By BOND LENSFIELD, NICOLE LORENZ, RICHARD SIVILS, FRANK SUAREZ Fall 2003

PROJECT TITLE: HARVESTING WATER FROM THE BEAR DOWN GYM AND NEARBY BUILDINGS

By BOND LENSFIELD, NICOLE LORENZ, RICHARD SIVILS, FRANK SUAREZ Fall 2003

ABSTRACT This semester, we studied water related issues in the state of Arizona. Our project for this semester is an investigation on how we can harvest water from the roofs of the Bear Down Gym, Science Library and Main Library buildings at the University of Arizona as well as storage of rain water at the swimming pool which is located behind the Bear Down gymnasium. This is a very important subject because the harvested rain water can be extremely beneficial for irrigation purposes which will save the University of Arizona thousands of dollars in water usage. We also investigated that the swimmingpool needs to increase in capacity. The existing swimming pool is 75' length by 60' width by 5.4' average depth. We recommend that the swimming pool be 75'x 60'x 10'. This new design would certainly hold all the water capacity from the three buildings without any problems whatsoever. Another important point to mention is the fact that the harvested water must be filtered in order to eliminate debris and dead leaves. Also, the storage container (swimming pool) would have to he chemically treated in order to prevent mosquitoes and other types of bacteria in the water.

UNVR 195A Water Resources in the Tucson Basin, Fall 2003

PROJECT TITLE: HARVESTING WATER FROM THE BEAR DOWN GYM AND NEARBY BUILDINGS

Water harvesting has the potential to be a great source of additional water to be used for irrigation and agricultural purposes around the world; however, difficulties in achieving a reliable system for water harvesting may be attributed to lack of funding or other unknown variables.

Recently, there have been a number of corporations, universities, water utility companies which have shown an interest in water harvesting methods. Our group had the task of analyzing three buildings and one swimming pool at the University of Arizona. Our research was focused on the harvesting potential of the Bear Down Gym, the Main and Science libraries. We obtained the roof areas and calculated harvested water, area of turf which could be irrigated and storage requirements, We also had the task of calculating how much harvested water could he stored in the pool.

MATERIALS AND METHODS

We contacted Brian Dolan, Construction Supervisor, and Grant McCormick, Campus Planner, at the facilities management at the University of Arizona. We requested the exact roof areas (square feet) of the Bear Down, science and main library buildings, as well as the swimming pool. Dr. Jim Riley also furnished our group with formulas and Excels Tables on how to calculate theharvest potential of rain water. The roof area and estimated turf to be

irrigated were entered in the interactive table. The required storage volume

and total harvested water were automatically calculated. Once we had the

necessary information from the buildings and swimming pool, then, we

could easily calculate how much water could be harvested or stored in a year.

RESULTS The following tables show how much water can be harvested from Bear Down Gym, Main Library, Science Library, and combinations of them each year. These are related to whether the harvested water could be stored in the existing old swimming pool or whether additional storage would be required

Table 1. ROOF AREA, POTENTIAL TURF AREA SUPPORTED AND STORAGE REQUIREMENTS FOR BEAR DOWN GYM

Interactive Type in roof area and Turf area. Will give water harvested and storage requirement

