TABLE OF CONTENTS

1.0	SUMMARY	1

2.0	PURPOSE AND NEED FOR THE PROJECT	3

3.0	DESCRIPTION OF THE PROJECT AND ALTERNATIVES	4

3.1	Alternative 1- Stabilization without Removing Steel Banding	4

3.2	Alternative 2- Rehabilitation of the Aqueduct and Removal of the

Steel Banding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.3	Alternative 3- No Action	6

4.0	DESCRIPTION OF THE EXISTING ENVIRONMENT	7

4.1	An Overview of the Site and Surroundings	7

4.2	Soils and Geology	7

4.3	Natural Growth of Algea and Moss	9

4.4	Water Resources	9

4.4.1	Water Quality	10

4.4.2	Wetlands	10

4.5	Threatened and Endangered Species	11

4.6	Air Quality	11

4.7	Socioeconomic/Community/Land Use	12

4.8	Noise	13

4.9	Historical and Cultural Resources	13

4.9.1	Construction of the Monocacy Aqueduct, 1829-1833	14

4.9.2	The Monocacy Aqueduct and the Civil War	16

4.10	Utilities and Services	17

4.11	Transportation	17

5.0	POTENTIAL ENVIRONMENTAL IMPACTS OF THE PROPOSED PROJECT ACTIVITIES AND ALTERNATIVES	18

5.1	No Action Alternative	18

5.2	Design Alternatives	18

5.2.1	Soils and Geology	18

5.2.2	Water Resources	18

5.2.3	Threatened & Endangered Species	19

5.2.4	Air Quality	19

5.2.5	Socioeconomic/Community/Land Use	20

5.2.6	Noise	20

5.2.7	Historical and Cultural Resources	20

5.2.8	Utilities and Services	22

5.2.9	Transportation and Parking	22

5.3	Summary	22

6.0	AGENCIES/PERSONNEL CONSULTED	24

7.0	REFERENCES	25

8.0	GLOSSARY	27

9.0	LIST OF ACRONYMS	28

APPENDICES

Appendix A	Monocacy Aqueduct Location Map

Appendix B	Monocacy Area Topographic Map

Appendix C	Classification of Soils of the Monocacy Aqueduct

Appendix D	National Water Quality Assessment--Potomac River Basin

Appendix E	National Wetlands Inventory Map

Appendix F	National Wetlands Inventory Acreage Report for Frederick County (to be provided)

Appendix G	Housing and Urban Development Hazard Boundary Map and Legend

Appendix H	Region 5 State Listed Threatened and Endangered Species

Appendix I	EPA Green Book Current Designation for Non-attainment Areas for Criteria Pollutants

Appendix J	Maryland Department of Business and Economic Development Socioeconomic Date for Frederick County, Maryland

Appendix K	Frederick County Zoning Map

1.0	SUMMARY

The United States Department of Interior (USDI), and the National Parks Service (NPS) (National Capital Region) are proposing an enhancement project to rehabilitate the Monocacy Aqueduct. The work proposed for the Monocacy Aqueduct is a part of the overall canal preservation, rehabilitation, restoration, and reconstruction program. This program is intended to provide a historically accurate setting for interpreting the history of the Chesapeake & Ohio (C&O) Canal and the importance of canal development to early transportation history. The C&O Canal National Park (NHP), owned by the NPS, is listed in the National Register of Historic Places.

The Chesapeake and Ohio (C&O) Canal National Historical Park administers a 185-mile long historic canal that extends along the north bank of the Potomac River from Georgetown in the District of Columbia to Cumberland, Maryland. The canal operated from 1832 to 1924, when a major flood damage to it prohibited further use. The Monocacy Aqueduct is located approximately 40 miles northwest of Georgetown near the town of Dickerson, Maryland. It was built to carry the canal boats over the Monocacy River and is the largest of the 11 C&O Canal aqueducts. The Monocacy Aqueduct, which spans the Monocacy River in Frederick County, just north of Montgomery County, is 516 feet long and consists of seven arches of 54-ft. spans. The aqueduct is considered one of the outstanding historical structures in existence in the United States. Numerous significant storms and floods in the past years have caused significant damage to the aqueduct, including creation of voids and cracks in the parapet walls and slight inclination of the upstream walls of the aqueduct toward the upstream side of the creek, missing stones on the tow path, displaced and missing stones on the underside of arches and in the parapet walls, and damaged pier walls. In 1975, the Federal Highway Administration installed a steel banding structure to "band" the walls of the aqueduct together and protect them from collapse.

The project, that is subject of this Environmental Assessment, is intended to evaluate the feasible alternatives for restoration and preservation of the Monocacy Aqueduct and to select and recommend the most technically and economically feasible alternative for consideration by NPS.

This Environmental Assessment (EA) examines three alternatives and their associated environmental effects. These alternatives include one no-action, and two design alternatives as follows:

Alternative 1:	Stabilization without Removing Steel Banding;

Alternative 2:	Rehabilitation of Aqueduct and Removal of Steel Banding.

Alternative 3:	No Action.

Information regarding the environmental effects of each alternative is described in Section 5 of the EA. All applicable permits will be obtained prior to initiating any of the design alternatives.

The estimated costs associated with each of the design alternatives are presented below:

Alternative 1:	Stabilization without removing steel banding	$3,105,000

Alternative 2:	Rehabilitation of aqueduct and removal of steel banding	$5,634,000

Coordination with appropriate Federal and State agencies is underway. Comments on this EA will be considered in the evaluation of the alternatives and selection of the preferred alternative.

Based on the Environmental Assessment, a Finding of No Significant Impact is recommended for all alternatives.

