Challenge

In October 2001, the city underwent water quality problems with their conventional water plant after repairs were made to the interior face of the Idaho Springs Dam. Turbidities in excess of 60 NTU were passed through the conventional plant and into the distribution system.

As a result, the Colorado Dept. of Public Health & Environment imposed a boil water order on the city. Following that, they required the immediate installation of a reliable filtration system.

The engineering firm of Harding ESE was retained to evaluate and recommend alternate solutions. After their evaluation and modifications to the existing conventional system, the results indicated that:

• Coagulation was still deficient
• Turbidity remained in suspension
• Significant Giardia Lamblia was present in both raw and finished water 

Solution

Harding ESE recommended microfiltration to meet the State’s mandate for improving filtration.  The MEMCOR® continuous microfiltration system was chosen based on a variety of factors, including:

• Capital cost
• Operating cost
• Membrane replacement cost
• Extensive experience in fast track project execution and delivery 

The consulting services of Parsons was retained to provide overall project management and direct communication to the owner. 

Three (3) MEMCOR CMF membrane units were provided containing 270 membrane modules capable of producing a peak capacity of 2.70 MGD. 

Results

The Idaho Springs Microfiltration project was operational within 115 days from start of construction. The city of Idaho Springs successfully used MEMCOR® microfiltration technology to pull themselves out of a public health crisis and to comply with future drinking water regulations. Other significant advantages of the CMF system are:

• Exceeds the requirement of 3-log (99.9%) removal of Giardia Lamblia
• Exceeds the future 2-log (99%) removal requirement for Cryptosporidium
• Produces finished water quality with 7-log microorganism reduction
• Provides effluent turbidity less than 0.02 NTU
• Increased water production by 35%

Saved overall costs greater than $3 million compared against planned improvements to the existing conventional system 

The Idaho Springs Microfiltration Project was the recipient of the Outstanding Design-Build Project of the Year Award for 2002, issued by the F.W. Dodge Colorado Construction monthly magazine.