This study, conducted at the request of Lehman Development Corporation, assessed leakage from the primary ('upper pond') and secondary ('lower pond') wastewater treatment lagoons. Through monitoring water surface levels and evaporation over a six-day period in June 2009, the findings concluded that there is no significant leakage, as the measured pond and pan evaporation rates were identical, resulting in a drop of 1/8" per day. The study aligns with Oregon Department of Environmental Quality guidelines, indicating that this level of drop is considered normal.

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Engin}ering
P.O. Box 519, 210 E Main
MT. VERNON. OR 97865
PHONE (541)932-4520
FAX (541)932-1430
EUAlL djst2@ortelconet
LEHMAN HOT SPRINGS
SEWER LAGOON LEAK STUDY
Need:
This study is performed at the request of Patrick Lucas, President of Lehman
Development Corporation.
Purpose:
The purpose of this study is to determine if there is significant leakage from ether the
existing primary or secondary wastewater treatment lagoons. For the purposes of this
study, the primary lagoon will be referred to as the "upper pond", and the secondary
lagoon will be referred to as the "lower pond".
Conditions:
• The test period is conducted from mid-day on May 27, through mid-day on June
3, 2009, or a period of 6 full days.
• There is no measurable precipitation through the test period.
• Temperature is near or approximately normal, with high temperatures in the 70s'
and lows in the 40s'
• Wind and Humidity are approximately normal for this time of year with no
extremes.
• There is no inflow to the lagoon system during the test period.
• Each Lagoon (Pond) is hydraulically isolated.

2. Methodology:
Leakage is determined as based monitoring the water surface levels in each pond.
Evaporation and precipitation are determined by floating standard, circular 47.5"xlO"
evaporation pans in each pond. As stated previously, there was no precipitation during
the test period, therefore only evaporation was accounted for.
Evaporation is determined by measuring the water level of the pan at the beginning of the
test period then again at the end. Evaporation conditions are maintained as near to those
in each pond by actually floating the evaporation pans in the pond on which evaporation
is to be determined, (Temperature, wind, and humidity). In order to account for normal
pan evaporation being normally less than pond evaporation, a factor of 0.75 is applied to
the pan measurements.
Leakage is then determined by comparing the pond water surface difference with the pan
water surface difference. Pond surface difference more than pan surface difference is
leakage. It should be noted that "Oregon Department of Environmental Quality"
Guidelines for estimating leakage from existing sewage lagoons, considers 1/8" per day
or less to be normal.
Raw Data as Measured in the Field
UPPER POND LOWER POND
Begin Test May 27,2009 @ 12:30 P.M.
Evaporation Pan Depth = 0.39' Evaporation Pan Depth = 0.35'
Water Surface Elevation = 98.76' Water Surface Elevation = 91.62'
Change in Pan Surface = 0.08' Change in Pan Surface = 0.08'
Change in Pond Surface = 0.06' Change in Pond Surface = 0.06'
End Test June 3, 2009, @ 11:30 A.M.
Evaporation Pan Depth = 0.31' Evaporation Pan Depth = 0.27'
Water Surface Elevation = 98.70' Water Surface Elevation = 91.56'

3. Leakage:
Upper Pond Leakage = 0.06' - 0.75(0.08') = 0
Lower Pond Leakage = 0.06'- 0.75(0.08') = 0
Over a 6 day period this is a pond drop of 1/8" per day and an identical pan drop of 1/8"
per day in each pond.
It should be pointed out that, a compilation of "Oregon Evaporation Station Averages"
taken in Ukiah (15 miles to the west) provide the following:
Average Evaporation in May @ 3.83" and Average Evaporation in June @ 4.38"
This provides an average monthly evaporation for the study period of 3.83", or 1/8" per
day as determined above.
Conclusion:
Within the scope and precision of this study or the "Oregon Department of
Environmental Quality" Guidelines for estimating leakage from existing sewage
lagoons". There is No Significant Leakage From Ether Pond.
BY:
Douglas M. Ferguson, P.E., P.L.S.
President
Ferguson Surveying & Engineering
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