2.0	PURPOSE AND NEED FOR THE PROJECT

The work to be performed on the Monocacy Aqueduct is part of the overall C&O Canal preservation, rehabilitation, restoration and reconstruction program under the auspices of the National Park Service (NPS). One of the major threats to the structural stability of the Monocacy Aqueduct is the potential collapse of the pier structure above the water level. The purpose of the project is to stabilize the aqueduct by overall repair and rehabilitation and through preservation and stabilization of piers/pillars.

Many severe storms and floods, in the past years, have caused damage to the center piers including the loss of considerable amounts of masonry, and misaligned or missing blocks. The upstream piers have slightly inclined toward the upstream side of the Creek and have created large cracks at the upstream walls. Officials of the C&O Canal National Historic Park have said the Monocacy Aqueduct could be destroyed by another Potomac River flood like those that struck the area twice in 1996. Accumulations of sediments and debris on the aqueduct chamber floor and infiltration of water into the canal structure have caused damage to the aqueduct floor and also a reduction in the hydraulic capacity of the canal.

The purpose of this project is an assessment of the existing condition of the Monocacy Aqueduct and analysis of the feasible design alternatives to produce the necessary information so that the NPS can determine specific treatments for the restoration and preservation of the Monocacy Aqueduct.

3.0	DESCRIPTION OF THE PROJECT AND ALTERNATIVES

The aqueduct is constructed of white and pink sandstone quarried from Nelson's quarries at the base of Sugarloaf Mountain, approximately four miles from the Monocacy. It is 516 feet long and consists of seven (7) arches. It is currently "banded" together by a metal structure installed by the Federal Highway Administration in 1975. The hydraulic cement used in the construction of this aqueduct is believed to have originated from Carrolton and Tuscarora, in Frederick County, Maryland, and from Shepherdstown, Jefferson County, West Virginia.

The goal of this project is to evaluate the alternatives for preservation of the Monocacy Aqueduct through stabilization, repair, and restoration of the aqueduct and selection and recommendation of the best alternative. The following design alternatives were considered for this project:

3.1	Alternative 1 - Stabilization without Removing Steel Banding

Alternative 1 considers preserving the aqueduct by stabilization and repair of the existing structure without removing the existing steel banding. The following tasks are included in this alternative:

Deteriorated mortar joints on all faces of the aqueduct should be pointed.

Cracked stones on the underside of the arches should be injected with grout.

Voids and large cracks on the underside of the arches should be filled with grout.

Missing or displaced stones on the underside of the arches and in the spandrel and parapet walls should be replaced.

Voids and large cracks in the parapet walls should be filled with grout.

Voids in the pier foundations should be repaired in accordance with the Bureau of Reclamation inspection report and cost estimate.

Remove debris from the pier foundations.

Remove the top layer of the earth from the floor of the aqueduct, remove the existing water proofing membrane and replace with a new membrane. Cover the membrane with protective material and fill.

Deteriorated, cracked, loose, and missing wood blocking between the steel banding and stone aqueduct should be replaced with new pressure treated wood.

Where elements of the existing steel banding have been damaged, they should be repaired or replaced. The steel banding should be tightened where loose.

Scaffolding and debris nets will be necessary to complete many of the work items.

Estimated cost: $ 3,105,000

3.2	Alternative 2 - Rehabilitation of the Aqueduct and Removal of the Steel	Banding

Under this alternative, the existing steel banding should be removed from the aqueduct and the aqueduct should be rehabilitated and restored without any further need for the steel banding. The following tasks are included in Alternative 2:

Deteriorated mortar joints on all faces of the aqueduct should be pointed.

Cracked stones on the underside of the arches should be injected with grout.

Voids and large cracks on the underside of the arches should be filled with grout.

Missing or displaced stones on the underside of the arches and in the spandrel and parapet walls should be replaced.

Voids and large cracks in the parapet walls should be filled with grout.

Voids in the pier foundations should be repaired in accordance with the Bureau of Reclamation inspection report and cost estimate.

Remove debris from the pier foundations.

Reconstruct three damaged pier walls that have bowed outward. The face stones will need to be tied to the interior stones.

Reconstruct north abutment wall foundation.

Remove all exterior steel banding in sections in a phased manner.

Remove fill and the drains from the canal bottom.

Pour a concrete slab on the canal bottom. Work is to be completed in sections and phased with the removal of the steel banding.

Provide a waterproof membrane on the aqueduct bottom.

Drill and pump grout into voids in the prism bed.

Drill and grout vertical bars into the berm parapet.

Inventory stones which are being removed and reset.

Provide a railing on towpath side.

Remove the existing concrete slab on the towpath.

Reset coping stones on towpath parapet using the stones stored onsite.

Provide an earthen ramp for transition of bike path to the aqueduct bed.

Scaffolding and debris nets will be required to complete many of the work items.

Estimated Cost:	$ 5,634,000

3.3	Alternative 3- No Action

No action would be undertaken to stabilize, rehabilitate, restore, or reconstruct the aqueduct.

4.0	DESCRIPTION OF THE EXISTING ENVIRONMENT

4.1	An Overview of the Site and Surroundings

The Monocacy Aqueduct is part of the C&O Canal National Historic Park (NHP) and is located near Dickerson, Maryland (Appendix A - Site Map). The aqueduct lies near mile 42 of the 184.5-mile stretches of the canal. The site is bounded on the east and west by mountains, one of which is Sugarloaf Mountain. Whites Ferry is to the east of the aqueduct and Nolands Ferry is to the north. The aqueduct is surrounded by the Monocacy State Natural Resources Area to the north and a small recreation area to the south. Appendix B shows the topography of the area. The nearest populated community is the town of Dickerson. It is a sparsely populated, small, rural area.

