ENVIRONMENTAL CONSEQUENCES

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ENVIRONMENTAL CONSEQUENCES
IMPACT TOPICS 203
IMPACTS OF THE PROPOSED PLAN 205
Cultural Resources 205
Natural Resources 211
Home and Office of the President 218
Visitor Experience 222
Special Events 227
Transportation 229
Socioeconomic Environment 233
Site Management and Operations 238
Irreversible and Irretrievable Commitments of Resources 241
The Relationship of Short-term Uses of the Environment and the Maintenance and Enhancement of Long-term Productivity 242
Cumulative Impacts 242
IMPACTS OF THE NO-ACTION ALTERNATIVE 245
Cultural Resources 245
Natural Resources 248
Home and Office of the President 249
Visitor Experience 250
Special Events 252
Transportation 253
Socioeconomic Environment 254
Site Management and Operations 254
Irreversible and Irretrievable Commitments of Resources 255
Cumulative Impacts 255
IMPACTS OF ALTERNATIVE 1 256
Cultural Resources 256
Natural Resources 260
Home and Office of the President 263
Visitor Experience 266
Special Events 269
Transportation 271
Socioeconomic Environment 274
Site Management and Operations 277
Irreversible and Irretrievable Commitments of Resources 278
The Relationship of Short-term Uses of the Environment and the Maintenance and Enhancement of Long-term Productivity 279
Cumulative Impacts 279
IMPACTS OF ALTERNATIVE 2 281
Cultural Resources 281
Natural Resources 285
Home and Office of the President 286
Visitor Experience 289
Special Events 292
Transportation 293
Socioeconomic Environment 296
Site Management and Operations 299
Irreversible and Irretrievable Commitments of Resources 301
The Relationship of Short-term Uses of the Environment and the Maintenance and Enhancement of Long-term Productivity 301
Cumulative Impacts 301
IMPACTS OF ALTERNATIVE 3 303
Cultural Resources 303
Natural Resources 306
Home and Office of the President 307
Visitor Experience 311
Special Events 313
Transportation 314
Socioeconomic Environment 316
Site Management and Operations 319
Irreversible and Irretrievable Commitments of Resources 321
The Relationship of Short-term Uses of the Environment and the Maintenance and Enhancement of Long-term Productivity 321
Cumulative Impacts 321

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IMPACT TOPICS

The environmental consequences of implementing the alternatives are considered in accordance with the National Environmental Policy Act. Even though the White House is exempted from compliance with the National Historic Preservation Act by section 107, impacts affecting cultural resources are being analyzed in the spirit of helping public officials to make decisions that are based on a full understanding of the environmental consequences, and to take actions that protect, restore, and enhance the environment.

The level of analysis throughout the "Environmental Consequences" part of this document varies in specificity. The analysis is generally adequate for identifying the type degree of impacts, for comparing the alternatives, and for selecting the proposed actions. Additional resource data and site-specific analyses, however, could be needed as individual actions were undertaken. The implementation of selected actions would depend on funding, which would most likely be obligated over a 20-year period or longer. Site-specific analyses (environmental assessments) in compliance with the National Environmental Policy Act would focus on design and construction details and effects on site characteristics, such as soils, groundwater, and vegetation. Elements such as energy conservation and site specific environmental practices would be considered as well. These analyses would be more cost-effectively completed at the time of design.

Mitigating actions listed in the first part of this document, "Alternatives, Including the Proposed Plan," would be taken during implementation. All impacts have been assessed assuming that mitigating measures had already been completed.

No impacts are discussed with regard to potential impacts of a design for Pennsylvania Avenue and Lafayette Park or for the design of security barriers on the north and south sides of the site. Designs and impacts for these projects will be fully analyzed in separate documents.

Impacts are discussed under the following headings, and under each heading impacts of actions that apply to a specific topic are discussed:

Cultural Resources-Impacts on the cultural landscape (including memorials and commemorative plantings), archeological resources, historic buildings and structures, and fine and decorative arts are described.

Natural Resources-Topics include subsurface soil and groundwater conditions that could affect proposed construction activities (known as a geotechnical evaluation), water resources (surface and groundwater)' and vegetation and soils

Home and Office of the President-For the Executive Residence, impacts are discussed for the first family (recreation space and privacy) and operations (storage and grounds maintenance operations). For the Executive Office of the President, effects are discussed for diplomatic and business visitors and staff in terms of visitor arrivals, parking, deliveries, and onsite circulation. Impacts on the news media are also discussed.

The Visitor Experience - Impacts on diplomatic and business visitors, the public (including visitors on public tours of the White House), pedestrians, and local residents are analyzed. The effects of noise

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on the public, particularly as a result of construction, are also considered.

Special Events-Impacts related to staging public events on the Ellipse and special events on the White House grounds are considered.

Transportation-Impacts are discussed for access and circulation; public parking; public transit, tour bus, and Tourmobile operations; and bicyclists.

The Socioeconomic Environment - Economic impacts on D.C. revenues, vendors, and local businesses are analyzed, along with impacts associated with construction and operations.

Site Management and Operations-Impact topics include site operations, maintenance, and utilities.

The following topics have been dismissed from further analysis, as explained below:

Wildlife' Floodplains, and Wetlands- As described in the "Affected Environment," there are no wetlands, or threatened or endangered plant or animal species, within President's Park or the White House grounds. In addition, neither President's Park nor the White House is within the 100-or 500-year floodplain.

Air Quality-The pollutants of concern in progressing to or maintaining air quality standards in the DC area are CO and ozone with its precursors (NOX and VOC). These pollutants are associated with vehicle emissions and therefore higher concentrations tend to result from peak traffic periods. At specific locations within the study area,

CO concentrations may increase or decrease with changes in the street network or traffic conditions. However, since either limited (approximately 170 spaces) or no additions to the parking supply and no increase in employees are proposed in the alternatives, vehicle emission levels in the metropolitan area are not expected to increase or to be impacted as a result of implementing any of the alternatives considered in this document.

Air quality within all proposed structures (underground parking facilities, underground pedestrian corridors, and the visitor center) would be addressed during design stages and in accordance with applicable industry standards and building codes.

Due to the urban setting of President's Park, effects on historic structures and buildings from exhaust fumes and airborne particulates, as well as traffic vibrations, would continue to be a problem in all areas. These effects are not expected to increase as a result of implementing the proposed plan.

