Charles City, iowa permeable pavement project report

Charles City Green Streets Evaluation and Design Report November 9, 2009

Prepared For Charles City 105 Milwaukee Mall Charles City, Iowa 50616 Prepared By Conservation Design Forum 375 W. First Street Elmhurst, Illinois 60126

Charles City Green Streets Evaluation and Design Table of Contents I. Introduction and Background...........................................................................1 II. Existing Conditions ..........................................................................................1

A. Background Data ..................................................................................1 1. Neighborhood Characteristics....................................................1 2. Topography, drainage, & Utilities ...............................................1 3. Floodplain ..................................................................................2 4. Soils ...........................................................................................2 5. Pavement Condition...................................................................3

B. Hydrologic Analysis ..............................................................................3 C. Analysis Results ...................................................................................4

III. Stormwater Management Plan ........................................................................5 A. Project Goals ........................................................................................5 B. Design Alternatives...............................................................................5

1. Replacement Storm Sewer ........................................................5 2. Stormwater Detention ................................................................5 3. Permeable Pavement Streets ....................................................6 4. Bioretention System...................................................................8

C. Recommended System.........................................................................9 D. Recommended System Performance Evaluation ...............................10

1. Prototype System Evaluation ...................................................10 2. Neighborhood System Evaluation ............................................13

E. Estimated Costs..................................................................................14

List of Tables Table 1: Existing Conditions Modeling Results ....................................................4 Table 2: Prototype Modeling Results .................................................................12 Table 3: Proposed Conditions Modeling Results ..............................................13 Table 4: Estimated Project Costs.......................................................................14

List of Figures (Follows report text) Figure 1: Project Location Figure 2: Flood Insurance Rate Map Figure 3: Project Drainage Boundary Figure 4: Prototype Street Drainage Boundary Figure 5: Prototype System Layout Figure 6: Prototype Street Cross Section Figure 7: Estimated Stormwater Discharges Figure 8: Estimated Project Costs

Appendices Appendix A: Detailed Subbasin Boundaries Appendix B: Permeable Paving Benefits, Limitations, and Alternatives Appendix C: Street Renderings and Engineering Cross Sections Appendix D: Project Cost Estimates

Charles City Green Streets Evaluation Page 1

I. Introduction and Background The historic west neighborhood of Charles City is experiencing nuisance flooding as well as deteriorating roadway pavement. The streets are primarily asphalt pavement with curb and gutter drainage to storm sewer inlets. Residents and City staff have reported nuisance ponding and flooding as a result of deteriorating drainage components and insufficient density of storm sewer to provide drainage throughout the neighborhood. The neighborhood is located west of the downtown commercial district and is generally bounded by the Chicago, Milwaukee, St. Paul & Pacific Railroad to the north, Ferguson Street to the south, Kellogg Street to the west and Johnson Street to the east. Although the area of concern is restricted to these boundaries, the area is influenced by drainage from outside this boundary. The neighborhood is also within close proximity to the Cedar River. However, the study area is located outside the floodplain of the River. The project area is shown in Figure 1. In May 2009, Charles City retained Conservation Design Forum to evaluate the system and develop a plan to address the identified issues. This report documents evaluation of the existing system and a proposed plan to address the identified issues.

II. Existing Conditions

A. Background Data

1. Neighborhood Characteristics The neighborhood follows the historic grid street pattern of the City with streets running southwest to northeast and southeast to northwest. The blocks are uniform in size with the northeast running streets having 330 foot blocks and the northwest running streets having 395 foot blocks. Most of the homes in the neighborhood are served by alleys that run in the general direction of drainage toward the River (northeast to southwest). The alleys are gravel but most have concrete aprons at the street.

2. Topography, Drainage, and Utilities The only existing source of topographic information was the USGS 7.5 minute quadrangle maps with a 10-foot contour interval. Due to the very flat conditions of the neighborhood, the 10-foot contour interval was insufficient to perform a drainage analyses. To provide necessary information for this study as well as suitable information sufficient for future reconstruction of the streets, a topographic survey was commissioned by the City and completed by Erdman Engineering, P.C. The survey included one-foot contours, within 30 - 60 feet of the right-of-way. The topographic survey indicated that slope of the street profile varies from 0.25% to 0.50% in most locations. This is very flat is likely contributing to ponding along the edge of pavement in many areas.


The Erdman survey also included rim, invert, and size information for sanitary and storm sewers and locations of water main and other utilities. A storm sewer pre-rehabilitation video survey was completed by Aries on August 10, 2009. The storm sewers along Joslin from Richings to Ferguson, Hulin from Joslin to Johnson and Spriggs from Johnson to Jackson, were videoed. The storm sewer infrastructure in these tapes was in good shape, overall, containing small areas of cracked pipe and extensive sediment throughout. Although the storm sewers are generally in good condition, many of the catchbasins at the intersections are in very poor condition and collapsing into the pavement. In addition, gutter along the edge of pavement is missing or in poor condition in many areas. This is leading to poor drainage and ponding in many areas.

3. Floodplain The study area is located in the Cedar River watershed and is located within several blocks of the River. Although the River has flooded portions of the City in the past, the study area has not been flooded by the River and is not located with the 100-year floodplain as depicted on the Flood Insurance Rate Map (FIRM) (Figure 2).

4. Soils The Floyd County Soil Survey (USDA, April 2009) indicates that the entire study area is composed of Waukee Loam, 0% to 2% soils. In the County report, this soil type is characterized by very flat (0 to 2% slope) but well drained conditions. The surface soils to a depth of 19” are loam and the subsurface soils below that depth are sand. The depth to water table is reported to be greater than 80 inches below the surface (80 inches is the deepest level reported by the county surveys). These soils are considered Hydrologic Soil Group B. A geotechnical investigation was conducted by Terracon Consultants, Inc for the study area. One boring was conducted per block. The investigation indicated conditions generally consistent with the County soil survey. The depth to the sand layer varied from two to six feet and the depth to water table generally varied from 12 to 14 feet with a depth to water table of 8.5 feet in the boring near the intersection of Howard and Ferguson. The RFP for the investigation requested recommendations for pavement design as well as permeability testing of the sand layer. The investigation found fill soils in some borings to a depth of two to six feet, with an average depth of two feet. Because the fill soils had not been properly compacted for roadway construction, the investigators recommended removal of the surface soils to a depth of 24 inches to prevent excessive and differential settlement. Three permeability tests were conducted on samples taken from the sand layer. The hydraulic conductivity testing showed permeability rates of 0.88, 1.70, and 1.60 inches per hour.


5. Pavement Condition A pavement condition report was conducted by the Iowa Pavement Management Program and the Center for Transportation Research and Education through the Iowa State University. Each section of roadway was given a PCI, or pavement condition index, ranging from very poor to excellent. The streets located within the project area range from excellent to very poor with most streets in the poor range. Illinois and Johnson Streets were classified as fair to good condition. Howard Street, Joslin Street, Iowa Street, and Kellogg Avenue were classified as poor condition. Hulin and Spriggs Streets were classified as very poor condition.

