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HomeMy WebLinkAboutExisting conditionsIOWA CITY DOWNTOWN AND PEDESTRIAN MALL STREETSCAPE PLAN UPDATE . DRAFT P | 8 FEBRUARY 2014 9 E x i s t i n g C o n d i t i o n s SECTION 2 Existing Conditions IOWA CITY DOWNTOWN AND PEDESTRIAN MALL STREETSCAPE PLAN UPDATE . DRAFT P | 10 SITE ASSESSMENT Downtown Iowa City has many strengths including a vibrant pedestrian realm, an eclectic mix of retail and restaurants, a memorable public art program, mature trees, and nationally recognized special events. Landmark destinations such as the Ped Mall, the Englert Theater and the Iowa City Public Library are used and enjoyed by lo- cals and visitors alike. Its rich history has resulted in approx- imately sixty national registry eligible structures within or directly adjacent to the study area. In short, the site assess- ment reveals a strong starting point for the project. As a simple by-product of time, some aspects and com- ponents of the downtown streetscape are in a state of decline. As an example, significant improvements have not been made at the Ped Mall since the 1998 Iowa City Downtown Streetscape Plan. Additionally, as the City has grown and evolved, the downtown boundaries have shift- ed and expanded. The full site assessment report is included within the Appen- dix. A summary of key observations follows. • Enhancements are needed at the public realm to bet- ter accommodate existing and future uses. For exam- ple, at the completion of Park@201, the north end of the Ped Mall and the adjacent Black Hawk Mini Park can be re-designed to realize their full potential as vibrant public spaces that welcome users to down- town. Other public spaces in need of updates include the children’s play area and the permanent stage. • The existing downtown lighting identity is limited and includes a wide range of inconsistent design styles. The ‘globe’ lights at the Ped Mall and the adjacent streets are inefficient and are nearing the end of their serviceable life. Safety is compromised at times due to inadequate illumination. A significant opportuni- ty exists for a consistent, multi-layered lighting design framework that will be more characteristic of a sus- tainable and contemporary destination. • Some infrastructure is aging and is not meeting current demands. Additional electrical capacity and access points are needed throughout downtown to support special events and holiday lighting. In its existing state, storm sewer capacity and inlet capacity is not suffi- cient in multiple areas. Existing water supply lines do not meet future build-out demands in multiple loca- tions. • There are inconsistencies in the basic streetscape ‘kit of parts’. Since 1998, six different planning documents have guided various parts of the study area. As a re- sult, basic streetscape components including sidewalk paving, lighting, planting design vary across the study area. Encouraging continuity across the basic street- scape components will improve downtown’s identity and ease maintenance demands on city staff. • Green infrastructure strategies are currently lacking across downtown. There is tremendous potential to im-Many of the existing limestone planters are sepa- rating and are in need of repair. EXISTING CONDITIONS | SITE ASSESSMENT plement sustainable strategies across downtown and reflect the ideals of a sustainable community. • Improving the pedestrian and bicycle experience throughout the district is a high priority. In particular, emphasis needs to be directed at Burlington, Gilbert, Market, and Clinton Streets. • A strong wayfinding framework is generally lacking. The existing oversized kiosks and posting pillars are no longer meeting their intended purpose and many are in a state of disrepair. A new wayfinding and identity program will allow the user to find information more quickly and easily with simple unified graphics. The existing alleys are under-utilized, poorly illumi- nated, and dominated by waste storage. FEBRUARY 2014 11 EXISTING CONDITIONS | SITE ASSESSMENT INCONSISTENT LIGHTING EXISTING BRICK SURFACING NORTH PEDESTRIAN MALL ENTRY The current lighting system across Downtown is a compo-nent that warrants significant investment. Many of the fix-tures are ‘tired’, exhibiting peeling paint and surface rust that is typical for fixtures that have been in-place for de-cades. While lamp conversions to LED have been start-ed, much work remains to improve light levels, ambiance, branding and energy efficiency. Sections of the brick paving across the Ped Mall are heav-ing and uneven. Vehicular tracking is visible across the easterly section near the Bread Garden and the Iowa City Public Library. To minimize maintenance challenges that go along with uneven pavement (snow removal, ponding water) and safety concerns (tripping and universal accessibility) se-lect areas of the Pedestrian Mall need to have the pavers and subbase reinstalled to create a safe and attractive walking surface. During public input meeting #1, the north Ped Mall entry was identified as the least favorite public space in Down-town Iowa City. It was described as ‘the most dangerous and intimidating space’ in Downtown Iowa City. The pub-lic complained about the ongoing loitering and about the groups that ‘hang out’ on the benches for