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Appendix M: Calculation of Costs for Alternative Scenario
Water Costs:
Water costs for the new scenario were based on the comprehensive list of watering use of specific campus areas. Where the new scenario called for xeriscaped planting beds, current water use of the area was reduced by 95%, whether the area is currently lawn or planting bed. This reduction is based on the theoretical water needs calculated for xeriscaped beds using evapotranspiration. Areas that will remain lawn were reduced in watering amount to 60% of yearly reference evapotranspiration, as calculated by the Environmental group (Section 5.1, Appendix C). For all the new watering amounts, the current water rate of $1.76 per CCF was applied to figure out the watering cost under the alternative scenario.
Other Costs:
Chemical costs were based on the reductions in chemical use that would be possible to maintain current lawn, as calculated by the Environmental group. The cost reduction was estimated to be the same as the % reduction in the amount of chemicals used. Xeriscaped planting beds were estimated to have no chemical costs since they will not require fertilizer, and possibly not require pesticides. Other cost reductions associated with lawn maintenance were estimated to equal the percent reduction in lawn area; including machinery fuel use, labor time, and maintenance. Yearly costs of the irrigation system were calculated based on a $150 per acre per year cost of replacing drip irrigation system. The supervision of the irrigation system would be insignificant compared to the current system since it would have a central computer control.
Alternative Landscape Installation Costs:
New irrigation system: The new irrigation system has two costs, one for the drip irrigation for the planting beds, and one for the sprinkler system for the remaining lawn area. Estimates for drip system parts range from $500 to $1200 per acre, not including labor. We used a cost of $1000 per acre, the median estimate in the range found. Costs of parts for the sprinkler system average about $2000 per acre without labor. Estimates of sprinkler irrigation installation with labor varied greatly, from $20,000 to $80,000 per acre, depending a lot on the type of landscape where the system is being installed. For this estimate we chose to use an irrigation installation cost of $35,000 per acre, including parts and labor. This price was chosen because it was an average of the estimates used, and Harvey Mudd has a flat campus that should not be difficult to irrigate, especially in the lawn areas. Estimation for labor costs of installing the drip system were placed at a quarter of sprinkler irrigation because of the ease of installation, this number needs to be confirmed.
Other Re-Landscaping Costs: Other Re-Landscaping costs included soil and mulch purchase and installation labor, plant purchase and installation, and de-lanscaping costs. All these costs were based on landscaping estimates obtained from a landscape architect (Kirkby). Topsoil costs were around $20 dollars per cubic yard, and mulch costs were about $25 per cubic yard. Labor hours needed for soil installation was 65 hours per 100 cubic yards, and for mulch was 40 hours per 100 cubic yards. Planting costs were estimated at $15,000 per acre. Clearing and de-landscaping costs were estimated at approximately $8,000 per acre. All labor costs were estimated at $30 dollars an hour, based on estimates from landscape contractors. Finally, new plant cost was based on planting of the experimental garden. Plants for this 3000-ft2 plot were purchased from Rancho Santa Anna Botanic Garden, and totaled $300.
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