"AMINANT LIMIT INTVI

1* 5

*This can be increased to 5 NTU if it can be shown that it will not inhibit disinfection.

REUSE PERMIT

Wastewater reuse is the use of reclaimed wastewater for beneficial purposes without discharge intermixing with a surface water of the state. Reuse of reclaimed wastewater is currently defined under the rules as "the use of reclaimed wastewater transported from the point of treatment to the point of use without an intervening discharge to the surface waters of the State for which water quality standards have been established (A.A.C. R18-9-701.1) 'I .

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Reuse can provide additional treatment to the effluent when properly applied around root zones of plants and the vadose zones of the soil strata. Reuse can be entirely consumptive, or it can serve a ground surface use followed by indirect aquifer recharge. Regardless of the type of reuse, the intent is a beneficial use of a resource that will augment wat.er supply of the state.

Reuse for the purpose of nutrient and toxicity reduction in the effluent stream is typically consumptive. Consumptive reuse means that all of the effluent applied is used by the application. This theoretically reduces the potential for a buildup of contaminates in the soil vadose zone and potential groundwater contamination. To ensure that a specific use will provide reduction of contaminates, thereby serving as a treatment process, the following criteria must be known.

1. How much effluent to apply to each crop or

2. Where to apply the effluent, and

3. How to apply the effluent.

vegetative use.

This information will be required to design and manage the system. It will permit the determination of specific crops, acreage, and crop rotation to assure that sufficient consumptive use is available to provide the required treatment of the effluent. Consumptive use is affected by many management and natural factors. Management factors are normally related to natural factors. These include effluent supply, effluent quality, planting cycles, crop, and cultivation. Natural factors include the climate, soils, and topography.

In order to assure that the reuse system developed is effective and long lasting, the water quality and volume must be known. The water quality must be consistent with the crops grown. The characteristics of the stream must be consumable by the crop without causing crop damage. A water balance must be performed to size the effluent irrigation area, determine the crop rotation to consume the effluent efficiently, and size the related storage reservoirs. The balance accounts for all water generated, reused, stored, bypassed, evaporated, transpired, and precipitated.

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Typical types of wastewater reuse include irrigation for agricultural and ornamental purposes , livestock watering, recreation, and industrial processes. Table 2 provides the current permit limits for specific reuses. Further clarification of the specific reuses are described as follows:

Orchards - Trees for ornamental and fruit bearing, Fiber Seed and Forage - Plants for textile production such as cotton or livestock feed such as alfalfa, Pastures - Native grasses for livestock consumption, Livestock Watering - Water folr livestock consumption, Processed Food - Crops such as tomatoes used for canning or ketchup, Restricted Access Landscape - Landscaped areas where public access is controlled such as a fenced cemetery or airport runway, Open Access Landscape - Landscaped areas open to the public such as a city park, school ball-field, or golf courses, Food Consumed Raw - Crops in cont.act with the effluent such as carrots, potatoes, or onions which may be consumed raw, Incidental Human Contact - Recreation lakes permitting public access such as boating, and, Full Body Contact - Recreation lakes permitting swimming.

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TABLE 2-A Allowable Permit Limits for Bpeaifia Reuses

Pi FECAL COLIFORM (CFU/lOO M1) geometric mean (5 sample min.) single sample 4000 not to exceed

TURBIDITY “U) ENTERIC VIRUS ENTAMOBA HISTOLYICA GIARDIA LAMBLIA ASCARIS LUMBRICOIDES COMMON LARGE TAPE WORM

4.5-9 4.5-9

1000 1000

4000 4000

4.5-9 6.5-9

1000 1000

4000 4000

none none detectable detectable

TABLE 2-8 Allowable Permit Limit8 for Specific ReU888

&ANDSCAPED AREAS FOOD INCIDENTAL FULL PARAMETER RESTRICTED OPEN CONSUMED " BODY

ACCESS ACCESS RAW CONTACT CONTACT Ph FECAL COLIFORM (CFU/lOO M1) geometric mean (5 sample min.) single sample 4000 not to exceed

