10.2 Soil, Terrain, Drainage, and Groundwater

Quick Answer: Leaching goes down toward groundwater. Runoff goes across the surface to ditches and streams. Coastal Plain sand is a leaching landscape; clay and slope are runoff landscapes. Keep mix/load away from wells, obey label setbacks, and use a backflow device under N.J.A.C. 7:30-10.2(h). Most aquatic-site treatments need a N.J.A.C. 7:30-9.3 permit before the intended date.

40 CFR 171.103(c)(3)(ii) and (iv) require Core knowledge of types of terrain, soil, or other substrate and of drainage patterns. Those words decide whether a legal rate on the label becomes a groundwater case or a fish kill. 40 CFR 171.103(c)(7)(iv) again requires prevention of pesticide loss into the environment — not only aerial drift. New Jersey overlays handling, rinsing, backflow, and aquatic-permit rules that the closed-book exam treats as operational, not optional.

Leaching versus runoff

Leaching is downward movement of pesticide (dissolved or as fine particles) through the soil profile toward groundwater. Runoff is overland flow of water that carries dissolved pesticide, bound particles, or granules into ditches, storm sewers, streams, lakes, or wetlands.

They are not the same exam answer.

Leaching is favored by:

• Coarse, sandy soil with large pores
• Low organic matter (less binding)
• High water solubility of the pesticide
• Persistence (the chemical lasts long enough to travel)
• Heavy rain or irrigation soon after application
• A shallow water table
• Preferential flow down wormholes, cracked clay, or gravel seams

Runoff is favored by:

• Fine texture (silt and clay) or compaction that will not let water infiltrate
• Slope
• Saturated soil
• Bare ground
• Intense rainfall that exceeds infiltration
• Hydrophobic thatch or a surface crust

A pesticide with high Koc (strong soil adsorption) tends to stay put or move with eroded sediment. A pesticide with low Koc and high solubility is a leaching candidate on sand. Those numbers do not appear on every label, but groundwater advisory statements, well setbacks, and “do not apply to sandy soils” statements are the label’s way of telling you the same physics. When the label states them, 10.2(a) makes them mandatory.

New Jersey soils and terrain

New Jersey is not one soil. Treat the state as three working landscapes.

Coastal Plain sand

South and much of central New Jersey sit on the Atlantic Coastal Plain. Soils are often sandy or sandy loam, acidic, and low in organic matter — especially in the Pinelands (Kirkwood–Cohansey sands). Infiltration is high. The water table can be shallow. That combination is a leaching landscape. A soluble insecticide or herbicide applied before a nor’easter on a Cape May, Atlantic, Ocean, or Burlington sand lot can move toward wells and the unconfined aquifer faster than the same product on a clay Piedmont lawn.

Do not treat “it soaked in, so it can’t run off” as a safety conclusion on Coastal Plain sand. Soaking in is how leaching starts.

Clay, slope, and Piedmont/Highlands

The Piedmont (roughly through Mercer, Middlesex, Union, Essex, and adjacent counties) and the Highlands / Ridge and Valley in the north have finer textures, more structure, and, in many sites, real slope. Infiltration can be slow. Intense summer thunderstorms produce runoff into storm sewers and trout streams. Compacted athletic fields and clay construction sites behave the same way even in South Jersey.

Terrain concentrates flow. A swale, curb cut, or tile outlet is a drainage pattern. 40 CFR 171.103(c)(3)(iv) is asking you to see that pattern before you spray. A 3B application that looks on-target on a sloping municipal field will still violate 10.2(c) and 10.2(f) if the first inch of rain carries residue into a feeder stream that was a reasonably foreseeable drainage path. “Other movement” in 10.2(f) is not limited to airborne spray.

Drainage patterns and surface water

Walk the site. Identify:

• Storm drains, yard inlets, and curb openings
• Ditches, swales, and tile outlets
• Streams, ponds, wetlands, and seasonal wet spots
• Downslope wells, cisterns, and neighboring ponds
• Impervious surfaces that shed spray into the street

N.J.A.C. 7:30-10.2(g) forbids cleaning or rinsing containers or application equipment in a manner that causes harm, injury, or damage, or a significant risk of that harm. Rinsing a boom into a storm drain is not “cleaning”; it is a point-source discharge toward surface water. 10.2(d) forbids direct application to a nontarget site — a pond that is not on the label is a nontarget site. 10.2(b) forbids mixing, loading, or handling in a manner that causes harm or a significant risk of harm, which includes concentrate spills on well pads and gravel pits.

If the site is waters of the State or a wetland, you are in aquatic territory.

Aquatic sites and N.J.A.C. 7:30-9.3 permits

N.J.A.C. 7:30-9.3(a) says no person shall apply an aquatic pesticide on any aquatic site without an aquatic pesticide permit from the Department prior to the intended date of application.

NJDEP treats an aquatic pesticide as a product whose labeling indicates it is intended for use on aquatic sites (with listed exceptions). All aquatic pesticides are restricted-use in New Jersey, including copper products. An aquatic site means waters of the State or wetland. Waters of the State include the ocean and its estuaries, springs, streams, and bodies of surface or ground water, natural or artificial, within the State.

