DATE: Tuesday, October 21, 1997             TAG: 9710210010

SECTION: LOCAL                   PAGE: B8   EDITION: FINAL 

TYPE: Opinion

SOURCE: BY GARY SZYMANSKI 

                                            LENGTH:   81 lines

BANKING, BORROWING AND THE GREAT DISMAL SWAMP

Last week celebrated the country's National Wildlife Refuges. It is only proper to examine current trends affecting our local National Wildlife Refuge, the Great Dismal Swamp.

The Swamp has endured change in the past, but the changes it is facing now will have irreversible effects. A sprawling expanse, bordered by rural landscapes and lush farm fields, is under pressure from economic development and suburban growth. The greatest pressure on the swamp exists at its northern reaches in Deep Creek, Bowers Hill and Western Branch, where developable land is scarce and access to infrastructure is growing rapidly. The eastern limits of the Swamp along Highway 17 will also be reworked with construction of a new four-lane connector to North Carolina, and the development that it will attract.

Most of the land adjoining and near the limits of the Great Dismal Swamp is low in relief, the difference between the elevation of the high and low points limited to several feet. As a result, drainage becomes the primary task before new development can ensue. Borrow pits and stormwater ponds are the typical remedy for dewatering a site and for providing a storm water collection point.

Huge borrow areas have been, or will be soon, constructed near the Swamp in Western Branch, Bowers Hill, Deep Creek, the Regional Landfill in Suffolk and along Highway 17 near Dominion Boulevard. They are dug deep, through the organic soils and into underlying strata of sand, which is marketed or used as fill material. Slowly, surface and groundwater migrate out of nearby wetlands and into these pits, where it is quickly evaporated away.

Peat- and humus-rich soils which were formed in the Swamp over thousands of years serve as moisture laden growing medium for the wetland plants which filter runoff and purify surface and groundwater through natural biological processes. An alteration of only a foot or two in the seasonal water table can disturb the balance for existing vegetation and degrade the soil and its ability to support a wetland habitat. After the damage to the wetland is done, the borrow area usually becomes coated with algae, and without sufficient circulation, stagnates, serving limited useful purpose in storm water purification.

Ironically, borrow pits and storm water management ponds have resulted in substantially more wetlands loss in Hampton Roads than filling operations. The collective impact of recent and ongoing borrow sites on the hydrology of the Swamp is not now known; however, the seasonal nature of the wetlands implies a fragile system that will most certainly be affected.

Wetlands banking is also a rather new concept that has implications for the Great Dismal Swamp. Wetlands banking, or swapping wetland area disturbed by development as part of a mitigation strategy, is being proposed in some areas near the Swamp. This concept, when applied to small, isolated pockets of wetland on a predominantly dry piece of land, makes good sense. The banked wetland will be a much larger habitat and, hopefully, a more diverse ecosystem, while allowing the full development of the mitigated property.

The banking process also raises some serious issues to how it would be applied and what its true result will be. Will it allow mitigation of large tracts of natural wetlands within the historical limits of the Swamp? Will it allow the swapping of wetlands in different watersheds, or of differing soil types? Will the banked wetland be easily incorporated into the Swamp, or is its location restrictive to wildlife? The answers to these questions will determine if wetlands banking is a detriment to the Swamp.

Wetlands banking also has the potential to change the basis of wetlands protection from a system based on science and field investigation to a system influenced by who has the ability to pay for banking practiced on less desirable property. It will be interesting to see what will become of these man-made wetlands when development pressure reaches them. Will the ditches be unplugged and some other swamp made? Banking seems to provide substantial reward for shifting wetland locations from economically attractive land to areas that are less valuable; perhaps areas that already lay in a flood plain, or within lands zoned for conservation or agriculture near the Swamp. In which case the swap would be a net loss of nontidal wetlands.

The Great Dismal Swamp forest supplies clean runoff to several tributaries of the Elizabeth River system and the Chesapeake Bay. It feeds the Western Branch at Drum Point Creek, Bailey's Creek and Goose Creek; the Southern Branch at Yadkin Creek, the Spillway at Deep Creek and Mill Creek; and it feeds the Nansemond River at Bennetts Creek. Not to mention the runoff into North Carolina waters.

How development is allowed to continue at the borders of the Swamp may well determine the fate of our National Wildlife Refuge. The time for more local protection and appreciation of the Swamp is long overdue. MEMO: Gary Szymanksi is a civil engineer residing in Chesapeake.

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