TURBIDITY ("1 ENTERIC VIRUS

ENTAMOBA HISTOLYICA GIARDIA LAMBLIA

ASCARIS LUMBRICOIDES COMMON LARGE TAPE WORM

4.5-9 4.5-9

25 2.2

75 25

5 1

125 per 1 per 40 liters 40 liters

none detect none detect

none none detect detect

---- ----

---- ----

6.5-9 6.5-9

1000 200

4000 800

5

125 per 40 liters

---- ---- none detect ----

1

1 per 40 liters

none detect none detect none detect ----

. When more than one reuse application applies, the most strinlgent criteria of each shall control the required w,ater quality.

UNDERGROUNID STORAGE AND RECOVERY AND RECHARGE PROJECT P E m

Reuse that is not consumptive or used in unlined ornamental and recreational surface impoundments will result in indirect or direct recharge of the aquifer. Indirect aquifer recharge is the result of excess effluent from an irrigation practice percolating into the aquifer. This typically occurs when there is more effluent available to the vegetation than can be consumed by that vegetation. Direct recharge of effluent results in aquifer augmentation through percolation or direct injection without any attempt to irrigate vegetation. Percolation of effluent can provide additional treatment as it travels through the vadose zone. Pilot studies have indicated that under ideal conditions viruses and pathogen reduction can be readily achieved. Under some circumstances denitrification and volatile organic reductions can be obtained.

Aquifer recharge or underground storage of effluent for future recovery is a form of direct augmentation of a water supply in the aquifer. When effluent is used for this purpose the treatment must be capable of meeting aquifer water quality standards at the point of impact with the aquifer. This means that no effluent that reaches the aquifer will cause or contribute to the degradation of the aquifer. Table 1 is a summary of the aquifer water quality standards for the State of Axizona.

Reuse of effluent for aquifer augmentation in Arizona is, pursued for a variety of reasons. Table 3 provides a summary of the reasons and the state permits that will be required. Under current rules a federal sludge permit will be required. If a discharge to a water of the state also occurs or if the reuse irrigation is within the 25-year flood plain that is tributary to a water of the state, an NPDES permit will also be required.

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TABLE 3 EFFLUENT APPLICATIONS AND PERIIITS

ADDliCatiOn Permits

Consumptive I r r i g a t i o n Aquifer P r o t e c t i o n Permit Reuse Permit

Su r face Impoundment Aquifer P r o t e c t i o n Permit Reuse Permit

I r r i g a t i o n wi th i n t e n t i o n a l Aquifer P r o t e c t i o n Permit i n d i r e c t recharge Reuse Permit

Rlecharge Permit

Direct recharge through w e l l s Aquifer P r o t e c t i o n Permit or p e r c o l a t i o n Riecharge Permit

Direct recharge f o r s t o r a g e Aquifer P ro tec t ion Permit and recovery Recharge Permit

Storage & Recovery Permit

Add i t iona l permits t h a t may be r equ i r ed through ADWR i nc lude i n j e c t i o n w e l l and recovery w e l l permits. A f e d e r a l NPDES permit i s requ i r ed i f r e u s e or recharge a c t i v i t i e s are wi th in a 25-year f lood p l a i n .

REUSE POTENTIAL IN OOODYEAR

The community of Goodyear currently consists of approximately 75 square miles of residential and farming areas. Residential areas provide homes for approximately 10,000 people. Many of these areas include golf courses and xecreational greenbelts. The balance of the community is farmed or fallow land. The long range plan for the community includes utilization of all of its resources to the greatest extent that is practical and feasible. One primary resource is the wastewater that is generated by the community. The City of Goodyear plans to utilize this resource to augment their "waterll resource and meet the ADWR requirements for safe yield in a manner that is economically feasible,. The goal for treated wastewater disposition is zero discharge by 1996.

During the years that Goodyear is a small community with a large service area they can utilize effluent for consumptive irrigation on cash crops produced by the local farmers and on the local golf courses. As the community grows and the effluent production begins to exceed the consumptive capacity inherent in the community. Goodyear can pursue direct and indirect recharge of the effluent. While the City grows through

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. this transition, effluent can also be used for recreational impoundments. This type of approach will allow the effluent to be used in less expensive \ways while the community is smaller and cannot afford large complex treatment systems, while the ,aquifers of the community are protected from effluent caused pollution and preserved for use by future generations of the City.