9.3(b) lists the permit exceptions. A permit is not required if:

1. The waters are not a potable source, have no outlet, and are bounded by land wholly owned or rented and controlled by one person (a closed ornamental pond on one property is the usual example).
2. The waters are not potable and the application is mosquito or fly control that already needs 7:30-9.2(a) community/areawide approval, or it is made by the appropriate mosquito-extermination lead agency under N.J.S.A. 26:9-1 et seq.
3. The site is a retention basin, a drainage ditch with no water flow, or a similar structure designed to collect water for percolation, not used as potable supply, with no normal outflow into natural waterways.
4. The product is a minimum-risk pesticide exempted under N.J.A.C. 7:30-2.1(m)5.

Everything else that is an aquatic pesticide on an aquatic site needs a permit. Apply on NJDEP forms at least 30 days before the intended date (9.3(c)). Information on the form must be accurate when submitted. The Department may charge a $75.00 fee (9.3(f)). Permits are not transferable (9.3(i)). Fulfill every condition on the permit (9.3(e)). Proposed changes need written Department approval before you apply (9.3(c)4). Records of actual treatment must match Form BPO-03 or, for sodium hypochlorite solution, Form BPO-06 (9.3(j)). Commercial aquatic work is Category 5. A Category 3B turf applicator who “just treats the weeds at the pond edge” with a terrestrial herbicide has both a label problem and a 9.3 problem if the deposit is on an aquatic site.

Wells, setbacks, and backflow

Wells are vertical shortcuts through the soil filter. Mixing, loading, spilling, or applying near a wellhead — especially on Coastal Plain sand — is a groundwater incident waiting for a laboratory result.

There is no single statewide foot-count in N.J.A.C. 7:30-10.2 that replaces the label. The label’s well, sinkhole, and water setbacks are the legal floor. Many product labels prohibit mixing/loading within a stated distance of wells (often on the order of 50 feet or more) and prohibit application within specified distances of wells, sinkholes, or surface water. When the label states a distance, using less is 10.2(a). Adding distance on sand, on gravel seams, or uphill of a well is 10.2(e) reasonable precaution. Do not invent a New Jersey statutory setback and then ignore a stricter label.

Site rules Core expects you to reason with:

• Identify all wells, including unused and abandoned wells, cisterns, and hand pumps, before you mix
• Mix and load so a spill cannot run to the well; never park the nurse tank at the wellhead because the hose is short
• Keep granular pile-ups and rinsate off the well pad
• Treat gravel well pits, dry wells, and sinkholes as direct conduits — they are not “soil”

N.J.A.C. 7:30-10.2(h) is the backflow rule: no person shall add water to pesticide handling, storage, or application equipment via a hose, pump, or other equipment unless that equipment is fitted with an effective valve or device to prevent backflow of pesticides or liquids containing pesticides into water-supply systems, streams, lakes, other sources of water, or other areas. A submerged hose in a spray tank is a back-siphonage setup. When supply pressure drops, tank mix can be pulled into a well, a hydrant, or a creek. Use an air gap, a check valve, or another effective anti-backflow device every time you add water. “I was only filling for a minute” is not an exception. Actual well contamination is not required for the violation.

Termiticide jobs already require a structure diagram that includes wells and drainage (N.J.A.C. 7:30-6.8). That record exists because subsurface termiticide next to a well is a classic contamination path.

Worked New Jersey scenarios

Scenario D — Coastal Plain leach. A 3B crew in Ocean County applies a soluble insecticide to a sandy residential lawn the afternoon before a two-inch rain, 30 feet from a shallow private well, without checking the labeled well setback. The water “disappears” into the sand. That is leaching risk, not proof of safety. Read the label setback; postpone if rain will push residue to the water table; do not treat the well radius as extra turf.

Scenario E — clay runoff. A 6A application on a sloped Union County right-of-way sits on compacted clay. A thunderstorm 40 minutes later carries visible residue to a storm inlet that outfalls to a named stream. Drainage was reasonably foreseeable. 10.2(c) and 10.2(f) apply even if the boom never left the right-of-way.

Scenario F — no backflow device. An operator dunks a garden hose into a tank at a farm hydrant in Cumberland County. The pump cycles off. 10.2(h) is already violated because the hose was not fitted with an effective backflow device.

Scenario G — pond without a permit. A homeowners’ association wants algae in a detention basin that outfalls to a brook treated with a copper aquatic algaecide. The basin has an outlet to a natural waterway and is not a 9.3(b)3 closed percolation structure. 9.3(a) requires a Department permit before the intended date, Category 5 competency, and restricted-use handling. Copper aquatic products are restricted-use in New Jersey.

High-yield traps

• Soaking in on sand is leaching, not “no environmental risk.”
• Label well setbacks beat any unofficial “50-foot rule of thumb.”
• A submerged fill hose without a backflow device violates 10.2(h) immediately.
• A pond with an outlet is not the 9.3(b)1 single-owner closed-water exception.

Official resources

• N.J.A.C. 7:30-10.2 pesticide use and/or application
• N.J.A.C. 7:30-9.3 aquatic pesticide permits
• NJDEP aquatic pesticide permit application and instructions