Guidance Manua pdf

 

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Figure 5-6.  MIB concentrations along the Arizona Canal on September 20, 2001, showing a “hotspot” of 

MIB production between Highway 87 and Mesa Road.  

 

 

Figure 5-7.  MIB Concentrations along the Arizona on during July 2000, showing “hotspot” of production 

between Squaw Peak and Deer Valley WTP. 

 

0

20

40

60

80

100

120

0

2

4

6

8

10

Distance (miles)

MIB (ng/L)

Deer Valley 

Squaw Peak 

∆

 MIB: 

> 60 ng/L 

16

th

 ST 

Central 

Northern 

19

th

 Ave 

7

th

 ST 

0

20

40

60

80

0

5

10

15

20

Distance (miles)

MIB (ng/L)

September 2001 

∆ 

MIB: > 30 ng/L 

87 FWY 

Mesa 

Pima 

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Canal sampling can also confirm the effectiveness of treatment of “hotspots” (Figures 5-8 

and 5-9) by demonstrating decreases in MIB/geosmin concentrations following the canal 

treatment. 

 

 

 

 

Figure 5-8.  Effect of

 

canal wall brushing on the reduction of MIB concentration. The treated Arizona Canal 

section was between Central and 19

th

 Avenue (August 2000). 

0

10

20

30

40

50

60

70

80

MIB (ng/L)

0

10

20

30

40

50

60

70

80

MIB (ng/L)

Before brushing 

After brushing 

Central 

 

 

 

19

th

 Ave 

Sampling sites 

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20

30

40

50

60

70

80

0

5

10

15

20

Canal distance (miles)

MIB (ng/L)

20-Sep

4-Oct

 

Figure 5-9.  Effect of canal

 

treatments (copper addition and canal wall brushing) on MIB production in the 

Arizona Canal upstream between Highway 87 and Mesa Drive. 

 

5.3.4  Biocide Coating on Concrete Canal 

 

Coating the concrete-lined canals could serve two benefits: (1) reduce frictional losses 

and increase hydraulic capacity of canals, and (2) reduce quantity of biomass attached 

to the surface.  Two types of products were field-tested.  First, a polymeric organic 

coating (Alphacoat 454), manufactured by Coating Systems Inc., has an active 

ingredient containing quaternary ammonium compounds with a trihydroxy silicone 

moiety. This ingredient is water-soluble and exists as a hydrated species. Thus the 

biocide is both water-soluble and becomes an insoluble polymer when bonded to a 

surface, by the process of evaporation of the water molecule.  If there are hydroxy 

groups present in the substrate there will be better bonding as in the case of concrete 

and masonry. The insoluble long chain polymer (-C

18

H

37

(CH

3

)

2

N

+

CH

2

CH

2

CH

2

Si(OH)

3

Cl-) 

imparts water repellency and the ammonium chloride gives the biocidal effectiveness.  

Second, a white-colored marine antifouling paint (EP2000) has been used on the hulls of 

boats to prevent algae and other marine microorganisms from attaching to the surface of 

the boats which reduce the efficiency of the marine vehicles.  It was determined that 

EP2000 produces hydrogen peroxide on the surface, a mild disinfectant.  Excess 

hydrogen peroxide can lead to chlorine consumption in water treatment applications, but 

was not considered significant at the low levels that may be produced in full-scale 

applications.  Both coatings reduce surface tension, which would have the effect of 

decreasing surface roughness on the canal.  Neither product currently has NSF approval 

for use in water treatment plants, but approval should be pursued.  Based upon field-

tests, a tentative recommendation would be to pursue the use of the antifouling paint. 

Before treatment 

After treatment 

87 FWY 

Mesa 

Pima 

Scottsdale 

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The canal surfaces would need to be cleaned and then coated while the canal walls are 

dry.  One to two coats of the product would be required.  The coating should be applied 

from 1 foot above the high water level to a depth of 3 feet below the normal water level.  

It is currently unclear how frequently the coating would have to be reapplied. 

 

5.4  WATER TREATMENT PLANT SOURCE SWITCHING  

5.4.1  Rationale 

 

Reduction of T&O problems can also be accomplished by source switching.  As used 

here, the term source switching means switching water production from WTPs receiving 

poor quality water to plant(s) receiving better quality water. 

 

Source switching can be useful to the WSD because the five main treatment plants 

receive water of varying quality (See Figures 2-1 and 2-2).  As noted in Section 2, the 

order of MIB concentrations in the inflows of the treatment plants is: 

 

(highest)     Deer Valley >> Squaw Peak >> Val Vista >> Union Hills     (lowest) 

 

From a standpoint of T&O management, production should be increased at the Union 

Hills and Val Vista WTPs and reduced at the Deer  Valley WTP, to the extent possible, 

during the peak of the T&O season (typically August to October). 

 

5.4.2  Potential for Source Switching 

 

The key factor that must be considered in using source switching is the total production 

capacity of the operable WTPs and the total consumer demand.  Total operational 

production capacity can be managed, to some extent, by conducting repairs at times 

other than the peak of the T&O season, so that operational capacity is at a maximum 

when source switching is needed.   

 

5.5  CONTROLS WITHIN WATER TREATMENT PLANTS 

5.5.1  Prevent In-Plant MIB or Geosmin Production 

 

Algae growth within WTPs pose both an operation problem and potential to form T&O 

compounds.  Algae “mats” can clog weirs and algae cells of all types reduce filter run 

times.  Substantial production of T&O compounds has not been observed in City of 

Phoenix WTPs, but MIB production within the WTP was observed by the City of Tempe 

and City of Chandler.  Therefore, it is important to control the growth of algae within 

WTPs.  The following techniques are recommended with certain qualifying statements: 

 

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