B. Hydrologic Analysis Using the soils, topographic, and storm sewer utility information, an assessment of the existing drainage system was conducted. The system was evaluated using the NRCS curve number and unit hydrograph methodology in HydroCAD v9.0, a software modeling system produced by HydroCAD Software Solutions. Based on the County soils report, the soils in the study area are Hydrologic Soil Group B soils. The systems were analyzed using the rainfall amounts and frequency distributions from Bulletin 71, also known as Midwest Climate Center Research Report 92.03. The 2-, 10- and 100-yr return period events were analyzed using the 1-, 2-, 3-, 6-, 12-, 18- and 24-hr storm durations to determine the capacity of the existing system for the critical duration rainfall events. As recommended within Bulletin 71, The 1st Quartile Huff distribution was used for the 1-, 2-, 3-, and 6-hr storm durations. The 2nd Quartile distribution was used for the 12-hr duration, and the 3rd Quartile distribution was used for the 18- and 24-hr durations. To evaluate the individual storm sewer reaches, the drainage area was divided into subareas using the topographic information provided by Erdman Engineering. This topographic survey contained information from the roadway centerline to approximately 30-60 feet beyond the right-of-way. It was used to determine ridgelines, roadway slopes and individual storm sewer inlet drainage area information. In addition, confirmation of ridgelines and other survey information was completed during a site visit on August 13th. In most areas, the drainage divide for the housing lots occurs at the middle of the building. Front yard runoff combines with runoff from the streets and flows down the gutter toward the storm sewer inlets at most intersections. The rear yards typically drain toward the alleys, which subsequently drain to the street. The runoff from the yards, streets, and alleys drain to the existing storm sewer infrastructure. Most of the intersections have catch basins and storm sewers. However, there is no storm sewer under Illinois or Iowa Streets. Thus, several of these intersections do not have catch basins and therefore runoff to those intersections must continue past the intersection to the next intersection. When flow rates exceed the capacity of the storm inlets or storm sewer, excess runoff continues down the gutter to the next intersection. At Joslin and Hulin, all the streets


drain toward the intersection so excess runoff will pond in the intersection until deep enough to exceed the high point on Joslin between Hulin and Ferguson. These drainage patterns were used to develop a drainage area map that was then used to develop an existing conditions model using HydroCAD. The drainage area map is shown in Figure 3. Detailed subbasin boundaries used to determine storm sewer discharges is included in Appendix 1. To determine runoff rates and volumes, the following curve numbers were used within the existing conditions model. Roadway Surface: 98 (NRCS TR-55, Paved parking lot, roofs, driveways) Unconnected Imp. Surface: 98 (NRCS TR-55, unconnected impervious surfaces) Open Space: 61 (NRCS TR-55, lawns, grassy open areas) The HydroCAD model produces hydrographs and those hydrographs are routed through the storm sewer system. Overflow down the gutter during events that exceed the storm sewer capacity was also modeled.

C. Analysis Results Table 1, below, shows the peak flow rates for the 2-year, 10-year, and 100-year events along with the critical storm duration that produced the peak flows for the existing street and storm sewer system. The storm sewer capacities for each of the intersections are also shown. Results are included for each intersection served by storm sewer.

Size Capacity* Peak Flow Critical Duration Peak Flow Critical

Duration Peak Flow Critical Duration

(in) (cfs) (cfs) (hrs) (cfs) (hrs) (cfs) (hrs)Howard & Hulin 8.00 0.42 1.68 2.00 5.00 1.00 12.12 1.00Howard & Ferguson 12.00 2.5 3.37 2.00 9.60 1.00 27.14 1.00Joslin & Spriggs 18.00 5.4 1.00 2.00 2.70 1.00 16.91 1.00Joslin & Hulin 18.00 8.5 2.35 2.00 6.62 1.00 22.91 1.00Joslin & Ferguson 24.00 16.0 2.94 2.00 8.27 1.00 23.91 1.00Johnson & Spriggs 27.00 18.6 10.44 2.00 24.96 2.00 77.32 1.00Johnson & Hulin 27.00 17.0 12.35 2.00 33.35 2.00 80.42 1.00Iowa & Ferguson 12.00 2.5 0.70 2.00 1.92 1.00 5.79 1.00

Flow rates that exceed storm sewer capacity* Full flow capacity with no surcharging

TABLE 1: EXISTING CONDITIONS MODELING RESULTS2-year Event 10-year Event 100-year EventStorm Sewer

As can be seen from the table, the storm sewers draining Howard at both Hulin and Ferguson do not even have 2-year capacity. The storm sewer draining Johnson at Spriggs and Hulin do not have 10-year capacity. The remaining storm sewers have 10-year or greater capacity, consistent with modern storm sewer design criteria. None of the storm sewers have 100-year capacity. At most intersections, the excess flow exceeding the storm sewer capacity drains down the gutter and the street. However, at Hulin and Joslin, where runoff must pond in the intersection before it can crest the downstream high point on Joslin, the computed peak elevation is 1009.20, which is approximately 1 foot above


the gutter line, flooding nearly the entire intersection and beginning to flood private yards on the west side of Joslin.

III. Stormwater Management Plan

A. Project Goals The purposes of the project include:

address existing poor drainage associated with missing and poor condition street gutters,

address poor pavement condition, reduce runoff volumes and rates to improve the performance of the existing storm

sewer system, and improve water quality and reduce runoff volumes for the project area to begin to

improve the quality of the Cedar River. The design standards followed included those provided by the City of Charles City, the Iowa Stormwater Management Manual, Iowa SUDAS (Statewide Urban Design and Specification Program) and those developed by CDF.

B. Design Alternatives There are a number of alternative systems that could be implemented to address the pavement, drainage, and water quality goals outlined above. Each of the systems that were considered are discussed below.

1. Replacement of Storm Sewer System Selected storm sewers could be replaced and additional storm sewers installed to address the storm sewer capacity and collapsed storm inlets. While increasing the size of the existing storm sewers and adding additional storm sewers could address the capacity and some of the ponding issues, it would not address several of the project goals including: nuisance ponding due to deteriorating street gutters; poor pavement condition; nor improving water quality and runoff volume reduction to improve the quality of the Cedar River. Further, the existing storm sewers are in relatively good condition and not in need of replacement. Thus, replacement of the existing storm sewers was not considered any further.

2. Stormwater Detention Stormwater detention facilities could be installed to reduce peak discharges within existing storm sewer systems. However, this neighborhood of Charles City is fully developed and there are no public parcels that could be used to locate a surface detention facility Further, like the storm sewer alternative, this system only addresses one of the project goals – storm sewer capacity issues. Thus, this alternative was not considered any further.


