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XERISCAPING SAVES W TER BUT DOES IT SAVE MONEY?Gary L. Wadel and E. Neal Weatherly, Jr.

UTHORS 1Associate Professor, Extension Horticulture Department and 2Head, Extension Landscape Architecture Department, TheUniversity of Georgia, Athens, Georgia 30602.REFERENCE Proceedings the 1991 Georgia Water ReSOLUces Conference held March 19 and 20, 1991 at The University of Georgia,Kathryn J. Hatcher, Editor, Institute of Natural Resources, The University of Georgia, Athens, Georgiao

INTRODUCflONXeriscaping, pronounced Zera-scaping , is a term

coined in Colorado 1981 to define the process of makinga landscape more water-efficient, not only the designphase, but also through proper installation and water-wisemanagement practices that conserve water. The conceptinvolves seven principles which are collectively called xeriscaping: 1 Proper planning and design; 2 Practical turfareas; 3 Efficient irrigation; 4 Soil improvements; SMulching; 6 ppropriate plant selection; and 7. Maintenance to reduce water needs (Wade et al., 1988). All areequally important in improving overall landscape water-useefficiency and water conservation.

The merits of the xeriscaping principles in waterconservation are reiterated again and again in numerouspublications and books on the subject, leaving the readerwith little doubt that xeriscaping will save water. However,in addition to the well-documented environmental andaesthetic benefits of xeriscaping, consumers often ask aboutthe economic benefits of xeriscaping. Does xeriscaping saveenough money to warrant a substantial capital out lay toretrofit an existing landscape? If consumers can be showneconomic benefits from xeriscaping, they will be more likelyto implement changes their present landscape.

In this study, a landscape ret rofi t model and computercost estimator program were utilized to project costs andpotential economic return on investment from xeriscaping.

:METHODSA hypothetical design depicting a typical before and afterresidential xeriscape retrofit was developed (Figure 1). To

compare consumptive water use befo re and after theretrofit, average water and wastewater rates were computedusing data from nine cities in metro tlanta(Tables 1, 2.).Water-use zones assigned to the landscape (Fig. 1) werethen used to est imate the annual water use and projectedwater and sewage costs before and after retrofit as shownin Table 3

Assumptions were made as to the projected irrigationrequirements of plants in each of the water-use zones,

following a two-month establishment period during whichthe plants were watered regularly. The amount of waterapplied was based on Georgia Cooperative ExtensionService recommendations to water thoroughly whenneeded to a depth of 6 to 8 inches with approximately l-inch of water (600 gallons pe r 1,000 square feet) (Landry,1986). Therefore , it was assumed that plants the highwater-use zones would receive I inch of supplementalirrigation water (600 gallons per 1,000 sq. ft.) an averageof three times per mon th f rom prilto October, and l-inch of water per month from November to March. Thosein the moderate water-usezones, on the other hand, wouldreceive I-inch of irrigation water once a month from Aprilto October, and no supplemental irrigation from November to March. Plants the low water-use zones of thelandscape would receive no supplemental irrigation at anytime during the year.

Figure 1a. Before Xeriscape Retrofit

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I Cost represents either residential cost or outside city cost, AtlantaRegional Commission Survery, 1990.

TABLE 2. Average Wastewater Rates of Eight MetroAtlanta Cities, May, 1990

\ J i t; Figure lb. After Xeriscape Retrofit

CityAustellFairburnForest ParkLocust GroveMariettaMcDonoughPalmettoPowder SpringsAve

Min. cost/2 OOO g t4.347.00

6.003.004.906.504.504.145.04

Added costper 1,000 gal.2.171.501.950.662.45'1.752.752.071.69

TABLE 1. Average Water Rates of Nine Metro AtlantaCities, May, 1990CityAustellDaculaDuluthFairburnForest ParkLawrencevilleLocust GrovePalmettoPowder SpringsAve.

Min. costf2 g ll3.508.257.007.006.004.847.008.256.896.53

Added costper 1,000 gal.1.753.383.301.501.952.172.50. 3.251.892.41

A computerized cost estimator for estimating landscapemaintenance costs was utilized to project direct costs ofmaintaining the landscape before and after the xeriscaperetrofit (Thomas t aI. 1990). Management schedules,areas serviced and estimated direct costs before and afterretrofit are shown in Tables 3, 4 and 5.Installation costs of the landscape retrofit were estimated using average unit retail prices of plants andmaterials (Table 6). It was assumed in this model that thelandscape would be installed by the resident who would notallocate his time as a direct job cost.Utilizing this model and data generated, consumptivewater use, water cost, and maintenance costs before andafter retrofit could be compared and used to forecastsavings and return on investment from xeriscaping.

ICost represents either residential cost or outside city cost. AtlantaRegional Commission Survey, 1990.TABLE 3. Surface Area, Estimated Annual Water Use, Projected Annual Water Cost, and Annual Sewage Costs by WaterUse Zone Before and After Xeriscape Retrofit.

Annual water use Projected Annual Projected AnnualSquare feet (gallons) Water Cost Sewage CostZone Before After Before After Change Before After Change Before After ChangeLow 0 3353 0 0Mod. 5788 3538 24310 14860 -9450 60.29 37.52 - 22.77 42.74 26.77 - 15.97High 3662 2509 57127 39140 -17987 139.39 96.04 - 43.35 98.20 67.81 - 30.39Total 9450 6047 81437 51723 -27437 199.68 133.56 - 66.12 140.94 94.54 - 46.36lAssumptions: High water-use zone receives I-inch of water (600 gal./lOOO sq. ft.) 3 t imes/month from April to Oct. and I-inch of water/monthfrom Nov. to March; Moderate water-use zone receives I-inch of water/month from April to Oct., and no supplemental water from Nov. to March;low water use zone receives no supplemental water after establishment.104

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TABLE 5. Areas Serviced and Estimated AnnualMaintenance Costs of Xeriscape Retrofit.