The Monocacy is the largest Maryland tributary to the Potomac River and forms near the Maryland and Pennsylvania border west of Harney, Maryland, at the confluence of Marsh and Rock Creeks. From its origin, the river flows south to Double Pipe Creek, marking the border between Frederick and Carroll counties. Continuing south solely within Frederick County, it flows west of Frederick City and empties into the Potomac River, approximately 58 miles from its source.

The Monocacy River and Aqueduct's historical significance during the Civil War, coupled with the aqueduct's classical architecture, help to preserve the past for future generations.

4.2	Soils and Geology

The two main soil types found in the area of the Monocacy Aqueduct are Huntington and Lindside. Appendix C contains a complete classification of soils by the U.S. Department of Agriculture, Natural Resources Conservation Service.

The soils of the Huntington series are fine-silty, mixed, mesic Fluventic Hapludolls. They are very deep and well drained. They formed in alluvium on flood planes with slopes ranging from zero to 3 percent. Typical pedons of Huntington silt loams, zero to 3 percent slopes, and occasionally flooded, and are about 6 miles west of Poolesville, 0.25 miles north of Whites Ferry, and about 150 feet east of the east bank of the Potomac River. The thickness of the solum ranges from 40 to 70 inches. The content of rock fragments is 0-3 percent in the solum. Chemical reactions range from moderately acidic to mildly alkaline. Huntington soil has the following profile:

0-2 inches: dark brown silt loam, brown dry; moderate medium granular structure; very friable, many roots; many fine interstitial pores; slightly acid, abrupt smooth boundary.

2-12 inches: dark brown silt loam, grayish brown dry; weak thick platy structure; friable; many roots; slightly acid; abrupt smooth boundary.

12-65 inches: brown silt loam; weak medium subangular blocky structure; friable; few fine roots; few faint grayish silt coatings; slightly acid.

The soils of the Lindside series are fine-silty, mixed, mesic Fluvaquatic Eutrochrepts. They are very deep and moderately well drained. They formed in alluvium washed mainly from lime-influenced soils. They are on flood plains with slopes ranging from 0 to 3 percent.

Typical pedons of Lindside silt loam have zero to 3 percent slopes, are occasionally flooded, and are about 5 miles south of Poolesville, and 3,300 feet south on Sycamore Landing Road from its intersection with River Road and 50 feet east. Lindside soil exhibits the following characteristics:

0-3 inches: dark brown silt loam; moderate thin platy structure parting to moderate fine granular; friable; many fine and medium and common coarse roots; many fine interstitial pores; slightly acid; abrupt smooth boundary.

3-9 inches: brown silt loam; common fine distinct strong brown mottles; moderate fine and medium subangular blocky structure parting to weak fine granular; friable; common fine and few medium and coarse roots; many very fine interstitial pores; slightly acid; clear smooth boundary.

9-22 inches: brown silt loam; moderate fine and medium subangular blocky structure; friable; few fine, medium, and coarse roots; many very fine tubular pores; neutral; clear smooth boundary.

22-33 inches: grayish brown silt loam; many fine and medium strong brown mottles; weak medium subangular blocky structure; friable; few fine roots; many very fine tubular pores; neutral; gradual smooth boundary.

33-54 inches: grayish brown silt loam; many medium distinct strong brown mottles; massive; firm; few fine roots; few very fine tubular pores; neutral; gradual wavy boundary.

54-65 inches: grayish brown clay loam; many large distinct strong brown mottles; massive; firm; neutral.

The depth to bedrock is more than 5 feet. The content of rock fragments ranges from 0 to 5 percent within a depth of 40 inches and is as much as 30 percent below that depth. The depth to low-chroma mottles ranges from 14 to 24 inches. Chemical reactions range from strongly acidic to mildly alkaline.

Both the Huntington and Lindside soils series are best suited for cultivated crops. Flooding is a hazard, but is rare during the growing season and seldom affects crops. The soil is soft when wet. Therefore, the use of heavy equipment should be restricted to dry periods. Both soils exhibit the same basic qualities as follows:

Permeability Moderate - Moderately Slow Available Water Capacity High - Very High Flooding Occasional (Dec-Mar) Potential for Frost High

4.3	Natural Growth of Algae and Moss

A light to medium growth of algae and moss was observed on the exterior surface of the stones of the aqueduct walls, which gives a greenish to yellowish look to the covered areas. This is a natural growth of the above organisms under the humid conditions.

Algae and moss, like other plants, take oxygen from the air and by the help of the chlorophyll in their tissue, they make organic food from inorganic material that they absorb from the environment. The waste product from this synthesis is carbon dioxide which is released to the environment. Carbon dioxide combines with the water in the humid environment to form a weak acid called carbonic acid. Carbonic acid can react with the minerals in the stones and slowly erode the rocks and stones in the immediate contact point. Therefore, heavy algal growth and growth of moss may be preceived as hazardous for the attached growth media. However, since this is a very slow process, it can not be considered a serious threat to the walls of the aqueduct and there is no action recommended for this occurrence.

4.4	Water Resources

The Potomac River, where it meets the Monocacy River, is classified as 1P. This classification designates the use as "basic fishable/swimmable water" and "public drinking water supply." The Monocacy River is classified as 4P upstream (above Route 40) and 1P downstream (below Route 40). The 4P designation indicates use as "recreational trout water" and "public drinking supply." The 1P designation is the same as described above.

4.4.1	Water Quality

The Monocacy is the largest Maryland tributary to the Potomac River. It continues south within Frederick County, flows west of Frederick City, and empties into the Potomac River near Dickerson, Maryland, approximately 58 miles from its source. The Monocacy River watershed is a sub-basin of the Middle Potomac River basin. The watershed area, covering 978 miles, is mostly located in the State of Maryland (about 75 percent) and extends as far as Gettysburg, Pennsylvania. Roughly three-quarters of the land in the watershed has been cleared for agriculture and currently supports about 3500 farms, averaging 150 acres each. The remaining land supports forests, the City of Frederick, and growing residential areas.