3. Permeable Pavement Streets Permeable paving could be used to replace the existing streets. Permeable paving allows rainwater falling on the surface of the pavement to pass through the surface and be temporarily stored in the gravel pavement base and/or infiltrated into the soils below the gravel base. There are many types of permeable pavement systems but the common trait is a pavement surface that allows rainwater runoff to pass through it rather than off it. For streets and daily use parking lots, the most applicable systems are constructed using interlocking concrete pavers, porous concrete, or porous asphalt. Beneath these pavement surfaces is a layer of open-graded stone that serves as the structural base as well as temporary storage of rainwater runoff. The temporarily stored rainfall runoff infiltrates into the subgrade and/or slowly drains into the storm sewer system. Depending on the permeability of the subgrade, these systems may include an underdrain system. A description of the benefits of permeable pavement and the permeable pavement types is included in Appendix 2. Although high permeability soils is not a prerequisite for using permeable pavement systems, the relatively high permeability sand layer in the Charles City project area makes this neighborhood highly suitable for a permeable pavement system. As discussed above, there are three basic types of permeable pavement and there are a variety of ways that the permeable pavement can be arranged within the ROW. The alternatives are discussed below: Permeable Pavers: Permeable Interlocking concrete pavers are manufactured with openings between pavers to allow water to pass through. Concrete pavers are manufactured of durable, 8,000 pound per square inch concrete. This is approximately twice as hard as typical cast in place concrete roads. A properly design permeable paver system has a design life of 50 years. The estimated unit cost of a permeable paver road is $530/linear foot for the road cross section proposed for Charles City. This includes removal of the existing pavement and installation of the stone base, required drainage, curbs, and the permeable pavers. It does not include the cost of sidewalks, driveways, and trees. Porous Asphalt: Porous asphalt is manufactured from a lean mix of asphalt that has a lower ratio of asphalt to aggregate. The lower asphalt content allows for continuous voids through the asphalt slab that allows water to pass through the surface. However, the lower asphalt content also results in a weaker pavement than conventional asphalt. Further, the expected life of porous asphalt is similar to or lower than conventional asphalt. The estimated unit


cost of porous asphalt road is $460/linear foot for the road cross section proposed for Charles City. This includes removal of the existing pavement and installation of the stone base, required drainage, curbs, and the porous asphalt. It does not include the cost of sidewalks, driveways, and trees. Porous Concrete: Like porous asphalt, porous concrete is manufactured from a lean mix of cement. Porous concrete suffers from some of the same limitations as porous asphalt such as lower strength and reduced life span. The estimated unit cost of porous concrete road is $590/linear foot for the road cross section proposed for Charles City. This includes removal of the existing pavement and installation of the stone base, required drainage, curbs, and the porous concrete. It does not include the cost of sidewalks, driveways, and trees. Asphalt Drive Lanes with Permeable Paver Parking Lanes: A hybrid system of asphalt drive lanes and permeable paver parking lanes was considered since a portion of many of the existing roads may still be serviceable. However, this system would require placement of ribbon curb on either side of the asphalt to serve as edge restraint for the permeable paver parking lanes. A cost study was performed for a typical 100 foot reach of road and the savings was found to be less than 5%. Utilizing two different paving types in the right of way requires two different maintenance regimes, resulting in staggered maintenance schedules and increased maintenance costs relative to either one of the two pavement types, alone. Finally, the smaller area of permeable pavement would result in a lower level of performance for reducing runoff volumes and rates. Selected System (Permeable Pavers): Although the estimated installed cost of permeable pavers is somewhat higher than porous asphalt (but lower than porous concrete), the increased durability, longevity, and aesthetics make permeable pavers the most cost effective solution. Further, there is virtually no savings and there is a reduced level of performance associated with using permeable paving in the parking lanes only. Replacing the existing paving with permeable paving can address all of the project goals, including: addressing nuisance ponding issues by installation a pervious surface and replacement of crumbling curb and gutter that would accompany the repaving project; reducing the load on the existing storm sewer system to address capacity issues; and improving water quality and reducing runoff volumes due to filtering of runoff through the pavement surface and infiltration into the underlying sand layer. Further, the water quality benefits of the permeable paving system makes it eligible for financing and grant


assistance under the Iowa’s ARRA Stimulus and SRF funding for Stormwater Quality Practices. The permeable pavement system would not capture runoff from the yards and alleys that drain to the street gutter and therefore would not have an opportunity to infiltrate. Thus, permeable pavement should be used in combination with other systems as described below. A permeable pavement system could also lead to increased infiltration and inflow into the existing sanitary sewer system if proper precautions are not taken. This can be addressed by capping the sanitary sewer main and lateral trenches with compacted clay.

4. Bioretention Systems Bioretention systems are composed of a surface of engineered soil underlain by a gravel storage layer. The engineered soils has relatively high permeability to allow runoff water to pass through the surface yet sufficient organic content and soil to provide a growing medium for plant material. Bioretention systems could be installed in a variety of ways within the street right of way to capture runoff from the streets and yards. Depending on the size and design of the bioretention system, it could address many of the project goals including: storm sewer capacity issues by storing runoff in the surface and the gravel layer to reduce runoff rates reaching the storm sewer system; and improving water quality and reducing runoff volumes reaching the Cedar River. However, the system would not address the issue of poor pavement condition. Thus, bioretention systems are being considered as a component of a permeable right of way system in combination with permeable pavement. There are several bioretention system options. Parkway Bioretention Swales: Bioretention swales could be installed in the parkway between the sidewalk and the curb. Runoff from the front yards entering the bioswale would infiltrate through the engineered soil and enter the gravel beneath the pavement. If the swales were sufficiently deep, they could provide treatment and infiltration for both the yards and excess runoff from the street surface running down the gutter. However, making the parkway bioretention swales sufficiently deep to accept runoff from the gutter is somewhat incompatible with preserving the existing parkway trees since the grade in the parkways would need to be lowered significantly to accept gutter runoff.


Bioretention swales are typically planted with either turf or with native and adapted plant species. Native species reduce the need for irrigation, herbicides, and pesticides. Although taller native vegetation can obstruct use of the parkway for unloading passengers from cars, it also discourages people from trampling the bioretention area. Trampling can also be reduced through the addition of a carriage walk. Intersection Bioretention Rain Gardens: Curb extensions could be installed within the street at the intersections to capture excess runoff flowing in the gutter. As with the parkway bioretention swales, runoff would filter through the soil and enter the gravel beneath the permeable paving. The curb extension system would be less subject to trampling, and could capture excess runoff from the street gutter without compromising all of the street trees. In addition, the system would be capable of providing at least 10-year infiltration capacity. The curb extension system would capture a greater proportion of runoff relative to the parkway bioretention swales since it would intercept excess runoff from the pavement as well as yard runoff. Cobble Infiltration Areas: Stone infiltration areas located in the triangular area between the service walks at the intersections could be used to provide drainage into the stone beneath the paving surface. The infiltration areas would be located behind the curb and runoff water draining through the gutter would enter the stone basin through a curb cut. Although the gravel in the stone basins have much higher drainage capacity than the engineered bioretention soil, the small area results in similar hydrologic performance as the parkway bioretention swales.

C. Recommended System To meet the stated project goals, the recommended plan is a system of interlocking concrete permeable pavers to address street runoff and bioretention systems to address runoff from the remainder of the block (yards and alleys). Renderings of the different bioretention options as well as engineering cross sections are provided in Appendix 3. The three bioretention options described in the previous section differ in three main areas: aesthetics, construction cost, and maintenance.

Aesthetics: The parkway bioretention swales and intersection rain gardens planted with non-turf vegetation would provide the greatest aesthetic impact. Properly managed, the areas could provide significant beautification. If improperly managed, they might appear weedy.

Cost: None of the alternatives are likely to affect overall cost of the project by more than 5% to 10%. However, due to the greater amount of curb, additional planting, and other system components, the intersection curb extensions would be the most expensive of the three alternatives.


Maintenance: There would be vegetative maintenance associated with the parkway bioretention swales and intersection curb extensions. The maintenance would primarily be associated with weeding and periodic supplemental planting to maintain proper appearance. The cobble infiltration areas will require periodic maintenance to remove leaves and other organic debris that could clog the surface. The maintenance would be similar to that required to keep curb storm sewer inlets clear. Parkway bioretention swale maintenance would be reduced by planting with turf such that the area would be maintained (mowed) by residents in a similar manner as current conditions.