TABLE 4. Landscape Management Schedule- Services andEstimated Frequencies by rea Before and AfterXeriscape Retrofit.

1Costs derived via Hort Management, Computer Cost Estimator forLandscape Managers, ver. 3.0, The University of Georgia CooperativeExtension Service Special Publication no. 1., Nov., 1990.Assumption: Labor wage of 10/hr

Frequency/yr.Before After

DISCUSSION

TABLE 6. Estimated Plant and Material Costs forModel Xeriscape Retrofit.Item Quantity Unit Cost Total Cost

1 gal. pit. 47 4.00 1883 gal. pit. 37 8.00 2975 gal. pit. 9 14.00 126Grnd Cover 430 0.80 344Annuals 300 0.30 90Mulch 44 4.00 176Total: 1221

By re-zoning the modellandscape when converting fromthe traditional to the xeriscape landscape, total irrigatedarea was reduced by 3403 square feet while consumptivewater use over a twelve-month period was reduced by27,437 gallons, providing an annual savings of 66.12 onthe water bill and 46.36 on sewage, based on May, 1990data from the Atlanta Regional Commission (Tables 1, 2and 3).During the xeriscape retrofit, the turf area was reducedby 3321 square feet, while the area devoted to ornamentalplants was increased by 1001 square feet (Table 5.). Aconsiderable amount of the landscaped area, 2200 squarefeet, was converted to pine straw mulch. By re-zoning thelandscape and changing its watering schedule, maintenancerequirements could also be adjusted as shown in Table 4.Less supplemental irrigation, combined with less frequentfertilization and conservative pruning, resulted in asubstantial reduction in the maintenance requirements ofthe xeriscape model. These savings equated to an annualdirect cost savings of 135 as shown in Table5. Therefore,total annual savings shown by this retrofit model is 247.48( 135 (maintenance) + 66.12 (water) + 46.36 (sewage .Finally, estimated installation costs, excluding labor,were used to forecast a time interval for complete returnon investment (Table 6). Assuming a 10 inflation inannual water and sewage rates and maintenance costs, themodel shows a potential return on investment in as littleas 3 years, 11 months (Table 7). A comparable bankreturn on a 1221 investment at 8 interest would requireapproximately nine years.

Since Xeriscaping is as much a behavioral concept asit is a physical concept, the authors do not wish to implythat physical changes to the landscape are necessary to savewater and money. Considerable savings can be realized bysimply recognizing when to water, how to water, the mostefficient methods for applying water and the differentwater requirements of plants in the landscape, and thenmodifying watering practices accordingly.

11

214

201110

Square feetBefore After Change7837 4516 -33211613 2614 + 10019450 7130 -2320Estimated Costs52 23 - 29530 335 - 195

m 167 + 89660 525 - 135

LandscapeWeed Control 2Fertilize 2Pest Control 2Prune 3ukh 1Flower BedsPrepare/plant 0Mulch 0Hand Weed 0Fertilize 0Pest Control 0Groom 0

TurfMow 32Fertilize 2Chem. Weed Control 2Pest Control 2Weed Eat 16Aerate 1

Task

Areas ServicedTurfOrnamentalsTotalsDirect CostsEquipmentLaborMaterialsTotals

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TABLE 7. Projected Time for Return on Investment onModel Xeriscape Retrofit

InstallationYear 1Year 2Year 33 yrs. 11 mos.

Savings/yr. 272.23299.45329.40362.34

Cost1221.00948.77649.32319.920.00

lAssumption: 10 increase in water rates and maintenance costs peryear.

SUMMARYUnder the parameters of this study, the process oretrofitting n existing landscape to make it more waterefficient has been shown to provide considerable economicbenefits. Landscape architects -and landscape contractorsare encouraged to use similar models to show their clientsthe economic benefits o xeriscaping. Most clients todaywant low-maintenance, environmentally sound landscapes,and xeriscaping fits this need. However, a successful marketing program for xeriscaping should promote not onlythe environmental and aesthetic benefits of the concept,but also the economic benefits, including appreciatedproperty value and enhanced resale potential.

LITERATURE CITEDAtlanta region water and wastewater rate survey. 1990.Atlanta Regional Commission, May 1990.Thomas, W. A., and G. L. Wade. 1990. HortManagement; computer cost estimator for landscape management, version 3.0. Georgia CooperativeExtension Service Special publication 1.How to Xeriscape. 1987. Special publication of the SouthFlorida Water Management District, West PalmBeach, Florida.Knox, G. W. 1988. Landscape design for waterconservation. Florida Cooperative ExtensionService fact sheet OH-72.Landry, Gil Jr. 1987. Turfgrass Water Management.

Georgia Cooperative Extension Service Leaflet 399.Robinette, G. o. 1984. Water conservation in landscapedesign and management. Van Nostrand ReinholdCompany, New York.Wade, G. L. K. D. Coder, E. N. Weatherly, Jr., G. Landry,J. T. Midcap and T. Tyson. 1988. Xeriscaping:seven steps to a water-efficient landscape.Georgia Cooperative Extension Service Miscellaneouspublication MP345.Welsh, D. F., W. C. Welch and R. L. DubIe. 1986.Landscape Water Conservation.... Xeriscape. TexasAgricultural Extension Service Bulletin B-1584.106