drainage master plan scope of services city

8/14/2019 Drainage Master Plan Scope of Services City

http://slidepdf.com/reader/full/drainage-master-plan-scope-of-services-city 1/8

of 8

Drainage Master Plan Scope of ServicesCity of New Orleans, Louisiana

Task 1: System Understanding

Task 1.3: Conduct Field Investigations and Survey of Major Drainage FacilitiesCamp Dresser & McKee Inc. (CDM) will conduct field investigations and surveys ofmajor drainage structures to supplement existing data. CDM understands thatavailable data to define invert elevations for the system are limited. To support Task 4,field survey will be completed to collect manhole rim and invert elevations for up to7,800 (approximately 15%) of the system manholes. Due to the large number of datapoints that are needed the field survey will include verification of pipe sizes and systemconnectivity in only 10% of the manholes surveyed and the lowest invert elevation ateach manhole surveyed. Available Geographic Information System (GIS) data anddrainage system maps will be used to determine these system characteristics. Inaddition, CDM anticipates that field investigations will be needed to supplementavailable data describing the structural integrity of the New Orleans Department ofPublic Works (DPW) drainage system, and to characterize aspects of the system thatinfluence storm water quality. CDM understands that recovery efforts by the City ofNew Orleans (City) and others have been completed or are planned in the near term.CDM bases this budget estimate and schedule on the expectation that efforts by otherswill be adequate for collecting data needed to complete the structural and storm waterquality elements of Task 5, and that data verification or supplemental data collectionwill be limited to general field reconnaissance and inspection of up to 520(approximately 1%) of system manholes. If additional effort is needed to addresscritical data gaps, CDM will provide DPW with recommendations and a proposal for

completing the additional effort.

Task 1.4: Review and Update Existing Geographic Information System Data CDM will review existing GIS data of the drainage system that DPW is responsible formaintaining. In support of model development under Task 4, CDM will updateexisting GIS data using available system maps, as-built plans, and collected field surveydata for up to 7,800 storm water system elements. Updated invert elevations andspatial coordinates are anticipated from the data collection effort under Task 1.3.Feature updates from available drainage system maps and as-built plans are anticipatedto include width of ditch, pipe diameter, length, material, location, and connections.



Drainage Master Plan Scope of ServicesMarch 25, 2009

Task 1.6: System Characterization Report Section CDM will prepare a report section to document the System Characterization effort thatincludes the following:

An understanding based on available information of the asset inventory, currentoperation, authority of stakeholders, capacity and condition of the DPWdrainage system. Effort included under Task 4 and 5 is anticipated to further

refine the system understanding with the completion of additional quantitativeanalyses.

Summary of drainage system characteristics based on available data Existing and proposed study area characteristics based on available data

Task 2: Data Management

Task 2.1: Research Current Data Management ProceduresCDM will conduct interviews of up to three DPW staff to confirm current datamanagement procedures used to track drainage system maintenance and

improvements

Task 2.2: Develop Standard Data Management ProcessCDM will develop a standard data management process that defines data format, datacontent, data collection, data storage, and data tracking for the project. The datamanagement process will be submitted to DPW for review and approval, and will beapplied during completion of this scope of work.

Task 2.3: Data Development and Submittal In accordance with the data management process defined in Task 2.2, CDM will submitdata collected under this scope of work under Task 1.3 and Task 1.4 to DPW forinclusion into the existing data sets currently maintained.

Task 3: Hydrologic and Hydraulic Model Software Evaluation andSelection

SWMM 5 was chosen as the H&H software package for development of the Drainage Master Plan.

Task 4: Hydraulic Model Build and CalibrationCDM will apply the US EPA Storm Water Management Model (SWMM) Version 5 for

this drainage master plan. SWMM 5 is a public domain hydrologic, hydraulic andwater quality model tool with all the features necessary for this program, and it isaccepted by the FEMA for floodplain applications.

of 8




Task 4.1: Define Model Approach CDM will develop a report section to document key aspects of the model approach.Model approach elements will include:

Description of model setup process Definition of pipes and facilities to be included in the model Definition of basin planning areas Needed GIS data development and processing needed to support the model

build Definition of applicable precipitation, both for calibration and assessment Description of baseline conditions Description of future conditions Identification of available data for model calibration Definition of model calibration process and objectives Discussion of anticipated short term and long term applications of the system

model Discussion of anticipated coordination with other agencies with respect to model

approach, development, and maintenance.

Task 4.2: Model Setup CDM will develop a preliminary model approach which will be presented to DPWduring a one-day workshop for finalization.