The alternatives were reviewed with City staff and presented to the City Council. Due to concerns over maintenance and impacts on snow plow operation, City staff and City council rejected the intersection curb extension rain garden alternative. Council was also concerned about maintenance requirements associated with alternative (non-turf) vegetation in the parkway. Based on the above, the selected alternative was the cobble infiltration areas at the intersections supplemented with engineered bioretention soil in the parkway within the excavated area behind the curb. The parkway bioretention swales will capture yard runoff and the cobble infiltration areas will capture excess runoff from the pavement, providing a similar level of performance as the intersection rain gardens. The surface of the cobble infiltration areas at the intersections will be covered with cobble to ease maintenance (allow vacuuming of the surface) and improve aesthetics.

D. Recommended System Performance Evaluation The system was evaluated at two levels – street level and neighborhood level – using HydroCAD. For the street level evaluation, a prototype model was developed for a typical street and its tributary area block to determine the runoff volume and rate reduction resulting from the proposed system. For the neighborhood level evaluation, the permeable pavement and bioretention systems were inserted into the model used to evaluate existing conditions. The neighborhood model was used to evaluate the influence of the proposed system on the existing storm sewer system.

1. Prototype System Evaluation The prototype block used to design the system and evaluate performance was Hulin between Joslin and Iowa. This is a typical block that receives runoff from the front yards on the south side of the street and from the backyards and alley for the entire block on the north side of the street. The block and drainage area are shown in Figure 4. Figure 5 shows the layout of the system and Figure 6 is a cross section of the street for the proposed system. The runoff from various areas is treated as indicated below

Front yards: The front yards drain toward the street and are intercepted by the parkway bioretention swales. Runoff filters through the swale surface to the gravel below the permeable pavement system as depicted in Figure 6.


Back yards and alley: The back yards drain to the alley and the alley drains to the alley apron that includes a trench drain that is open to the gravel below the permeable pavement system as depicted in Figure 6.

Streets: Rain falling onto the surface of the street drains through the permeable pavement surface.

Overflow: Excess runoff from the parkway bioretention swale, the alley trench drain or, or the permeable pavement surface drains down the gutter to the cobble infiltration area where it can drain through to the gravel below the permeable pavement system.

Storm Inlets: For very large events that exceed the capacity of each of the systems described above, the excess runoff will drain to inlets located in the cobble infiltration areas and into the existing storm sewer.

The curve numbers used with in the proposed conditions models (both protype and neighborhood) are as follows: Permeable Pavement Surface: 98 (NRCS TR-55, Paved parking lots, roofs, driveways) Unconnected Imp. Surface: 98 (NRCS TR-55, unconnected impervious surfaces) Open Space: 61 (NRCS TR-55, lawns, grassy open areas) Runoff is generated based on the Curve Numbers above and that runoff is then treated and passed into the gravel beneath the permeable pavement system as described above. Runoff water that enters the gravel is storage routed using HydroCAD. The following assumptions were used in the modeling of the system.

Parkway Bioretention Swales: The design infiltration capacity of the amended soil is 2 inches per hour and the swale surface is four inches below the top of curb to provide time for infiltration through the soil. Infiltrated water enters the gravel storage beneath the permeable pavement. Excess runoff drains over the curb and into the gutter system.

Permeable Pavement Surface: The design infiltration capacity of the permeable pavement surface is 2 inches per hour. Infiltrated water enters the gravel storage beneath the permeable pavement. Excess runoff drains over the curb and into the gutter system.

Cobble Infiltration Area: The design infiltration capacity of the gravel surface is 100 inches per hour and the gravel surface is located six inches below the gutter line to provide time for infiltration. Infiltrated water enters the gravel storage beneath the permeable pavement. Excess runoff drains to a catch basin that drains to the existing storm sewer system.

Gravel Storage: The gravel storage beneath permeable pavement system has a design porosity (void space available to hold water) of 36%. Based on permeability testing (Terracon, 2009), the average infiltration capacity of the sandy soils below the silty sand surface soils is 1.4 inches per hour. To be conservative, a design infiltration capacity of 0.88 inch per hour was used in the modeling. Runoff volumes that exceed the capacity of the sandy soils, drains along the street right of way within the gravel. The design hydraulic conductivity


of the gravel storage layer is 0.13 feet per second. Drainage through the gravel was modeled based on Darcy’s law. Once the water level in the gravel rises to the elevation of the perforated pipe, the pipe provides additional capacity to convey runoff through the system. The perforated pipe drains to the existing storm sewer system and is assumed to have a free discharge.

Based on the HydroCAD modeling of the prototype system using the assumptions above, the system achieves the following performance.

As shown in Table 2, the proposed permeable pavement system achieves zero discharge up to the 2-year event. For the 10-year event, the runoff volume is reduced over 60% and the peak discharge is reduced over 90%. Even for the 100-year event, the runoff volumes and rates are reduced over 30%. Although not included within the table, the proposed permeable pavement system is able to fully infiltrate runoff from the 1.25 inch rainfall, also known as the 90% cumulative frequency event and is therefore treating runoff from at least 90% of storm events as required by the Iowa Stormwater Management Manual. The proposed system is well exceeding the minimum State requirement since the runoff from up to a 3-inch rainfall event is fully infiltrated. In addition to the runoff volume and rate reduction, the system would provide significant water quality benefits. Based upon the expected pollutant removal efficiency provided by the EPA found within the Iowa Stormwater Management Manual, the following pollutant load reductions would be expected:

Rainfall* Existing Proposed % Reduction6-Month Event

Runoff volume (inches)* 1.91 0.28 0 100%Runoff Rate (cfs)** - 0.59 0 100%

1-Year EventRunoff volume (inches)* 2.36 0.45 0 100%Runoff Rate (cfs)** - 0.79 0 100%

2-Year EventRunoff volume (inches)* 2.98 0.75 0 100%Runoff Rate (cfs)** - 1.1 0 100%

10-Year EventRunoff volume (inches)* 4.38 1.59 0.59 63%Runoff Rate (cfs)** - 1.7 0.12 93%

100-Year EventRunoff volume (inches)* 7.07 3.6 2.46 32%Runoff Rate (cfs)** - 3.3 2.2 33%* Based on 24-hour rainfall** Based on critical duration storm

TABLE 2: PROTOTYPE MODEL RESULTS


Porous Pavement System Total Suspended Solids: 65-100% reduction Total Nitrogen: 65-100% reduction Total Phosporus: 30-65% reduction Infiltration Trench Total Suspended Solids: 50-80% reduction Total Nitrogen: 50-80% reduction Total Phosporus: 15-45% reduction

2. Neighborhood System Evaluation Modeling of the neighborhood storm sewer system under proposed conditions consisted of similar ridgelines as in the existing conditions. However small changes were made due to additional high points that were placed within the roadway profile to assist in proper drainage. The proposed system also has a reduced street width of thirty-one (31’) feet from back-of-curb to back-of-curb. Using the same assumptions for each of the system components and using the drainage area boundaries depicted in Figure 3, a model of the neighborhood level system was developed. As with the existing system, the detailed subbasin boundaries are included in Appendix 1. The modeling results are shown in Table 3, below. Comparison of Tables 1 and 3 reveals that the permeable pavement system would reduce peak flows in all areas. Some areas show a much more significant reduction in flow than others due to offsite tributary flows from standard pavement surfaces. For the 2-year and 10-year events, peak flows are reduced at least 75% at all locations except on Johnson, where most of the flow is from outside the project area. The peak flow reduction is less for the 100-year event but reductions are at least 40% at all locations except on Johnson and at Iowa and Ferguson.