First Amendment Demonstrations-No alternatives would affect the right of citizens to demonstrate within President's Park, in accordance with the First Amendment and current law.

The Presidential Inaugural Parade- No impacts to the inaugural parade are anticipated. Any construction under Pennsylvania Avenue would be scheduled so as to be finished before any future election. All other actions to Pennsylvania Avenue would be discussed as part of the long-term design for Pennsylvania Avenue.

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IMPACTS OF THE PROPOSED PLAN

Cultural Resources

Impacts on the Cultural Landscape

Analysis

President's Park and the White House would be managed in accordance with the principles of significant past landscape designs, including the L'Enfant, Downing, McMillan, and Olmsted plans. Character-defining features such as rights-of-way and walks would be respected. Guidelines and cooperative programs with adjacent property owners and jurisdictions would be enacted to help preserve the unique character that has been developed over time. The implementation of Design Guidelines for the site would help ensure that design elements and materials would be compatible throughout the area, helping create a unified appearance for all of President's Park.

Actions such as removing surface parking within President's Park, providing for tour bus parking in areas away from the park, and staging public tours from the visitor center rather than the Ellipse would all help restore the integrity of historical views, as well as a sense of openness and dignity to President's Park.

Establishing formal entryways to President's Park would add new architectural elements on the site and focus visitor traffic at these locations. Each entryway would be designed to be compatible with its surroundings; for example, entryways on Jackson and Madison Places would be designed to fit with the neighborhood character of Lafayette Park. Any adverse effects of entryways could be mitigated through design to ensure that these elements were compatible with existing design features.

During the construction of belowground facilities historic views could temporarily be affected by the storage of construction equipment, supplies, and structures.

Resource Management. More proactive programs would be implemented to reduce the potential loss of character-defining features, such as tree groves and allees. The continued propagation of culturally or genetically significant plant materials would ensure their continued availability.

More consistent management of activities and more comprehensive care of historic resources would ensure the long-term protection of the site character and enhance the sense of decorum.

The addition of memorials would not be encouraged on the site, helping ensure that historical views from and to the White House would be maintained.

Instituting a comprehensive program to monitor and manage commemorative plantings, including assessing soils and drainage, would identify any potential adverse impacts, allowing corrective measures to be taken immediately.

Archeological investigations would be handled so as to minimize any intrusions on traditional views.

Home and Office of the President. Proposed actions would all help restore the integrity of views from the White House across the Ellipse area to the Washington Monument and the Jefferson Memorial. The appearance of E Street would be softened by adding a landscaped median between the public traffic lanes and the restricted access lane for White

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House traffic. However, continued traffic across the park on E Street would still visually intrude on views south from the White House.

Diplomatic and business visitors would continue to arrive at multiple entries to the property, with no effect on the ceremonial character of the site. Continuing motorcade access to various points on the site would retain the ceremonial functions traditionally associated with the White House.

Redesigning West Executive Avenue as a pedestrian-oriented area that would be similar to East Executive would improve the appearance of this area, while retaining the roadway character. Vehicular access would still be allowed for motorcades and official visitors.

The proposed meeting facility under West Executive Avenue would be adjacent to the Old Executive Office Building (a national historic landmark); the proposed parking garage beneath Pennsylvania Avenue would be adjacent to the Lafayette Square National Historic Landmark District and the Old Executive Office Building, and near the Treasury Building (a national historic landmark), and the Ellipse parking garage would be near the Old Executive Office Building, the Treasury Building, the Fifteenth Street Financial Historic District, Pennsylvania Avenue National Historic Site, the Federal Triangle Historic District, and the Seventeenth Street Historic Area. Potential impacts from construction on the settings of these historic resources would need to be mitigated through sensitive design.

The 290-space parking garage under Pennsylvania Avenue would be accessed from the New Executive Office Building and from a new entrance on the north end of West Executive Avenue. While parking would be removed from West Executive Avenue and adjacent areas, an entrance portal on West Executive Avenue would be a new intrusion in the landscape. Using the existing portal in the New Executive Office Building would create no additional effect on the historic landscape.

Vehicular access to an underground Ellipse parking facility would be through portals on either side of 1 6th Street, between the Ellipse roadway and Constitution Avenue. These structures, as well as traffic entering and leaving the facility, would be a permanent intrusion on the formal and ceremonial vistas to and from the White House. Ventilation systems and pedestrian access points to the garage, as well as emergency exits, would need to be designed to minimize any additional adverse effects on the landscape. Locating access to parking garage pedestrian corridors south of E Street would avoid any potential impacts on First Division Monument and Sherman Park. However, additional aboveground intrusions in this area and the continued presence of traffic would potentially affect the setting of nearby historic structures and districts, intruding on the formal setting.

Constructing the underground Ellipse parking facility, utilities, and pedestrian and vehicular corridors would result in the permanent loss of an estimated 24 trees on the Ellipse, depending on the final location of facilities. If excavation was used as a construction technique, up to 31 additional trees could be at risk. These trees contribute to the present character of the Ellipse, and their loss would be an adverse effect on the cultural landscape.

Providing deliveries at a renovated facility in the New Executive Office Building, with underground deliveries to the White House complex, would reduce surface activities and improve the appearance and decorum of the site as both an executive office and residence.

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Impacts of the Proposed Plan Cultural Resources

On the north grounds of the White House, constructing news media facilities under West Wing Drive would potentially require the removal of a sugar maple planted by President Reagan in 1984. Other plantings at risk during construction could include the fern-leaf beech planted in 1972 by President Nixon. Constructing a staff circulation corridor along the north side of the White House would put two fern-leaf beeches near the west wing (one planted by President Johnson in 1968, and one by President Nixon in 1972) at risk. Underground construction north of the proposed staff circulation corridor on the north lawn for first family recreation space could put at risk or require the removal of a red maple planted by President Carter in 1977.

To mitigate any adverse effects, all landscape elements would be documented before disturbance by photography and mapping. For the proposed excavation for the parking structure and its tunnels, excavation would be restricted to previously disturbed areas (roadways) wherever possible. Monuments and trees would be protected by barricades, wrappings, and similar devices; monuments would be monitored for movement. To help protect the overall visual quality of President's Park, any required ventilation and emergency exit facilities would be located away from primary viewsheds and screened by landscaping and plantings.

