Timeline of Indian Creek Sediment Pollution Events

December 19, 2007

AWS detects severe sediment pollution in the waters of Northeast Branch, a major tributary of the Anacostia River. Seeking an explanation for the increased turbidity, AWS experts work their way north and east along Northeast Branch and Indian Creek to find the source of the problem (see Photo 1). The search leads to the sand mining operation run by Laurel Sand & Gravel Inc. AWS personnel note the discharge of an excessive amount of turbid water from the site. The pollution event is reported to MDE and the Prince George’s County Department of Environmental Resources (PGDER).

AWS personnel researched rainfall amounts in the Washington, D.C. metropolitan area on December 19 and each of the 5 days prior to their discovery. Table 1 gives the total amount of rainfall measured at Reagan National Airport on each day. Accordingly, it was determined that Indian Creek remained extremely turbid 3 days following the last appreciable rain.

Table 1.
Date	Precipitation at Reagan National Airport (in inches)
Dec. 14	0.00
Dec. 15	0.15
Dec. 16	0.72
Dec. 17	0.00
Dec. 18	0.00
Dec. 19	0.00

December 27, 2007

PGDER concludes a preliminary investigation of the reclamation site and issues a violation (#12-01-004) to the site’s stormwater permit holder, 1325 G Street Associate, LLLP. Under the terms of the violation, the permit holder is ordered to mitigate the existing pollution and prevent additional sediments from entering Indian Creek. In their report, PGDER inspectors note that supervision and enforcement for stormwater control policies at the reclamation site fall under the jurisdiction of MDE’s Minerals, Oils, and Gas Division. The violation is forwarded to that agency pending further action.

January 15, 2007

PGDER re-inspects the reclamation site and concludes that “sediment and erosion devices installed [were secured] per plans and specifi cation” [1]. The inspector emphasizes that re-inspection occurred immediately following a rainfall event.

AWS personnel research rainfall amounts in the Washington, D.C. metropolitan area on January 15 & 16 and each of the 5 days prior to the PGDER re-inspection. Table 2 gives the total amount of rainfall measured at Reagan National Airport on each day. Comparison with total rainfall amounts and timeframes researched during December 2007 (see above) and later in Febrary 2008 (see below) suggests that percipitation volume on and around January 15 was not significant enough to overwhelm stormwater control devices installed at the reclamation site.

Table 2.
Date	Precipitation at Reagan National Airport (in inches)
Jan. 10	0.18
Jan. 11	0.15
Jan. 12	0.0
Jan. 13	0.03
Jan. 14	Trace (<0.1)
Jan. 15	Trace (<0.1)
Jan. 16	0.0

January 24, 2008

MDE inspectors complete their own investigation of the reclamation site. In their report they describe a site undergoing “massive restoration and reclamation” [2]. While the same report acknowledges that a portion of silt fence around a stormwater retention pond has failed, it records
that the site has been maintained without major problems. The inspectors support this claim by noting additional stormwater controls throughout the site that appear to be functioning. Controls specifically mentioned include vegetative stabilization, silt bagging, and ongoing construction at a permanent (though non-functional) stormwater management structure.

February 1, 2008

The Washington, D.C. metropolitan area experiences a relatively heavy rainfall event. Precipitation reaches 2.05 inches. With the threshold for a one-year-storm event in Prince George’s County set at 2.7 inches of rain, this means that an event like the one on Feb. 1 could occur more than once a year.

February 3, 2008

Two days following the storm on Feb. 1, AWS experts note that water in Indian Creek is excessively turbid. AWS personnel track the source of turbidity back to the sand mining reclamation site. Seeking to compare the condition of Indian Creek with conditions on other
Anacostia tributaries, AWS travels to nearby Little Paint Branch. The stream comparison leads to photographic evidence of pollution on Indian Creek due to excessive turbidity (see Figure 1).

Figure 1. Photographic Comparison of Turbidity Levels on Indian Creek and Paint Branch Two Days Following a 2.05" Rainfall Event on February 1, 2008.

February 4, 2008

AWS returns to Indian Creek to confirm that sediment runoff from the reclamation site continues to pose a threat.

AWS personnel report to PGDER and MDE what they now consider an ongoing sediment problem at the reclamation site. PGDER inspectors arrive the same day to investigate the new complaint. They determine that sediment capture devices at the reclamation site—including a silt bag, a stone retaining wall, and several silt fences—have failed to cope with the rainfall delivered by the latest storm (see Photo 5).

February 5, 2008

MDE inspectors visiting the reclamation site confirm the failures noted by PGDER the previous day. The inspectors send notice to the site permit holder indicating that upgrades to all failed stormwater control devices must be undertaken immediately. They recommend that all silt fences on the property be replaced with supersilt fences, and that the toppled retaining wall be rebuilt using a trackhoe machine. Inspectors also announce their intention to discuss application of additional stormwater control measures at the reclamation site, including the use of a flocculent (i.e., a material that will cause sediment suspended in stormwater to aggregate and fall out of solution). Note: The MDE site report from Feb. 5 specifically notes that all control structures listed as failed had appeared on the schedule of sediment and erosion plans approved by MDE and the Prince George’s Soil Conservation District [3].

February 6, 2008

An AWS investigation reveals that excessively turbid water from the reclamation site continues to pollute Indian Creek.

February 12-13, 2008

Rain falls in the metropolitan region once again. Precipitation amounts measure 0.18 inches on the 12th and 1.17 inches on the 13th.

February 15, 2008

Once again, AWS reports excessive turbidity on Indian Creek emanating from the reclamation site. Once again, natural turbidity levels on nearby Little Paint Branch are recorded for comparison (see Figure 10). MDE inspectors announce plans to visit the reclamation site the following week. They note that gypsum may soon be used onsite as a flocculent.

Click here for video footage of sediment-polluted water from Indian Creek mixing with cleaner water from Little Paint Branch. (Filmed: February 15, 2008.)