Size Capacity* Peak Flow Critical Duration Peak Flow Critical

Duration Peak Flow Critical Duration

(in) (cfs) (cfs) (hrs) (cfs) (hrs) (cfs) (hrs)Howard & Hulin 8.00 0.42 0.36 18.00 1.23 1.00 5.58 1.00Howard & Ferguson 12.00 2.5 0.36 18.00 2.34 1.00 14.20 1.00Joslin & Spriggs 18.00 5.4 0.00 - 0.13 24.00 3.88 1.00Joslin & Hulin 18.00 8.5 0.00 - 0.23 24.00 9.32 1.00Joslin & Ferguson 24.00 16.0 0.51 2.00 1.43 1.00 13.53 1.00Johnson & Spriggs 27.00 18.6 9.93 2.00 23.66 2.00 67.80 1.00Johnson & Hulin 27.00 17.0 10.55 2.00 25.22 2.00 69.81 1.00Iowa & Ferguson 12.00 2.5 0.16 2.00 0.40 1.00 4.59 1.00

Flow rates that exceed storm sewer capacity

TABLE 3: PROPOSED CONDITIONS MODELING RESULTSStorm Sewer

* Full flow capacity with no surcharging

2-year Event 10-year Event 100-year Event

Flow rates for both existing and proposed conditions are also shown in Figure 7. The figure shows flow rates through the storm sewers as well as overflow rates down the street where the storm sewers have insufficient capacity to convey the runoff draining to them. The storm sewer and overflow rates in Figure 7 reflect the fact that, under


surcharge conditions, the storm sewers are able to pass greater flows than their full flow capacity listed in Tables 1 and 3. Examination of the overflow rates in Figure 7 show that the storm sewers are able to provide at least 10-year capacity at all locations under proposed (post) conditions. For the Joslin storm sewer, even the 100-year event is accommodated without overflow. As described previously, flooding of the intersection of Hulin and Joslin would occur under existing conditions. Under proposed conditions, the flooding of the intersection would be eliminated up to the 100-year event.

E. Estimated Project Costs Cost estimates for the proposed permeable pavement system were prepared and are included in Appendix 4. The estimated cost for the system is summarized in Table 4, below and in Figure 8.

Table 4 – Estimated Project Costs Roadway Total Cost Kellogg Avenue $ 380,000 Howard Street $ 479,000 Joslin Street $ 487,000 Iowa Street $ 374,000 Spriggs Street $ 823,000 Hulin Street $ 999,000

Total $3,542,000

FIGURES

CHARLES CITY GREEN INFRASTRUCTURE

FEMA FIRM MAPFIG-2

11/10/09

09001.01

ATB

TP

DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS

C 2009 by Conservation Design Forum, Inc.

Conservation Design ForumCivil Engineer:

375 West First Street

Elmhurst, Illinois 60126

630.559.2000 Phone

630.559.2030 Fax

www.cdfinc.com

Client:

105 Milwaukee MallCharles City, Iowa 50616641.257.6309 Phone641.257.6331 Fax

SOURCE: FEMA

LEGEND

PROJECT

STUDY AREA

N

W

S

E


PROJECT DRAINAGE BOUNDARY

FIG-3

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DRAWN BY

CHECKED BY

DATE REVISIONS





630.559.2000 Phone

630.559.2030 Fax

www.cdfinc.com

Client:


BACKGROUND FROM GOOGLE EARTH N.T.S.

LEGENDPROJECT STUDY AREA

DRAINAGE AREA

STORM SEWER


PROTOTYPE STREET LAYOUT

FIG-5

11/10/09

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DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS





630.559.2000 Phone

630.559.2030 Fax

www.cdfinc.com

Client:

105 Milwaukee MallCharles City, IA 50616641.257.6309 Phone641.257.6331 Fax

1"=40'

COBBLE INFILTRATION AREA

PARKWAY BIORETENTION SWALES

PERMEABLE PAVING


PROTOTYPE STREET CROSS SECTION

FIG-6

11/10/09

09001.01

ATB

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DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS





630.559.2000 Phone

630.559.2030 Fax

www.cdfinc.com

Client:


SOURCE: CHARLES CITY GREEN INFRASTRUCTURE ENGINEERING PLANS

N

W

S

E


ESTIMATED STORMWATER DISCHARGES

FIG-7

11/10/09

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DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS



375 West First StreetElmhurst, Illinois 60126630.559.2000 Phone630.559.2030 Faxwww.cdfinc.com

Client:



Storm Sewer Flow

PRE POST2- 1.24 0.3610- 1.23 1.23100- 1.23 1.25

Overflow

PRE POST2- 0.44 0.0010- 3.77 0.00100- 10.89 4.33

Storm Sewer Flow

PRE POST2- 3.37 0.3610- 3.89 2.34100- 3.91 3.96

Overflow

PRE POST2- 0.00 0.0010- 5.71 0.00100- 23.23 10.24

Storm Sewer Flow

PRE POST2- 1.00 0.0010- 2.70 0.13100- 6.25 3.88

Overflow

PRE POST2- 0.00 0.0010- 0.00 0.00100- 10.66 0.00

Storm Sewer Flow

PRE POST2- 2.35 0.0010- 6.62 0.23100- 13.32 9.32

Overflow

PRE POST2- 0.00 0.0010- 0.00 0.00100- 9.59 0.00

Storm Sewer Flow

PRE POST2- 2.94 0.5110- 8.27 1.43100- 23.91 13.53

Overflow

PRE POST2- 0.00 0.0010- 0.00 0.00100- 0.00 0.00

Storm Sewer Flow

PRE POST2- 10.44 9.9310- 24.96 23.66100- 26.35 32.55

Overflow

PRE POST2- 0.00 0.0010- 0.00 0.00100- 50.97 35.25

Storm Sewer Flow

PRE POST2- 12.35 10.5510- 32.69 25.22100- 40.64 40.74

Overflow

PRE POST2- 0.00 0.0010- 0.66 0.00100- 39.78 29.07

Storm Sewer Flow

PRE POST2- 0.70 0.1610- 1.92 0.40100- 4.64 4.59

Overflow

PRE POST2- 0.00 0.0010- 0.00 0.00100- 1.15 0.00

8" S

TO

RM

8" S

TO

RM

8" STORM

12" STORM

12" STORM

12" STORM

12" STORM

12" STORM

18" STORM

18" STORM

18" STORM

27"

STO

RM

27"

STO

RM

27"

STO

RM

18"

STO

RM

18"

STO

RM

24"

STO

RM

LEGEND

Flow Path

Pre-Development Post-Development

Flow Flow

2-year Event 1.00 0.0010-year Event 2.70 0.13100-year Event 6.25 3.88

N

W

S

E


ESTIMATED PROJECT COSTS

FIG-8

11/10/09

09001.01

ATB

TP

DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS



375 West First StreetElmhurst, Illinois 60126630.559.2000 Phone630.559.2030 Faxwww.cdfinc.com

Client:



HULIN STREET

SPRIGGS STREETKE

LL

OG

G A

VE

NU

E

$380,0

00

$999,000

$823,000

JOSL

IN S

TR

EET

$487

,000

IOW

A S

TR

EET

$374

,000

$479

,000

HO

WA

RD

STR

EET

APPENDIX A DETAILED SUBBASIN

BOUNDARIES


PRE-DEVELOPMENT SUBBASINS

AP-A.1

11/10/09

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DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS





630.559.2000 Phone

630.559.2030 Fax

www.cdfinc.com

Client:


HO

WA

RD

ST

RE

ET

HULIN STREET

KE

LL

OG

G A

VE

NU

E

HO

WA

RD

ST

RE

ET

FERGUSON STREET

HULIN STREET

ILL

INO

IS S

TR

EE

T

SPRIGGS STREET

JOSL

IN S

TR

EE

T

IOW

A S

TR

EE

T

JOH

NSO

N S

TR

EE

T

STORM SEWER

RIDGELINE


POST-DEVELOPMENT SUBBASINS

AP-A.2

11/10/09

09001.01

ATB

TP

DATE

PROJECT NO.