Additional detailed studies would be required at both the design and construction phases of a project to ensure that park resources were properly protected.

Redesigning the present NPS grounds maintenance facility on the south grounds of the White House would affect the landscape during construction. Through proper design, visual effects could be mitigated.

Visitor Use and Services. The portal to the pedestrian corridor from the White House visitor center to Lily Triangle would be a new element in the landscape. This area is near the Fifteenth Street Financial Historic District, the Pennsylvania Avenue National Historic Site, and the Federal Triangle Historic District. The Lily Triangle structure would be a heavily planted berm structure designed so as to blend into the existing landscape and to minimize any intrusion on historical surroundings. Any landscaping would take into account security concerns and possible use by homeless individuals.

The use of an underground corridor from the visitor center would relieve pedestrian congestion on the surface in the eastern portion of the site, thereby helping protect the site dignity and character.

Providing visitor amenities (such as benches, shaded outdoor seating areas, and drinking fountains), which would be designed in conformance with the Design Guidelines, would complement existing elements and minimize the intrusion of incompatible elements.

Public recreational opportunities would continue to be allowed in President's Park, but more passive activities would be encouraged, helping to preserve the park's formal character and ceremonial vistas.

Special Events. Requiring special events to reflect the dignity and purpose of the site, along with providing permanent infrastructure to produce special events, would reduce visual impacts on the setting of President's Park and help protect vistas to and from the White House.

Currently, setup for special events can take several weeks because of the need to install infrastructure (electrical lines, staging lighting, communication equipment, etc.). Providing permanent infrastructure onsite would

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ENVIRONMENTAL CONSEQUENCES

reduce the setup time and consequently adverse impacts on the visual character. Requirements that materials (such as fencing, scaffolding, and stages) be removed in a timely manner after an event would minimize how long intrusions were present.

Installing a permanent events plaza, with hard surfaces and infrastructure, in the northeast corner of the Ellipse would concentrate crowds, equipment, and impacts in a specific area, keeping temporary facilities out of views to and from the White House. The facility design would be consistent with the Design Guidelines so as to minimize any adverse effects on site character.

Transportation. Two eastbound traffic lanes on E Street would continue to separate the Ellipse from the rest of President's Park. While traffic patterns and uses would be changed within the Ellipse, historic roadway systems throughout the site would generally be retained.

Eliminating surface parking in the study area would reduce traffic congestion throughout President's Park, particularly at delivery points. This action would improve overall visual quality and allow unobstructed views to and from the White House.

The development of a comprehensive tour bus management plan in cooperation with the National Capital Planning Commission and the District of Columbia would identify outlying staging areas for buses, thereby eliminating bus parking within the historic sight lines, lessening traffic noise and confusion, and enhancing the site character.

Site Operations. Providing storage for frequently used items would facilitate daily operations. A nearby satellite maintenance facility would reduce inappropriate uses of historic structures, like current uses of the Bulfinch gatehouses for storage, and resulting visual impacts.

Conclusion

The proposed plan would seek to create a unified character for the White House and President's Park by implementing the Design Guidelines, removing surface parking, and providing new facilities underground. Proposed actions would all help restore the integrity of historical views from the White House across the Ellipse to the Washington Monument and the Jefferson Memorial, but continued traffic across the park on E Street would still visually intrude on views south from the White House and divide the Ellipse from the rest of the park area. Five commemorative trees on the White House grounds could be subject to damage or loss. Constructing an underground Ellipse parking facility would constitute an adverse effect as a result of new entry portals that would intrude on formal vistas. The permanent loss of 24 trees (during construction up to 31 trees would be at risk, depending on the construction method) would also affect the site's appearance. Potential impacts of new surface elements, such as entrance portals to underground facilities, on the settings of nearby national historic landmarks and districts would need to be mitigated through sensitive design. To help protect the overall visual quality of President's Park, any required ventilation and emergency exit facilities would have to be located in areas outside the primary viewsheds and screened by landscaping and plantings.

Impacts on Archeological Resources

Analysis

Proposals (1) to adopt an organized program for surveying, testing, and recording artifacts,

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Impacts of the Proposed Plan: Cultural Resources

(2) to prepare an archeological survey for the White House and President's Park, and (3) to make the collection available for study by scholars would all help protect archeological resources and ensure proper documentation.

Actions under the proposed plan that could affect archeological resources during excavations include (1) developing a meeting/conference facility beneath West Executive Avenue, (2) a 290-space northside parking garage and an 850-space parking garage beneath the Ellipse, plus a 4,000-square-foot maintenance facility, (3) news media facilities below West Wing Drive, (4) potential new recreation space for the first family belowground north of the residence, (5) a belowground expansion of the visitor center in the Commerce Building, (6) a special events plaza in the northeast quadrant of the Ellipse, (7) nine underground vehicular, pedestrian, and service corridors, and (8) a rerouted steamline from the Ellipse to rights-of-way along 17th Street, Constitution Avenue, and 15th Street.

Systematic preconstruction testing and controlled excavations would be done if impacts were likely; projects would be continually monitored in instances where there was a likelihood of artifacts being discovered. Potential effects could be mitigated through survey, monitoring, and recordation.

West Executive Avenue has served as a right-of-way since 1871; before that time this area had been open space between the White House and the Old Executive Office Building to the west. Pennsylvania Avenue has been a thoroughfare at least since the 1820s. It is unclear how much grade change has taken place on West Executive Avenue and Pennsylvania Avenue over time; some portions might be relatively undisturbed.

The 850-space Ellipse parking facility would require the removal of fill brought in by the Corps of Engineers in the 1870s. Historic archeological disturbance would be substantial, and mitigation would be both expensive and time consuming.

Conclusion

All actions affecting archeological resources would be mitigated through surveys, monitoring, and recordation. However, given the extent of disturbance, mitigation could be time consuming and costly.

Impacts on Historic Buildings and Structures

Mutual assistance would continue between the entities with jurisdiction over historic buildings within President's Park, including the Office of the President, the Executive Residence, the General Services Administration, the U.S. Treasury Department, and the National Park Service. Historic preservation and curation programs for buildings and collections would be closely coordinated.

