[Dewey-Darrow] Fwd: CITY OF EVANSTON e-newsletter: January 30, 2009

Fri Jan 30 15:44:12 CST 2009

"It is  not our differences that divide us. It is our inability to recognize, 
accept,  and celebrate those differences"

(Audre Lorde 1934-92)  

____________________________________
 From: MPress at cityofevanston.org
To:  city-newsletter at mail.cityofevanston.org
Sent: 1/30/2009 3:43:33 P.M.  Central Standard Time
Subj: CITY OF EVANSTON e-newsletter: January 30,  2009

PRESS  RELEASE 
DATE:              Friday, January 30, 2009 / TIME: 3:00 PM 
SUBJECT:         Continued water conservation measures requested 
FROM:              Rolanda B. Russell, Interim City Manager 

EVANSTON WATER PLANT RESUMES NORMAL OPERATION; 
CONTINUED VOLUNTARY WATER  CONSERVATION REQUESTED 
The City of Evanston’s water plant has resumed normal  operations after water 
intake was restricted due to ice build-up, but  customers are asked to 
continue voluntary conservation measures until at least  1:00 p.m. on Saturday, 
January 31. This involves curtailing non-essential  water usage, such as laundry, 
running the dishwasher,  etc. 
Customers should be aware that weather forecasts  indicate that conditions 
will remain optimal for ice formation to reoccur for  the next several days. 
Therefore, it is recommended that customers draw and  store drinking water before 
going to bed tonight in the unlikely event that  the situation reoccurs over 
the weekend.  
Residents are requested to check for status updates on  the City Web site 
(_www.cityofevanston.org_ (http://www.cityofevanston.org/) ), Evanston Community 
Media Center’s cable channel 16, and radio  station (1650-AM). A recorded 
message will be posted at (847) 448-8058 after  5:00 p.m. on January 30. 
We appreciate the citizens’ efforts during this  period. 
Read on for further information about today’s  events: 
Between the hours of 4:30 a.m. and 12:30 p.m. on  Friday, January 30, the 
City of Evanston treatment plant was unable to bring  water into the treatment 
process due to an icing condition on the  intakes.  During this time, the 
Evanston Water Plant continued to supply  high-quality water to its customers at a 
reduced rate from onsite storage. At  no point in time was the quality of water 
in the system compromised.  Communities which receive water from Evanston 
were asked to conserve water and  their water supply was not curtailed.  
Background: 
This situation can occur during winter  months, and the Evanston Water Plant 
modifies its operation anticipating that  this icing condition may occur. 
Pumping is decreased at night and increased  during the day to fill all of the 
potable water storage facilities. There is  normally sufficient storage of 
potable water at the water plant and in the  distribution system to wait out this 
type of  situation. 
Customers which use large amounts of water, such as  Northwestern University, 
St.  Francis Hospital and the North Shore  Medical Center, were contacted at 
8:00 a.m. and  asked to voluntarily reduce usage deemed non-essential (i.e. 
laundry,  dishwashing, etc.).  The cooperation from these facilities was 
excellent  and allowed the Water Utility more time to try to rectify the problem.  
However, because the situation did not improve, at 11:45 a.m. the City issued  a 
press release asking all customers to conserve  water. 
Read on for more information on frazil/ anchor ice  formation:  
The formation of frazil and anchor ice  depends on meteorological conditions. 
In 1982, Gee Tsang outlined the  conditions for frazil and anchor ice 
formation in simple terms:   
In common language,  one says that frazil and anchor ice are likely to form 
on a cold, clear night  when the wind is strong, the humidity of the air is 
low, especially if such a  night follows a cold, windy, cloudy day.     
As Tsang says, in mid-latitudes anchor  ice tends to form at night. On 
mornings following anchor ice formation events,  the sun warms the water and anchor 
ice is released.   
The drawing of lake water through the  intakes causes the water to super-cool 
(i.e. the water temperature is cooled  to below the freezing point). When 
this happens, ice can grow in the water  column. The first ice to appear is 
frazil (small disks or spicules of ice  suspended in the water column).  The 
drawing of the water into the  intakes causes the frazil ice to stick to the intake 
pipe itself, forming  anchor ice (ice attached or anchored to  something). 
Super-cooling is the process of chilling  a liquid below its freezing point, 
without the phase change from liquid to  solid. Super-cooling of water is 
ubiquitous in nature, and is a necessary  precondition for the formation of frazil 
and anchor ice. Water in rivers,  lakes, and seas is only super-cooled to 
about 0.01 oC.   

Mayre Press 
Deputy City  Clerk 
847-328-2100, ext.  2153 
847-448-8131  Fax 
_mpress at cityofevanston.org_ (mailto:mpress at cityofevanston.org)  
P  Please  don't print this email unless necessary.  

---
You are currently subscribed to city-newsletter as: sugrcreek at aol.com.
To unsubscribe go to http://www.cityofevanston.org/unsubscribe

**************From Wall Street to Main Street and everywhere in between, stay 
up-to-date with the latest news. (http://aol.com?ncid=emlcntaolcom00000023)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.pickacup.com/pipermail/dewey-darrow/attachments/20090130/53ae87e6/attachment-0001.htm>