A / B / C / D / E / F / G / H
IRRIGATION
Roof area sq.
ft. / 29354 / HARVESTED / REQUIREM. / NET / *
Turf area in sq.
ft. / 7338.5 / ET turf / Precip / Irr. Require. / Storage
sq. ft / on turf / ET-precip / Harv-Irr. / 9558
Cu. Ft from / ET Turf / 7338.5 / 7338.5 / For sq.ft. turf
Precip. / 29354 / 7338.5 / Cu. Ft. / cu.ft.
Month / ft. / cu.ft. / ft. / Cu, Ft / cu. Ft. / Cu. Ft.
January / 0.09 / 2568 / 0.17 / 1271 / 642 / 629 / 1939 / 7997
February / 0.08 / 2446 / 0.21 / 1571 / 612 / 960 / 1487 / 9483
March / 0.07 / 2079 / 0.35 / 2556 520 / 520 / 2036 / 43 / 9527
April / 0.04 / 1052 / 0.47 / 3437 / 263 / 3175 / -2123 / 7404
May / 0.02 / 465 / 0.58 / 4238 / 116 / 4122 / -3657 / 3747
June / 0.02 / 587 / 0.61 / 4512 / 147 / 4365 / -3778 / -31
July / 0.15 / 4330 / 0.53 / 3908 / 1082 / 2826 / 1504 / 1504
August / 0.15 / 4305 / 0.47 / 3420
_ / 1076 / 2344 / 1961 / 3465
September / 0.08 / 2324 / 0.42 / 3108 / 581 / 2527 / -203 / 3262
October / 0.07 / 1981 / 0.34 / 2470 / 495 / 1975 / 7 / 3269
November / 0.05 / 1590 / 0.21 / 1541 / 398 / 1144 / 446 / 3715
December0.09 / 0.09 / 2764 / 0.15 / 1113 / 691 / 422 / 2342 / 6057
TOTAL / 0.900.90
26492 / 4.52 / 33146 / 6623 / 26523 / -31

* Storage accumulated per month cannot exceed size of storage tank (given in gray area), If it does you need to adjust amount of stored water to equal size of storage tank.

APrecipitation in Tucson in feet

BHarvested water from roof area that you specify in cubic feet

CEvapotranspiration of water from a turf area in feet

DEvapotranspiration of water from your turf area in cubicfeet

EPrecipitation in Tucson on turf area you specified in cubic feet

FIrrigation requirement for your turf area (equals ET minus precipitation) cubic feet

GNet water accumulated (equals harvested water less the amount used for irrigation) in cubic feet

HAt top of column in gray box is calculated storage requirement in cubic feet

HIn the column is the total amount of water in storage each month in cubic feet

As you can see, the amount of storage needed to hold this water from the Bear Down Gym (9558 FT^3 of water) can be stored in the pool. Let's take a look at the Bear Down and Main Library.

Table 2 ROOF AREA, ESTIMATED SUPPORTED TURF AREA AND POTENTIAL HARVESTED WATER FROM BEAR DOWN GYM AND MAIN LIBRARY

A / B / C / D / E / F / G / H
IRRIGATION
Roofarea sq.
ft. / 95811 / HARVESTED / REQUIREM. / NET / *
ET turf / Precip / Irr. Require: / Storage
Turf area in sq.
ft. / 23953
Harv-Irr. / 31197
sq. ft / on turf / ET-precip
Cu. Ft from / ET Turf / 23953 / 23953 / For sq.ft. turf
Precip. / 95811 / 23953 / Cu. Ft. / cu.ft.
Month / Ft. / cu.ft. / ft. / cu. Ft / cu.Ft, / cu.Ft
8383 / 0.17 / 4150 / 2096 / 2054 / 6329 / 26100
January / 0.09
February / 0.08 / 7984 / 0.21 / 5128 / 1996 / 3132 / 4852 / 30953
March / 0.07 / 6787 / 0.35 / 8342 / 1697 / 6645 / 142 / 31094
April / 0.04 / 3433 / 0.47 / 11220 / 858 / 10362 / -6928 / 24166
May / 0.02 / 1517 / 0.58 / 13833 / 379 / 13454 / -11937 / 12229
June / 0.02 / 1916 / 0.61 / 14727 / 479 / 14248 / -12332 / -103
July / 0.15 / 14132 / 0.53 / 12757 / 3533 / 9224 / 4908 / 4908
0.15 14052 / 14052 / 0.47 / 11164 / 3513 / 7651 / 6401 / 11310
August
September / 0.08 / 7585 / 0.42 / 10144 / 1896 / 8248 / -663 / 10647
October
November / 0.07
0,05 / 6467 / 0.34 / 8062 / 1617 / 6445 / 22 / 10669
November / 0.05 / 5190 / 0.21 / 5030 / 1297 / 3733 / 1457 / 12126j
2256 / 1377 / 7645
9022 / 0.15 / 3633 / 19771
December / 0.09
TOTAL / 0.9086469 / 4.52108190 / 108190 / 21618 / 86572 / -103