Sediment continues to be a management problem for the basin. High levels of sediment suspended in surface waters, periodically force the closure of the drinking water supply from the river and create need for additional chemical treatment in drinking water from lower stretches and the Potomac.

Commercial operations involving dairy and animals, coupled with agricultural practices, have degraded both surface and groundwater resources. These practices contribute nutrients, agrichemicals, and sediment to the water. Animal waste and processed water from milking operations produce tons of nitrogen, phosphorus, organic material, and pathogens that affect water quality. Foul odor and taste, the appearances of surface water, and fecal coliform have been persistent problems. Failing septic systems also contribute to nutrient enrichment problems. Pesticide use presents yet another problem for the Monocacy River. Pesticide use has nearly tripled in the U.S. since 1964. As a result of these phenomena, the Maryland Department of Agriculture has targeted the Monocacy watershed as a top water quality management priority. Appendix D contains the National Water Quality Assessment for the Potomac River Basin which includes the Monocacy River.

4.4.2	Wetlands

Small areas of Palustrine forested wetlands exist to the north and south of the aqueduct (Appendix E). The Palustrine environment includes all non-tidal wetlands dominated by trees, scrubs, persistent emergents, emergent mosses or lichen, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5%. It also includes wetlands lacking such vegetation, but with all of the following four characteristics: (1) area less than 8- ha. (20 acres); (2) active wave-formed or bedrock shoreline features lacking; (3) water depth in the deepest part of the basin less than 2 meters at low water; and (4) salinity due to ocean-derived salts less than 0.5%. The wetlands in this area are characterized by broad-leaved deciduous trees that are temporarily and/or seasonally saturated. A report of the National Wetlands Inventory Acreage for Frederick County, Maryland is included in Appendix F.

During the site visit there were no visible signs of wetlands in the immediate area of the aqueduct. Along both sides of the towpath there were signs of some wetland indicator vegetation that appeared to be a remnant of seasonal flooding or a once functioning canal.

Based upon a review of the Department of Housing and Urban Development, Flood Hazard Boundary Map (Appendix G), the project site is located in an area designated as "Zone A." Zone A signifies areas of 100 year flood plain. The aqueduct and the canal have experienced frequent flooding with impacts ranging from minimal to hazardous, to the strcutural integrity of the canal, since the canal was constructed.

4.5	Threatened and Endangered Species

No threatened and endangered species of any kind have been recorded or documented by the State of Maryland Wildlife and Heritage Division for the Monocacy Aqueduct.

At the recommendation of personnel with the Natural Resources Branch of the C&O Canal National Historical Park, The Maryland Department of Natural Resources conducted a survey for the existence of the endangered Brook Floater mussel in Monocacy Aqueduct. A survey was completed on ***; Mr. *** of the Maryland Department of Natural Resources indicates that no endangered mussels have been found within the Monocacy Aqueduct.

4.6	Air Quality

Air quality is monitored by the Maryland Department of the Environment (MDE) through a series of monitors placed throughout the state. These monitors sample the air for a variety of criteria pollutants which include particulate matter (PM10), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), lead (Pb), and nitrogen dioxide (NO2). These critical pollutants are common throughout the United States and can injure health, harm the environment and cause property damage. Ground-level ozone is a major component of urban smog and presents a serious air quality problem in the state of Maryland.

The Frederick County Health Department installed an air monitoring station on Montevue Lane in Frederick Maryland, in 1995. The specific type of monitor used in Frederick is a Special Purpose Monitor System (SPMS). This type of monitor is used by State and local

agencies to fulfill very specific or short-term monitoring goals. The SPMS in Frederick is monitoring for ozone. The monitoring station is north of the project site.

The EPA Green Book, a publication listing currently designated non-attainment areas for all critical pollutants, lists Frederick County, Maryland as a non-attainment area for ozone (Appendix I).

4.7	Socioeconomic/Community/Land Use

Frederick County is Maryland's largest county covering 663 square miles. The County seat intersects five Interstate and National Highways that provide easy access to Baltimore, Washington, D.C., Gettysburg, PA, Harper's Ferry, WV, and Leesburg, VA. It is home to 5,700-acre Catoctin National Park, site of Camp David Presidential Retreat. Frederick County is also Maryland's largest dairy producer, providing one-third of the State's dairy production.

Frederick County's 7000 businesses employ 56,180 workers with approximately 85 of these businesses employing 100 or more people. Manufacturing accounts for 10% of total employment. The County's largest employers include Fort Detrick, State Farm Insurance, Frederick Memorial Hospital and Eastalco Aluminum.

The population count was 175,000 in 1995 and is expected to reach 203,200 by the year 2000, according to the Frederick County Census. The median age is 20-44 and is the largest percentage share by age. The unemployment rate is 3.9% and the estimated labor potential for 1995 was reported to be 61,751. The average household income is $47,137 and the 1993 median household income was $43,113.

There are several major State, Federal and municipal parks and historical and cultural attractions in Frederick County. The county offers a wide variety of recreational activities including fishing, hiking, canoeing, swimming, and a zoological park. A complete listing of socioeconomic/demographic information is presented in Appendix J. This information was obtained through the Maryland Department of Business and Economic Development.

The Frederick County Zoning Commission classifies the area surrounding the Aqueduct as a Resource Conservation Zoning District. This area is zoned to allow low intensity uses and activities which are compatible with the goal of resource conservation within mountain and wooded areas. These areas include rural woodlands, cultural, scenic and recreation resource areas. Environmentally sensitive areas within the resource conservation zone, which includes steep slopes, wetlands and habitats of threatened and endangered species, are protected from development. Appendix K shows the Frederick County Zoning Map for the project site.

