diff --git a/src/PamguardMVC/PamDataBlock.java b/src/PamguardMVC/PamDataBlock.java
index e0c3b9f7..68a4ab25 100644
--- a/src/PamguardMVC/PamDataBlock.java
+++ b/src/PamguardMVC/PamDataBlock.java
@@ -391,7 +391,7 @@ public class PamDataBlock<Tunit extends PamDataUnit> extends PamObservable {
 			isNetworkReceive = PamController.getInstance().getRunMode() == PamController.RUN_NETWORKRECEIVER;
 
 		if (!isOffline) {
-			t.start();
+			removeTimer.start();
 		}
 	}
 
@@ -469,7 +469,7 @@ public class PamDataBlock<Tunit extends PamDataUnit> extends PamObservable {
 		// }
 	}
 
-	Timer t = new Timer(500, new ActionListener() {
+	Timer removeTimer = new Timer(500, new ActionListener() {
 		public void actionPerformed(ActionEvent evt) {
 			int n;
 			if (shouldDelete()) {
@@ -2413,6 +2413,25 @@ public class PamDataBlock<Tunit extends PamDataUnit> extends PamObservable {
 		return unitClass;
 	}
 
+	/**
+	 * clean up datablock when it's no longer needed
+	 */
+	public void dispose() {
+		stopTimer();
+		clearAll();
+	}
+	
+	/**
+	 * Had some issues with the Timer holding a reference to the underlying PamDataBlock 
+	 * (RoccaContourDataBlock, in this case) and not releasing it for garbage collection.
+	 * Added in this method to force the timer to stop and release it's hold.
+	 */
+	@Override
+	public void stopTimer() {
+		super.stopTimer();
+		removeTimer.stop();
+	}
+
 	public void autoSetDataBlockMixMode() {
 		if (AcousticDataUnit.class.isAssignableFrom(unitClass)) {
 			// System.out.println(unitClass + " is acoustic data" );
diff --git a/src/PamguardMVC/PamObservable.java b/src/PamguardMVC/PamObservable.java
index da6a540b..0d693c99 100644
--- a/src/PamguardMVC/PamObservable.java
+++ b/src/PamguardMVC/PamObservable.java
@@ -93,7 +93,7 @@ public class PamObservable {//extends PanelOverlayDraw {
 		pamObservers = new ArrayList<PamObserver>();
 		instantObservers = new ArrayList<PamObserver>();
 		pamProfiler = PamProfiler.getInstance();
-		t.start();
+		cpuTimer.start();
 	}
 
 	/**
@@ -400,7 +400,7 @@ public class PamObservable {//extends PanelOverlayDraw {
 		}
 	}
 
-	private Timer t = new Timer(4321, new ActionListener() {
+	private Timer cpuTimer = new Timer(4321, new ActionListener() {
 		public void actionPerformed(ActionEvent evt) {
 			long now = System.currentTimeMillis();
 			if (cpuUsage == null) return;
@@ -420,7 +420,7 @@ public class PamObservable {//extends PanelOverlayDraw {
 	 * Added in this method to force the timer to stop and release it's hold.
 	 */
 	public void stopTimer() {
-		t.stop();
+		cpuTimer.stop();
 	}
 
 	public double getCPUPercent(int objectIndex) {
diff --git a/src/rocca/RoccaContourDataBlock.java b/src/rocca/RoccaContourDataBlock.java
index b295088d..1672c93d 100644
--- a/src/rocca/RoccaContourDataBlock.java
+++ b/src/rocca/RoccaContourDataBlock.java
@@ -1574,6 +1574,28 @@ public class RoccaContourDataBlock extends PamDataBlock<RoccaContourDataUnit> {
 	public double[][] getWavInfo() {
 		return wavInfo;
 	}
-	
+
+
+//	int nS, nT;
+//	@Override
+//	protected int removeOldUnitsT(long currentTimeMS) {
+//		// TODO Auto-generated method stub
+//		nT++;
+//		System.out.printf("Enter removeoldUnitsT, entry count %d\n", nT);
+//		int n = super.removeOldUnitsT(currentTimeMS);
+//		nT--;
+//		return n;
+//	}
+//
+//	@Override
+//	protected int removeOldUnitsS(long mastrClockSample) {
+//		// TODO Auto-generated method stub
+//		nS++;
+//		System.out.printf("Enter removeoldUnitsS, entry count %d\n", nS);
+//		int n  = super.removeOldUnitsS(mastrClockSample);
+//		nS--;
+//		return n;
+//	}
+//	
 	
 }
diff --git a/src/rocca/RoccaProcess.java b/src/rocca/RoccaProcess.java
index 71847953..7abe2577 100644
--- a/src/rocca/RoccaProcess.java
+++ b/src/rocca/RoccaProcess.java
@@ -544,7 +544,7 @@ public class RoccaProcess extends PamProcess {
 		        updateSidePanel(rcdb, true);
 		        saveContourStats(rcdb, rcdb.getChannelMap(), numDetections, sNum);
 //		        rcdb.setNaturalLifetimeMillis(0);
-		        rcdb.stopTimer();
+		        rcdb.dispose();
 		        rcdb = null;
 			}