Water and Pollution Control Department

Description of the Ames Water Pollution Control Facility

The Water Pollution Control Facility (WPC), completed in 1989, was designed to treat the following parameters (design year 2010).

	Avg. Annual	Avg. Wet-Weather	Max. Wet-Weather
Flow, mgd	8.6	12.1	20.4
BOD5, mg/L	173	160	140
BOD5, lbs/day	12,430	16,150	23,740
TKN, mg/L	47	49	41
TKN, lbs/day	3,540	4,950	6,930

Actual Water Pollution Control Facility loadings were as follows:

	2001 Average	2002 Average	2003 Average
Flow, mgd	5.57	5.36	5.30
CBOD5, mg/L	179	160	153
CBOD5, lbs/day	8,208	7,243	6,689
TSS, mg/L	212	208	192
TSS, lbs/day	9,795	9,300	8,508
NH3, mg/L	23.3	24.1	24.7
NH3, lbs/day	1,073	1,068	1,097

Plant components include climber screens/grinders, raw wastewater pumping station, equalization basins, grit removal, trickling filter pump station, primary clarifiers, first-stage trickling filters, solids contact/aeration basins, second-stage trickling filters, intermediate/final clarifiers, and a cascade aerator.

Solids are stabilized in primary and secondary digestion tanks. Anaerobically digested solids are stored in a lined lagoon until disposed of on cropland in accordance with federal land application regulations (40 CFR Part 503). The City of Ames Biosolids Land Application Plan was approved by the Iowa Department of Natural Resources and must meet the following limits.

Biosolids Parameter	Ceiling Conc., mg/kg	Cumulative Loading, kg/hectare	Monthly Avg. Conc., mg/kg	Annual Loading Rate, kg/hectare/year
Arsenic	75	41	41	2.0
Cadmium	85	39	39	1.9
Copper	4,300	1,500	1,500	75
Lead	840	300	300	15
Mercury	57	17	17	0.85
Molybdenum	75
Nickel	420	420	420	21
Selenium	100	100	100	5.0
Zinc	7,500	2,800	2,800	140
Total Nitrogen		Agronomic loading rate

This reference may be updated as needed without
program modifications.