DRAWN BY

CHECKED BY

DATE REVISIONS





630.559.2000 Phone

630.559.2030 Fax

www.cdfinc.com

Client:


KE

LL

OG

G A

VE

NU

E

HULIN STREET

HO

WA

RD

ST

RE

ET

HO

WA

RD

ST

RE

ET

SPRIGGS STREET

JOSL

IN S

TR

EE

T

HULIN STREET

ILL

INO

IS S

TR

EE

T

FERGUSON STREET

IOW

A S

TR

EE

T

JOH

NSO

N S

TR

EE

T

STORM SEWER

RIDGELINE

APPENDIX B PERMEABLE PAVING

BENEFITS

Appendix B – Permeable Paving Benefits, Limitations, and Alternatives - 1 -

I. Permeable pavement benefits, limitations & alternatives There are many types of permeable pavement systems but the common trait is a pavement surface that allows rainwater runoff to pass through it rather than off it. For streets and daily use parking lots, the most applicable systems are constructed using interlocking concrete pavers, porous concrete, or porous asphalt. Beneath these pavement surfaces is a layer of open-graded stone that serves as the structural base as well as temporary storage of rainwater runoff. The temporarily stored rainfall runoff infiltrates into the subgrade and/or slowly drains into the storm sewer system. Depending on the permeability of the subgrade, these systems may include an underdrain system.

A. Permeable pavement benefits Permeable pavements provide multiple benefits. First, as rainfall runoff passes through the surface of the permeable pavement, it is filtered of many pollutants common to urban and suburban rainfall runoff. Further, rainfall runoff released from the permeable pavement drainage system is much cooler than runoff from typical asphalt pavement, thereby reducing thermal impacts to downstream aquatic resources. In addition to the water quality benefits, permeable pavement systems provide stormwater rate and volume control benefits. Runoff that passes through the surface of the pavement moves laterally through the stone base, greatly slowing the rate at which that water moves through the system and providing time for infiltration and evaporation. In areas such as Carbon Cliff where soil permeability rates are relatively slow, underdrains are provided for proper drainage to prevent freezing in winter and excessive saturation of the subgrade. The discharge from permeable pavement underdrain systems can be restricted to meet release rate standards, where applicable. However, because the Carbon Cliff project is a retrofit of an existing system, no detention release rate standards apply to this project. Even with no restriction of the underdrain discharge, flow rates from the system are greatly reduced relative to conventional pavements, thereby reducing the necessary size of storm sewers, sometimes completely eliminating the need for storm sewers. Because water passes through the surface permeable pavement systems, the potential for ponding and icing is greatly reduced, even if potholes form over time. Anecdotal evidence from recent projects in the Chicago and Milwaukee area suggest that salting and other deicing activities can be reduced due to the shorter time that runoff is on the surface and able to freeze. Porous unit paving systems are extremely durable and capable of supporting heavy loads. Also, because of the open-graded stone base, the system is well drained and much less subject to frost heave than conventional pavement systems with a dense-graded base. Also, porous unit paving systems are flexible and, without breaking, can tolerate significant movement due to frost heave, poor soils, and other factors. Porous unit paving


(i.e., interlocking concrete pavers) can have a service life of over 50 years, which is two to three times longer than conventional asphalt or concrete pavement. Porous unit paving systems provide a significant aesthetic benefit relative to concrete and/or asphalt.

B. Permeable pavement limitations Permeable pavements cost more to construct than conventional asphalt or concrete pavement. However, the increased cost can at least partially be offset by a reduction in cost for storm sewer systems and detention (where required). Also, due to the cost associated with repaving streets, this strategy for addressing stormwater problems is most cost effective when combined with a pavement reconstruction program designed to address failing pavement. Because permeable pavements allow for infiltration of rainfall runoff into the subgrade soil, sanitary sewer inflow/infiltration may be exacerbated unless runoff water is prevented from entering the sanitary sewer utility trench. The use of sand for winter roadway deicing could, over time, clog the openings in the permeable pavement, causing premature need for remedial maintenance. Permeable pavements have been used in winter climates for decades in other countries and some of the oldest applications in the U.S. are over ten years old. To reduce the need for remedial maintenance, it is recommended that sand not be used on the permeable pavement roads. Porous unit paving systems are not suitable for high speed road applications where the stone fill between the pavers can be “vacuumed out” by the aerodynamic forces of vehicles passing at high speed. For high speed roads, pervious concrete and porous asphalt may be more appropriate than porous unit pavers. Pervious asphalt and concrete have lower strength for a given thickness of the stone base and wearing course than there non-permeable counterparts. Also, pervious concrete, and to a lesser extent pervious asphalt, are subject to “graveling” where there are a lot of sharp turning movements, particular by heavy vehicles. This occurs as the sliding tire surface abrades the surface and dislodges the aggregate in the concrete or asphalt. The life span of pervious concrete and asphalt surfaces are not longer and may be shorter than the life span of their non-permeable counterparts.

C. Permeable pavement alternatives As discussed above, there are three basic types of permeable pavement suitable for streets and there are a variety of ways that the permeable pavement can be arranged within the ROW. The alternatives are discussed below: Permeable Pavers: Permeable Interlocking concrete pavers are manufactured with openings between pavers to allow water to pass through. Concrete pavers are


manufactured of durable, 8,000 pound per square inch concrete. This is approximately twice as hard as typical cast in place concrete roads. A properly design permeable paver system has a design life of 50 years. The estimated unit cost of a permeable paver road is $530/linear foot for the road cross section proposed for Charles City. This includes removal of the existing pavement and installation of the stone base, required drainage, curbs, and the permeable pavers. It does not include the cost of sidewalks, driveways, and trees. Porous Asphalt: Porous asphalt is manufactured from a lean mix of asphalt that has a lower ratio of asphalt to aggregate. The lower asphalt content allows for continuous voids through the asphalt slab that allows water to pass through the surface. However, the lower asphalt content also results in a weaker pavement than conventional asphalt. Further, the expected life of porous asphalt is similar to or lower than conventional asphalt. The estimated unit cost of porous asphalt road is $460/linear foot for the road cross section proposed for Charles City. This includes removal of the existing pavement and installation of the stone base, required drainage, curbs, and the porous asphalt. It does not include the cost of sidewalks, driveways, and trees. Porous Concrete: Like porous asphalt, porous concrete is manufactured from a lean mix of cement. Porous concrete suffers from some of the same limitations as porous asphalt such as lower strength and reduced life span. The estimated unit cost of porous concrete road is $590/linear foot for the road cross section proposed for Charles City. This includes removal of the existing pavement and installation of the stone base, required drainage, curbs, and the porous concrete. It does not include the cost of sidewalks, driveways, and trees. Asphalt Drive Lanes with Permeable Paver Parking Lanes: A hybrid system of asphalt drive lanes and permeable paver parking lanes was considered since a portion of many of the existing roads may still be serviceable. However, this system would require placement of ribbon curb on either side of the asphalt to serve as edge restraint for the permeable paver parking lanes. A cost study was performed for a typical 100 foot reach of road and the


savings was found to be less than 5%. Utilizing two different paving types in the right of way requires two different maintenance regimes, resulting in staggered maintenance schedules and increased maintenance costs relative to either one of the two pavement types, alone. Finally, the smaller area of permeable pavement would result in a lower level of performance for reducing runoff volumes and rates.