Analysis

Home and Office of the President. Executive Residence-Each time a new family has taken up residence in the White House, there have been requests for recreational facilities to meet their needs, ranging from an indoor swimming pool, to a bowling alley, to a putting green, to an outdoor jogging track. These requests have always been accommodated in the most appropriate manner possible; however, there is a possibility that the incremental addition of recreation facilities over the long term could gradually affect the historic fabric or cultural landscape. Providing flexible recreation space, with state-of-the-art facilities, for use by future first families would help meet their needs while minimizing the potential for historic resources

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ENVIRONMENTAL CONSEQUENCES

and the surrounding cultural landscape to be adversely affected.

Executive Office Support Services - Excavation for the underground parking garage on Pennsylvania Avenue would require that sculptures, trees, and plant materials on the south side of Lafayette Park be temporarily barricaded to ensure their protection. Access to Blair House could be temporarily limited during construction. Foundation systems at Blair House and the other 19th century row houses west of Lafayette Park would need to be strengthened and shored.

Constructing a belowgrade meeting/conference facility would relieve some stress on cultural resources in the White House, the Old Executive Office Building, and the Treasury Building by offering alternative, state-of-the-art meeting facilities. Historic rooms within these structures contain furniture and fabrics not designed for modern uses, and temporary utility cables must be run for meetings and media events. Focusing these activities in one location with adequate utilities would help reduce the need to continually move materials and equipment in and out of the White House, lessening the potential for damage to museum pieces and historic fabric.

Providing controlled underground access for vehicular traffic and staff parking would alleviate some impacts on resources. Air and filtering systems in underground parking facilities near the White House would slightly reduce the effects of damage on stone and metallic resources as a result of airborne pollutants.

Security materials and equipment would continue to have effects on the site's historic fabric and cultural landscape. Efforts would be made to mitigate these effects through a continuing dialogue between the National Park Service and the U. S. Secret Service.

News Media - New or upgraded media facilities would reduce the potential for damage to cultural resources and historic fabric by providing additional space for circulation and deliveries, and by reducing electrical hazards.

Visitor Use and Services. Expanding the White House visitor center in the Commerce Building would be done with consideration for the structure's eligibility for listing on the National Register of Historic Places. Character-defining details and spatial arrangements integral to the building's design would be respected throughout the planing, design, and construction process.

Site Operations. With the development of a 4,000-square-foot maintenance facility as part of the Ellipse parking garage, incompatible uses of historic structures, such as the Bulfinch gatehouses, would be stopped. This would help protect the integrity of these historic structures.

Conclusion

A more proactive resource management program for historic buildings and structures would help ensure the continued protection of the historic fabric of nationally significant resources. Excavation for the northside parking facility would require that sculptures, trees, and plant materials on the south side of Lafayette Park be temporarily barricaded and that foundation systems at Blair House and the other 19th century row houses west of Lafayette Park be strengthened and shored. Establishing new meeting facilities would help relieve some of the overuse of historic rooms and subsequent deterioration of historic fabric.

An onsite maintenance facility would eliminate inappropriate uses of historic structures.

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Impacts of the Proposed Plan: Natural Resources

Security would continue to affect historic buildings and structures but could be mitigated by continued consultation between cultural resource and security agencies.

Impacts on Fine and Decorative Arts

Analysis

Providing storage and conservation facilities for fine and decorative arts within or immediately adjacent to the White House would allow for some objects to be kept on site, reducing the current potential for damage during repeated shipments on- and offsite. An onsite conservation facility, which could be provided with little disruption to the historic fabric of the White House, would allow damaged objects to be promptly assessed and prepared for shipment to a fully qualified conservator.

Conclusion

Short-term storage for fine and decorative arts within or immediately adjacent to the White House would reduce the potential for damage that could otherwise occur during repeated shipments of pieces. Damaged pieces could be fully assessed before transport to a conservator.

Natural Resources

The construction of any underground structures, as well as required construction techniques, could both affect and be affected by subsoil and groundwater conditions within the study area. The construction of these facilities could also cause changes in existing vegetation patterns.

To aid in understanding the possible natural resource impacts, the two suggested methods of construction-cut/cover and tunneling - are explained in the glossary, and the method proposed for each underground structure is identified in the cost tables in appendix E. Mitigating measures for impacts on vegetation and soils that would be used during construction are outlined in the "Mitigating Measures" section (pages 95-96).

As previously stated, many of the proposed actions have only been conceptually designed. For resources such as groundwater and soils, an initial analysis has been conducted to determine if a facility could be constructed. For other resources, such as trees, the general number that could be impacted or would be at risk are identified, hut individual trees that would be removed or replanted cannot be identified at this level of planning because during final design there could be minor changes in the size and location of a facility. When final designs were undertaken (once a proposed plan was approved and funding acquired), an environmental assessment would be conducted in order (1) to analyze site specific impacts, (2) to ensure that all facilities and design details were in agreement with the proposals and guidelines presented in this document, and (3) to identify measures to minimize or mitigate impacts to all resources and site activities.

Geotechnical Considerations

Subsoils

Description. Subsurface conditions in the vicinity of the White House have been investigated at various times by several geotechnical firms for both private and government projects. A general soil profile has been developed from these investigations in the study area (I Street on the north to Constitution Avenue on the south, and 15th Street on the east to 1 7th Street on the west).

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ENVIRONMENTAL CONSEQUENCES

In general the subsoils consist of 2.5' to 19' of fill (average depth of about 8') overlying 2' to 32' of natural silty clay and silts with occasional silty sand lenses, which are underlain by natural sands and gravels with clay and silt lenses. The fill encountered consists of a mixture of silty clays and clayey silts, with random sand and gravel lenses. Some construction debris (such as brick and concrete fragments and cinders) was reported in fill material on the north. Gneissic schist bedrock is reported at depths of 70' to 80' below the ground surface.

The consistency or relative density of the fill and underlying natural soils has been described as follows:

*Fill has been randomly placed, with little or no compaction, making the density characteristics very erratic.

*Natural silty clays, clayey silts, and silts are soft to very stiff.

*Sands and gravels are firm to very dense

* The upper 1' to 1.5' of bedrock is weathered.

Implications for Construction. Existing fill materials are not suitable for supporting foundations or features such as sidewalks, pavements, or other hardscape features. Depending on the type of construction, removal of all or a portion of the existing fill and replacement with properly compacted structural fill would be required.