extended pe-riods of time. IOWA CITY DOWNTOWN AND PEDESTRIAN MALL STREETSCAPE PLAN UPDATE . DRAFT P | 12 EXISTING PLAY SURFACING EXISTING POSTING PILLARS INCONSISTENT COMPONENTS EXISTING STREETSCAPE The existing kiosks and posting pillars are showing signs of deterioration. As depicted in the image, many of the existing bases are corroding. They are also over-sized and appear out of scale with the context. Many of their original uses such as pay telephones and newspaper vending are no longer relevant. A lack of consistency of basic streetscape components makes the public realm seem confusing and cluttered. The existing play surface is in need of replacement. The surface is uneven and cracking and is separating from the edge restraint. This creates tripping hazards and an un-safe play surface for children. Basic streetscape amenities are lacking along many of the streets. As examples, gateway elements are missing, there are gaps in the tree planting program, seating is currently unavailable along certain street sections, and street-lev-el blank facades reduce the visual interest of the streets-cape. EXISTING CONDITIONS | SITE ASSESSMENT FEBRUARY 2014 13 UTILITY ANALYSIS INTRODUCTIONThe planning team identified the utilities within the project limits, reviewed relevant information from the City, and worked with utility providers to determine the adequacy and condition of each utility system as it relates to the Yield Analysis section contained within the 2012 downtown and riverfront crossings master plan. Observations and recom-mendations for sanitary sewer, water service, storm sewer, fiber optic, natural gas, and electrical are provided in the following sections. The full utility analysis is included under separate cover. FIBER OPTIC / IT / COMMUNICATIONSContact was made with the City of Iowa City IT and Traffic departments to gain an understanding of possible future needs for conduit in the study area. The information re-ceived indicated that the existing conduit was reaching the end of its service life. The requested infrastructure con-sists of a conduit bank of (3) 2-inch SDR11 HDPE conduit throughout the study area with associated hand holes. Additional conduit may need to be considered for private utilities as fiber optic is limited in the area. Water main break along Washington in August 2013 NATURAL GASContact was made with MidAmerican Energy, the natural gas utility for the study area. Their current system is an ag-ing low pressure system that is, at times, unable to provide the volume of gas needed for application within the area. The utility recently installed a new line in the alley near Park@201 to serve the new 14 story structure. Represen-tatives indicated that they would replace all old gas lines within the study area in association with projects contem-plated by this study. Of note, they also indicated that their current meters are in the buildings in much of the area, and would be interested in looking at creative solutions that could move some of the meters to exterior locations where feasible. ELECTRICALMidAmerican Energy’s electrical infrastructure is general-ly buried underground in the Downtown District while the Northside Marketplace has overhead distribution. In both areas the majority of electrical infrastructure is located in alleys. A one block section along S. Gilbert Street between Washington and College will eventually be converted un-derground due to new development, but the time frame is currently not known. MidAmerican reports no other plans for major infrastructure improvements in the next ten years unless they receive additional customer requests. There is currently adequate capacity for current customers and expected future growth. However, additional electrical capacity is needed throughout downtown and specifi-cally along Iowa Avenue and Clinton and in the Ped Mall for special events and vendors. An electric utility map has been provided by MidAmerican Energy for the study area. EXISTING CONDITIONS | UTILITY ANALYSIS IOWA CITY DOWNTOWN AND PEDESTRIAN MALL STREETSCAPE PLAN UPDATE . DRAFT P | 14 EXISTING CONDITIONS | UTILITY ANALYSIS | SANITARY SERVICE FEBRUARY 2014 15 SANITARY SEWER The sanitary sewer analysis was based on information pro- vided by the City of Iowa City and consisted of sanitary sewer plan and profile records. In addition, LIDAR contour mapping was used to estimate areas contributing to the sanitary sewer outside the study area. The City of Iowa City Wastewater Division of the Department of Public Works performed video inspections of the subject sewer lines. The system was analyzed by determining the service areas for each reach of sanitary sewer and comparing the cal- culated flows from each service area to the calculated capacity in each pipe. Flows from each service area were estimated by the type of use. A peaking factor of 4.0 and a factor of safety for Inflow and Infiltration and other peak demands of 2.0 were applied. In general the available ca- pacity greatly exceeds the current demand. SPECIFIC ITEMS OF INTEREST Most sewers are installed at more than minimum grade. The only exception found is a length of 8-inch sewer along Linn Street between Washington Street and Iowa Avenue. Records indicate it is at a slope of 0.35% (0.40% minimum). Estimations show suitable