APPENDIX C STREET RENDERINGS &

ENGINEERING CROSS SECTIONS

APPENDIX D PROJECT COST ESTIMATES

Charles City Green Streets09001.02October 6, 2009

Cost Estimate

Roadway Total CostKellogg Avenue 379,949.90$ Howard Street 479,414.10$ Joslin Street 486,864.40$ Iowa Street 373,573.20$ Spriggs Street 823,265.30$ Hulin Street 999,214.70$

Total 3,542,281.60$

Charles City Green Streets09001.02

Cost Estimate - Kellogg Ave. (608 LF)

Item Quantity Unit Unit Cost Total CostPavement & curb demolition, including removal (18" deep) 1216 CY 15.00$ 18,240.00$ Excavation, class 13, subgrade (12" deep, 32' wide) 721 CY 15.00$ 10,815.00$ Excavation, class 13, trench (36" deep, 7' wide) 473 CY 15.00$ 7,095.00$ Porous unit paving, pavers & no. 8 setting bed, machine install 15808 SF 5.00$ 79,040.00$ Porous unit paving, no. 57 base, 24" 1442 CY 27.00$ 38,934.00$ Porous unit paving, no. 57 trench (36" deep, 7' wide) 473 CY 27.00$ 12,771.00$ Curb & gutter, 30" 1216 LF 18.00$ 21,888.00$ Filter fabric 2432 SY 2.00$ 4,864.00$ Concrete sidewalk & driveway, including base 1463 SF 6.00$ 8,778.00$ Demo existing storm sewer structure 5 EA 1,000.00$ 5,000.00$ Demo existing sanitary sewer structure 3 EA 1,000.00$ 3,000.00$ Storm sewer manhole 3 EA 2,550.00$ 7,650.00$ Storm sewer inlet 6 EA 2,000.00$ 12,000.00$ Cobble & stone infiltration area 6 EA 1,000.00$ 6,000.00$ Alley trench drains 0 EA 2,500.00$ -$ Sanitary sewer manhole 3 EA 2,550.00$ 7,650.00$ Perforated pipe, HDPE, 6" 608 LF 5.00$ 3,040.00$ Water main, PVC, 8" 608 LF 50.00$ 30,400.00$ Water service, complete, type K, 1.5" 12 EA 2,500.00$ 30,000.00$ Valve & vault, 8" in 48" 3 EA 3,000.00$ 9,000.00$ Fire hydrant, complete 3 EA 5,000.00$ 15,000.00$ Amended topsoil (18" deep, 36" wide, behind curb) 203 CY 60.00$ 12,180.00$ Seed, turf 688 SY 1.00$ 688.00$ Erosion control blanket, NAG S75 688 SY 2.00$ 1,376.00$

Total 345,409.00$ Contingency 10 % 34,540.90$

Design and Permitting Fees 6 % 20,724.54$ Grand Total 379,949.90$

October 6, 2009


Cost Estimate - Howard St. (733 LF)

Item Quantity Unit Unit Cost Total CostPavement & curb demolition, including removal (18" deep) 1466 CY 15.00$ 21,990.00$ Excavation, class 13, subgrade (12" deep, 32' wide) 869 CY 15.00$ 13,035.00$ Excavation, class 13, trench (36" deep, 7' wide) 571 CY 15.00$ 8,565.00$ Porous unit paving, pavers & no. 8 setting bed, machine install 19058 SF 5.00$ 95,290.00$ Porous unit paving, no. 57 base, 24" 1738 CY 27.00$ 46,926.00$ Porous unit paving, no. 57 trench (36" deep, 7' wide) 571 CY 27.00$ 15,417.00$ Curb & gutter, 30" 1466 LF 18.00$ 26,388.00$ Filter fabric 2932 SY 2.00$ 5,864.00$ Concrete sidewalk & driveway, including base 3805 SF 6.00$ 22,830.00$ Demo existing storm sewer structure 9 EA 1,000.00$ 9,000.00$ Demo existing sanitary sewer structure 4 EA 1,000.00$ 4,000.00$ Storm sewer manhole 4 EA 2,550.00$ 10,200.00$ Storm sewer inlet 9 EA 2,000.00$ 18,000.00$ Cobble & stone infiltration area 10 EA 1,000.00$ 10,000.00$ Alley trench drains 0 EA 2,500.00$ -$ Sanitary sewer manhole 4 EA 2,550.00$ 10,200.00$ Perforated pipe, HDPE, 6" 733 LF 5.00$ 3,665.00$ Water main, PVC, 8" 493 LF 50.00$ 24,650.00$ Water service, complete, type K, 1.5" 18 EA 2,500.00$ 45,000.00$ Valve & vault, 8" in 48" 3 EA 3,000.00$ 9,000.00$ Fire hydrant, complete 3 EA 5,000.00$ 15,000.00$ Amended topsoil (18" deep, 36" wide, behind curb) 245 CY 60.00$ 14,700.00$ Seed, turf 2037 SY 1.00$ 2,037.00$ Erosion control blanket, NAG S75 2037 SY 2.00$ 4,074.00$



October 6, 2009


Cost Estimate - Joslin St. (723 LF)

Item Quantity Unit Unit Cost Total CostPavement & curb demolition, including removal (18" deep) 1446 CY 15.00$ 21,690.00$ Excavation, class 13, subgrade (12" deep, 32' wide) 857 CY 15.00$ 12,855.00$ Excavation, class 13, trench (36" deep, 7' wide) 563 CY 15.00$ 8,445.00$ Porous unit paving, pavers & no. 8 setting bed, machine install 18798 SF 5.00$ 93,990.00$ Porous unit paving, no. 57 base, 24" 1713 CY 27.00$ 46,251.00$ Porous unit paving, no. 57 trench (36" deep, 7' wide) 563 CY 27.00$ 15,201.00$ Curb & gutter, 30" 1446 LF 18.00$ 26,028.00$ Filter fabric 2892 SY 2.00$ 5,784.00$ Concrete sidewalk & driveway, including base 3018 SF 6.00$ 18,108.00$ Demo existing storm sewer structure 12 EA 1,000.00$ 12,000.00$ Demo existing sanitary sewer structure 4 EA 1,000.00$ 4,000.00$ Storm sewer manhole 3 EA 2,550.00$ 7,650.00$ Storm sewer inlet 10 EA 2,000.00$ 20,000.00$ Cobble & stone infiltration area 10 EA 1,000.00$ 10,000.00$ Alley trench drains 0 EA 2,500.00$ -$ Sanitary sewer manhole 4 EA 2,550.00$ 10,200.00$ Perforated pipe, HDPE, 6" 723 LF 5.00$ 3,615.00$ Water main, PVC, 8" 746 LF 50.00$ 37,300.00$ Water service, complete, type K, 1.5" 18 EA 2,500.00$ 45,000.00$ Valve & vault, 8" in 48" 3 EA 3,000.00$ 9,000.00$ Fire hydrant, complete 3 EA 5,000.00$ 15,000.00$ Amended topsoil (18" deep, 36" wide, behind curb) 241 CY 60.00$ 14,460.00$ Seed, turf 2009 SY 1.00$ 2,009.00$ Erosion control blanket, NAG S75 2009 SY 2.00$ 4,018.00$