The underlying natural soils above the water table are generally suitable for supporting lightly to moderately loaded spread footing foundations, as are the sands and gravels. These soils are also suitable for supporting spread footings below the water table, but dewatering would be required during construction. Pilings driven into the very dense sands and gravels or to bedrock would be feasible for supporting heavily loaded structures.

Any belowgrade structure that would be in contact with the existing water table would require a permanent dewatering or drain system. This is especially true in the area of the Ellipse, where the water table is very near the ground surface. Any belowgrade structures in this area, such as the pedestrian corridor from the visitor center to Lily Triangle, would not only require a permanent drain system but might also need to be designed for hydrostatic uplift.

Excavation could be accomplished with conventional excavating equipment. Cut-and-cover construction techniques would also be suitable for most of the area. However, where site conditions constrain the limits of excavation, excavations would have to be shored. Tunneling in the natural clayey silts and silts might be feasible in some areas. Site-specific investigations would need to be conducted at each location to determine if the existing fill materials could sustain tunneling operations.

Groundwater Conditions

Description. Groundwater was encountered at depths from 2' on the south to 36' on the north. The shallowest groundwater was noted at the intersection of 1 7th and E Streets (2.0') and on the south side of the Ellipse near Constitution Avenue (3.5'). Average depth to groundwater is reported to be about 15' to 20' below the surface. There are also deeper aquifers below the 30' elevations that could be encountered and affect underground construction activities (per. comm., Dr. James O'Connor, Univ. of the District of Columbia).

Some geotechnical reports suggest that the construction of the Metro subways may have lowered the groundwater table somewhat due to drains constructed for the subway tunnels.

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This effect would be most notable on the northern end of the study area.

Implications for Construction. Dewatering of most excavations could probably be conducted from within the excavations during construction. However, where the depth of excavation extended into the water table, dewatering from outside the excavation using well points might also be required. This could occur if water-bearing lenses of sand were encountered.

The following additional studies would be needed:

*During design development stages, existing groundwater levels and subsoil data should be evaluated for each location and, where necessary, supplemented with additional soil borings and monitoring wells. Areas specifically lacking adequate information include the E Street corridor and the northern part of the Ellipse.

* Level I hazardous material investigations would be conducted. First, existing data sources would be searched for information on storage tanks, local groundwater quality, and records of past hazardous material spills or incidences within the study area. Second, a surface reconnaissance would be performed within the study area to identify any signs of contamination.

* Based on the results of the level I investigation, a level II sampling program might be undertaken to locate and identify any suspected contaminants in soils and groundwater. Any areas of contamination would be cleaned up.

*Information regarding waterproofing underground structures and other construction-related issues would continue to be solicited from informed sources, such as the Washington Metropolitan Area Transit Authority, the General Services Administration, and the Smithsonian Institution.

Conclusion

Based on existing subsoil and groundwater data, underground construction of all proposed facilities is possible without impact to either resource with the following requirements.

* Existing fill would have to be replaced with properly compacted structural fill to support foundations.

*Spread footing foundations could be used for lightly to moderately loaded structures; below the existing water table a permanent dewatering or drain system would be required. Heavily loaded structures could require piles driven into dense sands and gravels or bedrock.

*Excavation could be accomplished with conventional equipment, although shoring might be required.

Where information is incomplete, further site specific studies would be required during design development, including additional soil borings and groundwater levels and hazardous material investigations.

Impacts on Water Resources

The analysis of water resources is based on the following assumptions:

*Surface and groundwater in this area generally flow toward the Potomac River, which is approximately 6,000' south of the White House grounds and is a controlling factor for the elevation of groundwater in the study area.

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ENVIRONMENTAL CONSEQUENCES

* There are no known stormwater detention structures in the area, such as ponds or underground storage tanks that retain or detain and release stormwater at controlled rates. Thus, stormwater is assumed to be transported through the storm sewer system. Stormwater will flow through and discharge as quickly as the sewer system allows. This is mentioned because maintenance of the storm sewer system has historically been poor; backups in the system can create leaks that infiltrate into the surrounding soils' saturating them and making them unstable for supporting surface structures. Backups have also flooded wheelchair ramps and reduced vehicular access and parking.

Surface Water

Analysis. Few impervious surfaces would be added under the proposed plan. However, any new impervious surface facilities and land disturbance would reduce the potential for water to infiltrate, creating more surface runoff. Under most conditions runoff would be diverted to a stormwater management structure. However, because of the proximity of President's Park to the river, stormwater should not be detained since the discharge of detained water could coincide with storm runoff from farther up the watershed, causing a greater-than-normal peak at a later time

Effects of underground structures on surface waters would depend on construction techniques and surface support activities (see appendix E). Certain activities could compact surface soils (for example, heavy equipment traversing the site), causing additional runoff, or could contribute pollutants to stormwater runoff (for example, gas and oil spills or leaks from equipment at the site). To prevent such occurrences, best management practices and D.C. regulatory controls for stormwater management and soil erosion prevention would be followed during construction to protect storm sewers and receiving surface waters.

The reduction in aboveground parking on the Ellipse and West Executive Avenue would reduce the amount of oil, gas, and other wastes that would enter the stormwater system through runoff.

All proposed methods of stormwater management would be subject to review by the District of Columbia during the design of all surface and underground development.

Conclusion. Few impervious surfaces on the ground level would be constructed under the proposed plan, resulting in no long-term changes in stormwater volumes. Similarly, the development of any underground structures would probably have little to no effect on surface water quantity or quality.

Groundwater

Analysis. Building underground structures could require excavation sites to be dewatered (see geotechnical discussion). Dewatering wells would not draw down the water table to a constant elevation. As a well pumps the groundwater, a cone of depression forms, emanating from the point of the wellhead. This would be the lowest point of the groundwater table in the immediate area during pumping operations. The rate of pumping would depend on the rate of groundwater inflow into the construction area, which would be determined through additional testing at the site before excavation.

After construction one of two results could occur. If a permanent dewatering system was required around a new underground structure, a permanent lowering of the water table could occur where the system was installed.

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Impacts of the Proposed Plan: Natural Resources

However, if no permanent dewatering was needed, the groundwater table would most likely return to its predevelopment level.

