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HomeMy WebLinkAboutMinutes 1988"DRAFT, NOT APPROVED" MINUTES OF FLOOD AND POLLUTION CONTROL COMMISSION May 11, 1988 Members Present: Alderman Margaret Wold, Chairman Alderman John Bleveans Alderman Norris Larson Dr. Michael Goodkind Dr. Jerry Handler Members Absent: Alderman Roberta Warshaw Alderman Beth Davis Staff Present: Richard J. Figurelli, Supt. of Water s Sewers David Stoneback, Asst. Supt./Operations ,Tames Wolinski, Asst. Supt./Administration Others: Stephen T. Pudloski The meeting was called to order by the Chair at 7:50 F.M. Chairman Wold asked for a motion on her proposal to submit Steve Pudloski's name as a citizen member of the Flood and Pollution Control Commission (FPCC). Alderman Bleveans moved to recommend to the Honorable Mayor that at the earliest possible opportunity she appoint Steve Pudloski to the FPCC as a citizen member. Seconded by Dr. Handler. There being no further discussion, the Commission voted unanimously in favor of the motion. The minutes of November 18, 1987 were approved after a correction was made to the spelling of Dr. Goodkind's name on page 3. LONG RANGE SEWER PLAN Status Report Mr. Stoneback reported on the progress of the SWIM Team and the contracts for cleaning and TV inspection of sewers --hroughout the City. He also reported that from these inspecticns a list of major sewer failures, in need of immediate reps:-r, were made. Eight of these repairs are scheduled to be made with in-house personnel and a contract is being developed to make other spot repairs beyond the department's capabilities. The Chair asked for a clarification on the extent of some of these repairs. Mr. Stoneback explained that some could be as long as a block that were structurally failing and some may be only at the point where a house lateral was connected and a failure had occ,1rred. 11-1r. Figurelli commented that due to the large amount c: `ai.,ares at break-in connections to the main sewer, a policy �: requiring a sewer tap and sleeve for house laterals is now being implemented. a _2- Mr. Stoneback also reported that Alvord, Burdick & Howson had begun to prepare plans and specifications to make some of the needed repairs on the large diameter sewers that were discovered through their inspection. He also noted that this year we had allocated $60,000 for a vapor -rooting contract to chemically treat sewers that had tree root problems as indicated by the TV inspection. Sewer Improvement Expenditure Update The Commission accepted the report on expenditures made during Fiscal Year 1987/88. The Commissin reviewed the proposed expenditures for Fiscal Year 1988/89. Discussion ensued. Mr. Stoneback explained that we were not sure at this time what would be expended in the Research Park or when TIF funds would be available, therefore the amount shown in the 6700 account is the balance of the budgeted funds. Mr. Figurelli responded to the Chair that the unimproved streets listed were scheduled for this year and that sewer improvements would be made in conjunction with those projects. PROGRESS REPORT ON BASIN B03 Mr. wolinski reported on the meeting the SWIM Team held with Mr. Robert Molzahn, and his staff from Harza Engineering, to discuss the progress of their work on Basin B03. They have developed working computer models of the sewer system in B03 which includes the runoff hydrographs and transport block. The program will now be calibrated and alternatives studied to develop solutions which will be applied to the Long Range Sewer Improvement Program. This will be done as soon as flow monitors are received and installed in selected sewer lines at the manholes. The Chair asked if similar studies would be conducted in each basin. Staff responded that policies established in this first basin would be applied to all basins. The aerial topography photos and other studies and information being gathered will aid in developing working computer models for each basin as it is analyzed. Alderman Bleveans asked what this study will actually show as compared to all the previous studies we've had done and if we were getting close to the end of the studies. Staff explained that this was more than a study, that this was the actual development of preliminary designs and the beginning of solving the problem. This computer program will tell us what effect replacing or upsizing pipes, as proposed in the CH2M hit, study, will have on the rest of the basin and whether tha_ wcu?d be one of the solutions. -3- OTHER BUSINESS Alderman Larson discussed the need to keep storm or standing water in the City to a minimum to thwart the proliferation of the Tiger mosquito. It was also suggested that the North Shore Mosquito Abatement District be contacted to spray or treat known ponds of water. The next FPCC meeting was scheduled for July 13, There being no further business the meeting was adjourned at 9:20 P.M. Respectfully submited, Richard J. tigur lli "DRAFT, NOT APPROVED" il r "DRAFT, NOT APPROVED" MINUTES OF FLOOD AND POLLUTION CONTROL COMMISSION July 13, 1988 Members Present: Alderman Margaret Wold, Chairman Alderman Norris Larson Alderman Roberta Warshaw Alderman Beth Davis Dr. Michael Goodkind Members Absent: Alderman John Bleveans Dr. Jerry Handler Staff Present: Richard J. Figurelli, Supt. of Seater & Sewers David Stoneback, Asst. Supt./Operations James Wolinski, Asst. Supt./Administration Jim Tonkinson, City Engineer Bruce Zimmerman, Asst. City manager Others: Robert Molzahn - Harza Environmental Services John Velon - Harza Environmental Services Wade Moore - Harza Environmentil Services The Flood and Pollution Control Commission met on July 13, 1988, in the City Council Chambers. The Chair called the meeting to order at 7:55 P.M. The minutes of May 11, 1988 were unanimously approved as submitted. The next order of business was the Long Range Sewer Plan and the analysis of Basin 803. Mr. Figurelli introduced Mr. Robert Molzahn and his staff from Harza Environmental Ser•.