October 6, 2009


Cost Estimate - Iowa St. (723 LF)

Item Quantity Unit Unit Cost Total CostPavement & curb demolition, including removal (18" deep) 1446 CY 15.00$ 21,690.00$ Excavation, class 13, subgrade (12" deep, 32' wide) 857 CY 15.00$ 12,855.00$ Excavation, class 13, trench (36" deep, 7' wide) 563 CY 15.00$ 8,445.00$ Porous unit paving, pavers & no. 8 setting bed, machine install 18798 SF 5.00$ 93,990.00$ Porous unit paving, no. 57 base, 24" 1713 CY 27.00$ 46,251.00$ Porous unit paving, no. 57 trench (36" deep, 7' wide) 563 CY 27.00$ 15,201.00$ Curb & gutter, 30" 1446 LF 18.00$ 26,028.00$ Filter fabric 2892 SY 2.00$ 5,784.00$ Concrete sidewalk & driveway, including base 4161 SF 6.00$ 24,966.00$ Demo existing storm sewer structure 12 EA 1,000.00$ 12,000.00$ Demo existing sanitary sewer structure 3 EA 1,000.00$ 3,000.00$ Storm sewer manhole 3 EA 2,550.00$ 7,650.00$ Storm sewer inlet 10 EA 2,000.00$ 20,000.00$ Cobble & stone infiltration area 10 EA 1,000.00$ 10,000.00$ Alley trench drains 0 EA 2,500.00$ -$ Sanitary sewer manhole 3 EA 2,550.00$ 7,650.00$ Perforated pipe, HDPE, 6" 723 LF 5.00$ 3,615.00$ Water main, PVC, 8" 0 LF 50.00$ -$ Water service, complete, type K, 1.5" 0 EA 2,500.00$ -$ Valve & vault, 8" in 48" 0 EA 3,000.00$ -$ Fire hydrant, complete 0 EA 5,000.00$ -$ Amended topsoil (18" deep, 36" wide, behind curb) 241 CY 60.00$ 14,460.00$ Seed, turf 2009 SY 1.00$ 2,009.00$ Erosion control blanket, NAG S75 2009 SY 2.00$ 4,018.00$



October 6, 2009


Cost Estimate - Spriggs St. (1361 LF)

Item Quantity Unit Unit Cost Total CostPavement & curb demolition, including removal (18" deep) 2722 CY 15.00$ 40,830.00$ Excavation, class 13, subgrade (12" deep, 32' wide) 1614 CY 15.00$ 24,210.00$ Excavation, class 13, trench (36" deep, 7' wide) 1059 CY 15.00$ 15,885.00$ Porous unit paving, pavers & no. 8 setting bed, machine install 35386 SF 5.00$ 176,930.00$ Porous unit paving, no. 57 base, 24" 3227 CY 27.00$ 87,129.00$ Porous unit paving, no. 57 trench (36" deep, 7' wide) 1059 CY 27.00$ 28,593.00$ Curb & gutter, 30" 2722 LF 18.00$ 48,996.00$ Filter fabric 5444 SY 2.00$ 10,888.00$ Concrete sidewalk & driveway, including base 6619 SF 6.00$ 39,714.00$ Demo existing storm sewer structure 22 EA 1,000.00$ 22,000.00$ Demo existing sanitary sewer structure 6 EA 1,000.00$ 6,000.00$ Storm sewer manhole 5 EA 2,550.00$ 12,750.00$ Storm sewer inlet 18 EA 2,000.00$ 36,000.00$ Cobble & stone infiltration area 18 EA 1,000.00$ 18,000.00$ Alley trench drains 7 EA 2,500.00$ 17,500.00$ Sanitary sewer manhole 5 EA 2,550.00$ 12,750.00$ Perforated pipe, HDPE, 6" 1361 LF 5.00$ 6,805.00$ Water main, PVC, 12" 331 LF 60.00$ 19,860.00$ Water service, complete, type K, 1.5" 17 EA 2,500.00$ 42,500.00$ Valve & vault, 12" in 48" 5 EA 3,500.00$ 17,500.00$ Fire hydrant, complete 5 EA 5,000.00$ 25,000.00$ Amended topsoil (18" deep, 36" wide, behind curb) 454 CY 60.00$ 27,240.00$ Seed, turf 3781 SY 1.00$ 3,781.00$ Erosion control blanket, NAG S75 3781 SY 2.00$ 7,562.00$



October 6, 2009


Cost Estimate - Hulin St. (1521 LF)

Item Quantity Unit Unit Cost Total CostPavement & curb demolition, including removal (18" deep) 3042 CY 15.00$ 45,630.00$ Excavation, class 13, subgrade (12" deep, 32' wide) 1803 CY 15.00$ 27,045.00$ Excavation, class 13, trench (36" deep, 7' wide) 1183 CY 15.00$ 17,745.00$ Porous unit paving, pavers & no. 8 setting bed, machine install 39546 SF 5.00$ 197,730.00$ Porous unit paving, no. 57 base, 24" 3606 CY 27.00$ 97,362.00$ Porous unit paving, no. 57 trench (36" deep, 7' wide) 1183 CY 27.00$ 31,941.00$ Curb & gutter, 30" 3042 LF 18.00$ 54,756.00$ Filter fabric 6084 SY 2.00$ 12,168.00$ Concrete sidewalk & driveway, including base 9275 SF 6.00$ 55,650.00$ Demo existing storm sewer structure 30 EA 1,000.00$ 30,000.00$ Demo existing sanitary sewer structure 6 EA 1,000.00$ 6,000.00$ Storm sewer manhole 6 EA 2,550.00$ 15,300.00$ Storm sewer inlet 24 EA 2,000.00$ 48,000.00$ Cobble & stone infiltration area 24 EA 1,000.00$ 24,000.00$ Alley trench drains 5 EA 2,500.00$ 12,500.00$ Sanitary sewer manhole 6 EA 2,550.00$ 15,300.00$ Perforated pipe, HDPE, 6" 1521 LF 5.00$ 7,605.00$ Water main, PVC, 8" 1521 LF 50.00$ 76,050.00$ Water service, complete, type K, 1.5" 17 EA 2,500.00$ 42,500.00$ Valve & vault, 8" in 48" 6 EA 3,000.00$ 18,000.00$ Fire hydrant, complete 6 EA 5,000.00$ 30,000.00$ Amended topsoil (18" deep, 36" wide, behind curb) 507 CY 60.00$ 30,420.00$ Seed, turf 4225 SY 1.00$ 4,225.00$ Erosion control blanket, NAG S75 4225 SY 2.00$ 8,450.00$



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