4.8	Noise

No data was available regarding noise levels in the immediate area of the proposed project. Based upon conditions present during the October site visit, the ambient noise levels in the area of the aqueduct are very low. The aqueduct is located in a relatively isolated area. Any noise from construction activities should not impact the surrounding community.

4.9	Historical and Cultural Resources

Building of the C&O Canal was one of the most ambitious engineering projects of its time. It was part of an effort to connect the tidal Potomac with the Ohio River at Pittsburgh, a total distance of 360 miles. Unfortunately the canal never made it that far. Construction of the C&O Canal began in the late 1820s and had reached Seneca Creek by 1831, Harper's Ferry by 1833 and Hancock, Maryland by 1839. The final 60 miles to Cumberland took an additional 11 years to build due to the difficulty of constructing the Paw Paw Tunnel. It was not until 1850 that canal boats could traverse the entire 184.5 miles of the canal from Georgetown to Cumberland. The canal raised boats 605 feet via 74 lift locks which lifted canal boats, an average of about eight feet. Eleven aqueducts carried the canal across major tributaries: Seneca Creek, Monocacy River, Catoctin, Antietam, Conococheague, Licking, Tonoloway, Sideling Hill, Fifteen Mile, Town, and Evitts Creeks. The largest of these, the Monocacy Aqueduct, still stands 516 feet long with seven 54-foot arches.

The C&O Canal operated until 1924, but not without its share of construction problems and natural disasters. The first major flood was in 1877 which, combined with the canal boatman's strike, was the canal's first catastrophe. The second devastating flood occurred in 1889 and the financial aftermath caused the C&O Canal Company to go into receivership to the B&O Railroad. In 1892 the canal was finally repaired and back in operation.

In 1902 the Canal Towage Company was established and took charge of the canal. The C&O continued to operate until the catastrophic flood of 1924. Damage from this flood permanently put the canal out of business. In 1938 the Federal Government acquired the canal from the B&O Railroad, dedicated it as a public park and began restoration work.

The floods that plagued the C&O during its operating life continue to affect it. A powerful flood in 1936 submerged the C&O at Shepherdstown, WV under water for 62 hours. The Potomac River's level during this flood was 22 feet above the towpath at Shepherdstown . In 1942, a major flood destroyed previous restoration work. In 1972, Hurricane Agnes inundated the Potomac Valley and set many all-time high water marks along the Potomac. The damage from Agnes took years to repair. Torrential rains along the Potomac's mountain tributaries in 1985 caused another flood to damage the canal. The flood following the blizzard of 1996 further stressed the canal, including the Monocacy Aqueduct. Aerial photographs showed water completely covering the aqueduct and large clumps of trees resting on top of the submerged structure.

Today, the C&O Canal and 20,000 acres of parkland are designated as the C&O National Historic Park (NHP). The C&O NHP extends along the Maryland side of the Potomac for the entire distance. Except for one short stretch between miles 84.4 and 88.1 with a marked detour, the towpath runs the entire 184.5 miles from Georgetown to Cumberland.

In June of 1998, the National Trust for Historic Preservation added the Monocacy Aqueduct to its list of the nation's most endangered historic places.

4.9.1	Construction of the Monocacy Aqueduct, 1829-1833

On August 9, 1828, the C&O Canal Company requested proposals for construction of the Monocacy Aqueduct after acquiring the land to the east and west of the Monocacy River. This purchase gave the C&O Canal Company the "right of way" to the land. Later that month, the contract was awarded to Hovey & Legg for the construction of Aqueduct #2 across the Monocacy River.

Chief Engineer Benjamin Wright "prepared ground plans and elevations of the aqueducts at Seneca Creek and Monocacy River." The original plans read as follows:

...with a water way 19 feet at bottom--20 feet at top. The towpath parapet 8 feet wide and the other wall 6 feet wide. I have drawn the plan to 7 arches of 54 feet span each and 6 piers and two abutments. The piers are 10 feet thick, and a pilaster at each end of the pier projecting one or two feet and seven wide.

Construction of the aqueduct began in mid 1829. Delays plaguing construction included the acquisition of quality materials, availability of workers, delivery of materials, financial resources, weather conditions and changing of contractors. After inspection of Aqueduct #2 in late November of 1829, Chief Engineer Wright reported "Three piers were up to the skewbacks and one other was begun." Accordingly, Wright felt that if the foundation of the six piers was in and the abutments raised to the skewbacks, it would be better than to leave it as it is, because it might be finished during the next season. As it was then, he doubted whether the aqueduct could be completed in one season with economy.

In December of 1829, amidst problems and controversy, Hovey of Hovey & Legg abandoned the contract for Aqueduct #2 and left the work. Later in the same month A.P. Osborn teamed with Legg, proposing to complete the work according to the previous terms and prices. The proposal was accepted with minor changes. Problems with securing quality materials slowed progress once more. On July 7, 1830, Engineer Wright recommended to the board "that the three piers erected for the Aqueduct #2, of sand stone, be taken down, and be rebuilt of the granite from Johnson's quarry." The recommendation was adopted. For unknown reasons, Osborn requested permission to assign his portion of the contract to Byrne & LeBaron of Pennsylvania. One week later, the new contractors asked for an extension of time to complete Aqueduct #2. The date was extended to November 1, 1831.

Although Byrne & LeBaron began work on Aqueduct #2 about September 1, 1830, there is little documentation of their first month of work. Four inches of snow in December and subsequent snows slowed the progress of construction once again. In addition to weather, the condition of roads carrying materials and construction of a temporary railway to help carry materials affected development. In June of 1831, two engineers, by order of the President of the United States, were instructed to examine the canal. The engineers reported favorably on the progress and the integrity of the structure. By November 1831, work on the aqueduct had advanced to the fourth arch, one-fourth of which remained to be finished. The center was in place and work was beginning on the fifth arch. An epidemic of cholera and the upcoming winter's effects on the unfinished structure were of great concern to the contractors and engineers.