•ices to report on the progress of their work in Basin B03. Mr. Molzahn explained the basic purpose of lookinc at Basin B03 as a sample basin to develop a city wide program wto explore the ramifications of certain policy questions. 11 What frequency and duration of haseren,� and street flooding are acceptable? 2) To what extent will relief be provide: throughout each basin? The first policy issue also raises the question of whether or not basements will be protected from flooding better t]-an streets from flooding. without inlet control or separate -rtorm s�•wers, the combined sewer system will protect streets fr,7 floodinq better than it will protect basements. -2- The second policy issue addresses uniformity of protection. Projects that provide parallel relief for a portion of the basin will leave the upstream portion subject to overloading. In upstream areas the improvement will be primarily a reduction in duration of flooding rather than a reduction in its frequency. Chairman [fold asked why Basin B03 was chosen. Mr. Tonkinson explained that this basin has many of the typical problems found throughout the City, its small enough in size to easily analyze, and there are some surfacing and paving projects scheduled for the next few years which can be accomplished in conjunction with sewer improvements. Mr. Molzahn then proceeded, with the use of visual aids, to explain the sewer system and computer program analysis of B03. He explained the model now had to be calibrated for accuracy with the use of flow monitors which the City had purchased and were installing at key points to measure rainfall and runoff into the sewer system. Mr. Molzahn introducted two relief options that were being looked at in this analysis. A parallel relief scheme, whereby a second sewer line was run alongside the existing sewer, and a perpendicular relief scheme in which the new sewers are generally installed perpendicular to the existing system. Discussion ensued relating to the pros and cons of each approach. Inlet control or restrictors to pond water on the street for a time could be part of these options depending on the particulars of each basin or area of basin. It was stated a variety or combination of solutions could be used in each basin. Mr. Molzahn said there are two issued involved, which are engineering and costs related to each of these solutions, that needs to be addressed. Through the use of graphics, he illustrated the results of the computer program and what flooding could be expected in a storm of two-year duration and .:ear duration;. lie now need to look at topography maps, which rir- now being made, to determine where overland flooding would occur. The Chair asked if there were other policy issues other -than those brought forward tonight. Mr. Molzahn and staff responded that the information being presented was to keep tle Commission informed of the progress of the analysis to be s 3r•= the_.• appre•:ed of the Oirection it was going_ and that it was prr;, -ire to maK,- any policy decisions at this time. The intent k•a= only to introduce criteria that may be applied throughout -_';e City. The Chair asked if the program or plan we decided on would be done one basin at a time. Staff replied that a basin or group of basins was being studied to determine some policy decisions an,c criteria, but that the work would be influenced by other projects throughout the City such as street paving and rr-s--irfacing. A. .11 -3- The Chair thanked Harza for their presentation. The next meeting was scheduled for September 14, at 7:45 P.M. in Room 2404 of the Civic Center. There being no further business the meeting was adjourned at 9:55 P.M. Respectfully submitted, "DRAFT, NOT APPROVED" "DRAFT, NOT APPROVED" MINUTES OF FLOOD AND POLLUTION CONTROL COMMISSION November 16, 1988 Members Present: Alderman Margaret Wold, Chairman Alderman Norris Larson Alderman Roberta Warshaw Alderman John Bleveans Alderman Beth Davis Members Absent: Dr. Michael Goodkind Dr. Jerry Handler Staff Present: Richard J. Figurelli, Supt. of Water & Sewers David Stoneback, Asst. Supt./Operations James Wolinski, Asst. Supt./Administration Jim Tonkinson, City Engineer Tom Robins, Chief/Distribution & Sewers Patrick Leahy, Engineering Aide Others: Robert Molzahn - Harza Environmental Services John Velon - Harza Environmental Services Wade Moore - Harza Environmental Services The Flood and Pollution Control Commission met on November 16, 1988, in Room 2404 at the Civic Center. The Chair called the meeting to order at 7:50 P.M. The minutes of July 13, 1988 were unanimously approved as submitted. The next order of business was the Long Range Sewer Plan and the continued analysis of Basin