REUSE APPLICATIONS AVAILABLE TO GOODYFAR

The City currently has five basic types of effluent reuse that are available to augment the water supply. These uses fall into the following general categories:

- Urban Reuse, - Industrial Reuse, - Agriciiltural Reuse, - Recreational Reuse, and - Groundwater Recharge for Recovery.

Urban reuse includes application of reclaimed effluent wlithin the City on areas that do not require potable water. Areas that could be considered as viable urban reuse sites include parks, school yards and fields, roadway medians and shoulders, golf courses, general commercial uses, dust control, fire protection, and landscaped areas around commercial buildings and residences. The City of Goodyear is in an ideal position with regard to their current land use densities $and growth potential to implement many of these strategies as development occurs. As the area grows and utilities are installed to serve the community, systems to provide reclaimed effluent for use around the City can be installed as part o€ the development requirements. The result is that reuse distribution systems would be treated the same as water and sewer systems as far as a developer is concerned. This places the City of Goodyeair at a distinct advantage when compared to their big neighbor, the City of Phoenix, which must retrofit to implement this type of effluent reuse.

Industrial effluent reuse can take two basic forms. First, the industrial facility can collect their own wastewater, treat it, and reuse it. This may be cost effective for the large water consumers $where the water quality required does not have to be of potable quality. The second form occurs when the wastewater is treated by the City at their POTW and sold back to the industrial

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user at a rate that promotes effluent reuse but still pays for the associated costs not covered under the collection rates. Typical industrial reuse applications include evaporative cooling water, boiler feed water, process water, and irrigation of facility grounds. The first industrial reuse scenario can be implemented through the City's pretreatment program. This program can offer attractive conditions that promote the large water users to treat their effluent and reuse it. The second scenario can be implemented through a combination of the distribution systems installed by developers and attractive reuse rates that compete effectively with the potable water rates.

Agricultural reuse applications arc: the most plentiful in the community at this time, but they are the most difficult to utilize and achieve the City's zero discharge goal by 1996. The reason for this includes the following conditions prevalent in the agricultural community:

- The existing surface water supplies are provided to agricultural users at suppressed rates.

- Due to subsurface flows of the Gila River caused by discharges from the City of Phoenix POTWs and seasonal events causing the river to flow the City of Goodyear proper has a shallow perched aquifer zone near the river bed making pumped well water affordable.

- Agricultural water demands are a direct function of the weather, crop planted, and growth phase that the crop is in causing water demands to replicate feast or famine conditions.

Due to these conditions agricultural reuse in Goodyear is a viable supplement to meeting their zero discharge goals, but not the s o h solution.

Recreational reuse in Goodyear includes impoundments, habitat restoration, and open channel stormwater system st(abi1ization. Impoundments are typically manmade bodies of water that serve aesthetic purposes ranging from boating and golf course water hazards to commercial ponds and fountains. Impoundment conditions that are not readily suitable for effluent reuse due to the public acceptability, health and cost issues include swimming holes and ponds for fishing.

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Habitat reastoration include wetlands and riparian areas. Stabilization of open channel stormwater systems could be considered as urban reuse if turned into a park or habitat restoration if a riparian area is created. Either way it allows the communi.ty to simplify their erosion problems in a desert: environment while creating greenbelt areas that ultimately enhance the community and its potential growth.

Groundwater recharge is the most controversial method of effluent reuse and at the same time one of the most viable effluent reuse alternatives. Groundwater recharge occurs in two basic forms. Indirect recharge where the reclaimed effluent is used for another purpose and aquifer recharge occurs as an indirect benefit due to over irrigation or impoundment percolation. The primary disadvantage of this in Arizona is that limited aquifer credits can be obtained for indirect re<charge activities; therefore, it is not an attractive use of the reclaimed effluent . Direct recharge is the intentional application of reclaimed effluent into the aquifer through percolation or well injection systems. In Goodyear this practice would serve the following purposes :

- Replenishment of the aquifer, reducing or eliminating groundwater declines and controlling potential ground subsidence.