1832 was marked by shortages of cement, labor problems and slight modifications to specifications for all of the aqueducts, lock, and culverts of the canal. Finally, construction of the Monocacy Aqueduct was completed in April of 1833. It was watered shortly thereafter.

4.9.2	The Monocacy Aqueduct and the Civil War

The canal played an important role during the Civil War because it lay on the border between Union and Confederate territory. The canal's border position and its status as a major shipping route, made it a prime target for destruction by Confederate troops. The entire canal saw action throughout the Civil War.

Union troops under Brigadier General Charles P. Stone guarded the Potomac downstream from the Monocacy, and Bank's Department of the Shenendoah guarded the river from Monocacy to Shepherdstown. The primary mission of all these troops was to defend against the Confederate Army crossing the Potomac, and protect the C&O Canal.

In early September 1862, General Robert E. Lee wanted to take the war north of the Potomac after defeating Union troops in the Second Battle of Manassas. Major General D.H. Hill approached the Potomac at White's Ford on September 4. This crossing of the Potomac and the nearby Monocacy Aqueduct was guarded by men of the 1st Potomac Home Guard Regiment the 87th Ohio. The Union pickets fled and Hill's combat- ready veterans waded across the Potomac.

Men from General Hill's Confederate division were charged with wrecking key canal structures in the area. The canal was an obstacle to the army and presented a bottleneck for the troops. General Hill had troops wreck and drain the Little Monocacy Culvert. The berm and the towpath banks were cut down, a road of logs built across the waterway, and the artillery and trains moved across.

Thomas Walter, lockkeeper at Lock 27, was a collaborator with the Confederacy during the war, but did save the canal from major damage. Walter pleaded with Hill's troops not to destroy Lock 27 and the Monocacy Aqueduct. He suggested that they cut down the banks between the canal and the river rather than blow up the lock and aqueduct. A heated discussion ensued between the lockkeeper and General Hill. Hill finally consented to the alternate route after discovering that he did not have enough equipment or gun powder to bring down the aqueduct. Since Hill could not ensure the destruction of the aqueduct, he ordered the demolition of Lock 27. The lock was partially destroyed, disrupting canal service but the aqueduct was saved. Hill breached the culvert over Little Monocacy Creek, burned canal boats trapped in the level after draining the canal, recalled his troops and marched northward.

The following year, Major General John Walker's troops again tried to destroy the Monocacy Aqueduct. The intention was to recross the Potomac at Cheek's Ford and occupy Loundon Heights, eliminating the force holding the Harpers Ferry-Martinsburg area. The troops reached the mouth of the Monocacy about midnight and shots were exchanged. Walker organized fatigue details, passed out tools, and gave instructions to drill holes and place charges to blow up the aqueduct. After hours of working with dull drills, the engineer determined that the masonry was "possessed of extraordinary solidity and massiveness." The engineer reported that demolition of the aqueduct would require days not hours. The project was abandoned. The damage incurred by the aqueduct was repaired shortly thereafter.

4.10	Utilities and Services

Electricity is supplied to Frederick County by the Alleghany Power system and the Thurmont Municipal Light Company. Natural gas is supplied by Frederick Gas Company, a division of Washington Gas Light Company. Water service is supplied by 18 County operated plants serving a wide geographical area. The County operates 19 sewage treatment plants. The local telephone carrier for Frederick County is Bell- Atlantic. Detailed information is listed in Appendix J.

4.11	Transportation

Frederick County is serviced by several major highways, rail systems, national, international, and municipal airports and the Port of Baltimore for water travel. More detailed information is offered in Appendix J.

5.0	POTENTIAL ENVIRONMENTAL IMPACTS OF THE PROPOSED PROJECT ACTIVITIES AND ALTERNATIVES

5.1	No Action Alternative

The "No Action" alternative will have an adverse effect on historic and cultural properties. The C&O Canal is a National Landmark of the highest significance. The Monocacy aqueduct, which is the largest of the 11 C&O Canal aqueducts, is considered one of the outstanding historical canals and has been ranked as one of the high priority areas to receive attention for restoration and stabilization by the NPS. "No Action" for restoration and stabilization of this historical and cultural value will result in further deterioration and eventually collapse of the aqueduct structure. This is not consistent with the intent of National Park Service to restore this historical and national value.

The "No Action" alternative will not have an adverse effect on:

Soils and Geology

Water Resources

Endangered & Threatened Species

Air Quality

Socioeconomic/Community/Land Use

Noise

Utilities and Services

Transportation and Parking

5.2	Design Alternatives

Similar environmental impacts will be created by both of the two design alternatives.

5.2.1	Soils and Geology

Both of the design alternatives will have no permanent effects on soils and geology. A temporary effect may be created as a result of possible minor excavations during reconstruction of the damaged pier walls in Alternative 3. During construction, a sediment and erosion control plan may be required.

5.2.2	Water Resources

None of the two design alternatives will have any permanent effects on the Monocacy River. Temporary wooden supports will be installed under the arches, during construction. However, these supports will not alter or block the path of the Monocacy River.

The two design alternatives will have no temporary or permanent effects on the Potomac River.

None of the two design alternatives will have any temporary or permanent effects on wetlands in the area. Executive Order 11990 & DOT Order 5660.1A regarding preservation of the nation's wetlands specifies that repairs and maintenance of an existing facility typically are not considered new construction and therefore not considered a significant impact. Coordination with agencies having jurisdiction and expertise concerning wetlands will occur as required.

Since the Monocacy Aqueduct is an existing structure in a floodplain, according to Executive Order 11988 & DOT Order 5650.2, regarding floodplain management and protection, the proposed activities are not a significant encroachment, and the beneficial values of the floodplain will not be affected.