New surface development could reduce water infiltration into the soil (as stated previously for surface water impacts). However, these reduced infiltration levels would be minimal and cause an undetectable decrease in groundwater since most of the recharge area is well above this point.

Conclusion. New underground facilities would probably have little to no long-term effect on groundwater quantity or quality within President's Park. Each underground structure could displace groundwater and reduce the storage area relative to the volume of the structure. The addition of minor impermeable surfaces would have a negligible effect on groundwater quantity. Thorough, site-specific groundwater wells and testing would be conducted before any construction to ensure that effects would be minimized.

Impacts on Vegetation and Soils

Analysis

Vegetation could be affected as a result of constructing underground facilities and the special events plaza. Many proposed structures would require excavating areas that are now covered by streets, sidewalks, grass, and trees (referred to as cut and cover). Before excavation, vegetation within the excavated area would have to be removed, the new structure built, and the excavated soil returned. New plantings of similar genus and form would be used to restore the landscape following construction, but plants would likely vary in size and be substantially smaller than mature trees are now. If feasible, significant trees in an excavated area would be balled and temporarily stored for replanting in the same location. Replacement stock would be planned for and provided as needed. In some cases trees would be permanently removed and not replaced.

Not all underground structures would require surface excavation; some would be tunneled to protect significant surface resources. Only those constructed by means of cut and cover would likely cause surface disturbance, and thus are emphasized in the impact discussion below.

Dewatering activities related to construction would most likely not affect trees. Trees and vegetation within President's Park depend primarily on natural infiltration rather than groundwater. However, because the interrelationship between groundwater, surface water, and vegetation is often variable (see the following discussion about the Ellipse), soil moisture sensors would be used to monitor conditions during and after construction. Watering capabilities would be necessary if the soil became too dry.

Excavated soils would need to be disposed of as quickly as possible because of the lack of onsite storage areas. Such operations would require numerous trucks and increased transportation costs.

White House Grounds and West Executive Avenue. The largest areas of excavation for the proposed plan would be within or directly adjacent to the White House complex- under Pennsylvania Avenue, under West Executive Avenue and West Wing Drive, and along the north side of the White House.

Constructing news media facilities under West Wing Drive on the north grounds would potentially require the removal of four elms (approximately 20 years old) and a sugar maple (Reagan 1984). Other plantings at risk during construction could include a fern-leaf beech (Nixon 1972) and a 100-year-old

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yellow buckeye, both just northeast of the West Wing entrance. Approximately 13 oaks would be removed along the north end of West Executive Avenue.

The intent would be to limit construction activities for the staff circulation corridor to the confines of the existing drives and areas along the north side of the White House and the East and West Wings. However, a substantial amount of vegetation that lines these areas would be at risk during construction, including two fern-leaf beeches near the West Wing (Johnson 1968, Nixon 1972). Approximately 18 other trees adjacent to the East Wing would be at risk, including numerous Washington hawthorns' star magnolias, saucer magnolias, and potentially several fern-leaf beeches. Much of this vegetation was planted in the 1950s and 1960s. Various shrubs and ground covers would be potentially disturbed, including English ivy, azalea, and purple wintercreeper.

Underground construction could also occur north of the proposed staff circulation corridor on the north grounds of the White House. This development, if not tunneled (and at sufficient depth), could put at risk or require the removal of a red maple (Carter 1977) and several 1 00-year old trees (lindens, tulip tree, and red oak).

On the south grounds of the White House the proposed redesign of the grounds maintenance facility would need to respect plant materials and garden areas adjacent to the site. Of particular concern would be the preservation of the bald cypresses (planted prior to 1900) in and adjacent to the existing facility and the Children's Garden.

The development of guidelines for special events would also help protect the historical character and resources of the grounds.

Lafayette Park. Development under Jackson Place and Pennsylvania Avenue would not affect vegetation within Lafayette Park. Some street plantings along the west side of Jackson Place could be removed or at risk during construction; however, work would be kept within the street right-of-way as much as possible.

Ellipse. Constructing an Ellipse parking garage, along with vehicular and pedestrian access tunnels, would result in a long-term loss of trees, particularly American elms, on the northeast and northwest panels of the Ellipse and along the north and south sides of the Ellipse Drive near 1 6th Street.

Placing the entrance portals for the staff parking facility at the southern end of the Ellipse would require the permanent removal of approximately 13 elms along the north and south sides of the Ellipse Drive near 16th Street. The impact of the underground pedestrian corridors (which would emerge in the northeast and northwest panels at undetermined locations) would vary significantly depending on the method of construction, as described below:

* Tunneling the corridors approximately 10' to 20' below the Ellipse surface (the preferred and suggested method of construction) could result in the loss of two to four additional elms.

* Excavating the corridors from the ground surface would result in an impact area up to 72' wide for the length of the tunnel. This would result in the temporary loss of an estimated 25 trees, including 6 American elms along the Ellipse Drive, plus American basswood (or linden), hedge maples, and bald cypress. The loss could vary based on the route of the corridors and where they emerged on the Ellipse side panels. Losing these trees would be a significant visual impact during construction. While the trees would be replaced after construction, the new trees would be younger and much smaller than the existing trees.

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Impacts of the Proposed Plan: Natural Resources

 

The special events plaza would require the permanent removal of three or four American elms. Most of the plaza would occupy the site of the current Ellipse pavilion; thus, tree removal should not be extensive.

Constructing a pedestrian corridor from the visitor center to the Ellipse along E Street could result in the loss of seven trees, including three elms. Because of the belowground pedestrian access corridor, it is doubtful that these large trees could be replaced.

The effects on the elms and other tree species of dewatering activities that might be required during the construction of the Ellipse parking facility and, underground pedestrian corridors cannot be predicted. One hypothesis is that groundwater does not support vegetation on the Ellipse because the majority of the tree roots for species such as the elms are in the upper 18" to 24" of soil. The root zone extends from the ground surface to the bottom of the root systems of the surface vegetation; this zone is only saturated for brief periods following substantial rains and is not dependent on groundwater levels. However, phenomena such as capillary rise (when fine-grained soils act as a straw and draw moisture from groundwater towards the surface) could create an interrelationship between vegetation and groundwater. Because this interrelationship is variable, soil moisture would be monitored during and after construction. As a result, the capability to water trees might be necessary if moisture sensors indicated a threatening decline in soil moisture.