The combination of the Main library and Bear Down Gym require a storage of 31,197 cubic feet of water. This exceeds the volume of the old swimming

pool. Now let's examine the Bear Down Gym and Science Library buildings.

A / B / C / D / E / F / G / H
IRRIGATION
Roof area sq. ft / 54042 / HARVESTED / REQUIREM. / NET
Turf area in sq. ft
. / 13511 / ET turf / Precip / Irr. Require. / Storage
sq. ft / on turf / ET-precip / Harv-Irr. / 17597
Cu. Ft from / ET Turf / 13511 / 13511 / For sq.ft. turf
sq.ft.
Precip. / 54042 / 13511 / Cu. Ft. / cu.ft.
Month / ft , / cu.ft. / ft. / cu. Ft / cu. Ft. / cu. Ft.
January / 0.09 / 4729 / 0.17 / 2341 / 1182 / 1159 / 3570 / 14721
February / 0.08 / 4504 / ,0.21 / 2892 / 1126 / 1767 / 2737 / 17458
March / 0.07 / 3828 / 0.35 / 4705 / 957 / 3748 / 80 / 17538
April / 0.04 / 1937 / 0.47 / 6329 / 484 / 5845 / -3908 / 13630
May / 0.02 / 856 / 0.58 / 7803 / 214 / 7589 / -6733 / 6897
June / 0.02 / 1081 / 0.61 / 8307 / 270 / 8037 / -6956 / -59
July / 0.15 / 7971 / 0.53 / 7196 / 1993 / 5203 / 2768 / 2768
August / 0.15 / 7926 / 0.47 / 6297 / 1982 / 4316 / 3611 / 6379
September / 0.08 / 4278 / 0.42 / 5722 / 1070 / 4652 / -374 6005 / 6005
October / 0.07 / 3648 / 0.34 / 4548 / 912 / 3636 / 12 / 6017
November / 0.05 / 2927 / 0.21 / 2837732 / 732 / 2105 / 822 / 6839
December / 0.09 / 5089 / 0.1520491272 / 2049 / 1272 / 777 / 4312 / 11151
TOTAL / 0.90 / 48773 / 4.526102612194 / 48832 / -59
-5959

Table 3 ROOF AREA, TURF SUPPORTED AREA AND STORAGE REQUIREMENTS FOR WATER HARVESTED FROM BEAR DOWN GYM AND SCIENCE LIBRARY

As you can see, the pool capacity of 24,300 ft^3 is able to store 17,597 cubic foot of water. The combined roof areas of Bear Down Gym and the Science Library would harvest enough water to irrigate 13,51 1 ft^2 or about 30% of

a football field. Finally, let us examine the Bear Down Gym, Main Library and Science Library buildings altogether. Table 4. ROOFAREA, TURF SUPPORTED AREA, HARVESTED WATER STORAGE REQUIREMENT FOR BEAR DOWN GYM, MAIN LIBRARY AND SCIENCE LIBRARY