Removing debris from pier foundations may have a temporary impact on the water quality of the Monocacy River in terms of sediment loading and instantaneous increase in the suspended solids content of the water. However, the impact is not permanent or long term and is not considered a major impact.

Coordination with appropriate agencies (i.e., Maryland Department of the Environment, Department of Transportation, U.S. Army Corps of Engineers) will occur and all applicable permits will be obtained.

5.2.3	Threatened & Endangered Species

Threatened and endangered species of any kind have not been recorded or documented with the State of Maryland Wildlife and Heritage Division for Monocacy Aqueduct. The Marland Department of National Resources has confirmed that the existence of the endangered Brook Floater mussels in Monocacy Aqueduct is unlikely.

5.2.4	Air Quality

None of the two design alternatives will have any permanent effect on regional or local air quality. During the construction phase, small amounts of fugitive dust emissions and vehicle exhaust may occur. Measures should be taken to control and reduce these emissions.

5.2.5	Socioeconomic/Community/Land Use

There may be a small positive impact if the construction contractor hires local workers during the construction phase. Additionally, there may be an increase in tourism that can bring benefits to local businesses.

5.2.6	Noise

The completed project will not increase the existing noise levels. There will be a temporary increase in ambient noise levels during the construction phase. However, the negative impact is not significant.

5.2.7	Historic and Cultural Resources

In Section 4.8, historical resources related to the Monocacy aqueduct are identified. As described earlier, there are numerous historic resources in this area. The proposed project to rehabilitate the Monocacy Aqueduct, will have no effect on historic properties other than the aqueduct itself, the canal prism and the towpath in the immediate project area.

The Advisory Council on Historic Preservation (ACHP) regulations, "Protection of Historic Properties (36 CFR Part 800)" state that "an undertaking has an effect on a historic property when the undertaking may alter characteristics of the property that may qualify the property for inclusion in the National Register. For the purpose of determining effect, alteration to the features of a property's location, setting, or use may be relevant depending on a property's significant characteristics and should be considered."

After a determination is made that a proposed project would affect historic resources, the criteria of adverse effect are applied. "An undertaking is considered to have an adverse effect when the effect on a historic property may diminish the integrity of the property's location, design, setting, materials, workmanship, feeling, or association. Adverse effects on historic properties include, but not limited to:

(1)	Physical destruction, damage, or alteration of all part of the property;

(2)	Isolation of the property form or alteration of the character of the property's	setting when that character contributes to the property's qualification for the	National Register;

(3)	Introduction of visual, audible, or atmospheric elements that are out of character	with the property or alter its setting.

(4)	Neglect of the property resulting in its deterioration or destruction; and

(5)	Transfer, lease, or sale of the property."

Department of the Interior regulations describes the National Register Criteria: The quality of significance in American history, architecture, archeology, engineering, and culture is present in district, sites, buildings, structures, and objects that possess integrity of location, design, setting, materials, workmanship, feeling, and association, and that (a) is associated with events that have made a significant contribution to the broad patterns of our history; or (b) that is associated with the lives of persons significant in our past; or (c) that embodies the distinctive characteristics of a type, period, or method of construction, or that represents the work of a master, or that possesses high artistic values, or that represents a significant distinguishable entity whose components may lack individual distinction; or (d) that has yielded or may be likely to yield information important in history or prehistory.

Alternatives 1 and 2 will preserve the aqueduct and prevent further decline. None of these alternatives will have an adverse effect on the aqueduct, the canal prism, or the tow path, according to the ACHP criteria. The C&O National Historic Park, of which the aqueduct is a part, is of such historic significance that it meets all four of the National Register criteria. The proposed alternatives will not alter any of the characteristics that qualify the historic properties for the National Register. Both Alternatives 1 and 2 will rehabilitate the aqueduct by stabilizing the existing structure and restore or reconstruct damaged pier walls and north abutment wall. The difference between the two design alternatives is basically removal or non-removal of the existing steel banding. In both cases, there will be no negative impact on the historic values of the canal. Implementation of both of the design alternatives will have a beneficial effect on historic resources.

The National Park Service will insure that all rehabilitation activities will be carried out in consultation with the State Historic Preservation Offices (SHPO) at the Maryland Historic Trust and in accordance with the Secretary of Interior's Standards for Rehabilitation. Documentation will be forwarded to the ACHP for review, in accordance with the ACHP's regulations regarding the determination of No Adverse Effect.

Section 4(f) Evaluation- the C&O NHP is a publicly owned park, recreation area and significant historic site. As such, it is protected under Section 4(f) of the National Historic Preservation Act of 1966, as amended. Construction of the two design alternatives will involve only a temporary use of the land. The proposed action meets the following temporary occupancy criteria:

(1)	It will be of short duration.

(2)	It will not change the ownership or result in the retention of long-term indefinite	interests in the land for transportation purposes. The property is owned by the	National Park Service.

(3)	It will not result in any temporary or permanent adverse change to the activities,	features, or attributes which are important to the purposes or functions that qualify	the district for the National Register.

(4)	It will include only a minor amount of land, in comparison to the entire historic	district.

5.2.8	Utilities and Services

All two design alternatives will have no permanent effect on electricity, fuels, water, sewer, or telephone. In time, the NPS plans to develop a lighting plan for the park, including security lighting around visitor facilities.

5.2.9	Transportation and Parking

The project may generate a small increase in the number of vehicles traveling to and parking at the site. However, the traffic or parking impact will be very minor or negligible.

5.3	Summary

This Environmental Assessment evaluates the potential for environmental impacts associated with the restoration of the Monocacy Aqueduct. The proposed action is consistent with the overall C&O Canal preservation, rehabilitation, and reconstruction program to provide a historically accurate setting for interpreting the history of the C&O Canal.