Provide storage of reclaimed water for future recovery and use. In Arizona this practice can reoult in aquifer credits of a portion of the water recharged enhancing assured water supply conditions.

- Provide further treatment to the effluent through the vadose zone of the soil layers for either of the two previously described purposes.

Aquifer recharge in the City of Goodyear is only viable in areas that are not adjacent to the elevated aquifer levels caused by the Gila River subsurface flows. These levels decline to the northwest as the aquifer transitions from plentiful conditions to declining conditions. The northern third of the community contain viable areas that. will permit recharge activities reducing the potential that the community will contribute to the declining conditions of this aquifer. Additionally, the recharge activities

-

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will provide the community with an assured water supply for a larger population bas,e allowing growth to occur within the City.

TREATMENT REQUIRED FOR REUSE IN GOODYEAR

THE GOODYEAR PLAN

The wastewater treatment master plan for the City of Goodyear is based on an estimated average flow at predicted ultimate buildout conditions of 21 MGD. This is based on the predicted population densities and land uses over the 51 square mile service area for the 157th Avenue 1uYwTP. The additional 24 square miles within the City of Goodyear has been in a planning transition phase due to RTC controls; however, planning has been accomplished in a manner that w.ill permit inclusion of this area when politically feasible.

The City realized that as the economy started its upswing, that they were in an ideal position to grow very fast in the Phoenix metropolitan area. This position is the result of the! following conditions:

- The southern and eastern reachies of the metropolitan area are currently growing up against Indian reservations. The western and northern areas are not faced with these boundary conditions.

- The City of Goodyear is located along Interstate 10, providing direct access to downtown Phoenix within approximately 30 minutes. This provides Goodyear with two distinct advantages over other metropolitan areas :

Residents can live further away from the big city hustle and bustle, and

Travel time to the metropolfitan hub is shorter than closer east and south metro areas due to high capacity highways.

- A Five Star resort is currently located in the northern part of the service area and is promoting housing starts for upper middle and upper income residents. Because oif this type of growth, Goodyear envisions itself as the *@Scottsdale of the West Valley".

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The wisdoim of the community leaders has stepped forward as they actively plan for the future. This planning has included assurance that the community has the resources to grow into their potential in an environmentally safe and economical.ly sound manner. This approach involves two goals that are so closely tied together in Arizona that they are often evaluated as one, assured water supply and environmental protection from wastewater supply. Because of this consideration and Arizona Water Law promoting supply augmentation, the City of Goodyear does view their solution for environmental protection from wastewater as part of their solution to assured water supplies.

Current planning was initiated with the following key goals in focus:

- Provide an economical means to treat the potential wastewater flows that could be generated in the area to levels that will protect the environment.

- Gain control of the growth in the region through control of the water rights and augmentation of water supplies, and

- Facilitate an environment that will draw developers to the area and ultimately promote growth of the area.

From a wastewater prospective, protecting existing water supplies was and is the first criteria that must be net. The City's evaluation of this considered treatment to meet existing and foreseeable future regulatory requirements. This included evaluation of:

- Secondary treatment processes to provide biological treatment.

- Advanced treatment processes to meet reguliitions for beneficial consumptive reuse and possible future recharge.

- Disinfection processes that would not only control pathogens and viruses , but would also reduce the potential of toxic formations that could contaminate aquifers.

Solids; treatment that would reduce pathogens and control vector distribution of contaminates, and

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- Facility hydraulics and expansion phasing to permit plant expansion to proposed buildout in steps that will be affordable to the community.

