Draft Feasibility Study for the Expansion of Southeast Library

Transcription

1 DC public Library KH KEAST & HOOD METROPOLITAN E N G I N E E R I N G I N C S H A P I RO-O BRIEN Draft Feasibility Study for the Expansion of Southeast Library Draft Submission: November 4,

2 OVERVIEW AGENDA OVERVIEW Need for Expansion EXISTING FACILITY ANALYSIS Historic Preservation / Architecture Code / ADA Compliance Zoning Code Site Utilities Structural Conditions MEP Findings Mechanical Findings Electrical Findings Plumbing Findings Recommendations for Existing Facility BARRACKS ROW DESIGN Architectural Analysis Infrastructure Analysis Structural Analysis MEP Findings Mechanical Findings Electrical Findings Plumbing Findings Cost / Risk / Benefit Analysis ALTERNATIVE DESIGNS Options Considered Option 1: Underpin / Excavate within Existing Footprint Option 1: Cost / Risk / Benefit Analysis Option 2: Underpin / Excavate with Pre-Fab Tunnel, Expand under Plaza Option 2: Cost / Risk / Benefit Analysis Option 3: Attic Expansion RECOMMENDATIONS Short Term For Expansion

3 OVERVIEW NEED FOR EXPANSION Reasons for Expansion: Update the facility to meet 21 st Century needs Strategic plan studies indicate needs of community residents Maintain the Historic Building Goals for Expansion: Space and Service Consideration for New Library One large meeting room One smaller conference room 3-4 study rooms Ample table workspace with electrical power and lounge style seating areas Large staff workroom Additional outside materials return near entrance Complete restroom modernization and expansion Larger staircase Friends storage space New elevator Modernization of HVAC ADA upgrade for compliancy Some type of garden or outside seating area Large stroller area Children computer stations Open play area

4 EXISTING FACILITY ANALYSIS Aerial of library and Eastern Market Station looking west Aerial of library looking north Aerial of library and Eastern Market Station looking east Aerial of library Eastern Market Station looking south

5 EXISTING FACILITY ANALYSIS HISTORIC PRESERVATION/ ARCHITECTURE Not designated as either a District or National Historic Site Should be considered Contributing to the Capitol Hill National (and DC) Historic District Opened in 1922 Built with a grant from the Carnegie Foundation. Many interior renovations including the removal of a large stair just inside the main entrance only a few years after it opened. Library was designed by Architect Edward Lippincott Tilton who designed over 200 Libraries.

6 EXISTING FACILITY ANALYSIS CODE/ADA COMPLIANCE = ADA Compliant Elements = Non-Accessible or Not Code Compliant Elements Main Reading Room Level Classified as Assembly A-3 in DC Building Code No accessible egress from the main level reading room Elevator would need to be on generator. The restrooms appear to meet the current accessibility code. Accessible entry via ramp and elevator. The existing stairs are narrow Mezzanine does not have compliant egress/access. No sprinkler system but below threshold. Single means of egress appears to meet code. Lower Level

7 EXISTING FACILITY ANALYSIS ZONING CODE RF-1 Zoning (Yellow in Diagram) Lot Area is 6,431 SF Building Floor Plate is 4,132 SF Total Building is 9,600 SF Lot Occupancy is 64.25% RF-1 Zone Allows: Library Use 35 Foot Building Height 3 Stories excluding Penthouse 1 Story /12 Foot High Penthouse Setbacks are based on other buildings on the block 20 Rear Yard Setback No Side Yard Setback on a corner lot RF-1 Zone Restrictions: Maximum Non-Residential Lot Occupancy is 40% Building pre-dates May 12, 1958 Zoning so existing Lot Occupancy may remain but cannot be increased

8 EXISTING FACILITY ANALYSIS SITE UTILITIES GIS sewer map Site Utility Services 2 Water service to east 4 or 6 Sanitary lateral to east Gas service southwest corner Electric service to south Stormwater discharges to ground surface All sufficient to accommodate existing facility 7 th Street SE Utilities 18 and 24 Combined sewers 6 and 20 Water mains Likely Washington Gas and Pepco underground facilities no records received GIS water map

9 EXISTING FACILITY ANALYSIS STRUCTURAL CONDITIONS Heavy timber trusses, bracing & wood rafters support roof Attic floor is wood joist framing First floor framing believed to be wood joist framing or concrete and terra cotta infill Perimeter bearing walls and foundation are brick masonry Footings unable to be observed Basement floor is concrete slab on grade One area framed with wood platform Moisture damage and staining observed in attic and along exterior foundation walls Mortar joint deterioration in brick Rusting of steel lintels above exterior openings Basement floor finishes distressed near wood framed area

10 EXISTING FACILITY ANALYSIS MECHANICAL FINDINGS Investigation limited Much of the mechanical systems are original Portions of the HVAC system are not fully operational Heating boiler is relatively new The air handler, hot and chilled water pump system, piping, duct work, exhaust fans should all be replaced The air cooled chiller and fan coil units are new and can remain