Environmental impacts were evaluated for the following media: soils and geology, water resources, endangered and threatened species, air quality, socioeconomic/ community/land use, noise, historic and cultural properties, utilities and services, and transportation and parking. The findings are as follows:

Soils and Geology- the two design alternatives will have no permanent effect. If excavation is necessary during construction, a sediment and erosion control plan will be developed.

Water Resources- the two design alternatives will have no permanent effect on water resources. There may be a temporary impact during construction and removing debris from pier foundations due to disturbance mixture of sediment and debris with the water.

Endangered and Threatened Species- There is no record of existence of endangered and threatened species in the proposed Monocacy Canal construction and restoration zones.

Air Quality- Both of the design alternatives will have no permanent effect on regional or local air quality.

Socioeconomic/Community/ Land Use- There may be a small positive impact to the local economy if the construction contractor hires local workers. Additionally, there may be a small increase in tourism benefitting the local community.

Noise- There may be a temporary increase in ambient noise levels during construction. The completed project will not increase existing noise levels.

Historic and Cultural properties- Both of the design alternatives will preserve the Aqueduct and prevent further decline. None of these alternatives will have an adverse effect on the Aqueduct, the canal prism, or the tow path, according to the ACHP criteria. The C&O National Historic Park, of which the Monocacy Aqueduct is a part, is of such historic significance that it meets all four of the National Register Criteria. The proposed alternatives will not alter any of the characteristics that qualify the historic properties for the National Register.

Utilities and Services- The two proposed alternatives will have no permanent effect on electricity, fuels, water, sewer, or telephone.

Transportation- The project may generate a small increase in the number of vehicles traveling to and parking at the site.

After evaluating the proposed actions and the potential environmental impacts, it has been determined that there will be no significant negative environmental impacts associated with any of the design alternatives. The preparation of a Finding of No Significant Impact is recommended.

6.0	AGENCIES/PERSONNEL CONSULTED

USDA Natural Resources Conservation Service

92 Thomas Johnson Drive

Suite 230 North Amber

Frederick, MD 21702-4300

Rebecca MacLeod, District Conservationist

301-695-2803

Department of Natural Resources

Wildlife and Heritage Division

580 Taylor Avenue

Annapolis, MD 21401

Mr. Mike Slattery

Frederick County Planning Commission

Winchester Hall

12 East Church Street

Frederick, Maryland 21701

Rick Brace

Development Review Planner

301-694-1143

7.0	REFERENCES

Alliance for the Chesapeake Bay, Inc. 1996. The Monocacy and the Chesapeake Bay. (<http//www.gmu.edu/bios/bay/acb/fact/monocacy.htm>) Accessed October 17, 1997.

Department of Housing and Urban Development, Federal Insurance Administration 1974. Flood Hazard Boundary Map, Poolesville, Maryland (Frederick County).

Environmental Protection Agency (EPA) 1997. EPA Green Book Currently Designated Nonattainment Areas for All Criteria Pollutants Listed by State and County. (<http://www.epa.gov.oar.oaqps/greenbk/ancl.html#MARYLAND>) Accessed November 4, 1997.

Frederick County Maryland. Frederick County Maryland Demographic Data. (<http://econ.co.frederick.md.us/demog/demog2.htm#location>) Accessed October 9, 1997.

Great Outdoor Recreation Pages (GORP). C&O Canal Historical Park - Maryland. (<http://www.gorp.com/resources/us_nhp/md_cando.htm>) Accessed October 17, 1997.

Parsons, John 1981. Chesapeake & Ohio Canal National Historical Park District of Columbia/Maryland General Plan.

Unrau, Harlan 1976. Historic Structure Report The Monocacy Aqueduct Historical Data Chesapeake and Ohio Canal National Historical Park. Denver Service Center Historic Preservation Team, National Park Service, Department of Interior.

USDA Natural Resources Conservation Service 1997. Classification of the Soils of the Monocacy. (Computer printout obtained Oct 20, 1997)

U.S. Department of Interior, Bureau of Reclamation, Memorandum To: Regional manager of Resources & Technical Services, From: Brent H. Carter, USBR Diving Officer and Regional Geologist, Subject: Underwater Examination, Monocacy Aqueduct, 1995.

U.S. Department of Interior, Geological Survey 1988. Topographic Map, Poolesville Quadrangle, 7.5-Minute Series, Scale 1:24 000.

U.S. Fish & Wildlife Service (FWS) 1996. National Wetlands Inventory County Acreage Report for Frederick County, Maryland. (<ftp://www.nwi.fws.gov/acres/md/md021sumtxt>) Accessed October 10, 1997.

U.S. Fish and Wildlife Service. Region 5 Endangered and Threatened Species listed Species by State. (<http://fws.gov/~r9endspp/statl-r5.html#LnkMD>) Accessed October 10, 1997.

U.S. Fish and Wildlife Service 1981. National Wetland Inventory Map. Poolsville Quadrangle.

U.S. Geological Survey (USGS) 1994. National Water Quality Assessment, Potomac River Basin. Contaminants Found During Stream Survey in Potomac Rive Basin. (<http://wwwdmdtws.er.usgs.gov/publications/press_release/pr93051.htm>) Accessed December 4, 1997.

8.0	GLOSSARY

Pedon	The smallest volume that can be called a soil.

Solum	The upper part of a soil profile in which the process of soil formation is active.

9.0	LIST OF ACRONYMS

C&O	Chesapeake and Ohio

EA	Environmental Assessment

MDE	Maryland Department of the Environment

NHP	National Historic Park

NPS	National Park Service

SHA	State Highway Administration

SPMS	Special Purpose Monitor System

USDI	United States Department of Interior