CDM will develop a baseline condition hydrologic and hydraulic model. Because of theconnected nature of the S&WB drainage system and the DPW drainage system, CDMhas budgeted for DPW to obtain and provide the S&WB hydrologic and hydraulicsystem model for CDM’s use during this task. CDM anticipates that Task 4.1 willdefine baseline land use conditions, future land use conditions and baseline drainagesystem conditions. CDM’s level of effort for this task is based on explicit inclusion ofdrainage system elements between 18 inches and 36 inches (up to 685 miles of pipe),with system simplification where possible with continuity of pipe size and less than0.5% change in slope. CDM will estimate appropriate boundary conditions at locationswhere the DPW drainage system connects to drainage facilities that are theresponsibility of other agencies. If DPW or CDM determines that additional detail isrequired or that downstream facilities need to be modeled then CDM will provide DPWwith recommendations and a proposal for completing the additional effort that wouldbe required.

Task 4.3: Model Calibration, Application, and Report Section As determined during Task 4.1, CDM will calibrate the baseline condition model toavailable local rainfall data, flow data, and observed extent of flooding (available highwater marks). CDM anticipates the effort under this task to occur in two parts. Thefirst phase will include model validation with available information to describe andquantify drainage system performance. The second phase will include comparison ofmodel results to measured flow data. CDM assumes that calibration will be completed with

a minimum of two (2) rainfall events, and as many one (1) inch/twenty-four (24) hour events as

of 8




occur within the 12 week period for a maximum of 20 locations throughout the DPWdrainage system. Selection of the most appropriate events for calibration purposes will beagreed upon by DPW and the CDM team, in case the number of events is greater than required. See Task 4.5.2 for a definition of recommended calibration events.

CDM will apply the calibrated models for the 2, 5, 10, and 25 year ½-hour design storms

and the 100-year 24-hour design storm using an NRCS (formerly SCS) Type III rainfalldistributions for existing and future land use conditions. CDM will develop peak floodstage summary tables for up to 1950 junctions and tables of peak flows for outfalls tothe S&WB storm water system.

CDM will identify flooding problems based on the depth of flooding and develop aflood location summary layer in the GIS. CDM will summarize model calibration andresults in a report section.

Task 4.4: Model Maintenance Plan Report Section CDM will develop a plan and process for continued maintenance and updates to thebaseline model and relevant DPW GIS data. The plan will also include recommendedtraining for DPW staff to gain and maintain proficiency with the model software.

Task 4.5: Flow Monitoring In support of Task 4, flow data will be collected by CDM at strategic locations withinthe system for comparison with simulation results.

Task 4.5.1 Flow Monitoring PlanCDM will and review the available flow data, obtained by DPW from the S&WB, anddetermine locations for up to 20 flow meters. CDM will perform field reconnaissance to

determine the adequacy of the locations selected in the flow monitoring plan. The planwill include descriptions of monitoring equipment, locations and when the flow meterswill be deployed. CDM will submit the recommended flow monitoring plan to theDPW for review and approval.

Task 4.5.2 Flow Meter Installation and Data CollectionCDM will install, calibrate and maintain installed flow meters at the locations identifiedin the approved Flow Monitoring Plan. To define level of effort, CDM assumes that 20flow meters will be installed in the DPW drainage system (less than 36-inch diameter)for a period of 3 months.

The minimum rainfall event for calibration will be one inch in 24 hours. The minimumdifference between the two rainfall calibration events will be ½-inch. If two rainfallevents that meet these standards are not captured during the first 12 weeks of themonitoring period, CDM will provide the DPW with recommendations and a proposalfor fees associated with the extension of the flow monitoring period for immediateprocessing by DPW.

of 8




Task 4.5.3 Flow Monitoring Report SectionA report section will be prepared by CDM to present and quantify the collected flowdata. The report section will include documentation of the flow meter installations, fieldcalibrations, maintenance logs, data review and data processing.

Task 4.6: Rain Fall Monitoring

For model calibration purposes, CDM assumes that adequate precipitation gauges arelocated throughout the study area to correlate rainfall with measured flows in thedrainage system. If a lack of existing precipitation gauges is identified, CDM willprovide the DPW with recommendations and a proposal for installation of additionalgauges for measurement during the flow monitoring period.

Task 4.6.1 Rain Fall Gauge Installation and Data CollectionCDM will install, calibrate and maintain rain fall gauges at locations identified by CDMand approved by the Department of Public Works. To define level of effort, CDMassumes that 16 tipping bucket, recording rain gages will be installed and monitored for

a period of 3 months. CDM will develop a report section documenting the gages,locations, and data collected.

Task 5: System Assessment

Task 5.1: Develop Planning Standards and Design Criteria

CDM will review existing drainage system design criteria relevant to hydraulicperformance. CDM will develop recommended planning standards and design criteriaapplicable to the hydraulic performance of the drainage system, including appropriaterainfall events to assess system capacity and develop potential improvements. CDMwill draft a report section summarizing this review.