The events plaza would help prevent soil compaction, repeated turf damage, and perhaps loss of other trees throughout the Ellipse by focusing activities (such as the Pageant of Peace) around the plaza and using existing hard surfaces.

Using the White House visitor center to stage public tour groups would eliminate repeated damage to both soils and turf on the Ellipse by allowing the removal of the tour staging area. Pedestrian movements on the Ellipse would become more random and less impactive in terms of soil compaction and turf damage. As a result, this area could be more easily restored and maintained year-round. Eventually replacing the steamline across the Ellipse would eliminate current turf impacts.

Conclusion

During construction, an estimated 42 trees would be removed: 5 on the White House grounds, 13 on West Executive Avenue, and 24 on the Ellipse and the side panels. Permanently removing 20 American elms throughout the Ellipse would represent a 9% reduction of the 215 elms in this area. Approximately 52 trees would be at risk depending on the construction method: 21 trees on the White House grounds (including 5 commemorative trees, representing 13% of these historic plantings), and up to 31 trees on the Ellipse. Construction methods would be carefully chosen, and vegetation and soil mitigation measures would be applied during construction to preserve trees where feasible and cost-effective. Disturbed areas would be restored after construction. Where possible, commemorative plantings would be removed, cared for in a nursery, and replanted in the same locations.

Turf impacts on the Ellipse due to the steamline would be eliminated once the line had been replaced. Soil compaction and turf maintenance would be improved due to the relocation of major visitor activities.

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ENVIRONMENTAL CONSEQUENCES

Home and Office of the President

Impacts on Executive Residence Operations

Analysis

Noise from construction and the visibility of construction activities could intrude on peace and quiet for the first family. Measures to minimize disruptions would be identified before any construction was initiated.

Indoor Recreation Space. Approximately 3,000 square feet of indoor, multipurpose space would accommodate various indoor recreational activities for future first families. For example, a sports court (basketball/volleyball), weight room, game room, TV room, sauna, and whirlpool bath could be provided. The space would be private, secure, and immediately accessible from the Executive Residence. This type of space would help provide flexibility in meeting future first families' needs and offer a greater sense of normal living conditions for both children and adults. The first family would be able to use the facility without encountering staff members and business visitors crossing through the site. (Outdoor recreation space on the south grounds would continue to be available.)

Privacy. Staff within the White House complex (Old Executive Office Building, the West Wing, and Treasury) currently use the ground floor of the White House for access throughout the site to conduct daily business, decreasing the sense of privacy for the first family within the residence and increasing wear and tear on carpets and historic furnishings in the corridor. Proposed underground pedestrian/ service corridors for staff end business visitors along the north side of the White House would eliminate the need to use the ground floor for staff circulation and deliveries and would provide additional privacy for the first family.

Storage. Currently, items such as furnishings, chairs for state dinners, music stands, staging and other equipment for special events, and supplies are brought into the complex from offsite locations as needed. Because all deliveries are routinely checked by security, the frequent transportation of items on- and offsite is an inefficient process. Some smaller items are stored in inappropriate locations within the residence (such as stairwells, offices, recreation areas, and corridors), resulting in congested conditions and safety hazards.

Providing approximately 10,000 square feet of storage space under Pennsylvania Avenue, with an underground connection to the Executive Residence, would allow frequently used items to be kept onsite, giving staff timely and easy access to them. Not having to store items in work areas or corridors would allow these spaces to be used as they were originally intended, reducing safety hazards. The new storage space could also be expanded in the future, if needed. An underground connection between the Executive Residence and the storage facility would allow items to be moved around the site without interfering with other daily operations.

Public Access. The various functions associated with the White House, the first family's need for privacy, the need for security, and the public's desire for access to the White House would continue to have to be balanced. Public access would still be afforded through White House tours, which would normally be scheduled five days a week, as long as they were not precluded by presidential business or official functions. Public access would also continue to be provided during events such as the Easter egg roll, garden tours, and Christmas candlelight tours.

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Impacts of the Proposed Plan: Home and Office of the President

Conclusion

New indoor recreation space and staff circulation corridors would benefit future first families by helping meet needs for leisure and privacy. Indoor recreation space would also provide flexibility in meeting first family needs and offer a greater sense of normal living conditions for both children and adults. Staff would no longer have to pass through the Executive Residence when moving about the site. The first family's privacy and security needs would continue to be balanced with the public's need for access to the White House.

New storage space would make Executive Residence staff operations more efficient and allow spaces now used for temporary storage to be used as they were intended, reducing safety hazards. An underground corridor between the Executive Residence and the storage area would reduce interference with other operations when items were being moved from one location to another.

Impacts on Executive Office Support Services

Analysis

Visitor Arrivals. Diplomatic and business visitors would be able to enter the White House complex at various points. Arrivals would continue to be accommodated at the entrance to the West Wing on West Executive Avenue, at the entrance to the East Wing on East Executive Park, and at the north and south porticos. In addition, an underground entrance to the proposed meeting facility below West Executive Avenue would provide immediate access for persons attending White House conferences. The removal of parked vehicles on West Executive Avenue would simplify arrivals to the West Wing.

Meeting/Conference Space. Providing state-of-the-art utilities for teleconferencing, visual displays, and sound, as well as computers, would allow more productive communications and presentations. The proposed facility would provide the type of accommodations currently available to most corporations. Spaces and seating arrangements would be adaptable for various meeting sizes, up to a maximum of about 200 individuals. Placing such a facility next to the West Wing would also make it more efficient for presidential staff to prepare for meetings and conferences.

The space would be within the secured portions of the White House complex and would be immediately accessible to the West Wing and the Old Executive Office Building. This location would allow the president to attend meetings without the security needed when meetings are held outside the complex, thus reducing security expenditures.

Parking. Providing a total of 1,140 replacement parking spaces for diplomatic and business visitors and staff would meet current needs, minimize inconvenience to staff, and be easily accessible and secure. Onsite parking facilities would also accommodate various work schedules. The nature of White House operations requires many staff members to work long or staggered shifts, or to be on call and able to get to the White House within a certain amount of time if paged. Staff often work beyond the hours when public transit is available. Pending the construction of these facilities, interim parking would be leased in existing facilities within a 1 0-minute walk of the White House.