B03. Alderman ti;arshpw lodged a complaint that she felt there was not enough time to read the report which was delivered the day before the meeting. Mr. Figurelli apologized and explained the intent was only. to get the supplementary report, which answered the questions raised at the last meeting, to them prior to the meeting and that Mr. Molzahn was here from Harza to make a presentation on this report. The Chair then asked hIr. Molzahn to begin his presentation. Mr. Molzahn said he would review the original report and then go over the contents of the supplementary report. He stated we are addressing two problems, street ponding or flooding and basement back-ups caused by surcharged sewers. Through the use of graphics, he illustrated the results of the computer program and what flooding_ could be expected in storms of two and five year -durat-ian.. He also reviewed the two relief options, a paralled or perpendicular relief scheme. -2» Mr. Molzahn then moved on to the draft report supplement which presented the results of model calibration, revisions to the preliminary findings, and information regarding partial sewer separation. This new information provided a basis to address two major policy issues, what frequency and duration of basement and street flooding are acceptable and to what extent will relief be provided throughout the basin. Adjustments were made to the computer model characterization to match the data from the flow monitors during two September storms. Results showed the computer model to be very conservative and were adjusted to provide for a slightly conservative design giving runoff volumes of 40% safety factor. This made the improvements which would be provided by the relief sewers proposed significantly greater than indicated in the Draft Report. In the perpendicular relief sewer scheme the revised sizes and lengths result in revised construction cost estimates. For the 2 year design storm system the construction cost estimate is revised from $4.5 million to $3.5 million. For the 5 year design storm estimate, the construction cost estimate is revised from $6.4 million to $4.2 million. The revised costs range from $17,500 to $21,000 per acre of basin relieved. Inlet control to the combined sewers such that all excess flow is retained on the street is an alternative to this approach. The very low relative capacity of the smaller, lateral sewers requires that all runoff from rain intensities greater than 0.2"Ar to 0.4"/hr be stored or diverted at street level. Upsizing the entire combined sewer system to reduce street ponding is judged prohibitively expensive and disruptive. The only remaining option is partial sewer separation. The alternative of partial sewer separation wa-s approached by initially assuming that no runoff would be allowed into the existing combined sewers. The topographic maps were then studied to evaluate where surface runoff would flow and eventually pond. These points of ponding were then provided with storm sewer inlets and a system of storm sewers were developed and sized to convey the runoff to the North Shore Channel. The estimated construction cost of the partial sewer separaticn scheme designed for a 5 year storm is $3.7 million. Cv.7pared to the perpendicular relief sewer schemes, this alternative provides better protection of basements. With respect to street ponding, this scheme will cause 60 to 90 minutes of street flooding wherever there is no new storm sewer. The two approaches have similar construction costs, but quite different performance levels. Relief combined sewers will provide about a 10 year level of protection for almost all streets and reduce the annual probability of basement flooding to N -3- between 10% and 20% (once in 10 years and once in 5 years) throughout the basin. The partial sewer separation approach will reduce the annual probability of basement flooding to less than 5% (once in 20 years) (contingent on development of acceptable, restricting inlets), but street ponding in several residential blocks will occur for up to 60 minutes annually. This street ponding can be reduced by extending the storm sewer system and adding to the construction cost. The Chair opened the meeting to general discussion of the two alternatives that Mr. Molzahn presented concerning level of protection, flexibility of policy adopted, cost, equity, street ponding, and damage to streets. The Chair noted that a common element to both alternatives for Basin B03 is a sewer along Poplar Street. This street is currently being designed for paving by City staff and a decision on underground utilities is required to carry this local project forward. This study indicates that a 48" sewer can be designed as part of this street project without committing to either the perpendicular relief combined sewer scheme or the partial storm sewer separation scheme at this time. Alderman Bleveans moved to proceed with the design of the 48" sewer. Seconded by Alderman Larson. The motion was approved unanimously. The Commission also approved the concept of the partial sewer separation scheme and directed Staff to further examine this concept. The next meeting is scheduled for January 18, at 7:45 P.M. in Room 2404 of the Civic Center. There being no further business, the meeting was adjourned at 9:05 P.M. Respectfully submitted, "DRAFT, NOT APPROVED"