From a water augmentation prospective, reuse of reclaimed effluent was and is a primairy criteria that must be met. The City's evaluation of this reviewed how reuse of reclaimed effluent affected the treatment requirements to meet existing and foreseeable future regulatory requirements and assured water supply demands. This included evaluation of:

- Consumptive use applicati.ons and

- Indirect and direct aquifer recharge

The result of these evaluations formed a marriage of goals that evolved into an affordable expansion phasing of the 157th Avenue WWTP. This is due to the treatment benefits that are available through the different reuse alternatives in the community. These reuse alternatives provide additional benefit to the community through direct augmentation of the water supply. The results of this evaluation revealed the following approach towards meeting these goals:

- During the early growth periods of the community, conventional secondary treatment followed by tertiary filtration will meet both wastewater treatment and water supply augmentation goals. This will be accomplished through consumptive reuse of the reclaimed effluent.

- As wastewater flows begin to outpace the available consumptive uses in the community recharge of the reclaimed ef f 1ue:nt will be pursued for future recovery. This will require advanced treatment processes to reduce the potential of aquifer contamination.

Through this evaluation, based on long term planning objectives, it was determined that an extended aeration activated sludge process will be the most economical secondary treatment process to use. The primary reason stemmed around the flexibility it provided for modif icat.ion to meet future treatment requirements. Initi,ally, while

requirements, and

applications and requirements.

1 consumptive reuse alternatives are available to consume the reclaimed stream, contaminates are controlled through complete uptake by the use. Subsequent. expansions can be enhanced through allowing the process to evolve from conventional extended aeration to a modified extended aeration complete mix process, thereby allowing increased wastewater flows to be treated in smaller tank volumes. As consumptive reuse applications fail to keep pace with the wastewater flows generated by the community, the process can be readily modified to provide biological nutrient removal (BNR). Nutrient control of most concern in Arizona is nitrogen. Goodyear has planned to remove this through a four stage biological process, and basin partioning has been built into the initial construction phases.

In additioln to BNR, when recharge activities are actively pursued the disinfection process must not be allowed to transform organic precursors, typically volatile organics, into trihalomethanes (THM). These are deemed carcinogenic and must be kept out o f the aquifers. The most cost effective method of control of THM for this facility was determined to be ultraviolet radiation disinfection. However, as long as effluent can be used for consumptive purposes, chlorination is the most econoiaical form of disinfection. Ultraviolet disinfectilon only becomes cost effective when compared against chlorination/dechlorination due to chemical costs. Chlorination facilities used during early phases of growth will be relocated to the recyc1.e processes in the future phases to provide process control; therefore, equipment purchases inow are useful in the future.

In the evtent that volatile organics cannot be removed from the recycle stream to levels that meet aquifer water quality standards, the hydraulics of the facility have been set to include two additional treatment processes. Chemical coagulation and flocculation have been provided for upstream of the tertiary filtration process. This is intended to allow solid particle enhancement to facilitate its removal. Granular activated carbon (GAC) has been provided for downstream of the tertiary filtration process to provide a media for organic adsorption soluable organic carbon that cannot be effectively filtered out of the stream. However, if soil-aquifer treatment i t s capable of removing the volatiles in the stream, neither coagulation/flocculation or GAC may be needed in the treatment train.

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CONSUMPTIVE REUSE

Consumptive reuse of effluent is the use of the flows in a manner that all of the constituents are consumed by that use. A typical example of this is irrigation of a crop. During irrigative practices effluent is only applied to the crop in amounts that the crops will consume. Crop consumption includes the liquid, organic, and inorganic fractions of the flow. Portions of these characteristics are beneficial to the crop while other factors cannot be taken up, or cause damage to the crop. For a true consumlptive reuse plan to be effective, treatment levels and crop selection must coincide in as fair as the characteristics and needs of each. This means that the treatment of the wastewater must remove the characteristics of the flow that cannot be consumed or will cause damage to the crop that is irrigated. Additionally, the crop to be irrigated must be compatible to the characteristics of the effluent stream. A second form of consumptive use includes lined impoundments for recreational, decorative, or livestock use. Leakage is not permitted and effluent is only applied in quantities that meet the specific needs of the impoundment.

Currently, the effluent flows generated by the Goodyear service area can be used in consumptive manners. Existing golf courses and cash crops are capable of utilizing the entire eff liuent stream generated. This ability enables thta treatment processes to be less complex because the vegetation consumes the contaminates keeping them away from the public and waters of the state. There are two basic types of effluent reuse that the City is pursuing. IIRestricted access" , and I'Open Access1@.

