M E M O R A N D U M

April 28, 2006

 

                     To:                  PBCSD Board of Directors

 

                     From:              Michael Niccum, District Engineer

 

                     Subject:          Forest Lake Reservoir Project

                 _________________________________________________________________________

 

PROJECT STATUS

 

Anderson Pacific Engineering Construction, Inc. (Anderson Pacific) made good progress on construction of the Forest Lake Reservoir Components of the Expanded CAWD/PBCSD Wastewater Reclamation Project.  The contractor performed initial testing of the microstrainers, plant feed pumps, chemical feed systems for chlorine injection and pH adjustment and miscellaneous mechanical and electrical equipment in the chemical building.  Instrumentation subcontractor Tesco Controls installed programming for the instrumentation controls located at the chemical and maintenance department buildings and calibrated a number of measuring devices required for automatic control of the treatment facility.  Recycled water from the reservoir is available for the distribution system through manual operation of the treatment facilities. 

 

The reservoir is filled with recycled water to the permitted storage capacity of 325 acre-feet or 105 million gallons.  No water has been observed to date from the leak detection system below the liner.  Water stored in the reservoir initially had a green tint indicating the presence of algae, which was confirmed by high chlorophyll and pH concentrations measured in water sample testing.  Poor water clarity in the reservoir was confirmed by a Secchi disc measurement of less than 18 inches.  Within the past two weeks the water in the reservoir become clearer with a Secchi disc measurement of approximately 6 feet and the green tint was replaced with a light brown tint.  Water samples are collected weekly and chlorophyll and pH concentrations also dropped significantly.

 

Professor Alex Horne, Professor Emeritus, Ecological Engineering, University of California at Berkeley and an expert limnologist, participated in the design of algae control measures including the mixer and air flow bubbler systems.  Professor Horne recently visited the project and indicated all reservoirs experience considerable fluctuations in algal growth levels initially.  He believes the initial green color was a large concentration of small green algae.  He collected water samples for microscopic examination, observed a species of rotifer that eat or graze on algae was abundant and the rotifers were healthy with full green guts.   Algal growth occurs in the upper layer of the reservoir exposed to sunlight.  Algae control measures were designed to keep the reservoir water moving and keep the algae from settling in the upper layer.  Professor Horne has recommended adding a species of

 

crustacean zooplankton that graze at a rate about 100 times greater than rotifers to help keep the reservoir balanced naturally.  While the application of chemicals like copper sulfate or chlorine is a very effective method of killing algae, the algae grazers are also killed and the natural balance of the reservoir goes back to square one.

 

A copy of the current construction schedule is attached.  Completed work items are indicated in red.  Substantial completion of the project, when the project improvements will operate automatically, is scheduled for May 19th and final completion is estimated at the end of May. 

 

Anderson Pacific has earned $10,977,046 or 94 % of the revised construction contract amount of $11,656,726.  E2 Consulting Engineers has earned $929,356 or 95 % of the budget of $978,420 for construction management services. 

 

ADDITIONAL  WORK

 

Change order number 11 was executed by the General Manager in April increasing the sum of the construction contract by $125,000 as described below.

 

Change Order No. 11 (+$125,000) 

a)      Install four security cameras mounted on two new poles near the outlet structure and on the chemical building.  Signals will be transmitted wirelessly to from the remote locations to the chemical building (+$65,000)

b)     Install fiber optic line between Forest Lake chemical building and maintenance building. (+$60,000)

 

Ten change orders totaling $720,726 have been executed to date increasing the contract value to $11,656,726.  The Board previously authorized the General Manager to approve change orders for this project within an aggregate limit of $775,000, or 7 % of the original contract amount of $10,936,000.    The four-way construction and operations agreement requires the consent of the Pebble Beach Company prior to reimbursement for any changes above the 5 % contingency level.   

 

 

Reviewed:     

 

General Manager: RA     Date:  4/21/06

 

Agenda Item No. 11A