Providing a 290-space parking facility under Pennsylvania Avenue for motorcades, diplomats, and senior staff would replace parking now provided within the White House complex. Some parking would also be provided for security vehicles now parked offsite. A

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staging area for presidential and diplomatic motorcades would provide flexibility in planning and staging motorcades (currently there may be eight or nine motorcades on some days). Motorcades could continue to arrive on the or underground, as needed. Vehicles waiting for senior staff (potentially 5 to 10 cars at any one time) would be out of view until needed. An underground facility would also protect visitors, staff, and drivers from inclement weather, and a corridor would provide immediate, secure access to the White House and the meeting/conference facility.

Two portals into the northside parking facility (by way of the New Executive Office Building and West Executive Avenue) would allow more efficient access, and uses could be separated by designing each entrance to access a different level of the parking facility. For example, motorcades, diplomats, and business visitors could use the West Executive Avenue entrance, while senior staff could use the NEOB entrance, thus preventing staff cars from intermixing with diplomatic, business visitor, and motorcade traffic. If uses were not separated, traffic into the parking facility would be allocated between the entrances based on street or portal capacity, thus minimizing vehicle movements on West Executive Avenue. Both portals would be within areas that are currently secured, so no additional security staff or equipment would be required.

The New Executive Office Building has the capacity to accommodate additional vehicle entries and exits. The entrance and delivery area would be managed to ensure efficiency of access and deliveries.

While an additional 850 staff parking spaces would be provided by the end of this plan, surface parking on the Ellipse would be removed starting four years after the plan was approved. This schedule would allow design plans for the Ellipse roadway and side panels to be implemented over the short term, immediately enhancing the overall appearance of the site. During this interim period staff would have to park in leased spaces within a 10-minute walk of the White House.

The primary pedestrian access for the staff in the Ellipse parking facility would be an underground pedestrian corridor for daily use and emergency egress. Staff would walk through the corridor and emerge on the surface at the northeast or northwest side panels south of E Street. To continue on to the White House complex, staff would cross E Street either at 15th Street or 17th Street. Although inconvenient, crossing E Street is part of the daily experience for most staff at present and thus would not be a new inconvenience.

Studies show that walking times from existing staff parking spaces throughout President's Park range from approximately 1.5 minutes to over 8 minutes. (The walk from the lower Ellipse to the southwest gate at State Place and West Executive Avenue is the longest at 8 minutes and 23 seconds.) Thus, parking in an Ellipse facility, and in the interim in leased spaces offsite (within the area from 14th Street west to 19th Street, and from I Street south to Constitution Avenue), would provide similar walking times.

Field studies by GSA staff in 1996 indicate approximately 4,500 public parking spaces within 26 parking garages within the study area. A total of 850 parking spaces would be available until the Ellipse facility was built, although no one operator would be able to provide all the spaces. These spaces are currently being used by other leaseholders, area employees, and the public.

Providing an Ellipse staff parking facility would offer security and protection from weather. A secure facility would also eliminate theft and damage that have occurred to

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Impacts of the Proposed Home and Office of the President

cars parked on the Ellipse roadways. Perceptions of interim leased parking by White House staff vary. Some perceive parking outside President's Park as being farther away and less safe During the period when parking would be leased offsite, escorts or shuttle services could be provided after business hours to ensure staff safety.

Providing parking for White House staff (in the short term in leased parking spaces and in the long term in a new federal facility) would likely increase parking costs for employees beginning the fourth year after the plan was approved. In accordance with current federal policies, parking costs are paid by employees. Monthly leased parking rates for the downtown D.C. area in 1996 averaged $146.

All access to the White House during construction would be retained.

Deliveries. Most daily deliveries to the White House complex would be handled through the renovated facility at the New Executive Office Building. Deliveries would be distributed to locations throughout the White House complex by means of underground service corridors, minimizing current congested situations involving delivery trucks, moving and parked vehicles, pedestrians, and service vehicles. Additionally, the NEOB delivery area would utilize an existing secured facility, thus reducing the need for large numbers of new, additional security staff and facilities. Deliveries for the White House would be carefully managed to avoid any conflict with NEOB deliveries. Continuing the surface delivery of some large items throughout the White House complex would remain the most efficient practice.

Observations and discussions by the appropriate agencies indicate that designating one manager at the New Executive Office Building to schedule deliveries would improve efficiency and allow the facility to accommodate routine deliveries to the White House complex.

Staff Functions. Separate underground pedestrian and service corridors would reduce conflicts with other activities occurring within the site. Staff access to other portions of the complex would be facilitated by removing parked vehicles on East and West Executive Avenues, providing for underground deliveries' and eliminating the need to use corridors for temporary storage. For example, parallel pedestrian/service corridors along the north side of the White House would allow for the efficient and safe movement of goods, materials, and people. Staff and visitors would also be able to move more conveniently across the site in inclement weather. Providing additional media storage and work space would reduce congestion for staff and other visitors moving past the west colonnade.

Providing better information and orientation for visitors as they enter President's Park would reduce the time spent by personnel at the gatehouses answering questions.

Conclusion

New facilities for meetings, parking, deliveries, and staff circulation would benefit the Executive Office of the President by meeting current and future needs, reducing conflicts with daily operations in the Executive Residence, and protecting significant cultural resources, as described below:

*Developing state-of-the-art meeting/conference space, with infrastructure for teleconferencing, visual displays, sound, and computers, would allow meeting setups to be handled more efficiently.

*Providing 1,140 onsite replacement parking spaces would meet current needs. The 290-space northside parking facility would be immediately accessible to the White House for official visitors and senior staff; it would also offer protection from inclement weather and facilitate motorcade operations. The 850-space Ellipse facility would be nearby for staff. Interim leased parking (within a 10-minute walk of the White House) could be perceived as being farther away and less safe; however, shuttles could be provided. Staff parking costs, whether for spaces in leased facilities or a new federal facility, could become the responsibility of individual employees. If the employing agency paid parking costs, the value of parking, could be taxed.

Accommodating deliveries through a secure, centralized facility and under-ground service corridors would minimize present conflicts on the surface between delivery trucks, pedestrians, and parked and moving vehicles. Also, daily deliveries could be handled more efficiently.

Providing an east/west corridor for staff between the Old Executive Office Building and the Treasury Building would reduce conflicts with Executive Residence daily operations and public tours.

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Comprehensive Design Plan Continued