A / B / C / D / E / F / G / H
IRRIGATION
Roof area sq. ft. / 120499 / Harvested / REQUIREMENT / NET / *
Turf area in sq. ft. / 30124 / ET turf / Precip / Irr. Require. / Storage
Sq. ft. / On turf / ET-precip / Harv-Irr. / 39234
Cu. Ft. from / ET Turf / 30124 / 30124 / For sq. ft. turf
Precip. / 120499 / 30124 / Cu. F. / Cu. Ft.
Month / ft. / cu.ft. / ft. / cu.ft. / cu.ft. / cu.ft.
January / 0.09 / 10544 / 0.17 / 5219 / 2636 / 2583 / 7961 / 32827
February / 0.08 / 10042 / 0.21 / 6449 / 2510 / 3939 / 6103 / 38930
March / 0.07 / 8535 / 0.35 / 10491 / 2134 / 8357 / 178 / 39108
April / 0.04 / 4318 / 0.47 / 14111 / 1079 / 13031 / -8713 / 30395
May / 0.02 / 1908 / 0.58 / 17397 / 477 / 16920 / -15012 / 15383
June / 0.02 / 2410 / 0.61 / 18521 / 602 / 17919 / -15509 / -125
July / 0.15 / 17774 / 0.53 / 16044 / 4443 / 11600 / 6173 / 6173
August / 0.15 / 17613 / 0.47 / 14040 / 4418 / 9622 / 8051 / 14224
September / 0.08 / 9540 / 0342 / 12758 / 2385 / 10373 / -833 / 13391
October / 0.07 / 8134 / 0.34 / 10139 / 2033 / 8106 / 28 / 13419
November / 0.05 / 6527 / 0.21 / 6326 / 1632 / 4694 / 1833 / 15252
December / 0.09 / 11347 / 0.15 / 4569 / 2837 / 1732 / 9615 / 24867
TOTAL / 0.90 / 108750 / 4.52 / 136063 / 27187 / 108876 / -125

The water harvested from combination square footage of the above buildings exceeds that of the pool and thus it can not store 39234 cubic feet of water.The pool could hold 24,300 ft^3. The turf areas in front of the Bear Down

Gym and Science Library were calculated to be 6125 sq. ft. From the above results, the water harvested from the three buildings is more than enough to provide irrigation water for the turf in front of Bear Down Gym and Science Library.

We also investigated the possibility of increasing the pool size. The existing swimming pool is 75' length by 60' width by 5.4' average depth. We recommend that the swimming pool be increased to 75'x 60'x 10’. It would then hold 45,000 cubic feet.

Our results are summarized below:

TABLE 5

BUILDINGS / POTENTIAL ANNUAL
HARVESTED WATER (FT^3) / ROOF
AREAS (FTA2) / POTENTIAL TURF
AREA
SUPPORTED(FT^2)
BEAR DOWN
GYM / 25,500 / 29,354 / 7300
MAIN LIBRARY / 59,800 / 66,457 / 16,600
SCIENCE LIBRARY / 22, 500 / 24, 688 / 6200
TOTAL / 107,800 / 120,499 / 30,100

DISCUSSION The University of Arizona should take into serious consideration the fact that annually, Bear down Gym can potentially harvest 25,519 cubic feet of water each year. This water can easily be used to irrigate the mall area, landscaping, and other areas that require other sources of water besides rain water for moisture. If a plan is implemented to harvest water from the

gym's roof, the initial cost might be high but in the long run the value of the water saved will outweigh these costs. The harvested water from the Bear Down Gym and the Science Library could be used to irrigate 13,51 1 ft^2 of turf. It might be enough to provide most of the irrigation needs of Bear Down field, just north of the football stadium. The old swimming pool could easily provide the required storage of 17,597 cubic feet.

CONCLUSION

It is clear from the above investigation, that it really behooves the University of Arizona to implement some kind of a water harvesting program. The University can no longer ignore the benefits of water harvesting because it will save them thousands of dollars per year. The initial investment could vary depending on the complexity of the system but overall, it can outweigh the cost. The other advantage of this is that it reduces water dependency on the city of Tucson.

REFERENCES City of Tucson: How to Harvest Water; September 5th, 1999

Special thanks to Brian Dolan, Grant McCormick. Dr, Jim Riley and Arin Haverland for their contributions on this report.