Restricted access consumptive reuse aipplications involve the use of effluent in applicaitions where the potential for human contact or incidental consumption of the contaminates is controlled. This means that the potential exposure to the human population through direct olr indirect contact with the contaminates of the effluent are controlled to a level that attempts to preclude this occurrence. Treatment requirements for this application are limited to secondary treatment, but control of access to the site or the products produced is restrictive. The treatment must remove all of the inorganics that can not be consumed by the use. Typically, this means that

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secondary treatment must be efficient enough to eliminate the potential of inorganic pinfloc flows passing over the clarifier weirs. In some cases, inorganics such as nitrogen provide economic benefit through supplementation of fertilization reducing the overall cost of that activity. Most organics that are conveyed by well treated secondary effluent can be consumed or transformed in acceptable forms by the use. Examples of restricted access reuse applications in Arizona include prison yards, highway medians, I and subsurface root irrigation practices.

open access consumptive reuse applications do not have the same level of access control to the potential contaminates in the stream. Therefore, the level. of treatment required is more restrictive. In Arizona this is a process control dictating tertiary filtration in addition to secondary treatment. The logic is that control of the suspended matter is a direct indication of the potential €or harmful pathogens to be present in the stream. In addition to filtration the levels of disinfection are increased resulting in fewer potential viruses in the stream. Examples of open access reuse applications include golf courses, landscaped areas of commercial sites, decorative ponds, and parks and school fields.

INDIRECT OR DIRECT RECHARGE

Recharge i i n Arizona is performed to augment the water supp1.y. The volume of water recharged to an aquifer is important to the bean counters because credits arle established towards meeting assured water supplies. This means that if reclaimed effluent is placed in the aquifer, a portion of that water will be available in the future for use. In active management areas, Arizona requires that a percentage of the water recharged to the aquifer be left unclaimed for future uses. This ranges from 5 to 15 percent dependant on circumstanc:es. The intent is to reverse trends that may be resulting in declining aquifer water surf ace levels. Indirect recharge occurs when a source of water is not consumed by its intended use allowing the excess to percolate through the vadose zone, potentially reaching the aquifer. Examples of indirect recharge include over irrigation of a crop or seepage through an unlined impoundment.. If water volume is important to the user from an accounting perspective, indirect recharge is a poor use of the resource because limited credits to the aquifer can be accumulated.

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Up to 5% of the potable water consumed may be I

credited to indirect recharge if the poltential can be substantiated. Direct recharge is a deliberate act of inducing a water source into (an aquifer. Their are two primary means that are used for deliberate recharge activities. The first is through percolation and the second is through well injection.

Percolation is accomplished by surface spreading the reclaimed effluent and allowing it to move from the surface to the aquifer by infiltration and percolation through the soil. During indirect recharge activities this act occurs around root zones of crops or impoundment floors that are not sealed. Direct recharge activities in Arizona typically involve riverbeds and infiltration beds as means for initiating infiltration and percolation. Ideally, these areas have the following charac eristics:

Soil porosity and grain size matrjtx to permit rapid transmission of water.

No geologic layers present that wfll restrict the movement of water to the aquifer.

Capacities to adsorb trace elements and heavy metals and to create environments where microorganisms can decompose organics.

A distinct advantage to percolation techniques is the potential for soil-aquifer treatment to occur allowing for an improvement in the water quality between spreading activities and contact with the aquifer. In general terms, this means that the above ground treatment in a treatment facility may not be required to meet aquifer waiter quality standards at its point of discharge if the soil can improve the quality to levels that meet or exceed these standards prior to contact with the aquifer. It has been shown that soil aquifer treatment systems can potentially reduce the cost of meeting aquifer water quality standards by up to forty (40) percent. The treatment required is a direct function of the soil treatment: potential; however, in Arizona, this minimum requirement is secondary treatment. General guidelines for treatment requirements are tied to the aquifer water quality standards and the ultiimate use of the reclaimed water. Additional treatment requirements can include denitrification, volatile organics reduction, trace element reduction, turbidity control, and trihalomethane control.