11 EXISTING FACILITY ANALYSIS ELECTRICAL FINDINGS Electric service is 400A, 3 phase, 4 wire, 120/208V Main electrical panel serves various feeding panels All feeders from the switchboard to panels and switches are copper Electrical outlets are in satisfactory condition Lighting system 2x4 and 2x2 fluorescent in general offices and reading rooms continuous 1x4 fluorescent in hallways, storage and utility rooms wall mounted fluorescent in stairwells industrial pendants in mechanical, electrical and telephone/data rooms Exit lighting is found at egress exit corridors and double as Emergency lighting Fire alarm system

12 EXISTING FACILITY ANALYSIS PLUMBING FINDINGS Domestic hot and cold water systems are original The gas fired hot water heater is past its useful life The gas service appears to be low pressure The diesel emergency generator is not operational

13 EXISTING FACILITY ANALYSIS RECOMMENDATIONS Architectural Add accessible egress from main level, put elevator on emergency generator power to achieve Structural Investigate and address water damage and staining Address mortar joint damage Investigate and address rusted lintels Investigate and address basement floor distress Mechanical Update and replace HVAC components Replace piping system Replace exhaust fans Relocate piping that is above electric panels Electrical Replace 400A service equipment Replace main panel Replace feeding panels Outlets reaching end of useful life within a few years Generator is in poor condition Plumbing Update leaky piping Install backflow preventer

14 BARRACKS ROW DESIGN - ANALYSIS MAIN READING ROOM LEVEL 7 TH STREET RENDERING LOWER LEVEL AT GRADE UNDERGROUND EXPANSION METRO PLAZA RENDERING

15 BARRACKS ROW DESIGN ARCHITECTURAL ANALYSIS Design is heavily focused on Metro Plaza Depth of sewer pipes require 2 ½ story deep tunnel Tunnel ceiling low points block services Underground addition is 13,520 SF with 1,350 SF pop-up (14,780 SF) Conflict with WMATA s clearance Fines for impacted tree removal Library Site Setbacks Metro Clearance Underground Addition Metro Structures Conflict Impacted Tree

16 BARRACKS ROW DESIGN INFRASTRUCTURE ANALYSIS Site Utility Impacts Remove & replace sanitary lateral Sanitary waste from underground addition will need to be pumped to new lateral (additional long-term O&M costs) Remove & replace water service Upsize to 4 to accommodate fire suppression (sprinklers) Electric service may need to be removed & replaced No impact to gas service No impact to stormwater 1899 Sewer Plan

17 BARRACKS ROW DESIGN INFRASTRUCTURE ANALYSIS 7 th Street SE Utility Impacts Anticipate open-cut excavation for underground building with partial width stages across 7 th Street SE All underground utilities within excavation need to be removed & replaced Will require bypass pumping of sewers Will require temporary water lines Partial width construction will allow for just one sewer and one water line to be bypassed at a time Other utilities expected to be found (Wash. Gas, Pepco) that also must be bypassed, removed & replaced Traffic Impacts Must maintain vehicular and pedestrian traffic Partial width construction under 7 th St. SE will minimize impacts, allowing for movements in one direction DDOT may require closure and detour

18 BARRACKS ROW DESIGN STRUCTURAL ANALYSIS A B C D Underpin Historic Library building to excavate 2 ½ stories. Groundwater level between elevations 56-0 and The structure and foundation below requires permanent dewatering and pumping Tunneling below the road is not feasible. The existing utility pipes will need to be bypassed for excavation The existing roof would need to be removed to make framing suitable for equipment loads D C A WATER TABLE B

19 BARRACKS ROW DESIGN MECHANICAL FINDINGS New gas fired boiler for heating New heating hot water pipe loop and pumps New chilled water pipe loop and pumps Split system air condition units in basement remain Fan coil units for heating/cooling remain The air handling unit and condensing unit to be replaced Fan coil units serving the first floor to be replaced HVAC controls replaced New roof-mounted HVAC unit New exhaust fan to serve reading room New elevator will require ventilation New air cooled condensing unit to serve the basement

20 BARRACKS ROW DESIGN ELECTRICAL FINDINGS Upsize electric service to 600A, 3 phase, 4 wire, 120/208V New main distribution panel Replace breakers serving equipment to remain Wiring replaced on an as-needed basis Lighting, electrical and telecom outlets will be provided in new space to meet code and owner requirements A new emergency generator should be installed New fire alarm components connected to the existing control panel

21 BARRACKS ROW DESIGN PLUMBING FINDINGS Check water service for proper sizing Double check valve backflow preventer Backflow preventers installed on new equipment New domestic hot water heater with recirculating pump Gas service will be evaluated for capacity A new gas meter and regulator may be required if a gas fired emergency generator is provided Sanitary piping will need to be extended and modified If the total building area exceeds 12,000 sq. ft., sprinklers will be required for the entire building