capacity, howev- er the lower velocity may cause maintenance issues. A 12 inch sewer runs in the east-west alleyway adjacent to the Hamburg Inn 2, 214 N. Linn Street. Video inspec- tion indicates that the service located 57.7 feet from the upstream manhole is broken with visible voids (and grease). The aging brick construction sanitary manhole at the intersection of College and Linn is in need of rehabilita- tion or replacement. A communications cable has penetrated the 8-inch clay sewer approximately 61 feet north of the intersec- tion of Burlington and Gilbert. A sanitary sewer connection is likely from 321 E. Mar- ket to the Beer Creek storm sewer. If the connection is active, route to an existing 8-inch sewer connection in the alley south of the building. This work should be considered as an immediate action, and not be tied to possible future streetscape improvements. FUTURE FLOW ESTIMATES Future flows were estimated for potential buildings identi- fied in the 2012 Downtown and Riverfront Crossings Plan. The yield analysis identifies fourteen potential structures ranging from four to twelve stories. The structures identified in the South downtown yield analysis could add an ad- ditional 0.556 MGD. This is below the calculated 1.1MGD capacity of the existing Burlington Street sewer. Proposed structures at Linn and Washington should utilize the avail- able capacity in the 15-inch Washington Street sewer in- stead of connecting to the 8-inch sewer along Linn Street. Other proposed structures are on sewer lines with signifi- cant excess capacity. 1. 2. 3. 4. 5. OTHER RECOMMENDATIONS As work is done in the study area, the City wishes to re- place the existing sanitary castings with the City of Iowa City logo castings to help differentiate it from the storm sewer system. EXISTING CONDITIONS | UTILITY ANALYSIS | SANITARY SERVICE IOWA CITY DOWNTOWN AND PEDESTRIAN MALL STREETSCAPE PLAN UPDATE . DRAFT P | 16 EXISTING CONDITIONS | UTILITY ANALYSIS | WATER SERVICE FEBRUARY 2014 17 Replace the 6” line along Dubuque, north of Burlington due to age and condition. Replace the 6” line along Washington between Linn and Van Buren with 8” line for increased capacity. FUTURE DEVELOPMENT Static pressure in the system is between 80 to 89 psi in the north market place area and 90 to 99 psi in the downtown district. This should allow for acceptable pressure for three, four, or possibly five story buildings to have adequate do- mestic pressure on the upper floors. Any significant build- ings being contemplated may require booster pump sys- tems to be designed specifically for the structure by the project mechanical engineer to meet domestic and fire flow requirements. WATER SERVICE The water service analysis was based on information pro- vided by the City of Iowa City and consisted of water mapping, reports and diagrams identifying system pres- sures, and discussions with and memoranda from water department staff. In assessing the adequacy of a system pressure, flow and reliability are considered. Pressure un- der static conditions is primarily influenced by elevation and the pressure head supplied by either elevation or pumping. Flow is influenced by system pressure, pipe di- ameter, pipe length, and the extent to which the system is networked. Reliability is influenced by redundancy, loop- ing, valving, pipe age and condition, replacement of pipe known for breakages, and, if too high, system pressure. In reviewing the potable water system, water mains were identified for replacement based on these factors. Con- sideration should be given to replacing the water main on any street for which significant pavement replacement is contemplated. OBSERVATIONS AND RECOMMENDATIONS Replace the 16-inch main line running along Gilbert to Washington and then turning west to Linn Street due to age and condition. The City has experienced breaks along the line. Replacement is recommended due to age and condition. Replace the 12-inch cast iron main along Washington Street from Clinton Street to Linn Street and continuing along Linn Street to Burlington Street due to age and condition. Replace the existing 6-inch lines along Gilbert Street and College with a 12-inch main to accommodate proposed development, and to improve system hy- draulics, help create a “perimeter loop” around the downtown district, and create redundancy for critical structures. Replace approximately 250 feet of existing 6-inch main along Burlington Street to 8-inch main due to capacity. The 12-inch lines proposed for College and Linn Streets provide a perimeter loop allowing for reduced con- struction on Burlington Street (Hwy 1). Replace the 8-inch main along Burlington Street from Capitol Street to Linn Street with a 12-inch main due to condition and capacity. The existing line has expe- rienced several breaks. Replacement would form part of the downtown district perimeter loop and improved hydraulics. Replace the 8-inch line along Clinton Street from Burl- ington to College due to condition. Upsize the 4-inch main to 8-inch along Bloomington Street from Linn to Gilbert due to capacity. Upsize the 6-inch main to 8-inch along Linn from Bloom- ington to Davenport due to capacity. Replace the 6-inch main (same size) along Jefferson Street from Dubuque to Gilbert due to condition. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. EXISTING CONDITIONS | UTILITY ANALYSIS | WATER SERVICE IOWA CITY DOWNTOWN AND PEDESTRIAN MALL STREETSCAPE PLAN UPDATE . DRAFT P | 18 EXISTING CONDITIONS | UTILITY ANALYSIS | STORM SEWER SERVICE FEBRUARY 2014 19 Storm sewer segment along Dubuque Street from Iowa Avenue south has been identified as having two sepa-rate breaks. Spot repair is recommended. Along Dubuque, just south of Intake 3452, video inspec-tion identified a water service bored though the sewer. Spot repair is recommended. The 24-inch diameter sewer line running Along Wash-ington Street west of Gilbert has experienced multiple issues and should be replaced and relocated under the roadway. The flooding reported at the intake in the lowest level of the parking ramp at the SW corner of Gilbert and Iowa may be due to the elevation of the intake in relation to the HGL of the 12inch sewer along Gilbert. Confirming the elevation of the intake and the adjacent sewers would provide additional insight to the issue. The area is access controlled, so appropriate contacts for admis-sion to this parking area would be required. The existing 24-inch sewer along Linn Street in the Northside Market Place area seems be somewhat un-dersized. If significant surface improvements are pro-posed in this area, upsizing the 24-inch sewer and the 27-inch sewer to should be considered. Again, field ver-ification by a survey crew to establish the actual condi-tions is recommended. The drainage infrastructure within the pedestrian mall is not well documented. Given the other drainage issues in this area (flooding of the building entrance at the former Cappanna/Wedge, 136 S. Dubuque Street, and the ventilation grate at the Bread Garden, 225 S. Linn Street) additional study including field data collection for this area is recommended. OTHER STORM SEWER RECOMMENDATIONSLIDAR 2-foot contour maps and the 1978 Ralston Creek Storm Sewer maps were utilized to identify depressions or sumps in the ground surface that might be unserved by storm sewer causing localized ponding. A series of three sumps in the north market area were noted located on Market Street, the mid-block alley, and Jefferson Street between Linn and Gilbert. All three are on the route of the 42-inch by 42-inch box culvert and are shown as served by intakes. A topographical survey of the area is recom-mended. As work is done in any area of the study, the City wishes to replace the existing storm sewer castings with City of Iowa City logo castings to help differentiate it from the sanitary sewer system. STORM SEWER The storm sewer analysis was based on information pro- vided by the City of Iowa City and consisted of storm wa- ter mapping, Excel database files, and 1978 maps of the Ralston Creek storm sewers. The information provided is incomplete, and does not in many significant ways allow for a detailed analysis. Much effort was made to reconcile conflicting information or to make assumptions necessary to estimate the capacity of the existing system. In addition to the materials provided by the City, LIDAR contour maps were utilized to estimate the contributing drainage areas influencing the study area. No field survey was authorized for the study. Because the mapping available is schemat- ic, separation distances from sanitary sewer and water mains were not able to be calculated. The system was analyzed using a 5 year return period. Where pipe slopes were not available estimates were made using surface slopes from LIDAR contours. Except for the far north area draining in to the north side market place, a runoff coefficient of .98 was used. Therefore, ad- ditional build-out will not increase the impervious area. In general the system is effective. STORM SEWER AREAS OF CONCERN There may be a capacity issue with the 15” diameter storm sewer running north-south along Dubuque Street north of Burlington. Additional study to ascertain the actual size/slope and contributing area should be con- sidered before surface amenities are constructed in this area. If significant work is to be done along Gilbert and Burl- ington, consider re-routing the 24-inch diameter storm sewer pipe that currently runs under the Robert Lee Recreation Center. At the Clinton Street intersection with the Ped Mall, City staff indicates that a storm manhole is buried under a planter. Access to the storm sewer should be included in future improvements to this area. The alley in the block north of Washington and west of Dubuque is either without storm sewer or privately sew- ered. If improvements to this area are contemplated, the potential for improved drainage should be part of the scope. The City dye tested these lines in Novem- ber 2013 and found they were connected to the storm sewer on Iowa Avenue. The mid-block alley between Linn and Dubuque in the block south of Iowa Avenue was identified as having a drainage issue related to the Yacht Club, 13 S. Linn Street. The 12-inch sewer drains a relatively small area. If sump pumps from adjacent buildings are present, ca- pacity may be impacted. The surface drainage does not appear to effectively channel runoff to the sewer, which may be causing some of the drainage problems. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. EXISTING CONDITIONS | UTILITY ANALYSIS | STORM SEWER SERVICE