Task 6: Review of Regulatory Requirements

Task 6.2 Regulatory Recommendations CDM will provide samples of regulatory ordinances which have been developed forsystems similar to the DPW system. Additionally, CDM will develop up to twoversions of municipal ordinances to incorporate planning standards and design criteriafor large residential, commercial, and industrial development and include these

recommended ordinances in a report section.

of 8




Task 7: Design Standard and Guidelines

Task 7.1 Review and Evaluate Planning Review ProcessCDM will evaluate DPW’s standard planning review process for new developmentsand redevelopment as it relates to the drainage system. Develop recommendations formodifications to the standard planning review process to incorporate updated planning

standards and design criteria. If necessary, recommend review process modifications toadhere to applicable regulations and ordinances.

Task 7.2 Review Standard Construction ProductsCDM will review standard construction products used by DPW for drainage systemimprovements and develop a list of potential new products based on technologyadvances. Develop recommendations for standard construction products to complywith updated design standards and applicable regulations. These products willinclude:

Pervious pavement

Rainfall capture basins• Detention

• Retention

• Rain gardens

• Infiltration basin Bioretention filtration system Gravity and Pumped Injection Wells Hydrodynamic devices

Task 7.3 Develop Technical Guidance for Drainage System Permits

Develop guidelines for permit applicants to follow during design and construction ofdevelopment and redevelopment projects to comply with applicable regulations andupdated drainage system planning standards and design criteria. The guidelines willinclude the following elements as they apply to the drainage system:

DPW’s plan review process Standard construction design details and specifications for DPW approved

standard construction products

of 8




Task 8: Maintenance Program

Task 8.1 Review and Evaluate DPW Maintenance ProceduresCDM will hold a one-day workshop with DPW to discuss, review, and evaluate DPWmaintenance procedures.

Task 8.2 Develop Maintenance Program Recommendations Report SectionCDM will develop maintenance program recommendations in a report section thatinclude drainage system maintenance responsibilities of DPW, property owners, andother agencies. Also provide recommendations for DPW maintenance activities and thefrequency of recommended maintenance.

Task 9: Rate Study

Task 9.1 Review Existing and Past DPW Funding CDM will collect information from DPW about existing and past funding that includes:

Current property tax millage rates dedicated to drainage facilities Existing and historical rates and rate increases for the drainage system over the

past ten (10) years and a summary of reasons for each of the past rate increases.

Task 9.2 Funding Alternatives for Drainage Expenditures CDM will develop up to three (3) funding alternatives to cover projected drainagesystem program expenditures

Task 9.3 Independent Review of Municipal Funding for Drainage Contact, collect and evaluate the following information from five (5) independentmunicipalities that are comparable to New Orleans:

Existing rate structure for drainage system costs Historical rate increases as they relate to drainage system costs during the last

ten (10) years Sources of drainage system related funding

Task 9.4 Recommended Rate Structure CDM will prepare a rate review report section that includes:

Interpretation of collected data described in the above items under this task Information collected from the independent municipalities surveyed Funding alternatives to cover the cost of the recommended CIP Recommended rate structure and rate changes

of 8




of 8

Task 10: Capital Improvement Plan

Task 10.1 Alternative Analysis CDM will recommend levels of service (LOS) for flood control improvements and willcomplete an alternative analysis of two (2) improvement options to developrecommendations for rehabilitation, repair, upgrade, and/or replacement of critical

drainage facilities to meet existing and future system needs.

CDM will apply SWMM for the respective design storms and the two alternatives forexisting land use conditions. CDM will produce summary tables of peak stages andflows for the two alternative conditions and compare these to existing conditions todetermine levels of improvement.

CDM will estimate capital, operation, and maintenance costs for the alternativessummarized by outfall planning area.

CDM will summarize the two alternatives, LOS recommendations, and results of thealternatives analysis in a report section. CDM will produce a GIS layer identifying thecomponents for the recommended alternative.

Task 10.2 Capital Improvement Plan and Drainage Master Plan Report CDM will develop a CIP plan report that includes recommended drainage systemimprovements to meet established hydraulic, structural and storm water qualitycriteria. The recommended improvements will include a project summary sheet foreach recommended drainage system improvement that includes a location map, projectdescription and estimated cost. The recommendations will also identify priorities ofdrainage system improvements and provide a recommended schedule for completingdrainage system improvements. Additional report content will include:

Capital costs that include construction cost and annual maintenance cost Assessment of cost effectiveness of the recommended alternatives Identification of environmental and other significant impacts of the proposed

drainage system improvements Outline of criteria that developers must follow for new construction or

modifications to the existing drainage system Summarization of all tasks completed in this scope of work, including report

sections submitted under previous tasks

drainage master plan scope of services city

Documents