22 BARRACKS ROW DESIGN COST/RISK/BENEFIT ANALYSIS Estimated Costs COSTS BY TRADE: Benefits Expansion of almost 15,000 SF more than doubles the existing building size Large spaces provide flexibility for use Design activates the Metro Plaza and contributes to the larger goals for the public space Potential Risks Structure below the groundwater elevation requires permanent dewatering Dewatering has potential impact on foundations of adjacent buildings Possible vibration impact on adjacent historic buildings Requires land use agreement with another DC agency Depth of tunnel requires thick concrete and creates more opportunity for leaks Proximity of Metro triggers additional reviews and approvals

23 ALTERNATIVES OPTIONS CONSIDERED 1. Underpin/Excavate within Existing Footprint Current Zoning allows 3 stories, only 2 existing Avoid tunnel and Metro Plaza 2. Underpin/Excavate with Pre-Fab Tunnel and Expansion under Plaza Utilize pre-fab tunnel to phase road closures and speed up installation time Reconfigure expansion space to avoid WMATA clearance 3. Attic Expansion Utilize height of attic space rather than excavate

24 ALTERNATIVES OPTION 1: UNDERPIN/EXCAVATE WITHIN EXISTING FOOTPRINT A B C D E 4,132 SF for new story Underpin existing Historic Library building to excavate 1 story only Increased Lower Level height and new story below remain above groundwater level Expansion remains within existing footprint, avoids land use agreement for Metro Plaza and tunnel Existing roof configuration remains, locate new equipment on south side of building similar to chiller that was installed behind a green wall E Ground Floor B A D A C WATER TABLE Lower Level New Level

25 ALTERNATIVES OPTION 1: COST/RISK/BENEFIT ANALYSIS Estimated Costs COSTS BY TRADE: Potential Risks Possible underpinning impact on adjacent structures Possible vibration impact on historic buildings Benefits Expansion avoids land use agreement with another agency Expansion space is about 630 SF more than program requires Estimated cost is almost 1/3 of Barracks Row Design Increased headroom in existing Lower Level by dropping slab Excavation stays above anticipated groundwater level Opportunity to rework stairs and elevator for code compliance New building systems configured for better efficiency

26 ALTERNATIVES OPTION 2: UNDERPIN/EXCAVATE WITH PRE-FAB TUNNEL AND EXPANSION UNDER PLAZA Prefabricated tunnel area Alternative underground space Design is focused on Metro Plaza but space is evenly distributed Depth of existing sewer pipes require 2 ½ story deep tunnel Continuous 20 foot wide tunnel engineered for loads above Tunnel is primarily circulation Underground addition is 8,570 SF with 1,350 SF popup (9,920 SF) Underground zone avoids WMATA conflict Tunnel size avoids tree removal Library Site Setbacks Metro Clearance Underground Addition Metro Structures Conflict Impacted Tree

27 ALTERNATIVES OPTION 2: COST/RISK/BENEFIT ANALYSIS Estimated Costs COSTS BY TRADE: Potential Risks Structure below the groundwater elevation requires permanent dewatering Dewatering has potential impact on foundations of adjacent buildings Possible vibration impact on adjacent historic buildings Requires land use agreement with another DC agency Depth of tunnel requires thick concrete and creates more opportunity for leaks Proximity of Metro triggers additional reviews and approvals Benefits Expansion of 9,920 SF doubles the existing building size Large spaces provide flexibility for use 1,850 SF Prefabricated tunnel can arrive in segments for phased installation 7 th Street does not have to be completely shut down Faster tunnel installation $10 Million savings over poured in place concrete with full excavation Design activates the Metro Plaza and contributes to the larger goals for the public space

28 ALTERNATIVES OPTION 3: ATTIC EXPANSION INITIAL CONSIDERATIONS: Site investigation of existing mezzanine space revealed a large existing well space under a skylight Exploration of the attic space revealed enough height below portions of the roof for occupiable space Attic expansion would avoid excavation REASONS NOT TO PURSUE: Zoning only allows 3 occupied stories Full 3,500 SF program space could not be achieved Accessible circulation and elevator would take up most of the attic level Historic District prohibits roof line alterations so natural light as well as fire rescue would be issues Existing structure is not adequate to support additional loads

29 RECOMMENDATIONS and CONCLUSION RECOMMENDATION SHORT TERM: In the short term, the focus should be on implementing the items listed under the Existing Facilities Analysis Recommendations If one of the expansion options will be pursued in the next year, defer items that will be demolished in that effort For example, placing the elevator on generator power RECOMMENDATION FOR EXPANSION: Alternative Design Option 1: Underpin / Excavate within Existing Footprint is Recommended 1. The square footage of the desired program is achieved within the existing site and complies with Zoning. 2. The preliminary estimate is $10 Million which is $9 Million less than the other Alternative Design and over $19 Million less than the Barracks Row Design. 3. An additional story can be gained with additional ceiling height for the Lower Level while staying above the groundwater elevation. 4. The Alternative Design has lower long term operating costs because there is no dewatering or pumping required and no additional maintenance or landscaping costs in the Metro Plaza. 5. The design focuses on the Library s site and does not attempt to acquire new property or add extensive space beyond the program.