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Direct injection involves pumping reclaimed water directly into the groundwater zone of the soil strata. It is typically used where hydrogeologic conditions are not conducive to infiltration and percolation. These conditions could be caused by topography, confined aquifer conditions, availability of land, or the potential for percolation/infiltration activities to cause property damage. The treatment required for injection facilities are much more stringent than percolation systems. The reclaimed water quality must meet or exceed aquifer water quality requirements when it leave the treatment plant. Control systems must be at levels that if there is a system or quality breakdown the facility discharge is bypassed to another destination and is never injected into the aquifer.

Regardless of the type of recharge incorporated into an augmentation system, there are minimum criteria that must be met:

The quality of the reclaimed effluent can not cause or contribute to a violation of the aquifer water quality standards.

- The act of recharge can not cause any damage to property or others that may be affected by the increased water volumes in the soil strata.

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THE CURRENT PHASED EXPANSION

The expansiion phase currently under construction is a 2.1 M[GD extended aeration activated sludge facility with tertiary filtration. Secondary basins werle designed to be capable of process conversion to meet the ultimate process needs for BNR. Tertiary filtration is provided to meet the reuse requirements for open access reuse of reclaimed effluent. Disinfection is currently accomplished using chlorination since the effluent uses are (entirely consumptive making the THM potential in the aquifer theoretically zero. Additional secondary basin volume required for the ultimate BNR process is currently being used for aerobic digestion. This is allowing the facility to postpone the ultimate solids treatment facilities until a later date when the population base is larqer and the cost can be deferred across more users. Figure 2 provides a simplified plan of the master planned treatment site.

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MASTER PLANNED TREATMENT PLANT CURRENT EXPANSION PHASE UTE MASTER PLANNED FOR 21 MCD MVANDD W T W

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3 157TH AVENUE WWTP MASTER PLANNED SITE

With the current development plans that are currently on file with the City, is assumed that Goodyear may be capable of continuing with this type of treatment scheme up to approximately a 7 MGD treatment capacity. This is based primarily on seven planned or existing golf courses in the planning area. Rule of thumb in central and southern Arizona is 1 MGD for each par 72 golf course based on annualized average daily demands.

The next expansion is expected to optimize aeration basin space through a small process change from conventional extended aeration to a modified extended aeration/complete mix activated sludge process. This change is planned to keep the construction cost down while allowing for another 2.1 MGD expansion phase to occur.

THE NEXT ] ? W I N G STEP

Current pl.anning in the community is now beginning to focus on the future recharge for recovery aspects alf this long term plan. Goodyear is looking into potential recharge sites around the community., Criteria for these sites are currently being reviewed and developed. The primary goals of this next planning step will be to determine two primairy potentials from the selected recharge sites.

- Determine the volume of reclaimed effluent that may be recharged through infiltration beds during an average annual period, and

- Determine what soil-aquifer treatment potential may be evident at the recharge sites; in order to determine what additional treatment may be required at the 157th Avenue WWTP .

In addition to these primary goals this analysis should determine other key factors of the recharge system. These will include:

- The direct effects that recharge activities will have on local aquifer characteristics.

- The level of mixing that could occur between the reclaimed effluent and the natural aquifer water.

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1 - The duration of time that the reclaimed effluent will be resident in the aquifer prior to recovery from various locations in the aquifer system, and

- The potential aquifer water qual.ity at the time of recovery.

The ideal objective of this next phase of planning will be to show that the water quality and quantity in the aquifer will improve as a result of recharge and recovery activities. If this result prevails, the City's primary treatment facilities will be on the wastewater side of the water cycle and the water side will only require disinfection to use as a potable supply. Worst case conditions will require that the recovered water from the aquifer will have 1.0 undergo additional treatment to be of potable quality. This case is no worse than what is currently required of surface waters used for potable purposes. The benefit of augmenting available water supplies with reclaimed effluent is that it can be accomplished without construction of the massive transmission system required to obtain access to the publicly acceptable surface supply.

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